THE DEVELOPMENT OF AN ALTERNATIVE BUILDING SYSTEM BASED ON THE USE OF AN EXISTING STANDARDIZED COMPONENT: PRECAST, PRESTRESSED, HOLLOW-CORE CONCRETE SLAB by LASZLO SIMOVIC Bachelor of Architecture, Institute of Technology Illinois (1982) SUBMITTED TO THE DEPARTMENT OF ARCHITECTURE IN PARTIAL FULFILLMENT FOR THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN ARCHITECTURE STUDIES at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY June, © 1984 Laszlo Simovic, 1984 The author hereby grants to M.I.T. permission to reproduce and to distribute publicly copies of this thesis document in whole or in pert. // - n (i Signature of Author aszlo Simovic epartment of Architecture May 11, 1984 -. Certified by........... ....... . L - ; . * 3- Waclaw Zalewski Professor of Structures Thesis Supervisor -- Accepted by N. John Habraken, Chairman Commitee for Graduate Students Departmental MA 5SSACHiUS3ETTT'S INS~ITUTE OF TECHNOLOGY JUN 19 1984 LIBRARIES Room 14-0551 MITLibraies Document Services 77 Massachusetts Avenue Cambridge, MA 02139 Ph: 617.253.2800 Email: docs@mit.edu http://Iibraries.mit.edu/docs DISCLAIMER OF QUALITY Due to the condition of the original material, there are unavoidable flaws in this reproduction. We have made every effort possible to provide you with the best copy available. If you are dissatisfied with this product and find it unusable, please contact Document Services as soon as possible. Thank you. The images contained in this document are of the best quality available. THE DEVELOPMENT OF AN ALTERNATIVE BUILDING SYSTEM BASED ON THE USE OF AN EXISTING STANDARDIZED COMPONENT: PRECAST, PRESTRESSED, HOLLOW-CORE CONCRETE SLAB by LASZLO SIMOVIC Submitted to the Department of Architecture, Massachusetts Institute of Technolog y, on May 11, 1984, in partial fulfillment of the requ irements for the Master of Science in Architecture Studies degree. ABSTRACT The primary of scope implementation for a new this thesis is a conceptual building systems approach. This system is based on a standardized, economically and widely used prefabricated structural component. The type concrete in floor design feasible in question is a precast, prestressed, hol low-core slab, extending it s use from its current application and roof decks to load-bearing wall panels. The system incorporates three additional stuctural members in order to perform autonomously: continuous prefabricated and bolts steel high-strength beams, concrete reinforced prefabricated reinforced concrete support panels. Its application, though primarily directed towards industry, can be utilized in the commercial and areas as well. the housing industrial Thesis Supervisor: Waclaw Zalewski Title: Professor of Structures ii In Commemoration To My Late Grandmother, Marija Simovic lii ACKNOWLEDGEMENTS thanks and foremost, I would like to attribute special First love, their for and Michael Simovic, Eva parents, my to financial their and my wel'l-being, for concerns constant support throughout my educational endeavors, and to my younger my Michael Jr., for his love and for taking care of brother, father in my absence. an Sass, Marton extend my sincere graditude to to I wish and guided influenced, has close friend, who and architect taught me everything I know in the architectural profession to and interests perspective my broadening ultimately date; goals. to thank Magda Sass, also ike I would her for and support, mora interests, perpetual l y shared with me. for h er k indne ss enduring has she a c lose friend, who gave I wish to acknowledge Vaso Bera, have becomming an architect and to whom I of idea the great merr iments in sharing wonderful memories. I would I ike to thank all my colleagues at M.I. T. of source constant and for their friendship architecture. in studies graduate through my me had and Harvard inspiration devoted professor at l.l.T., Erdman I must ack nowledge a truly my min d, induced me to "think" and "penetrated" who Schmocker, to critica Ily analyze my work with a relentless eye. wit I wish to thank Reinhard Goethert alias "Shrimp" for his and humor in making the learning process "a piece of cake" and thoughts his assistance in organizing the contents of my for in a cohesive hierarchy. Wac Iaw Professor advisor, least, to my the not but Last il liant br his with me inspired and has shared who Zalewski, left a undoubtedly has mind remarkable whose and ideas, me. on lasting impression iv TABLE OF CONTENTS ABSTRACT. .............................................. ii ACKNOWLEDGEMENTS.........................................iv 1.0 1.1 1.2 1.3 INTRODUCTION................................ Standardized Prestressed Concrete Components . Manufacturers of Prestressed Concrete Slabs.. Definition of Prestressed Concrete... 2.0 2.1 2.2 2.3 2.4 2.5 REQUIRED STRUCTURAL COMPONENTS. Prestressed ConcreteSlab....... Prestressed Concrete Wall Panel Reinforced Concrete Beam....... Reinforced Concrete Support Pan High-Strength Steel Bolts...... 3.0 3.1 3.2 3.3 3.4 3.5 DETAILED CONSIDERAT IONS.. . . Foundation Details. .0 Wall Details....... . Roof Details....... . Typical Sections... Optional Structural Detai l s 4 .0 4 .1 4 .2 SEQUENCE OF ERECTION..Assembly Method #1.... Assembly Method #2.... 5 .0 5 .1 5 .2 FINISHES.................. Interior.................. Exterior.................. 6 .0 6 .1 6 .2 6 .3 6 .4 6 .5 DESIGN CONSIDERATIONS..... Modules................... Spans/Heights............. Design Restrictions....... Exterior Fennestrations... Applications.............. 7 0 7 1 7 2 ECONOMICS OF SYSTEM....... The Attributes of Precast, Prestressed Economics of This System.. ............ 8.0 EVALUATION .6 -.. .. . . . . . . . . . . . 1 2 6 7 .10 .11 .11 .15 .18 .20 .23 .24 .29 .37 .41 .49 . . . . . . .54 .55 .61 .73 .74 .78 . . . . . Concrete. & CONCLUSION......................... ..... ..... a APPEND IX.................. ..... 0 Milestones of Prestressed Concrete Properties Peculiar to Pre stressed Co n cre t e. ..... 0 Materials of Concrete..... ... ..... 0 Tendons................... .. ... ..... 0 Acoustical Properties..... ... ..... 0 Thermal Properties........ .84 .85 .86 .87 .87 .88 . 98 . 98 1 00 102 04 05 09 11 15 18 27 v Fire Resistance.........................................136 Coordination with Mechanical, Electrical and Other Substems.............................................140 Structural Fasteners.................................. Bibliography.........................................151 vi 1.0 INTRODUCTION I the 1950's, when prestressed concrete was introduced in Since the United States, its milieu had developed into what is now a architectonical of and accepted method acknowledged widely is in the building industry. Its greatest asset construction applications. feasible economically the to contributed virtually been have attributions concrete's Prestressed residential, in: projects encompassing limitless, Its applications. and industrial commercial institutional, and versatile be to proven equally been has relevance to scale flexible. 1.1 STANDARD PRESTRESSED CONCRETE COMPONENTS concrete prestressed standardized of varieties are There Each market. today's in produced mass are that components applications design specific pertains member corresponding section following The limitations. apparent with along an inventory of prestressed concrete components with presents brief overviews of prescribed applications and limitations. 1.1.1 Double Tees a with are a basic floor and roof panel member tees Double long for excellent are They feet. 80 of range span cantilevers. Designed to simplify and speed erection of single and multi-story structures. Double tees create a unique effect when used vertically as exterior wall panels. b-rn13L 1.1.2 Single Tees in are used for floor and roof structural decks tees Single Ily heavy ranging up to 120 feet, or for especia span longer each Normally 8, 10 and 12 feet w ide, requirements. load ing Single ge. covera quick, unit pr ovides large, and consequently mechanical where ceilings, exposed for tees ar e popular cess. When ac easy for stems between channeled be can services for s haped custom be can ends tee single canti lev ered, architec tural treatment. 2 1.1.3 Hollow-Core Slabs Hollow-core slabs find major application in residential, commercial, institutional and industrial structures where flat ceilings are desired. The bottom sides acts as the ceilings; the top side as the floor of the room above. Hollow-core slabs provide an effective barrier to airborne and impact sounds, and their voids can be used to carry mechanical services. They are generally designed for use in shorter spans up to 40 feet. 1.1.4 Channel Slabs Channel slabs provide a very rigid structural member with minimum deflecti on characteristics. T hey are ideal where heavy and roof loads are encountered in short and medium span floor ranges. rC 1.1.5 7HANNEL S LA E JS3S I-Beams I-beams find application general ly as a long-span support extremely heavy loads. Available in spans feet, I-beams serve as the main girder beam-and-deck-systems. beam to to 100 in many 3 1.1.6 Box Beams Box beams are used primarily as girders In heavy-load type large design, the proper mechanical services. 1.1.7 in bridge construction, and also structural framing systems. With various accommodate can voids Inverted T Beams tota I structural and ledger beams reduce T beams Inverted on in a building because deck members can be su pported depth hollow They are generally used with double tees and ledges. core slabs for structural framing. U.'; INVERTED T BEAMS AND LEDGER BEAMS 1.1.8 Piles and Columns Piles are used as foundation supports where poor load-bearing octagonal They are available in square or conditions exist. cylindrical sections, in size s from 10 to 24 inc hes; hollow Precast diameter. in up to 54 inches piles are availab le columns are integra I component of the precast column-beam-deck system which makes rapid installation possible. 4 1.1.9 Wall Panels multi-story panels are used for partial, f ull-story, or Wall use. load-bearing or wal I curtain either for heights sculptured, plain, in le availab are panels wall Customized or exposed aggregate units of almost any size, shape textured for materials insulation They also may include color. or improved thermal characteristics. 1.2 MANUFACTURERS OF PRESTRESSED CONCRETE SLABS prestressed of manufacturers number of major are a There hollow-core concrete slabs throughout the United States, each serving the same function. They are: Flexicore, Spancrete, Spiroll, Dynaspan, Dy-Core and Span Deck. Each manufacturer's product is distinguishable by the different shape of the voids at the center of the slabs, the standard widths in which they are manufactured and the configuration of the profiles. ?iGO.01 Flexicore (1'-4 & 2 -0) Spancrete (3'-4 & 5 -0) 1.0 .0.0.O.O.O0\ Spirolt (4'-0) 0.(0.0.0.0.O.0. Dynaspan (41-0 & 8'-0) Dy-Core (4'-0) Span Deck (4'-0 & 8'-0) 6 1.3 DEFINITION OF PRESTRESSED CONCRETE and structural architectural concrete is an Prestressed material of great strength. Prestressed architectural and concrete units are given predetermined, engineered structural stresses which counteract the stresses that occur when a unit is subjected to loads. This is accomplished by combining two strands and high materials: high tensile steel quality concrete. There are two methods of prestressing high strength tensile steel strands: post-tensioning and pretensioning. prestressed concrete means that the steel Post-tensioning has gained concrete Is placed and after the tensioned specific strength. is a stretched high tensile steel strands are In pretensioning, Concrete abutements at each end of the casting beds. between the strands. As the is then machine extruded to encase the bonds to the tensioned steel. When it sets, concrete strands reaches a specified strength, the tensioned concrete released from the abutements. This stresses the concrete, are built-in tensile putting it under compression and creating strength. Most commonly used prestressed concrete utilizes pretensioning to its adaptibility to mass-production in a plant. This due manufacturing operation takes place in an all-weather enclosed resulting in completely finished prefabricated members plants for ready delivery to the job site. 1.3.1 Ordinary Concrete Beam Even without a load, the ordinary concrete beam must carry own considerable weight - which leaves only a portion of strength available for added loads. its its 7 Under load, cracks. the bottom of the beam will develop hairline 1.3.2 Prestressed Concrete Beam In a prestressed concrete beam, before it leaves the plant, a slight arch is noticeable. Energy is stored in the unit by the a high action of the highly tensioned steel which places An upward the lower porti on of the member. compression in force of is hereby created which in effect relieves the beam having to carry its own weight. The upward force along the load applied to the unit. length of the beam counteracts the 8 fundamental idea of this thesis was initiated by friction The connections -commonly associated with steel connections. It is used to service load transmission by friction through physical are of adjoining surfaces of members after the bolts contact connections Friction-type below). fig. (See pretensioned. a higher factor of safety against slip and thus is most offer suitable when stress reversal or cyclical loading may occur. acknowledged as slabs, concrete hollow-core Prestressed, for primarily position, in a horizontal applied is today, the extracting with eals d thesis roof decks. This and floor existing and slabs from its notorious concrete prestressed wall load-bearing a new and unconventional one: to context components, and non load-bearing wall pane Is. Chapter 2.0 deals with the descri ption of prestressed concrete additional the with along modif ications, its and slabs autonomus an a.chieve to required components structural building-system. 3.0 concentrates on major deta ils/solutions regarding Chapter by means of accomplishing structural integrity of connections the elements in question. Chapter 4.0 explains the chronological sequence of assembly of the structural elements with two examples. 5.0 addresses the selection Chapter interior/exterior applications. of possible the design periphery of explores 6.0 Chapter accompanied with a typ i cal housing application. deals wi t h the economical issues of 7.0 Chapter conventional in relation to comparisions with systems. finishes this for system system this construction Chapter 8.0, a conclusion and future research is drawn, based anay Isis of prestressed hol low-core concrete slabs. on the 9 2.0 REQUIRED STRUCTURAL COMPONENTS 10 The essential components of this system consists of five slabs, elements: prestressed hollow core concrete structural reinforced concrete wall panels, prefabricated prestressed support reinforced concrete concrete beams, prefabricated panels and high-strength steel bolts. 2.1 Prestressed Hollow-Core Concrete Slab A typical cross-section of a prestressed concrete slab that is into either floor or roof decks is shown in Fig. incorporated 1. The holes or voids in the slabs are there to reduce weight of the concrete at the neutral axis. There unnecessary are number of thicknesses available pending on the span and tendons the anticipated service loads. (Note the prestressed at the bottom of the slab). 2.2 Prestressed Concrete Wall Panel Prior to alterating the existing function of prestressed required hollow core concrete slabs, three modifications are 1) the standardized elements. See Fig. 1. They are: to the of prestressed tendons at the "top" of the slabs augmentation the the slabs are casted to secure symetrical forces in when camber any unwarranted (to eliminate tendons prestressed effects), 2) the elimination of two voids near both ends of the slab to permi t maxi mum a -solid section to create compressi on forces (section where prefabricated beams is attached to member) and 3) holes that are drilled t hrough the members (at the solid sections) to allow install ation and permanent positioning of high-strength steel bolts. Holes may either be drilled at the job site or preferably pre- dri I led at the manu facturing plant. The diameter of the holes depends on on the types incorporated bolts that will be of p ending service loads. 2.2.1 Alterred Profile There may be an optional alteration on the profile of the is to shown in Fig. 2. This elements concrete prestressed insure a weather-tight joint especially at the perimeter with form (varies standard doing so, the And in walls. manufacturers) of the concrete dispatch machine would have to profile. be replaced to the new specification of the desired The new form will cost a considerable amount, however, very could on the amount of members extruded, it depending likely off-set the initial investment. Also, the new profile would only be manufactured once. 2.2.2 Solid Prestressed Concrete Wall Panel wa II concrete prestressed trade-off if solid is a There less are used versus the hollow core concrete panels: panels concrete is required to carry virtual ly the same load (thi nner 11 required and fewer prestressed tendons are wall th ickness), of center the in juxtapositioned they can be idealily because the wal I panels. ( see Fig. 2). Typical Voids Prestressed Tendons at Bottom Onlyr PRESTRESSED CONCRETE FLOOR SLAB Eliminate Voids When Casting. I Hole Pre-Drilled for Structural Steel Bolt Optional Hole for Added Support Prestressed Tendons at Top & Bottom I .00. * .I S H_ (N Io 0 % PRESTRESSED CONCRETE WALL PANEL TYPICAL PRESTRESSED CONCRETE COMPONENTS Fig. 1 12 Hole Pre-drilled for Structural Steel Bolt .Prestressed Tendons at Top & Bottom Cont. Neoprene Strip PRESTRESSED CONCRETE WALL PANEL Modified Profile Prestressed Tendons Located Center of Panel Hole Pre-drilled for Structural Steel Bolt Cont. Neoprene S' p C;J 0 * Ti II II I I SOLID PRESTRESSED CONCRETE WALL PANEL PRESTRESSED CONCRETE WALL PANELS Fig. 2 13 2.2.3 Exsiting Prestressed Concrete Wall Panels concrete manufacturers have produced a prestressed Spancrete load-bearing wall panel system deriving from prestressed concrete slab production as shown below. system of panels ascertain exactly the same principal or This restriction: of this thesis but it has one inherent concept they are limited to one-story height intervals. The decking system bears directly on top of the wall panels at panels Interval, with the proceeding wall each floor positioned on top of the decking system aligning directly over the preceding lower wall panels. joints is by exposed reinforcing bars in the connection The creates is grouted afterwards. This type of connection that the problem of lateral rigidity after a certain height. It is interesting to note the various profiles designed in the panels to meet certain conditions including an interlocking system, butt joints and a mitered corner condition. MITERED CORNER A-Max. 45P 14 2.3 Reinforced Concrete Beam A vital component of this system is the prefabricated concrete following performs the which 3) Fig. in (shown beams functions: prestressed concrete 1) Provides a temporary bracing for wall panels at the initial stages of erection. panels when 2) Aligns prestressed concrete wall positioned in place. 3) Creates a ledge or bearing support for prestressed concrete floor slabs. 4) Increases overall lateral rigidity. The design parameters for the beams are: function of anticipated or 1) The sizes of beams vary as a surface area for the required the and loads service prescribed appropriate friction connection. with 2) Holes are to be drilled through the beams to align with and panels wall concrete prestressed the in holes in for recessing boltheads and nuts provided countersinking concrete beams. (Grouted afterwards for waterproofing and the to prevent loosening of the connection). with 3) Concrete beams are to be continuous to correspond may (Beams of the total load-bearing wall length. width the in restrictions length to due segmented be to have transportation). structural 4) The concrete beams may be designed in three rebars, ordinary using concrete reinforced mediums: steel tensile high prestressed using concrete high-strength steel tensile high using concrete post-tensioned and strands, cables applied and tensioned after beam is postioned in place. and segmented, be are required to beams concrete the If decided is the type of structural medium that on depending to are four connections that are valid in order there upon, are: They 4. Fig. of the beams, shown in continuity achieve steel implanted with connection welded connection, bolt and dowels steel with (not shown in dia.), connection anchors above. post-tensioning method as described 2.3.1 Steel Angle, may also be used to serve the same angles Steel (see Fig. 3). Listed below are beam concrete the advantages and disadvantages. function as the some of Advantages Takes up less space. Readilt available. Easily concealed for interior finishes. Compatable with corrigated sheet metal and/or steel bar 15 joists for decking. Elimination of follow-up grouting as beams to conceal boltheads and nuts. in the case of concrete D isadvantages Needs Fireproofing. -Hole Pre-drilled for Structural Steel Bol-t STEEL ANGLE Varies Hole Pre-drilled for Structural Steel- Bol- Countersinking for Grouting U) ci) PREFABRICATED CONCRETE L Cu Varies TYPICAL CONTINUOUS STRUCTURAL BEAMS Fig. 3 16 Grouted Plugs for Bol ts Corr idor /-Steel 0 0 0 DoweI--- U Reinforced Concrete Beam Cori-idor Bolted (--Support Panel Beyond4 Prestressed Concrete Beam Corr idor 4-Conc. Wa I Beyond -*I Post-Tensioned Beam CONNECTION OF PREFABRICATED REINFORCED CONCRETE BEAMS Fig. 4 17 2.4 Reinforced Concrete Support Panel be to support panels are required concrete The re inforced with requirements to specification according prefabr icated the of application. The height construction each s pecific vary may panel may vary according to floor heights, thickness wall the thickness of the prestressed concrete on dependi ng vary may panel the of top the at ledge panel s, the and See beam. concrete the of depth the height and to accordi ng Fig. 5. concrete reinforced function of the prefabricated sole The continuous the for panel support a literally is panel support and tentative It serves consecutively as a beams. concrete at member termination the also is It support. permanent wall load-bearing concrete the prestressed of end either system. system is very crutial in the economy of the component This for waiting no is erection in t hat there during especially are they until beams concrete to position and hold the cranes valuable and place which may take up substancial in bolted erection of sequence the ates initi component this Also, time. is the only member that requ ires temporary bracing at the and prestressed construction until the first series of of onset place wall panels and floor s labs are positioned in concrete and grouted. positioned is panel suppor t concrete reinforced The to the bearing wal Is and the concrete beams. It perpendicular is also stacked on top of each of her with steel dowels or pins and grouted for alignment. there are two, three or four support panels Normal ly depending on the length of the load-bearing walls. required 18 r Steel Dowel for Alignment & Placement of Upper Panel0) 00 7 -Width of Conc. Beam Hole for Temporary Bolting of Concrete Beam -Width of Adjacent Prestressed Concrete Wall Panels -Width of Conc. Beam 4-, 0 C a) 0. Width of Adjacent Prestressed Concrete Wa Panels I Female Connection for Support Panel Below - TYPICAL'SUPPORT PANEL FOR CONCRETE BEAMS Fig. 5 19 2.5 High-Strength Steel Bolts The final structural component; the key element that makes steel system autonomous, is the high-strength this building bolts. Its only function is to fasten the concrete beams to the prestressed concrete wall panels to create a friction-type connection. Three types of bolts are applicable to this system: steel hexagon head bolts, hi gh-strength steel high-strength interference-body bolts, and the Huckbolt, (manufactured by the Huck Bolt Company). 2.5.1 Hexagon Head Bolts designed by basic types of high-strength bolts are The two hexagon-head heavy A325 and A490. These bolts are ASTM as (See Fig. 6 hexagon nuts. semifinished used with bolts, carbon steel A325 bolts are of heat-treated medium below). having an approximate yield strength of 81 to 92 ksi depending on diameter. A490 bolts are also heat-treated bu t are of alloy steel having an approximate yield strength of 1 15 to 130 ksi nuts can be the Bolting of on diameter. also depending or with tightened either by turn-of-the-nut technique an impact wrench. High-Strength Interference-Body Bolt High-Strength Hexagon Head Bolt Fig. 2.5.2 6 Interference-Body Bolts bolts have a rounded head and raised that has ribs These serrati ons around the shank as well as parral lel to the shank. The act ual diameter of a given size of ribbed bolt i s slightly larger than the hole into which it is driven. (See F ig. 6). In driving a ribbed bolt, the bolt actually cuts into the edges and then around producing a relatively tight fit the hole bo Ited as mentioned above. The is interference-body bolt avai lab le in A325 and A490 characteristics. 20 2.5.3 Huckbolt A325 and also meeting ASTM Specifications of The Huckbolt, specific are cut to exact final length required by its A490, position in the design. One end of the bolt has a formed head; coarse end is equiped with two concentric annular other the inserted fine grooves, as shown in Fig. 7. The bolts are and of the designed holes which have been cased in both through the concrete beams and through the prestressed concrete wall bolt A metal lock colar is Inserted by hand over the panels. end and around the finer annular grooves. A specific hydralic machine tool then tightly clamps around the courser grooves at the end and stresses the bolt to approximately 70 per cent of is stress strength. Just before this point of its ultimate reached, the tool clamps around the collar, swaging this into position on the finer grooves, to hold the stress in the bolt. stress is increased As soon as the swaging is done, the to break off the bolt end at a deep grooved section slightly, formed in the bolt just in front of the swaged lock collar. Installation techniques are shown in Fig. 8. oCob0y1 Fig. 7 21 Fig. 8 2.5.4 Washers Washers are required for any of the bolts mentioned above. They should be oversized to assist transmission of compressive forces from the bolts to the concrete beams or steel angles. strength and structural also have sufficient They should applied on both the nut-side and bolt-side. 22 3.0 DETAILED CONSIDERATIONS 23 3.1 Foundation Details Fig. 9 & 10 are detail connections of wall panels to the direct bearing of wall. They both deal with foundation of poured-in-place wall panels on top prestressed concrete concrete foundation walls with variations of exterior surfaces or finishes. The first detail is exposed concrete wall panels and the second is with an added exterior cladding. The latter two details (Fig. 11 & 12) involves bearing of wall thereby footing, concrete on top of the dirrectly panels eliminating costly formwork, labor and pouring of transported concrete - a substantial savings both in time and labor. Note: extra precautions should be taken when grouting joints particularly of all wall members and thourough waterproofing for basement applications. 24 V Poured-in-Place Conc. Slab - Weld Angle 2"x0'-4 Cast into Panel Prestressed Concrete Wall Panels (Exposed) I Cont. Weld Plates Anchored to Fndn Wall 11 r 3" Min 1" Grout, Shim & Caulk \I- 0 2" Rigid Insulation Cont. #5 Rebars at Top & Bottom (- Poured-in-Place Conc. Foundation Wall TYPICAL CONNECTION OF WALL PANELS TO FOUNDATION WALL (Exposed Wall Panels) Fig. 9 25 Poured-in-Place Conc. Slab I Prestressed Concrete Wall Panels Weld Angle 2"xO'-4 Cast into Panel I'- Cont. Weld Plates Anchored to Fndn Wall Exterior Cladding 1" Grout, Shim-& Caulk 1" Max. a; Grade 0 2" Rigid Insulation Cont. #5 Rebars at Top & Bottom 0 I (- Poured-in-Place Conc. Foundation Wall TYPICAL CONNECTION OF WALL PANELS TO FOUNDATION WALL (With Exterior Cladding) Fig. 10 26 Poured-in-Place Conc. Slab Prestressed Concrete Wall Panel (Exposed) Grade Provide Waterproofing 2" Rigid Insulation-, - Panels Shimmed & Grouted Cont. Groove in Footing Furnished to Line & Grade 3" Min. Concrete Footing TYPICAL CONNECTION OF WALL PANELS TO FOOTING (Slab-on-Grade) Fig. 11 27 Grouted Joint Concrete Topp (Optional) 14-Exterior Cladding 1~ / - - mi m - / / / d . --- #3 Rebar Grouted into Keyways I -High-Strength Steel Bolts -Prestressed Concrete Floor Slab Grouted Fill Cont. Concrete Beam BASEMENT Provide Waterproofing _---#3 Rebar Grouted into Keyways and/or Voids in Panels Cont. Groove in Footing Furnished to Line & Grade Panels Shimmed & Grouted Concrete Footing -- TYPICAL CONNECTION OF WALL PANELS TO FOOTING (With Basement) Fig. 12 28 3.2 Wall Details of of the fol lowing details are load-bearing connections All concrete prestressed wall panels with concrete prestressed floor slabs. pane Is The first detail (Fig. 13) dea Is with continuous wall of connecti on the showing lengths) floor five to (two conti nuous concrete beams with the floor slabs. panel wall non-continuous detail showing a a Fig. 14 is vertical continuity is achieved. connections. This is where a typical plumbing chase detail is 15 Fig. water lines and other me chanical par stacks, and econom ically withi feasibly intergrated can be achieved without unnecessa ry drilling slabs by simply eliminating portions of between the concrete beams. soil how shows be aphenalia can It n the system. through the floor panels wall the The following four details (Fig. 16, 17, 18 & 19) concentrates s labs, addressing connections w ith floor wall exterior on alternative exterior and interior finishes. ( Descr ibed in more detail in Chapter 6.) 29 Prestressed Conc. Wall Panels Grouted Joint Prestressed Conc. Floor Slabs #3 Rebar Grouted into Keyways Concrete Topping (Optional) 1" Min. --- - minim m / 7 / I- 1/8"x3" Hardboard Brg. Strip High-Strength Steel Bolts Grout Fill Cont. Conc. Beam SECTION A-A on Page 91 TYPICAL CONCRETE CONNECTION OF FLOOR SLABS TO LOAD-BEARING WALL PANELS (CONTINOUS) Fig. 13 30 Prestressed Conc. Wall Panels Grouted Joint Prestressed Conc. Floor Slabs #3 Rebar Grouted into Keyways Concrete Topping (Optional) m r. -own- m m /. 1/8"x3" Hardboard Brg. Strip H igh-Strength Steel Bolts Grout Fill Cont. Conc. Beam SECTION A-A on Page9l TYPICAL CONCRETE CONNECTION OF FLOOR SLABS TO LOAD-BEARING WALL PANELS (NON-CONTINUOUS) Fig. 14 31 Grouted Joint After Plumbing Installation -Concrete Topping (Optional) -Prestressed Conc. Floor Slabs Space for Plumbing Chase -Cont. Conc. Beam (Prestressed Conc. Wall Panel Beyond SECTION B-B on Page9l TYPICAL PLUMBING CHASE Fig. 15 32 1" Min. Exposed Prestressed Conc. Wall Panels SECT ION C-C on Page 91 TYPICAL CONCRETE CONNECTION OF FLOOR SLABS TO EXPOSED LOAD-BEARING WALL PANELS (CONTINUOUS) Fig. 16 33 Metal Studs with Batt Insul. Textured Plywood (Board on Batten, Beveled Siding, Tongue & Groove Planking, etc.) m - - m / - 111' -Cont. Conc. Beam Grout Filled Metal Studs with Batt Insul. -Stucco Finish SECTION C-C on Page 91 OPTIONAL EXTERIOR FINISH (Wood, Stucco) Fig. 17 34 Rigid Insul. Face Brick ------ 7--m - / - -Cont. Conc. Beam Grout Filled Concrete Block -Rigid Insul. SECTION C-C on Page 91 OPTIONAL EXTERIOR FINISH (Brick, Concrete Block) Fig. 18 35 Exposed Prestressed Conc. Wall Panels Grout Filled .Metal Studs With Batt Insul. -Gypsum Board Finish SECTION C-C on Page 91 OPTIONAL EXTERIOR FINISH (Exposed Concrete) Fig. 19 36 3.3 Roof Details The first detail (Fig. 20) shows a typical parapet with an alternative stone or sheet metal coping. Fig. 21 is a typical The following roof. condition roof detail. detail (Fig. 22) shows a typical cantilevered 37 Alt. Stone Coping Sheet Metal Coping. Wood Blocking 3/8"x8" Anchor Bolt Grouted into Keyway 3" Min. Wood Cant Built-up Roofing over Rigid Insul.- 1 Exterior Cladding Prestressed Conc. Wall Panels Rigid Insul. #3 Rebar Grouted into Keyways Prestressed Conc. Roof Slabs 1/8"x3" Hardboard Brg. Strip High-Strength Steel Bolts Grout Filled Cont. Conc. Beam TYPICAL PARAPET WALL DETAIL Fig. 20 38 Built-up Roofing over Rigid Insul. Sheet Metal Gravel Stop Wood Blocking 3/81"x8"1 Anchor Bolt Grouted into Keyway Rigid Insul. #3 Rebar Grouted into Keyways High-Strength Steel Bolts Grout Filled Cont. Conc. Beam Exterior Cladding Prestressed Conc. Wall Panels TYPICAL ROOF DETAIL Fig. 21 39 Sheet Metal Fascia-d High-Strength Steel Bolts Grout Filled Cont. Conc. Beam - Exterior Cladding Prestressed Conc. Wall Panels #3 Rebar Grouted into Keyways TYPICAL CANTILEVERED ROOF DETAIL Fig. 22 40 3.4 Typical Sections is a section through the The first detail (Fig. 23) prestressed concrete floor slabs with the prestressed concrete wall panels, continuous concrete beams and bolt connections in e levation. The next detail (Fig. 24) is a section through the prestressed concrete panels looking down towards the prestressed wall concrete floor slabs and the continuous concrete beams below the floor slabs (dotted line). section through the The (Fig. 25) is a following detail at the concrete support panels and wall concrete ressed prest pane I that supports the continuous con crete beam. f Ioor is a section through the prestressed concrete 26 Fig. corr idor at the concrete beams the continuous and slabs the at and panel support concrete the towards looking prestressed concrete wall panels. showing Fig. 27 is a transverse section through the corr idor the prestressed concrete floor slabs, non load-bearing and the panels prefabricated wall concrete prestressed segmented concrete beam used for lateral support. corridor the also a transverse section through Fig. 28 is show i ng the prestressed concrete floor slabs, non load-bearing wa I I panels using typical concrete beam for lateral support. Fig. concrete wa I I is a section through the prestressed 29 the the concrete support panel at the exterior of panel and bu i Id ing. 41 41 Prestressed Concrete Wall Panels Beyond 11 Concrete Topping (Optional) #3 Rebar Grouted into KEYWAY prestressed Concrete Floor Slab Prestressed Tendons QQ~rJOOQI lu.. Cont. Concrete Beam High-Strength Steel Bolts SECTION D-D on Page 91 SECTION THROUGH FLOOR SLABS Fig. 23 42 1' - m - - Grouted Vert. Keyw ay Prestressed Conc. Wall Panel Prestressed Tendon Grouted Joint High-Strength Steel Bolt F - 1 #3 Rebar Grouted nto Keyway K ED 1" Min. Width of Conc. Beam (Below Slab) (-Prestressed Conc. * Floor Slab - DETAIL E on Page 91 SECTION THROUGH LOAD-BEARING WALL PANELS Fig. 24 43 CORRIDOR I LI I V _ Grouted Joint (-Prestressed Conc. Floor Slab-) Cont. Conc. (Below Slab) Prestressed Conc. Wall Panel (Non Load-Bearing) )7 o00oDoY. I i I I 7I I~ I I I I I I I I I Conc. Support Panel Grouted Vert. Keyway Prestressed Conc. Wall Panel (Load-Bearing) Prestressed Tendon -Grouted Joint ---High-Strength Steel Bolt 1" Min. Width of Conc. Beam (Below Slab) (-Prestressed Conc. Floor Slab--k ' D -TAIL F on Page 91 SECTION THROUGH WALL PANELS AT CORRIDOR Fig. 25 44 -- 1" Min. i- '~ Prestressed Conc. Floor Slab Grouted Joint #3 Rebar Grouted into Keyway -Conc. Topping (*Optional) S- ~ 04101 7- --- / m m \ - -- m I, / 1/8"x3" Hardboard Brg. Strip Cont. Conc. Beam Prestressed Conc. Wall Panels Beyond Conc. Support Panel Beyond SECTION G-G on Page 91 SECTION THROUGH FLOOR SLABS AT CORRIDOR 26 F ig. 45 CORRIDOR - - ] I t- I _ Prestressed Conc. Wall Panel Conc. Topping (Optional) Prefab. Conc. Beam Bracing (Resting on Top of Cont. Beam Beyond) Prestressed Conc. Floor Slab .o.Q.&0000000 _ . I I -I- --1I 1 I I I I I I I I I I I I I I I I I I ____ ' Butt Joint Prestressed Conc. Wall Panel Beyond Post-Tensioned Tendons Cont. Conc. Beam Beyond I A I I I I I SECTION H-H on Page 91 SECTION THROUGH FLOOR SLABS AT CORRIDOR (Optional Concrete Beam Bracing) Fig. 27 46 CORRIDOR - Prestressed Conc. WalI Panel Grouted Joint Conc. Topping (Optional) Prestressed Conc. Floor Slab Post-Tensioned Tendons I I I I I I 0o0*000 SooiO.Q00(o 0 1 I I I I I Butt JointCont. Conc. Beam Beyond Intermediary Conc. Beam Bracing High-Strength Steel Bolt Prestressed Conc. Wall Panel Beyond 0 SECTION H-H on Page 91 SECTION THROUGH FLOOR SLABS AT CORRIDOR (Optional Concrete Beam Bracing) Fig. 28 47 EXTERIOR Optional Prestressed Conc. Wall Panel (Non Load-Bearing)-7 Conc. Support Panel Grouted Vert. Keyway - --. ---- Prestres sed Tendon Grouted Joint High-Strength Steel Bo it 1" Min. Width of Conc. Beam (Below Slab) T Prestres sed Conc. Floor Sl Bb Cont. Co nc. (Below S lab) Prestres sed Conc. Wall Pan (Load-Be aring) DETA IL J on Page 91 SECTION THROUGH LOAD-BEARING WALL AT EXTERIOR WALL Fig. 29 43 3.5 Optional Structural Members substituding Fig. 30 shows an alternative structural medium reinforced prestressed continuous the for a ngles steel concrete wall panels. prestressed non -conti nuous shows the connection of 31 Fig. and guide a as beams flange wide using paneIs concrete either the panels with we Ided stee I angles on of connection side. Fig. wall of prestressed 32 shows an exterior condition panels using structural T's and a steel plate. final detail The concrete beam. (Fig. 33) shows an alternative concrete prefabricated Prestressed Conc. Wall Panel Grouted Joint .1 #3 Rebar Grou ted into Keyway Prestressed Conc. Floor Slab 2 1/2" Min. Concrete Topp ing (Optional) 7-li at... - - High-Strength Steel Bolts 1/8"x3" Hardboard Brg. Strip Cont. SECTION Steel Angle A-A on Page9l TYPICAL STEEL CONNECTION OF FLOOR SLABS TO LOAD-BEARING WALL PANELS (CONT.) Fig. 30 50 Prestressed Conc. Wall Panel Grouted Joint #3 Rebar Grouted into Keyway Prestressed Conc. Floor Slab 2 1/2" Min. - - - - -Concrete Topping (Optional) - / / I -{- 1/8"tx3" Hardboard Brg. Strip - Cont. Steel Angle Welded to Wide Flange - Cont. Steel Wide Flange NOTE: Provide Holes for Rebars SECTION A-A on Page 91 TYPICAL STEEL CONNECTION OF FLOOR SLABS TO LOAD-BEARING WALL PANELS (NON-CONT.) Fig. 31 51 Prestressed Conc. Wall Panel 4F Exterior Cladding Prestressed Conc Floor Slab #3 Rebar Grouted into Keyway 2 1/2" Min. Conc. Topping (Optional) '-I U -0 Elm Sq. Steel Plate High-Strength Steel Bolts Grouted Joint 1/8"1x3" Hardboard Brg. Strip Cont. Steel T with Welded Webs SECTION C-C on Page9l TYPICAL STEEL CONNECTION OF FLOOR SLABS TO LOAD-BEARING WALL PANELS (CONT.) WITH EXTERIOR CLADDING Fig. 32 52 Exterior Cladding Prestressed Conc. Wall Panel Prestressed Conc Floor Slab " min. Conc. Topping (Optional)- ---- 7- m umin~ -p 1~ / -'I_ Grouted Joint 1/8"x3" Ha Brg. Strip High7Strength Steel Bolts Cont. Conc. Beam #3 Rebar Grouted into Keyway SECT ION C-C on Page 91 TYPICAL CONCRETE CONNECTION OF FLOOR SLABS TO LOAD-BEARING WALL PANELS (CONT.) WITH EXTERIOR CLADDING Fig. 33 53 4.0 SEQUENCE OF ERECTION 54 There are two methods of assembling the prestressed concrete Both of which one is more econom i cally feasib le. components descriptions of assembly procedures will be described starting with the initial development. For both cases, The assumptions is that the foundation walls, the footings of the foundation (two options of support for or the prestressed concrete wall panels) have been casted and sequential the have reached sufficient strength to proceed erection process of construction. 4.1 Assembly Method #1 is appling the initial development the method This concept at a rudimentary basis. The method a pparently had some erection resulted in revamping the order of which drawbacks member , structural additonal an with and prefabricted a concrete support wall. This is described in more detail in the second method of assemby. There are four procedures or steps one floor height. Step that completes a cycle or 1 The setting of prestressed concrete wall panels preferab hand Iing high (for quick, easy length of one story grouted bracing) on top of the foundation walIs and for bracing is requi red staggered format. Temporary member. l y at and in a each 55 Step 2 Lifting of prefabricated concrete beams on either side of the prestressed concrete wall panels and held in place until high-strength steel bolts are positioned and bolted. Procedure are the same for each load bearing wall. Note: two cranes is required simultaneously. STEP 3 Reinforcing Placing of the prestressed concrete floor slabs. grouted. are positioned between every keyway a nd steel bars its bracing may be removed after grout has reached Temporary subsequent yield strength. 56 Step 4 Positioning of corresponding prestressed concrete wall panels, also in a staggered format to infill initial voids developed Height may at ground level and to give additional support. only to desired lengths (limitations vary according to additional though restrictions conventional transportation temporary bracing may be required if members are too high). concrete wal I Note: the bolts of the adjacent prestressed slide may have to be loosened to allow wall panels to panels level concrete beams. Grouting may proceed at ground between between vertical keyways. Step 5 Same as step 2 57 Step 6 Same as step 3 Step 7 Same as step 4 58 Step 8 wall panels (non concrete prestressed of Placement slots or slipped through continous are that load-bearing) between prestressed concrete fl oor slabs to create a spacings sheer wall for lateral rigidity. Grout al I vertical keyways. of wall is conviently located on adjacent sides Note: sheer central corridor. Step ~9 Same as step 2 59 Step 10 Same as step 3 60 4.2 Assembly Method #2 This is the subsequent method method. assembly preceeding are: an additional structural support panels) and concrete of erection. Step due to some imperfections of the two the The difference between member (prefabricated continuous a switch in the sequencial steps 1 The prefabricated concrete support panels are placed on top of The braced. grouted and temporarily walls, foundation the forthcomming the to perpendicular placed are panels anticipated the of ends both at panels, load-bearing load-bearing walIs and at the shear walIs as shown. this in is a substancial reduction of bracings there Note: procedure. Step 2 desi gned the concrete beam i s hoisted on prefabricated The the w panels ( ith only of the s upport side one on ledges into and exception of end walls), and bolted through the beams the panels. in cranes are not required and there is a savings two Note: rete conc the s supporting panel the support having by time the eliminating valuable ti me consumed by holding and beams method. assembly first the in as beams by the crane Step 3 a in panels wall concrete prestressed of placement The order on top of the foundation walls (or footings) sequencial and grouted. The concrete beam acts as a temporary support for panels and eventually a permanent connection. The lengths the the panels may be of longer lengths and should vary in one of the of that are staggered at the top ends increments story continues construction when panels to add support and rigidity in height at the following stages of erection. wall concrete of staggaring the prestressed need No Note: lengths. longer of panels, and panels are Step 4 The corresponding concrete beam is placed on the opposite side of the prestressed concrete wall panels and onto the ledges of the support panels. order sequential a may proceed in procedures bolting The throughout the length of the load-bearing walIs. Step5 Placing of prestressed concrete floor slabs. Reinforcing steel bl bars beam are inserted between every keyway and grouted. is introduced to give lateral support. Concrete are the five procedures or steps that completes a cycle These or one floor height. Step 6 Same as step 2 and 4 Step 7 the step of placing Same as step 5 with the additional concrete wall panels (non load-bearing) on either prestressed side of the central corridor which acts as a shear wall as in the previous assembly procedure. Step 8 Same as Step 9 step 2 and 4 Placing of the next series of prestressed concrete wall panels between the staggered ends of the panels below, and step 4. Step 10 Same as step 5. 62 ~ 'N I - 'N K PROCEDURES OF ASSEMBLY Step One Support Panels on Foundation Wall 63 A A A Step Two Cont. Conc. Beams Bolted to Support Panels 64 0 .C- 'U 0) C -~ 0 C L\ Step Four Cont. Concrete Beams & Bolted 66 0 L L E Go U) (D L C/) o0 L 00 .0 C, '.0 A Step Six Conc. Support Panels, Conc. Beams & Bolt 68 Step Seven Conc. Floor Slabs & Non Load-Bearing Conc. Wall Panels 69 Step Eight Conc. Support Panels & Cont. Conc. Beams 70 06 E co 0 CL a'- (U 0 0 Step Ten Concrete Floor Slabs 72 5.0 FINISHES 73 5.1 INTERIOR FINISHES 5.1.1 Floors Floor systems of prestressed concrete slabs readily lend Some finishes. themselves to virtually any available floor underlayment types of finishes of mastic, may requ ire an gypsum concrete or concrete, while others are applied directly to the prestressed concrete slabs with only a minimum amount concrete Under layment or topping of surface leveling. is floor when a resilient covering is used. required The should be thouroughly cleaned slabs concrete prestressed before application of any und erlayment or concrete topping. of the top surface of the installed deck will Condition depending on span, load, openings and other details. vary a concrete topping is desired, it can be designed to act When structurally with the prestressed concrete slab as a composite material. or it can be assumed to act only as a fill system, the topping of affect the specification choice will This material and placement. 5.1.2 Concrete Finishes When concrete is to be used structurally or as a wearing psi. Color 3000 specify a minimum of surface, one should pigments, hardeners or wearing aids may be added. Similar Where terrazzo. prevail for cast-in-place details should concrete slab align joints with the prestressed practical, joints. 1 1/2" Min. Conc. Topp ing Prestressed C Floor Slab 74 5.1.3 Floor Coverings on Underlayment one should be speci fied similar to the mate rial Underlayment latex concrete, haltic general types: asp following of the underlayment of Thi ckness underlayment. mastic concrete, construction off level to enough only be should irregularities. used be procedures should and specifications S imi tar bed which normally require a mortar f oor ing materials p lacing, such as cut stone or precast terrazzo. for for Asphalt or Vinyl Tile or Sheet Floor Covering Underlayment Fin. - Level Prestressed Conc. Floor Slab 5.1.4 Carpeting sk im carpeting directly on prestressed concrete slabs, a For r ities irregula where applied be should leveling coat of mastic exceed 3/16 in. A minimum of 55 oz. pad should be specif ied. Carpeting over Pad Prestressed Conc. Floor Slab 75 5.1.5 Exposed Ceiling Slab - Painted smooth concrete slabs have an exceptional ly prestressed The vibration thourough the of because obtained surface, underside beds. casting concrete in steel forms in the dense the of Nicely rounded corners are built into the individual units. a paneled ceiling is desired in residential, commerc ia I, When hospital or similar applications, simply caulking the school, econom ica I between the slabs and painting is the most joints solution. waterproof coat should be rubber latex paint or a prime The finish The slab. concrete other any for desirable sealer as is an or finish wal I flat paint, oil rubber, be may coat by obtained is appearance distintive A finish. emulsified stippling the final coat. 5.1.6 Other Ceiling Treatment simply the most economical ceilings are obtained by Although treatments caulking and painting as outl ined above, additional can be applied which produces a variety of results. tiles that are applied directly onto the Cei Iing concrete slabs. prestressed is app lied acoustical material when acoustical control Spray be fiber or other acoustical material may mineral required, textured a on the slab's surface creating d irectly sprayed finished. 5.1.7 Suspended Ceiling conventional hung ceilings may be in conjunction with All in slabs by inserting the hangers concrete prestressed joints between slabs before grouting. also be hung ceilings may Alternative Iy, grouted, by drilling underside of the cores the hangers in the cores. Hangers dril ling the the are slabs after and then inserting be installed from the top of the also may through the cores, provided topping will be the suspended ceiling of purpose Principal ducts, pipes or other mechanical parapenalias. is to slab used. by conceal 76 Galv. Strap Hanger Installed Before Slabs are Grouted essed Conc. Slab Suspended Ceiling 77 5.2 EXTERIOR CLADDING applied are a number of possible materials that can be There concrete the facade of the exterior prestressed to directly concrete continuous the directly on bearing panels, wall wall the leave one may simply choose to course Of beams. exposed which also presents a wide variety of finishes panels and textures. 5.2.1 Brick/Block system. concrete block is compatable with this and/or Brick veneer brick to similar is methodology construction Its that is difference only The 34. Fig. See construction. building the of perifery the around required is scaffolding when laying the brick/block on the facade. 5.2.2 Wood/Stucco compatible alternative, and/or stucco finish is another Wood construction. also applied similarly to brick veneer is and See Fig. 35. 5.2.3 Exposed Concrete as far as the most flexibil ity provides concrete Exposed be can finishes The variations. color and finishes textures, I wal concrete prestressed the when cases most in applied reduction. cost a manufactured are panels The interior side of the prestressed concrete wall panel s wil I Fig. some sort of insulation: rigid or batt insulation. need board shows metal studs with batt insu lation and a gypsum 36 finish. patented a with finish can be achieved exterior unique A the compacts and screeds process. A revolving roller Corewall the create to panels the of surface top the on concrete the varying By Fig.37). (see effect architectural desired the to attached discs of number a of spacing and profile available. is finishes sculptured of variety wide a roller, Fig. 38 gives us a sampling of exterior finishes achieved by various means. that can be 78 Rigid Insul. Face Brick -Cont. Conc. Beam *Grout Filled Concrete Block -Rigid Insul. SECTION C-C on Page 91 OPTIONAL EXTERIOR FINISH (Brick, Concrete Block) Fig. 34 79 Metal Studs with Batt Insul. Textured Plywood (Board on Batten, Beveled Siding, Tongue & Groove Planking, etc.) m / *Cont. Conc. Beam Grout Filled Metal Studs with Batt Insul. Stucco Finish SECTION C-C on Page 91 OPTIONAL EXTERIOR FINISH (Wood, Stucco) Fig. 35 80 -Exposed Prestressed Conc. Wall Panels Grout Filled .Metal Studs With Batt Insul. -Gypsum Board Finish SECTION C-C on Page 91 OPTIONAL EXTERIOR FINISH (Exposed Concrete) Fig. 36 02 m -4 ~tJ Ca ~tA'.' *~mrrnr:rw:: r ~sjcrkrrcmuch~iaM "it , Will-.' cv * rtznninnita"amn act 1et~r1 ur rw!r it,. F ~m ii ~0 V Exposa AggregCOl - RIDDOO Exposed Aggregat Fig. 38 83 6.0 DESIGN CONSIDERATIONS 84 6.1 Modules mention manufacturers concrete prestressed the Among width alternate are there introduction, the in previously dimensions of hollow-core concrete slabs that varies with each 4'-O, producer. The scope of dimensions are: 1'-4, 2'-0, 3'-4, 5'-0 and 8'-0 widths. on these dimensions, the designer will need to know the Based are members concrete prestressed where location nearest dimensions width standard the acknowledge and produced the as the manufacturer. This should serve with associated concrete prestressed of system module the for basis large In incorporated into the design. members hollow-core manufacturers three or two be may there areas, metropolitian a relative close proximity which presents the designer within with a more flexible module selection. an module sizes plays to say, the determination of Needless and economy, regarding two major criterias: role important design flexiblity. The larger the width dimension, i.e. larger the more economical it becomes simply on the basis of member, fewer with erection quicker and requirements labor less on depends also project members. The design flexibility of the integration of the module dimensions because of the imposition and economical, in order to be efficient, design the into functional. The ideal module dimension of prestressed concrete elements is and/or possible comb i nations of 4'-0 widths ( if needbe). 8'-0 the in sizes are an architectonic dimens on of these Both construction industry. The modules should be aligned both horizontal ly and vertical ly slabs. floor wall panels should correspond to the the i.e. This should prevent any unneccessary cutting of elements. More is that bars allocation of reinforcing the is important, to slabs concrete placed in keyways at ends of the prestressed adjoining floor slabs or wall panels (if exterior walls). the wal I the accomplish this, the floor slabs and to order In the through penetrate to rebars have to align to allow panels wal I panels. 85 6.2 Spans/Heights Floor Spans of lengths definite limitation of maximum span is a There 40'. to 35' from ranging slabs floor concrete prestressed Considerations should be given to the allowable service loads, concrete not or ratings and whether fire codes, building determined. be used before span dimensions are will topping These considerations wi ll effect the locations of load-bearing space and functions the effects ultimate ly which walls, allocations between the walls. Wall Heights is lengths for prestressed concrete wall panels maximum The ranges that on the allowable transportation limitations based the plus 10" for If a typical floor height is 8 45'. around of 45' of length a then (8'-10), thickness slab floor floors 5 panel will accommodate wall concrete prestressed An obvious and substantial savings increase in labor lengths. and production one-time time with construction and costs handling of one wall member versus five wall panels associated with Spancrete's load-bearing prestressed concrete wall system mentioned in chapter 2.2.4. heights is substantially more flexibility with ceiling There the on Based system. wall precast other any with than various with panel wall concrete prestressed continuous for that are drilled through the wall panels holes lengths, fluctuate to drilled be can beams, concrete attachment of the 8' floor intervals e.g. one floor height can be desired any floor proceeding the and height 12' at be can next the high, implied additional any without high 10' be can height prefabricated costs with the exception of the constructional the to correspond to panel support concrete reinforced prestressed the the waste of materials. Also, and heights, concrete wall panels can come in any desired lengths up to 45' due to the the production methodology of the members. 86 6.3 Design Restrictions The design restrictions of this system confronted by the designer is limited to straight load-bearing walls/party walls its on (depending width or length the extends that be must walls The building. the of application) parallel with each other (for bearing support juxtapositioned decking system). Also, the distance between the continuous of there depends on the decking system used and walls straight respective maximum spans. 6.4 Exterior Fenestrations As far as deciding on what type of exterior fenestrations may want to apply, he or she is only limited to de signer or her immagination. 6.4.1 the his Perpendicular to Load-bearing Walls exterior walls that are perpendicular to the load-bearing The desired limitless as far as the type of materials are walls light the type of wall construction. It can range from a and curtain wal I to a solid masonry wal I construction with punched The curtain wall construction would be secured onto openings. the longitudinal edge of the prestressed concrete floor slabs. At the same time, the masonry wall can be constructed the full run or slabs, adjacent the floor building the of height in result would This slabs. floor the between intermittedly a of emphasizing contrasting materials with possibility the subdivision of horizontality. continuous also be provided by protruding the can Balconies beams and floor slabs beyond the reinforced concrete concrete support panels. Cantilevering has certain limitations based on the Also, beams. concrete continuous the of design the is restricted to extend the length of the cantilever designer the full length of the concrete floor slabs unless masonry to construction is used. 6.4.2 Parallel to Load-Bearing Walls exterior walls running parallel to the load-bearing walls The presents more restrictions than walls running perpendicular to of The designer must consider the structural integrity it. the system in that there should be a continuity of wall the wall of wall panels. A certain amount concrete prestressed panels may be deleted for opennings of windows and/or doors. wide material selection on these facades also presents a The in choices, though its applications are limited of spectrum continuous the between that it should be applied sense the concrete beam. 87 Cantilevering may also be achieved by eliminating the corrsesponding wall panels, and by extending the prestressed concrete floor stabs (bearing over the continous concrete beams) beyond the exterior wall plane. 6.5 Applications This building system may be incorporated building type in the construction industry. 6.5.1 in virtually any Residential This system applicable slabs. is geared spans of to the housing industry primarily of its the prestressed concrete floor and roof In apartment building, the central or double- l oaded corridor l . This is to the most economica is considered system public understand when we consider that every square foot of corridor serves two apartments instead of one. Each bui Iding type has a modifying effect on the apartments placed w ithin its confines. The central corridor type, limits the of the apartments minimally. What determines the layo ut is kind of apartment layout the designer is able to work out based on the total building length and depth. order to be economically feasible the typical floor should In contain a maximum number of apartments. Given the minimum room determined by the program, just so many apartments can widths fit into the available building length. The number of apartments in this length can be improved on if each apartment shorter is arranged - keeping the gross area constant - with will and increased depth. Naturally, this exposure exterior narrow on the apartment. Bedrooms become so put constraints the exterior and desks must be placed along that dressers wall, thus eliminating the option of floor-to-ceiling In The inner ends of the rooms become darker. fenestration. spite of all this, buildings with narrow, deep apartments tend to be more economical: using the same gross square foot area, they have smaller perimeters and less exterior wall. one-bedroom, show efficiency, illustrations The following two-bedroom, and three-bedroom apartments with average depth and depth as well as with increased exposure and exterior reduced exterior exposure. They also show the consequences of using some of the apartment space ("borrowing") to accommodate core elements along the central corridor. It is important to be aware that the apartments are reflecting more the marketing conditions than living averages styles. 88 6.5.2 Commercial, Industrial, & Institutional and industrial commercial, in applications are There on are certain restrictions based only There institutional. and spans of the decking systems. In commercial maximum the composed applications, the perimeter walls may be industrial prestressed concrete wall panels while the interior may be of to system beam support, e.g. post and of means other of obstructions otherwise unavoidable if wall panels are prevent used. 89 I LEGEND Load-Bearing Prestressed Concrete Wall Panels Non Load-Bear i ng Prestressed Concrete Wa I I Pane I s 0 NMI I I. IL Balcony 8'-0 wide Modules C i- E C A A, H, Elev. H~ G StaiwellCorridor 4HF B B Prestressed Conc. Floor Slabs D 1 1 4'-0 wide Modules 4D I LEGEND ---- Load-Bearing Prestressed Concrete Wall Panels Non Load-Bearing Prestressed Concrete Wall Panels LAYOUT OF PRESTRESSED CONCRETE ELEMENTS '~0 Shaft j 18'-0 j L 21'-0 1 F I Efficiency Apartment I -I r- _ Efficiency 7 Layout LEGEND Load-Bearing Prestressed Concrete Wall Panels Non Load-Bearing Prestressed Concrete Wall Panels 92 12' -0 A r F 16'-0 b- 16/-0 S121-0 F U One Bedroom Aartment *~ 12'-O lb .A ________ 12/- ~ , 16'-0 Ii II II II IF II II Ii II II One Bedroom Layout LEGEND Load-Bearing Prestressed Concrete Wall Panels Non Load-Bearing Prestressed Concrete Wall Panels 93 12' -0o 2 12'-0 121-0 - * -- - iwf~ -- 16/-0 1'O -. - -- - -1 -- - w i 12'-0 61 F 12'-Q 1 2--Q .a F 16/-0 16/-0 F Two Bedroom Apartment LEGEND Load-Bearing Prestressed Concrete Wall Panels Non Load-Bearing Prestressed Concrete Wall Panels 94 12'-0 12'-0 -L J F II 24 - 0 _______________________________ 16'-0 28' -0 -I _____ __________________________ ii .1 *1 __________________________ Two Bedroom Layout LEGEND Load-Bearing Prestressed Concrete Wall Panels Non Load-Bearing Prestressed Concrete Wall Panels 95 Three Bedroom Apartment LEGEND Load-Bearing Prestressed Concrete Wall Panels Non Load-Bearing Prestressed Concrete Wall Panels 96 24I-0 r28/-0 24' -0 ti Three Bedroom Layout 12t- 11. r 1 - 0 a I. 2 - 6 - a Three Bedroom Apartment LEGEND Load-Bearing Prestressed Concrete Wall Panels Non Load-Bearing Prestressed Concrete Wall Panels 97 7.0 ECONOMICS OF THE SYSTEM 98 on ly be The use of precast, prestressed concrete units can effective more economically be to shown be justified if it can than building with traditional methods. Section 7.1 addresses the advantages of conventional precast, concrete that is existing in todays market, while prestres sed as far deals more directly with this system as 7.2 section economy is concerned. 7.1 The Attributes of Precast, Prestressed Concrete Less Construction Time Precast, prestressed concrete components can be uniformly mass and conditions manufacturing controlled under produced of production year-round for allowing environments, at proceeds work foundation and excavation while components, Components schedule. construction Compressed the site. Result: structure usually erected directly from the truck to the are or access for projects with limited site ideal it (making those with on-site material storage space). Total construction because reduced also are costs labor on-site and time components fit readily into place. Improved Construction Efficiency smaI ler components, standardized With used, resu It ng be can crews erection savings. Lower and in more time efficient money and Interim Financing Costs major rates and cost of interim financing are mortgage High conce rns of builders, owners and developers who face potential a ob taining from construction during f inan cial risks schedule and/or cost to mortgage, or loan const ruction of precast, time construction reduced The overr uns. financial these minimizes effectively concrete prest ressed risks . Cost Control Cost information is monitored from preliminary studies through and/or designer the a Ilows which completion contract to of start very the from price a reliable from developer to work the anticipated project. Mortgage Companies More Receptive project lower are more receptive to the companies Mortgage prestressed of precast, benefits inherent the and costs concrete. More accurate predictions of the completion date can be made due to the reduced construction time. 98A Early Enclosure for Other Construction the structure can be erected so qui ckly, other trades Because the for provided A working platform is sooner. start can for need the rises, eliminati ng structure the as trades scaffolding. Earlier Occupancy prestressed precast, why reason This bottom-line is the a are the economical choice. The faster strustures concrete building is completed, the sooner it can be put to use by its - and precast, prestressed structures save construction owner time. Energy Efficiency energy excepti onal provides concrete prestressed Precast, of use the life of the building. The throughout efficiency and heating concrete provides greater prestressed precast, outside-air its to due ef ficiency equipment cooling temperature control, condensation protecti on, infiltration and thermal storage capabilities. stability Earthquake, Fire Resistance rel iable absolutely concrete provide s prestressed Precast, dependence total ithout fire protection of lives and property w insurance reduced systems, often resulting in sprinkler on in areas ed us widely are components prestressed rates. Precast, severe to subject ar which California, and Alaska as such earthquakes Lower Insurance Costs the properties of fire on Based insurance concrete, prestressed insurance rates to owners. and durab.ility companies precast, of lower offer Design Versitility concrete prestressed of precast, possibilities design The to applied been have virtually limitless and are components great the to In addition of structure. form every nearly be can components other components, standard of variety and sizes shapes, of number infinite almost in custom-made finishes. High Durability, Low Maintenance under prestressed concrete components are produced Precast, consistently in conditions, resulting factory high-qua lity durable products that require minimal. future maintenance. 99 7.2 Economics of This System The basic prerequisite for any successful, systems can be simply stated as: 1) 2) 3) 4) economical building Largest possible elements Repetitive elements Minimal or no temporary bracing Safe, simple, proven connections This construction of reduces costs in approach of type detai I ing, and erection. Thes e benefits are production most fully realized when the systems approach is introduced in the ear Iy design stage. Precast, prestressed concrete decks reduce cost by reducing need and in certain cases, eliminating the height, building for fireproofing altogether. The followi ng a cost precast, table is of estimation floors concrete sl abs for roofs and prestressed hol low-core Data, Cost (grouted) from the Means Building Construction 1984. CREW C-J1 SLABS Prestressed roof and floor members, grouted, 4" deep 6" deep j 8"deep 4 10" deep 12" deep The following table prestressed concrete from the same source. DAILY OUTPUT 4,875 5,850 UNIT SF. High rise, 4' x 8', 4" thick, smooth gray Exposed aggregate 8' x 8', 4" thick, smooth gray Exposed aggregate 20' x 10', 6" thick, smooth gray Exposed aggregate 30' x 10', 6" thick, smooth gray White face . BARE COSTS INST. TOTAL .51 .43 2.81 2.78 TOTAL INCL O&P 3.23 3.17 7,200 2.50 .35 2.85 3.22 .8,800 2.75 .28 3.03 3A1 9,500 3.10 .26 3.36 3.77 cost estimation is a wall panels for high-rise I WALL PANELS. MAT. 2.30 2.35 CREW DAILY OUTPUT C-I1 288 UNIT S.F. 288 512 512 1,800 1,8002,100 2;100 " precast, of construction MAT. 6.70 7.25 6.70 7.25 8 8.75 8 9.25 BARE COSTS INST. I TOTAL 8.35 8.35 4.70 4.70 1.34 1.34 1.15 1.15 15.05 15.60 11.40 11.95 9.34 10.09 9.15 10.40 TOTAL INCL O&P 18.75 19.35 13.75 14.35 10.60 11.45 10.35 11.75 100 bare costs of precast, Total added together equals $18.71, cost of $3.74 per sq. ft. prestressed concrete wall panels divided by 5 gives us an average and profits, of precast concrete wal I pane Is overhead Total added together equals $21.56, divided by 5 gives us an average cost of $4.31 per sq. ft. panels estimati on of precast concrete wall cost For a page previous the on table see low-rise construction deduct 25% for install ation costs. and profits of precast overhead total The $101.70, divided by 8 gives us $12.71 per sq. concrete ft. prestressed costs that of precast, compare we If and the precast concrete wall panels, we can slabs see a substantial difference. The average cost of mater ial per sq. ft. $3.74 is slab an average of cost panels $11 .62 versus construction construction. for and equals concrete obviously for precast, prestressed concrete wall concrete while the precast low-rise for $10.68 per sq. ft. high-rise for ft. sq. per precast, for, profits for overhead and costs average The the while ft. sq. per $4.31 is slab concrete prestressed precast concrete wall panels cost an average of $12. 71 per sq. for for low-rise concstruction versus $13.80 per s q. ft. ft. high-rise construction. panels should be mentioned that the precast concrete wall It structural additional a curtain wall where an as used are framing construction (concrete or steel) is required to "hang" are slab panels. Whereas the prestressed concrete wall the the incorporates also but as an exterior cladding used also walls load-bearing or walls as either non load-bearing panels for either interior of exterior applications of the building. result of these large price variations is due to the fact The 400 the prestressed concrete slabs are mass produced on that to cut be Ily economica be can and beds casting 600* to are lengths while the precast concrete wall panels specified to designed to designer*s specifications with reqards custom size, color, shape and texture. possible cost reduction can be attrib uted to the fact Another The eliminated. completely be can walls foundation that the onto rectly di wall panels can bear concrete prestressed in money and me ti saves which obviously footings foundation expensive formwork. 101 8.0 EVALUATION & CONCLUSION 102 The research thus accomplished was done at a conceptual level, and idea top surface. It is an original the skimming. over into refined and developed development, which could be further a marketable new methodology of construction. research would need to be done in the design flexibility More this system. Some of the questions that could be addressed of are: -How high can one build with this system? and single a the load-bearing walls from offset one -Can straight wall plane? -How would this system comply with the building codes? the determine to necessary be would calculations -What structural sizes of the componets? What are the cost analysis of this system that could provide a justification to its applicability in real practice? regarding at could bve looked investigation thorough What various finishes and claddings? manifests conclusion, based on this research, this system In context vast adaptability in today*s construction market its with a substantial savings. 103 APPENDIX 104 MILESTONES OF EVENTS AND DEVELOPMENTS IN NORTH AMERICAN PRESTRESSED CONCRETE INDUSTRY (1939-1958) Summarized of events listing is a chronological below linear of use practical of the influencing development the prestressed of concrete in the United States and other parts the western hemisphere. YEAR EVENTS 1939 First experimental prestressed concrete piles driven by the Raymond Concrete Pile Corporation in New York Harbor. 1944 Roebling engineers begin study of steel and research in prestressed 1946 Prestressed concrete floor slab designed by Roebling is complete in Roebling's Chicago warehouse. First prestressed concrete structure in the United States and first use of Roebling materials specifically developed for prestressed concrete, such as factory-made prestressed cable assemblies consisting of cold-drawn hot-galvanized acid steel wire, and specially designed end terminals. 1946 Tests of three sets of four prestressed concrete beams begin at Tulane U niversity under the direction of Professor Walter Blessey. 1947 Lumberville suspension bridge completed. Floor was prestressed by means of Roebling*s 1/2 in. (12.7 mm) diameter high strength rods having threads at their ends for prestressing and anchoring. 1947 to the United visit Professor Magnel's first States (sponsored by the Belgian American Educational Foundation). 1949 Rio Paz suspension bridge, connecting Guatemala to El Salvador, open to highway traffic. It features precast prestressed concrete floor slabs similar to the Lumberville bridge. 1949 Start of fire tests on prestressed concrete elements at Korchamwood, Great Britian by the British Joint Fire Research Organization 1949 Start of- construction of the substructure of the Walnut Lane Bridge and of the manufacture at the site of the full-sized 160 ft. (48.8 m) long test girder. First use of stress-relieved wire, an prestressing concrete. 105 American innovation (Roebling). 1949 Start of test to failure of full-sized Walnut Lane test girder (October 25,1949). Beginning of site casting of actual girders. 1949 Concrete Products Company of America starts production of box girders in America's first pretensioning plant, at Pottstown, Pennsylavania. 1950 Fayetteville, Tennesse Stadium. Use of Roebling galvanized prestressed concrete strands and anchor fittings. 1950 Turkey Creek Bridge, Tennessee. Completion of first American prestressed concrete bridge using concrete blocks and Roebling developed prestressing materials. 1951 Fritz Research Laboratory at Lehigh University, Bethlehem, Pennsylvania, begins tests on box girders. Sponsored jointly by the Department of Highways of Pennsylvania and Roebling. The program was to last more than 20 years, continuosly. 1951 Formation of Precompressed Concrete Company Ltd. (PRECO), first Canadian firm entering the prestressed concrete field. 1951 Illinois Cooperative Highway Research program was conducted at the University of Illinois, under the direction of Professor Chester Siess. Questions and answer session at the AASHO Committee meetings on Bridges and Structures and Bureau of Public Roads. It marks the beginning of University of Illinois' research in prestressed concrete. 1951 First United States National MIT sponsored prestressed concrete conference. 1951 First American pretensioned prestressed concrete bridge using non-stress-relieved strands as manufactured by American Steel and Wire Corporation completed in Hershey, Pennsylvania. 1951 Completion of first California prestressed concrete foot bridge using headed wire. 1952 Completion in Mid-West of first buildings using prestressed girders and permanent slabs stressed by headed wires. 1952 Bureau of Public Roads (now Federal Highway 106 short "criteria" Administration) publishes its be used in the design of post-tensioned prestressed concrete bridges. to 1952 The Fritz Laboratories at Legigh University published their first Progress Report in the program of prestressed concrete research begun in 1951. It was to give the impetus for the construction of the prestressed concrete box girders. 1953 September 10, formation of Prestressed Concrete Development Group of Canada. 1953 Prestressed concrete research programs began on a large scale on a systematic basis at a number of leading American Universities in addition to Lehigh University. 1953 University of Florida, Gainsville, Florida - In cooperation with the Florida State Roads Department: A study concerning plastic flow and shrinkage of prestressed concrete. Fourteen such prestressed concrete girders cast at various Florida bridge construction sites were held under observation for -several years. 1953 University of Illinois, Urbana, Illinois, with the Illinois Division of Highways and the U.S. Bureau of Public Roads - As Research Associate Professor of Civil Engineering, Professor Chester Siess was extremely interested in shear strength of prestressed concrete beams. Consequently, a most elaborate program was established. Much of the work was the responsibility of Eugene Zwoyer, then Research Associate in Civil Engineering. 1953 University of California - Beginning with the on site testing of the Arroyo Seco Pedestrian Bridge in 1951, continnuing throughout 1952, laboratory tests on prestressed concrete under the simulus of Professor T.Y. Lin were in full swing by 1953. At that time, full emphasis was on prestressed concrete thin shells and flat plates. Findings were to be the basis for the subsequent design and construction of the cantilever thin shell roof for the Caracas Stadium for which Felix Kulka of T.Y. Lin International was responsible. 1953 Portland Cement Association Research and Development Laboratories, Skokie, Illinois - At PCA*s laboratories, consideration was being given commence large research programs to include full size girders, all under leadership of Dr. Alan to 107 Bates, Dr. Eivind Honestad and Dr. Alan Mattack. Reports of many tests were published by PCA. 1954 January 28, 1954 Canadian Conference on Prestressed Concrete at University of Toronto. Professor Magnel attended as did many Canadian and American engineers. Particularly valuable were the tests on full-sized beams reported by Cleveland's Austin Company. 1954 Use of the first time ready-mix concrete. 1954 Publication by the Bureau of Public Roads of the revised and expanded "Criteria For Prestressed Concrete Bridges" for both pretensioned and post-tensioned concrete. 1954 Founding of Prestressed Concrete 1954 Prestressed Concrete Institute published the edition of the Tentative Specifications for Pretensioned Prestressed Concrete. 1955 Bureau of Public Roads, Highway Research Board and others complete arrangements for construction of.$12 million (increased before completion of Project to $27-million) road test project of AASHO, in Ottowa, Illinois. Project included prestressed concrete bridges. In 1962, AASHO revealed results in an extensive three-volume report. At least three sets of data influenced subsequent prestressed concrete bridge design in that tensile stresses would be allowed in concrete prestressed with strands. (Up to then no bottom tensile stresses were allowed at midspan of girders.) 1957 First World Conference of Prestressed Concrete at San Francisco sponsored by the PCI with the cooperation of National Professional Societies. 1958 Publication by the ACI-ASCE Joint Committee 323 of the Tentative Recommendations for Prestressed Concrete. in Canada of 5000 psi Institute. first 108 PROPERTIES PECULIAR TO PRESTRESSED CONCRETE Shrinkage fami lar of concrete is a process known to everyone Shrinkage vol ume total its cures, concrete As reinforced concrete. with three all in shrink to tends it and slightly decreases dimensions. from When the tension in pretensioned strands is transferred compressive anchorages to the concrete members, the external all exist ing the closes concrete in the created force cracks and both the concrete member and the stra nds shrinkage of the widths to the sum of the amount equal an shorten est great ge is cracks. Although the rate of shrinka shrinkage t ime some for is first cast, it continues member when the ing continu the Since operation. prestressing after th e in now is which concrete the in cracks cause cannot shrinkage fi na I the In shortening. additional causes it compressi on, the pretensioned strands shorten an amount equal to analysis, the total shrinkage. This shortening causes a reduction of the tensile stress in the strands. Elastic Compression compression of the concrete member takes place as Elastic force is applied. As in any elastic material prestressing is a function of the modulus of elasticity of magnitude concrete and the intensity of the compressive stress. the its the the when tension is under initial Since the pretensioned strand the it, to bonded is stress member under zero concrete shortens an amount from the anchorages to the concrete member. Creep concrete, of Creep shortening inelastic by a is caused It func a is magnitude tendons Pretensioned creep. is flow, plastic often referred to as which takes place over a period of time. its and stress, compress ive constant stress. that of tion of the intens ity entire the shorten an amount equal to Relaxation of cause tendons is the fourth of prestressing Relaxation initial at an used are tendons these Since loss. stress tension of 65 to 70 percent of their ultimate strength, they, high constant creep or pl astic flow to the a undergo too, those from different are somewhat however, Conditions, stress. in the concrete. If a weight were hung on a tendon to create a the strength, 70 per cen t of its ultimate to equal stress member would slowly elongate or creep as the concrete tendon 109 a In an actual structure the tendon is not held at shortens. As it is not even held at a constant length. load; constant the concrete member shortens from the factors mentioned above, the tendons shortens too. There is a certain amount of plastic a cause cannot it since which, tendon the within flow reduction in stress is called "relaxation." 110 MATERIALS OF CONCRETE Properties In reinforced concrete structures the usable concrete strength tensile the by the behavior of the member. When limited is psi, in the reinforcing steel exceed 18,000 or 20,000 stress deflection. and begins to show excessive cracks member the these develop concrete is strong enough to 3,000-psi Since seldom are strengths reinforcing, higher the in stresses spec if ied. of used in prestressed concrete, although made concrete The full same basic ingredients, is much stronger, since its the strength can be utilized. In this case the governing factor is of made majority of members are A fabrication. economical concrete, although some fabricators are appreciably 5,000-psi of strengths and most specifications permit a minimum higher psi. 4,000 High-strength concrete has several advantages: 1. A smaller cross-section area can be used to carry a given instances many in dead weight and less means This load. shallower members, giving more clearance. 2. Its higher modulus of elasticity decreases camber, which is frequently a problem in-prestressed concrete because of the relatively high negative moment that exits under the dead-load reduces also elasticity of modulus high The condition. stress in pretensioned members cuts down the and deflection loss due to elastic shortening. 5,000 E,= 33 w 4,000 .a 3,007.,00 0 Unit weight w pcf I11 3. Members can be prestressed and equipment released for the compressive required in minimum time because the pour next reached of concrete at time of initial prestress is strength In some cases fabricators of pretensioned members use sooner. a mix which gives a higher compressive strength of concrete at pouring maintain to time in prestress initial of time schedule. 4. In bridges and other members exposed to freezing or salt plus density and high strength of combination the spray virtually concrete prestressed makes cracks from freedom maintenance-free. Placing for aids several employ fabricators concrete Prestressed achieve to concrete low-slump high-strength the handling satisfactory placement and rapid curing. standard equipment are Vibrators are frequently screeds Vibrating such as double T*s and channels. for all used on type. work of this members area-type cement and admixtures such as P lastiment are entraining Air the ma intaining the workablity while increase to employed beca use and ultimate strength is av oided ratio water-cement of source a is the rich mix paste *in cement extra the additional shrinkage. Curing is an equipment permit frequent reuse of Rapid curing to prestressed factor in the economical producti on of important 39 and especially of the pretensioned type. Figure concrete a on curing speed obtained by s team curing the illustrates and under pipes through hot oil located circulating typical h igh-early-strength use Many concrete. curing the beside cement. Calcium chloride existing test data properties of high is not used to accelerate action is indicate that its strength tendons. because curing damaging to the 112 6,000 5,000 PROCEDURE 'a CL 1- Delay steam 4 to 6 hr ~~2- Raise steam 1* per min to 145* F 4,000 :E 3-Hold steam at 1450 for 18 hr MIX Cement 658 lb Sand 1,195 lb Stone 1,908 lb Water 34.7 Gal 03 a) 3,000 0. u Plastiment 21 to 28 oz 1,000 0 0 4 8 12 16 20 24 28 Age, days Fig. 39 113 Lightweight Concrete members Prestressed concrete fabricated satisfactorily from that are pretensioned light-weight concrete. can be and concrete betwe en regular-weight chief differences The concrete of the same ultimate strength are in the lightweight elastic properties. Shortening of lightweight concrete due to creep plus shrinkage regul ar-weight of shortening than the is greater usuall y concrete under similar conditions, but with properly designed in the for not excessive and can be provided is mixes it design. of many lightweight aggregates are such that it is Properties it making thus their water content, measure to difficult sl ump to know how much water to add to the mix. A difficult a obtain to as a check. In order used sometimes is test as product it is often desirable to use regular sand uniform the fine aggregate even though it does increase the weight of the finished product. products. of lightweight aggregates know their own Producers They can recommend mixes and handling methods to give concrete with the design properties. They should also have test reports in be expected and shrinkage can creep what indicate to concretes made from their product. Prestressed concrete members made of lightweight concrete have of made members identical than endurance fire a longer One possible exception is thin slabs regular-weight concrete. heat than 3 in.) in which fire rating is determined by (less transfer through the slab. 114 TENDONS General Properties in minimize the drop for high-strength tendons to need The force due to stress losses. Satisfactory tendons prestressing from and wires of combinations or wire from made are special bars, all of which are fabricated with high-strength from proiperties. These tendons differ concrete prestressed the meet to order in ways several in steels other most concrete. prestressed of requirements particular in essential is tension initial to elongation Uniform the is Fig 40 force. prestressing accurate an obtaining uncoated 0.196-in.-diameter a of curve stress-strain shape general (Its wire. concrete prestressed stress-relieved tendons.) concrete prestressed of types all of is typical For all practical purposes, this curve is a straight line to a psi 175,000 initial tension of 165,000 to the above point used for 0.196-in. wire. Tendons do not have a yield normally continues like that of ordinary steel where elongation point the of stress. They do reach a point where increase without large remains and rapidly of strain to stress increases ratio is the tendon fails. This change in slope of the curve until the a necessary property. When a beam is overloaded and also tendon the ultimate, approaches tendon the in stress causing a visible deflection which warns impending elongates, fai lure. In addition to high strength and special elastic properties, a high must have a low coefficient of relaxation.at the tendon stresses used. 7,000 240,000 220,000 6,000------- 200,000 5,000 180,000 160,000 'k :- 4,000 140,000 0 4; 0 120,000 100,000 Stress-strain Curve 0.196" Diameter Uncoated Stress-relieved Prestressed -concrete Minimum Ultimat -Wire 1Strength = 250,000 psi 80,000 60,000 40,000 40,000 3,000 2,000 i,000 20,000 0 0---------o:ooo5o d a0oooo Elongation, in. per in. 0- Elongation, in.per in. Fig. 40 115 Wire high-carbon a wire is made by drawing concrete Prestressed As steel rod through several conical dies. round hot-rolled and the rod passes through each die, its diameter is decreased the length is correspondingly increased. In the process, its crystals that made up the rod are drawn out into long parallel strenath. give wire its extremely high tensile which fibers properties drawn wire does not have the uniform plastic Cold elongate in the prestressed concrete. As the crystals needed yield they develop stresses in excess of their fibers, into The resulting wire is made up of fibers which are full point. the stresses. When a tensile load is applied to internal if each fib er elongates the same amount. The stress due to wire, elongatio n is added to the internal stress, and soon the this fiber with the highest internal stress reaches the point where of s train to stress increases rapidly. From here on ratio its will fiber wil I elongate with the others but its stress this the increase so rapidly. Since the internal stresses in not various fibers are not uniform, first one fiber, then another, resulting The point. yield the reach another will then load-e longation curve of the wire is not uniform. The internal st resses in the cold drawn wire are eliminated by is it to a stress-relieving pr ocess in which it subjecting a short to a mo derate temperature (750* to 850* F) for raised and of time (15 to 30 sec.). This is not heat-treated period any to wire the of the ultimate strength chan ge not does desired the has which degr ee. It does create a wire noticable internal of because it is free properties elasti c uniform stresses. the strength, up to 70 per cent of its ultimate stresse At of elasticity of uncoated stress-relieved prestressed modulus this While is approximately 29,000,000 psi. wire concrete is accurate for design calculations, it is sufficiently value recommended thgat the stell fabricator*s load-elongation curve elongation particular wire be used in computing the the for required in jacking wires to a specific tension. Seven-Wire Strand strands concrete stress-relieved uncoated Seven-wire normally tendons the are to ASTM Designation A 416 conforming used in pretensioned bonded members. F ig 41 is a photograph of a seven-wire strand and Fig 42 is the load-elongation curve. Each strand is made up of seven cold drawn wires. The center 116 wire is straight, and the six. outside wires are laid helically around it. All six outside wires are the same diameter, and the center wire is slightly larger. The difference in diameter is sufficient to guarantee that each of the outside wires will bear on and grip the center wire. This is an important detail in members where the tension in the strand is developed through bond. The six outer wires are bonded to the concrete both by adhesive bond and by mechanical bond of the concrete in the valleys between the wires. Under tension each of the outer wires bears on the center wire, and the resulting friction makes the center wire elongate with the outer wires. If the center wire were too small, the outer wires would bear the center each other to form a pipe through which against wire would slip without carrying any load. the seven wires are formed into a strand, the strand is After subjected to a stress-relieving process. The result is a internal elastic properties and free of strand with ideal stresses. Satress-relieving the individual wires before the does not produce a satisfactory strand because stranding outer wires are subjected to severe twisting in the stranding opertion, which creates internal stresses. These are removed only when the stress-relieving operation follows the stranding operation. Fig. 41 24,000 22,000 20,000 18,000 16,000 . 14,000 6 12,000 a 3 10,000 8,000 6,000 4,000 2,000 Nominal diameter - } in. Guaranteed minimum ultimate- 20,000 lb Nominal area -0.0799 sq in. Elongation in 10 ft at recommended prestressing load (14,000 lb)-0.750 in. 0) o o o0 6 6 6 6 6 6 6 6 6 6 6 6 6 Elongotion, in /in. Fig. 42 117 ACOUSTICAL PROPERTIES General a basic purpose of architectural acoustics is to provide The clearly environment in which desired sou nds are satisfactory (noise) by the intended listeners and unwanted sounds heard are isolated or adsorbed. determine conditions, the architect/engineer can most Under the acoustical needs of the space and then design the building both to satisfy those needs. Good acoustical design utilizes and barriers sound surfaces, reflective and absorptive isolators. Some surfaces must reflect sound so that vibration the loudness will be adequate in all areas where listeners are sound surfaces absorb sound to avoid echoes, Other located. isolated is and- long reverberation times. Sound distortion floor-ceiling and is not wanted by selecting wall it where equipment generated by mechanical Vibrations constructions. must be isolated from the structural frame of the builing. The problems of sound insulation are usually considerably more complicated than those of sound absortion. The former involves of orders level, which are of greater sound of reductions large These be achieved by absorption. can than magnitude of sound level from space to space can be achieved reductions also by continuous, impervious barriers. If the problem only to necessary be may it sound, borne structure involves into the discontinuities layers or introduce resilient barriers. absorbing materials and sound insu Sound There purposes. different for used from an 8 in. concrete wall; absorption insulation is not available from porous, applied to room surfaces. be may that the basic mechanisms of that recognize sound insulation are quite different. lating materials are is not much sound similarly, high sound lightweight material It is important to and sound absorption Sound Transmission Loss Sound tran smission loss measurements are made at 16 frequences at one-thi rd intervals covering the range from 125 to 4000 Hz. performance desired of specification To simpli fy Class Transmission single number Sound the characteri stics (STC) was developed. ceiling produces a wal I, floor or reachi ng sound Airborne reduced with radiated is and el ement in the vibrations on the other side. Airborne sound transmission loss intensity their walls and floor-cei ling assemblies is a function of of weight, stiffness and v ibration damping characteristics. 118 sound Weight is concrete's greatest asset when it is.used as design, but different insulator. For sections of similar for each STC increases approximately 6 units the weights, 43 doubling of weight as shown in Fig. both of results test acoustical The impact insulation of loss and transmission hollow-core slabs are shown in Fig. 44 sound airborne in. 6 and 8 Table 1. presents the ratings for precast concrete walls and various assembly The effects of assemblies. floor-cei I ing are improvements The treatments in Table 2 shown are slightly but in some cases the total effect may be additive, less than the sum. Absorption of Sound The sound absorption frequences individual coefficients (NRC). coefficien t an or as be can average at specified absorption of A dense non-porous concrete surface typically absorbs 1 to 2 There of 0.015. an NRC has and of sound incident of percent surfaces are specially fabricated units with porous concrete provide greater absortion. In the case where additional which absorption of precast concrete is desired, a coating of sound acoustical material can be spray applied, ascoustical tile can can be adhesive, or an acoustical ceiling applied with be Most of the spray applied fire retardant materials suspended. and used to increase the fire resistance of precast concrete floor-ceiling systems can also be used to absorb sound. other Most 0.75. of the sprayed fiber range from 0.25 to The NRC cementitious types have an NRC from 0.25 to 0.50. Acceptable Noise Criteria As a rule, a certain amount of continuous sound can be level An "acceptable" it becomes noise. before tolerated with the room occupants nor interferes neither disturbs communication of wanted sound. The most generally accepted and commonly used noise criteria (PNC) Criteria as the Preferred Noise are expressed today of extensive 45 These values are the result curves, Fig sound pressure based on the human response to both studies level and frequency and take into account the requirements for represent ... The figures in Table intelligibility. speech with goals. They can also be compared general acoustical in assist to specific rooms in levels noise anticipated evaluating noise reduction problems. as such be from an exterior source may sounds Undesirable in as speech be generated may automobiles or aircraft, or they They apartment. or music in an adjacent classroom an adjacent 119 (a) Sound Transmission Class (STC) 1/4" 1/80" 1/21" Air Space .030 Vinyl 1/4 " 1/81" 1/4" 1" Air Space 1/4" 35 3/4" 36 1/4" Laminated 1" 1/2" 1/2" 1/4" Laminated 38 - 1/2" Air Space - 2 3/4" Insulated glass 4 3/4" Insulated glass 6 3/4" Insulated glass 1/2" - 1/4" 1 " Plate or Float 1/4" - - 1 1/2" Insulated glass 3/4 " Plate or float 1 " Insulated glass STC 23 28 31 31 34 - - 1141" Plate or float 1/2 " Plate or float 1 " Insulated glass 1/4 " Laminated Outside Light 1/8" Construction Space Inside Light Type and Overall Thickness 1/8 " Plate or float - 2" Air Space 4" Air Space 6" Air Space 1/4" 1/4" 1/4" 37 39 40 42 (b) Transmission Loss (dB) Frequency (Hz) 125 160 200 250 315 400 500 630 800 1/4 inch plate glass - 24 22 24 21 24 23 21 23 26 1000 1250 1600 2000 2500 3150 4000 33 36 37 39 40 40 29 31 33 36 40 41 44 28 STC 27 1 inch insulating glass with 1/2 inch air space - 31 STC 25 30 25 29 22 26 24 20 27 27 32 30 34 35 33 1 inch insulating glass laminated with 1/2 inch air space - 38 STC 41 40 38 38 37 37 35 34 31 28 Table 2 - 65 60 flat or ribbed panels. tees with topping, hollow core slabs z 0 O ---- 50 z ST - 0.1304 W + 43.48 statistical tolerance ±2.5 STC z 0 0/ 45 40 40 90 80 70 60 50 WEIGHT PER UNIT AREA - (W) IN. 100 Fig. 43 120 Assembly No. STC lIC 49 55 - 58* - 63* 58 54 - Wall Systems 1 2 3 4 5 6 4 in. flat panel, 54 psf 6 in. flat panel, 75 psf Assembly 2 with wood furring, 3/4 in. insulation and 1/2 in. gypsum board Assembly 2 with 1/2 In. space, 1 5/8 in. metal stud row, 1 1/2 In. Insulation and 1/2 in. gypsum board 8 in. flat panel, 95 psf 14 in. prestressed tees with 4 in. flange, 75 psf Floor-Celling Systems 7 14 in. prestressed tees with 2 in. concrete topping, 75 psf 54 24 8 Assembly 7 with carpet and pad, 76 psf Assembly 7 with resiliently suspended acoustical ceiling with 1 1/2 in. mineral fiber blanket above, 77 psf 54 72 59 51 10 11 12 Assembly 9 with carpet and pad, 78 psf 8 in. hollow-core prestressed units, 57 psf Assembly 11 with carpet and pad, 58 psf 59 50 50 82 28 73 13 8 in. hollow-core prestressed units with 1/2 in. wood block flooring adhered directly, 58 psf 51 47 Assembly 13 except 1/2 in. wood block flooring adhered to 1/2 in. sound-deadening board underlayment adhered to concrete, 60 psf 52 55 15 Assembly 14 with acoustical ceiling, 62 psf 59 61 16 4 in. flat slabs, 54 psf 49 25 17 5 in. flat slabs, 60 psf 52* 24 18 6 in. flat slabs, 75 psf 55 34 19 8 in. flat slabs, 95 psf 58 34* 20 10 in. flat slabs, 120 psf 59* 31 21 5 in. flat slab concrete with carpet and pad, 61 psf 52* 68 22 10 in. flat slab concrete with carpet and pad, 121 psf 59* 74 9 14 *Estimated values Table 1 121 Impact Insulation Sound Transmission Loss 70 -- 60-- -o 8in.hollow core, STC-50 C', C', 0 -. 1 -j 50--- w z 0 C') 40 -- - 6in.hollow core. STC-48 z z 0 0 - 30- -- -- - a., I- - 20-- 10. c.4 0 0 '4 ) C4 00000V0 a0 - An 0 0 0 q1W 00 ' 4'0 0 0 n 0 C 0 0 0 0 '00 FREQUENCY, Hz Fig. 44 woso ... 60 1101 -. '-,0 - PNC 65 ver y ,PNC 60 noisy PNC 55 nos .:NC 50 401moderate PNC PNC 45 4o ao 0 2 25 ver -PNC PNC 15 threshold of hearing OCTAVE BAND CENTER FREQUENCY, Hz Fig. 45 122 may be direct impact-induced sound such as foot-falls on also roof a lightweight on impact rain above, floor the construction or vibrating mechanical equipment. the designer must always be ready to accept the task of Thus, as sound many potential sources of intruding the analyzing at to their frequency characteristics and the rates related to be is The level of toleration that occur. they which be must space the occupy will who those by expected of charcteristics Fig. 46 gives the spectral established. exterior noise sources. Fig. 47 provides similar data common on common interior noise sources. Establishment of Noise Insulation Objectives minimum to the is specified as control acoustical Often values of the dividing partition system. Municipal insulation of Department lending institutions and the codes, building STC airborne both list (HUD) pment Develo Urban and Housing living different for values IIC impact and values As an examp le, "HUD Minimum Property Standard environments. Multiple Housing" has the following requirements: STC Location of Partition Between Between living units living units and p ublic Location of Between Between space Floor-Ceiling living units living units and public space 45 50 STC I IC 45 50 45 50 the objectives are established, the designer then should Once and 1., Table data, e.g., Fig 43 or available to refer select the system which best meets these requirements. In this can systems have superior properties and concrete respects, with minimal effort comply with these criteria. Composite Wall Considerations otherwise an Doors and windows are often the weak link in effective sound barrier. Minim al effects on sound transmission of will be achieved in most cases by a proper selection loss 2 Mounting of the glass in its frame should be Table glass, the reduce to eliminate noise leaks and to with care done vibrations glass plate Sound transmission loss of a door depends on its material and and the sealing between the door and the frame. construction, There is a mass law dependence of STC on weight (psf) for both wood and steel doors. The approximate relationships are: For steel doors: STC = 15 + 27 log W the doors: STC = 12 + 32 log W where W = weight of wood For 123 120 jet aircraft takeoff 5100ft 100 bus w 80 heavy truck -20 f t w propeller aircraft akoff-500 ft - cc 60 automobiles - 20 ft LU 40 z 0 W, 20 0 63 125 250 500 1000 2000 4000 8000 FREQUENCY, Hz Fig. 46 120 S100 80 in w 60 40 C 20 20 20 63 125 250 500 1000 2000 4000 8000 FREQUENCY, Hz Fig. 47 124 door, psf These are relationships deviation can be expected for 48 Fig isolation elIements, purely empirical any given door. and a large acoustic the effective used to calculate be can of a composite wall system which contains of a each with known individual transmission loss data. Leaks and Flanking with an otherwise The performance of a building section small can be seriously reduced by a relatively STC adequate hole or any other path which allowssound to bypass the paths barrier. All noise which reaches a space by acoustical called flanking. through the primary barier is other than windows, flanking paths are opennings around doors or Common connections, and television electrical outlets, telephone at and duct penetrations. pipe and Although not easily quantified, an inverse re lationship exists between the performance of an element as a pr imary barrier and its propensity to transmit flanking sound. In other words, the probability of existing flanking paths in a c oncrete structure is much less than in the one of steel or w ood frame. Vibration Isolation equipment with of vibrations produced by The isolation be frequently can starting forces of operation unbalnced concrete heavy by mounting the equipment on a accomplished is type resilient supports. A slab of this on placed slab called an inertia block. gravity blocks can provide a desirable low center of Inertia large bt generated as those for theusts such and compensate a "house weight, less unbalanced with equipment For fans. slab is sometimes used below the resilient mounts to keeping" a rigid support for the mounts and to keep them above provide inspect. to where they remain cleaner and easier the floor glass This slab may also be mounted on pads of precompressed fiber or neoprene. If static deflection of the floor is more than a small mounts, resilient the static deflection of the of fraction of the part danger that the floor will act as is a there system. Prestressed concrete floors supporting such vibrating 125 equipment can be built stiff to avoid this effect. A deflection much less than the o the rwise satisfactory 1/360 of the span, away from its c ent er, also reduces static deflection. ca o 1-- 2 of total area of wall occupied by window or openin -Percent o S-door, z o 10 10 - 15 15-e 200 30 40 -j I 50 60 - 1 2 - 3 4 5 6 78910 15 20 30 40 5060 DECIBELS TO BE SUBTRACTED FROM TL OF WALL FOR EFFECTIVE TL OF COMPOSITE BARRIER Fig. 48 126 THERMAL PROPERTIES General heat and standards prescribe in many ways the codes Thermal is it buildings. Therefore, for requirements transmission heat important to have basic knowledge about the heat loss and design many materials. Some of the fundamentals and of gain losses heat the compare and to analyze needed are that aids envolopes. building and heat gains through unique prestressed concrete construction have a and Precast storage thermal and thermal inertia with their advantage codes, some in recognized is advantage This properties. heavier to account for the bennifits of procedures however, materials are not usually given. given trend is toward more insulation with little regard The that assuming Before to its total impact on the energy saved. area, glass less is needed, mass effects, insulation thick be should controlled ventilation and infiltration reduced building include may considerations Further considered. from reflections or shading color, exterior orentation, vegitation, or surfaces surrounding structures, adjacent direction aspect ratio, number of stories, and wind building and speed. that noted the information and design criteria where Execpt of "Handbook from or derived from ASHRAE taken are follow Fundamentals", also known as the ASHRAE Handbook, and from the Building 90-75, "energy Conservation in New Standard ASHRAE Design", also known as the ASHRAE Standard. Thermal Properties of Materials, Surfaces and Air Spaces based The thermal properties of materials and air spaces are of number the established tests The tests. state on steady to units (Btu) that pass from the warm side thermal British temperature degree per hr ft per sq per side cool the results either side of the item being tested. The difference of the tests determine the conductivity, k, per inch thickness compound non-homogeneous For sections. for homogeneous conductance, and air spaces the tests determine the sections C, for the total thickness. The values k and C do not include conductances. The inside surface conductance, fi, and surface the outside surface conductance fo, are considered separately. The resistance method is used to determine the overall thermal of wall, floor and roof sections. Therfore, the effectiveness resistance, R, i.e., the reciprocal of k, C, fi, Nd fo must be not are materials construction of The R-values known. hand other the the direction of heat flow. On by influenced on depending the surfaces and air spaces differs R of the 127 orientation, horizontal. of velocity properties. or s 1op ing is whether they are vertical, that Also the R-values of surfaces are eff ected by the ref Iect ive their by the surfaces and at air surfaces and 4. give the thermal resistances of 3 . Tables 3 1/2 in. air spaces. Values in Table 4 . can be used for and all air space thickness with very little change in the overall flow heat Where exception. one with section, of the R Table down, the procedure given in footnote 1, is direction 4 should be used. used 5. gives the thermal properties of most commonly Tab le since given are u-values only glass, For materials. bui Iding The resistance. thermal no almost has alone the glass of the surfaces of the glass contribute mostly to res istances the U-va Iue. weight various of the thermal properties gives Table 6 gives also It concretes. insulating including concrete, concrete prestressed used the commonly some of f o R-values floor, roof and wall units. determined and resistances are usually conductances Thermal dry oven their in materials building for reported and condition. Conductances and resistances for concrete are often reported in its normally dry condition as well as its oven dry concrete of condition the is dry Normally condition. an equilibrium amount of free water after extended containing Values warm air at 35 to 50% relative humidity. to exposure considered in the tables are based on concrete that is given normally dry. combination should be noted that normal ly dry concrete in It as R-value same insulation generally provides about the with be noted also It should concrete. dry oven insulated equally content, normally dry concrete, because of its moisture that oven ability to store a greater amount of heat than the has dry concretes, a property somewhat beneficial when considering dynamic thermal response of concrete. Thermal Storage Effects of roofs and has been known that walls it time some For temperature to react material massive any or concrete cooling and and therefore reduce heating slowly variations has engineering application of this concept however, loads, now to only estimating mass effects. Computers limited been it possible to better account for mass effects with hour make by hour calculations for 24 hours, a week, a month, or a year. the as that load computer studies show peak 24-hour Some loads of walls increases the heat flow rates and peak weight roofs two Fig 49. compares the heat gain through decrease. exposed different weights but with equal U-values and having 128 Thermal resistances, Rf, of surfaces Still air, RU Position of Direction of Surface Heat Flow Vertical Horizontal Horizontal Up -Down Nonreflective Surface Reflective Surface Nonreflective Surface 0.68 0.61 0.92 Moving air, RI A (_) B_(2) 15 mph 3( 1.35 1.10 2.70 1.70 1.32 4.55 0.17 0.17 0.17 7% mph( 4 0.25 0.25 0.25 (3) Winter design (4) Summer design (1) Aluminum painted paper (2) Bright aluminum foil Table 3 Thermal resistances, R., of air spaces 1 ) Position of Air Space Direction of Heat Flow Air Space Mean Temp. *F Reflective Surfaces Nonreflective Surfaces One SideMs One Side 3) Both SidesM 10 30 1.01 0.91 2.32 1.89 3.40 2.55 3.63 2.67 10 0.85 2.15 3.40 3.69 10 30 0.93 0.84 1.95 1.58 2.66 2.01 2.80 2.09 - 1.23 3.97 8.72 10.37 - 1.00 3.41 8.19 10.07 Temp. Diff. *F Winter Horizontal (walls) 50 50 Horizontal (walls) 90 Up (roofs) 50 50 Down Horizontal (floors) 50 Summer Vertical Winter Summer Down (rr afs) 90 (1) For 3 1/2 iri. air space thickness. The values with the exception of those for reflective surfaces, heat flow down, will differ about 10% for air space thickness of 3/4 in. to 16 in. (2) Aluminum painted paper (3) Bright aluminum foil Table 4 129 Thermal properties of various building materials1l) Material Insulation, rigid Cellular glass Fiberglass Mineral fiber, resin binder Mineral fiberboard, wet felted, roof insulation Wood, shredded, cemented in preformed slabs Polystyrene - cut cell surface Polystyrene - smooth skin surface Polystyrene - molded bead . Polyurethane Miscellaneous Acoustical tile Carpet, fibrous pad Carpet, rubber pad Floor tile, asphalt, rubber, vinyl Gypsum board Particle board Plaster cement, sand agg. gyp, LW. agg. gyp, sand agg. Roofing, 318 in. built-up Wood hard Wood soft Wood plywood Unit Weight, pcf Resistance For thickPer Inch ness shown, of thickR ness, Ilk 8.5 4 to 9 2.63 4.00 15 3.45 16-17 2.94 22 1.67 1.8 4.00 3.5 5.26 1.0 1.5 3.57 6.25 18 2.50 Transmittance, U 2.08 1.23 0.05 50 50 0.90 1.06 116 45 105 0.20 0.63 0.17 70 45 32 34 0.91 1.25 0.83 0.33 Glass doors & windows Single, winter Single, summer Double, wintera Double, summera 1.13 1.06 0.65 0.61 Doors, metal Insulated, winter Insulated, summer 0.19 0.18 for all concretes, including insulating concrete for roof fill. (1) See Table 6. (2) 1/4" air space. Table 5 130 Thermal properties of concrete l) Description Concrete Weight, pcf Concretes including normal weight, lightweight and lightweight Insulating concretes Thickness, In. 145 140 130 120 110 100 90 80 70 60 50 40 0.075 0.083 0.11 0.14 0.19 0.24 0.30 0.37 0.45 0.52 0.67 0.83 30 1.00 20 1.43 Normal weight 2 and solid slabs teesa( 145 Normal weight hollow core slabs 145 Structural lightweight teest2 ) and solid slabs 110 Structural lightweight hollow core slabs (1) Resistance, R For thickPer Inch ness shown, of thickI/C ness, ilk 110 2 3 4 5 6 8 0.15 0.23 0.30 0.38 0.45 0.60 6 8- 1.07 1.34 10 12 1.73 1.91 2 0.38 3 4 0.57 0.76 5 0.95 6 8 1.14 1.52 8 2.00 12 2.59 Based on normally dry concrete (2) Thickness for tees is thickness of slab portion including topping, if used. The effect of the stems generally is not significant, therefore, their thickness and surface area may be disregarded. Table 6 131 to identical summer simulated temperatures. Heating Loads The ASHRAE Handbook recognizes the effects of mass on a building's ability to retain heat, however it does not offer a wall to account for the effect. Computer studies of ten way show conditions weather exposed to ten different each types outward flow heat of walls increases, the as weight that be can U-values result, the steady-state a As decreases. The to account for mass effects on walls and roofs. modified days degree the number of heating as change modifications changes. The modification M-factors are given in Fig. 50. Cooling Loads in the of mass on cooling loads are reflected The effects differences, temperature the use of equivalent by designs and The TDeqw (walls) and 8 . as given in Tables 7. TDeq, sections the of weight the as decrease (roofs) TDeqr increases. Building Envelope Performance and Trade-Off Considerations component permit codes and Standard some ASHRAE The one is, the stated overall Uo-value of any That trade-offs. be may floor, or wall roof/ ceiling, as such assembly, decreased, components and the Uo-val ue for other increased provided the overall heat transmission for the entire building criteria. does not exceed the total allowed by the envelope For buildings where the fl oors are not exposed to the outdoors the allowed overall envelo pe hourly loss is: where: = = = = = temperature differen ce, indoor to outdoor, F overall area of wall s, sq ft overall are of roo f, sq ft overall heat transmi ssion value of walls, Btu/hr ft2 F overall heat transmi ssion value of roof, B tu/hr ft2 F All values in the brackets of the equation can be those given in the code or standard providing the the values is not increased. altered from summation of for altering concept is usefull particularly The trade-off floor or roof criter ia without exceeding the total loss wall, different for the envelope. The concept also permits allowed exposures. and south e, north exampl for on, Uw-values of elements coup led with trade-off of trade-offs Component of such as opaque vs. glass, permit a great deal components, with fewer Also, design. enve lope in building freedom requirements, more efficient building design are prescriptive possible. 132 Heat gain comparison for light and heavy roofs 12 - U (t 8 -- C- 0 8 4 0- 12 20 16 24 (noon) (midnight) Time, hr Fig. 49 Modification factor, M, for heating designs (for use in modifying steady state U-values) 0 0 'U Degree days Fig. Wall temperature difference, TD Weight of Wall lb I ft 2 TD , *F 0-25 44 26-40 37 41 -70 30 71 & above 23 Table 7 50 Roof temperature difference, TD__ Weight of Roof TD@qr lb I ft2 0-10 11-50 51 & above Table *F 70 50 40 8 133 Condensation Control is building on the interior of a condenses which Moisture its or building the to damage cause can and unsightly of condensation the is undesirable more Even contents. it where assembly ceiling or wall building within a moisture in not readily noticed until damage has occurred. Al I air is more carrying water with warm air some contains buildings moisture than cold air. In many buildings moisture is added to or laundering, cooking, industrial processes, by air the a wall, the -inside surface temperature of If humidifiers. or ceiling is too cold, the air contacting this surface floor its be cooled below its dew point temperature and leave will the on occurs surface. Condensation its on water excess surface with the lowest temperature. the of humidity relative the occurs, condensation Once any since increased be cannot building a of space interior cold the on simply condense will vapor water additional an of temperature inside the then, effect, In surface. contained limits the relative humidity which may be assembly any for U-values gives 51 Fig space. interior an in relative inside and temperatures outside of combination humidities above which condensation will occur on the interior surfaces. Relative humidity at which visible condensation occurs on inside surfaces. Inside temperature, 70F* 1.2 100 M La z 0.8 20% o --- z cc 1 Double gi 0.6 -30 - -Storm w 40% I0.4 -- 50% 160 7 0.2 0 -30 -20 -10 0 10 20 30 40 OUTSIDE TEMPERATURE. F Fig. 51 135 FIRE RESISTANCE Introduction prestressed concrete members can be provided with any Precast building by fire resistance that may be required of degree fire companies, and other authorities. The insurance codes, of building assemblies is determined from standard resistance and Testing defined by the American Society for tests fire Materials. To insure that fire resistance requirements are satisfied, the various by use tabulated information provided can engineer authoritative bodies, such as Underwriters Laboratories, Inc., codes. American Insurance Association and model building the fire standard of results on the based is information This other and ceilings include may that assemblies of tests "Fire UL the of edition 1978 The components. building Directory" alone provides information on more than Resistance concrete prestressed incorporating precast assemblies, 120 members. of resistance fire of tabulated data, the absence the In be can concrete members and assemblies prestressed precast calcultaions These most cases by calculation. in determined based on engineering principals and take into account the are the as known standard fire test. This is a of conditions is It resistance. fire determining of Design Method Rational the by part in sponsored research extensive on based Portland Concrete Institute and conducted by the Prestressed Cement Association and other laboratories. Standard Fire Tests of Prestressed Concrete Assemblies America test of a prestressed concrete assembly in fire The Standards. of in 1953 at the National Bureau conducted was Since that time, more than 150 prestressed concrete assemblies America. in tests fire standard to subjected been have of many of the tests were conducted for the purpose Although were tests the of most ratings, fire specific serving whose studies conjunction with broad research in performed prestressed of objectives have been to understand the behavior these to fire. The knowledge gained from subjected concrete fire of lists (1) of development resulted in the has tests procedures (2) and components, concrete prestressed resistive for determining the fire endurance by calculation. have elements types of prestressed concrete different Many tees, double joists, elements These tested. fire been slabs, tees, single tees, solid slabs, hollow-core mono-wing In beams. I-shape and beams, ledger beams, rectangular wall roofs with thermal insulation and loadbearing addition, elements these also been tested. Nearly all of have panels 136 been exposed directly to fire, but a few tests have been have protection additional specimens that received on conducted etc. ceilings, coatings, from the fire by spray-applied Fire Tests of Flexural Elements of en durance a that the structural fire shown have Tests on depends t elemen concrete prestressed precast flexural factors, the most important of which is the method of several fact ors Other unrestrained. or restrained i.e., support, size and shape of the element, thicknes s of cover (or include the of ce nters between the distance the precisely, more surfac e), and the nearest fire-expo sed tendons prestressing as endurance load intensity. The fire and type, aggregate of the rise temperature for criteria the by determined unexposed surface (heat transmission) depends pr imarily on the concrete thickness and aggregate type. Single Course Slabs unexposed the the temperature rise of slabs, concrete For depends mainly on the thickness and agg rega te type of surface unit inc lude factors important less Other concrete. the weight, moisture condition, air content, and max imum aggregate strength, Within the usual ranges, water-cement ret io, size. and age have only insignificant effects. (heat transmission) of 52 shows the fire endurance Fig thickness. and type slabs as influenced by aggregate concrete by obtained slab, this thickness may be hol low-core For a curves The width. by its area sectional dividing the net cross air-entrained concrete made with air-dry aggregates represent a nominal maximum size of 3/4 in. and fire tested when havibg the was at the standard moisture condition. On concrete the lightweight, as designed are aggregates concrete graph, sand-lightweight, carbonate, or siliceous. in unit generally increases with a decrease endurance Fire of the infl uence concretes, structural for but weight, aggregate type may overshadow the effect of the unit weight. improved concrete, fire endurance is For normal weight for this reason The size. the maximum aggregate decreasing a decrease with increases cement paste content the that aggregate size. Members Restrained Against Thermal by is in Expansion large a of beneath an interior portion occurs fire a If to tend the heated portion will slab, concrete reinforced In and push against the surrounding part of the slab. expand the unheated part of the slab exerts compressive forces turn, the heated portion. The compressive force, or thrust, acts on the bottom of the slab when the fire test occurs but, as near 137 the fire progresses, the line of action of the thrust rises as mechanical properties of th e heated concrete change. This the thrust is generally great enough to inrease the fire endurance significantly. be expansion to thermal can of restraint The effects The thermal thrust acts in as shown in Fig. 53 characterized which, force, similar to an external prestressing a manner increases the positive moment capacity. to the in bending moment capacity is similar increase The effect of added reinforcement located alond the line o f action the thrust. It can be assumed that the added reinf o rcement of By this thrust. strength (force) equal to the yield has and magnit u de the to determine possible is it approach, fire giv e n a thrust to provide required the of location endurance. Code and Economic Considerations to is of dealing with fire resistance aspect important An understand what the benefits are to the owner of a buildi ng in his in incorporated materials of selection proper the and code areas, fall into two These bennifits structure. economics. of codes are laws that must be satisfied regard l ess Building the represent i ng d esigner, The considerations. other any in the no option in the code regulations., only has owner, regulations. these materials and assemblies that meet designer/owner benefits are often overlooked by the Economic at the time decisions are made on the structural system. team through of fire resistive construction consideration Proper economic owner the will provide analysis cost life-cycle bennifits over other types of construction in many areas, e.g. under areas larger allowable gross costs, insurance lower and types of building construction, fewer stairwells certain mortgage longer value for loan purposes, increased exits, terms, and better resale value. To ensure an owner of the best using analysis his investment, a life-cycle cost on return fire resistive construction must be prepared. of history the is considerations theoretical the Beyond es. fir in actual excellent performance of prestressed concrete Structural integrity has been provided, fires are contained in the area of origin, and, in many instances, repairs consist of of re-occupany leading to early only treatment "cosmetic" structure. 133 Fire endurance (heat transmission) of concrete slabs 5 4 CC, X z LU 1 1'/2 5 4 3 2 7 6 SLAB OR PANEL THICKNESS, IN Fig. 52 Axially restrained beam during fire exposure C.G T 4 @ 0 Hr, T-0 1 M M Te @3 Hr (curved due to deflection of beam) Fig. 53 139 COORDINATION WITH MECHANICAL, ELECTRICAL AND OTHER SUB-SYSTEMS Introduction buildings is used in a wide variety of concrete Prestressed of is services other and plumbing lighting, mechanical, with importance to the designer. Because of increased environmental electrical and of costs for mechanical ratio the demands, installations to total building has increased substancially in recent years. This section is intended to provide the designer satisfy economically to perspective necessary with the some and electrical requirements, and to describe mechanical of the installation of other sub-systems. Lighting and Power Distribution For many applications, the designer can take advantage of fire resistance, reflective qualities and appearance of prestressed structure by leaving the columns, beams and ceiling concrete high using reflective paint and properly spaced By exposed. flourescent lamps installed in a continuous strip, the output designer can achieve a high level of illumination at a minimum concrete precast these reflective paints, using By cost. convential as be made as efficient can channels lighting fluorescent fixtures. Electrical Floors machines, and other increasing use of business The and adequate for the need stresses systems communication communication electricity and of suppling flexible means on service. Since a cast-in-place topping is usually placed prestressed floor members, conduit runs and floor outlets can shallow height buried within this topping. With be readily electrical systems, a comprehensive system can be provided in for conduits thin topping. The total height of a resonably 1-3/8 comprehensive electrical systems is as little as these in. Most systems can easily be included in a 2 to 4 inch thick electrical as Voids in prestressed slabs can be used slab. raceways as shown in Fig 54 When the system is placed in a structural composite slab, the and ducts and conduits must be carefully examined of effect Tests on coordinated with reinforced steel. location their structural that shown have ductwork burried with slabs strength is not normally impared by the voids. of prestressed high load-carrying capacity the of Because high-voltage to locate it is possible concrete members, of areas near the transformers, heavy with substations, consumption with little or no expense. 140 30 AMP. 125 VOLT ELECTRICAL. OUTLET ELECTRICAL PANEL SINGLE STATION TEEPON OR0 +P4ONOUTLET TELEPONE SUPPLY CLOSET L15=04MCIL25 0 ffr S-ke FINISH FLOOR 2" FLOOR PILL TELEPONE CULL CAPACITYt 30 1.4.S CULL AREAs 27.1 SQ. IN. (' PLUS SLAS) 1e Fig. 54 141 Ductwork The designer may also utilize the space within the holes inside prestressed hollow-core concrete slabs for distribution ducts for heating, air-conditioning, or exhaust systems. These have oval, round or rectangular voids of varying size members systems. can provide ducts or raceways for the various which in cores drilled in the field can provide access and Openings distribution. The voids in the slabs are aligned and connected to provide continuity of the system. Other Sub-Systems ceilings, crane rails, and other sub-systems can be Suspended items accomodated with standard manufactured hardware easily and embedded plates as shown in F ig 55 Systems Building As more and more systems buildings are built with precast and of method this in intrest as and concrete, prestressed the of more that expect can we increases, construction building sub-systems will be prefabricated and pre-coordinated with the structure. This leads to the conclusion that those parts of the structure be logically should skills labor most the require that The field. the in installation to prior prefabricated basic of preassemblies be can components prefabricated systems or electrical/mechanical. To reduce on-site plumbling combination or units bathroom prefabricated labor, Fig modules have been developed as shown in bathroom/kitchen Such units include bathroom fixtures, kitchen cabinets and 56 as well as wall, ceiling, and floor surfaces. Plumbing sinks, to are often connected and assembled prior to delivery units molded sites. These bathroom/kitchen modules can be job the To components. drywall from fabricated or units plastic on the built be plant can module the floor, double a eliminate designed be or the walls of the unit can member structural enough for all fixtures to be wall hung. In the latter strong the units are placed directly on a Drecast floor and in case with are located in a stack f ashion mult-story construction a directly over the one below. A bloc k-out for bathroom one are conn ections is provided in the precast floor and chase made from each unit to the next to provide a verti cal plumbing in wet-wall plumbing systems, as shown Prefabricated stack. Fig 57 , incorporate preassembled piping systems using snap-on or no-hub connections made up of a variety of material s. These flooring prestressed require a block-out in the only units economy and are also arranged in a stack fashion. Best units a bathrooms are backed up to each other, since when results bathrooms. common vertical run can service two Some core modules not only feature bath and kitchen 142 components, but also HVAC components all packaged in one unit. prestressed can also be easily accomodated in modules These structural systems by placing them directly on the prestressed members with shimming and grouting as required. 0 ;0-1..... 00 ''.. 0 0 0 O.00-0-0Q .OD' 010QQQ 0 0 0 0 Fig. 55 143 Kitchen/bathroom modules can be pre-assembled on precast prestressed slabs ready for installation in systems buildings Fig. 56 144 Prefabricated wet-wall plumbing systems incorporate pre-assembled piping Fig. 57 145 STRUCTURAL FASTENER High-Strength Bolts by designed The two basic types of high-strength bolts are hexagon-head heavy ASTM and A490. These bolts are as A325 bolts, used wi th heavy semifinished hexagon nuts, as shown in in bolts 58. The threaded portion is shorter than for Fig A325 rolled. and may be cut or nonstructural applications, an having steel medium carbon heat-treated bolts are of on depending ksi 92 to 81 of approximate strength yi eld alloy of are but heat-treated also are bolts A490 diameter. ksi steel having a n approximate yield strength of 115 to 130 depending also on diamater. bo High-strength comm on most The 3/4 in. and 7/ 8 design are 3/4 i n in. from 1/2 to 11/2 range in diameter Its are diameters used in building construction bri dge in., whereas the most common sizes in . and 1 in. High-strength bolts are tightened to develop tensile stress in the on in a predictable clamping force results which them is joint a through loads service of joint. The actual transfer being pieces the in developed due to the friction therefore, designed are containing high-strength bolts Joints joined. ultimate for basis the is slip where type, friction as either or as bearing type, where bearing of the bolt shank strength; against the hole is the basis for ultimate strength. with ca librated bolts may be either these of Instal lation wrench ordinary wrenches, aaor more commonly with any torque Ives invo method r using the "turn-of-the-nut" method. The latte the from starting making an additional angular turn of the nut snug position. Ribbed Bolts bolts of ordinary rivet steel which have a rounded head These and raised ribs paral lel to the shank were used for many years given alternative to rivets. The actual diameter of a an as into hole the than larger slightly is bolt ribbed of size bolt the bolt, ribbed In driving a driven. is it which a producing hole the edges around the into cuts actually particularly was bolt This type of fit. tight relatively had which bearing connections and in connections in useful stress reversals. A modern variation of the ribbed bolt is the interference-body shown in Fig 58 which is of A325 bolt steel and instead bolt wel I longitudinal ribs has serrations aro und the shank as of around serrations the of Because to the shank. parral lel as an called often the ribs, this bolt is through shank the 146 bolt. Ribbed bolts are interrupted-rib bolt in the hole is desired and it the of turning the nut without the s means head as may be requried with bolt the bolts. A325 ordinary Ttpes of used when tight fit permits tighten ing multaneous hold ing fitti loose smooth of by of ng High-Strength Bolts At the present time the two basic types of high strength bolts A490, the A325 bolt, for most common situations, and the are for use on higher strength steels where an excessive number of is bolt A325 otherwise be required. The might bolts A325 on apart degrees 120 by three radial lines spaced iodentified and heads Both types of bolts have heavy hexagon head. the Another nuts. hexagon semifinished heavy with come their is bolts A325 and A490 the both of characteristic it thread lengths, the shorter thread lengths making shorter to exclude the threads from the shearing plane. Figure easier and A325 Table 9. show the control dimensions for and 59. A490 bolts and the methods of identification. bolts ASTM A490 bolts are substituted for A325 Occasional ly, bolts A490 longer thread dimension is required, the a when standard as same hexagon head and thread length the having A307 bolts but having the same strength as A325 bolts. bearing for A variation of the standard A325 and A490 used have a bolts These olt. b interference-body is the connections high-strength and may be used with the standard head button type interference-body with self-locking nuts. The or nuts bolts have particular applications wher e high bearing capacity is desired together with stress reversa Is or vibratory loads. Installation Techniques required the developing general methods of two are There calibrated One is called the pretension indicated in Table ... wrench method and the other the turn-of-the-nut method. The calibrated wrench method includes the use o f manual torque specific power wrenches adjusted to stall at a and wrenches of amount the controlling of studies Early value. torque by many perf ormed measurements were torque by pretension investigators including Stewart and Maney. Mane y reported that variations in tensile stresses produced by a gi ven torque were percent. 10 as +/- 30 percent with an verage of + /high as fie Id by this variation, which was also confi rmed to Due Bolted and Rivet ed on Council Research the experience, calibrated has recommended that torque or Joints Structural in be set to produce a bolt tension 5 to 10 percent wrenches excess of the value indicated in Table... in the early 1950's and Beginning was method turn-of-the-nut the 1960's continuing into the the whereby developed 147 High-strength hexagon head bolt High-strength interference-body bolt Fig. 58 High-Strength Bolt Dimensions Nut Dimensions. In. Bolt Dimensions, In. Nominal bolt size. D Heavy Hex Structural Bolts Height. H Width across Bats F Heavy Hex Nuts Thread length % % %. %" 116 0/6 1%f % I'/, 1/8 %/ 1%. /6 "/. Is/ 1%1l'. 2 1/, 11/ 2./m 2% 1 "/.4 'w 2/3 './Is Fig. 1 % 1 "/ / /, 1%.1 1% 1%/ 11'%. 2 21/4 21/ 31/4 11/. 1%/ 2 Height. H Width across flats W "4/6. "/.4 1%." 1%3 2 2 2% 1/32 1 ' %3/ 59 AISC- 1.23.5 IEqual to 70 percent of specified minimum tensile strengths of bolts, rounded off to the nearest kip. Table 9 148 specified a in the bolt is obtained by force pretensioning which position nut from an initially snug the of rotation to a specific amount of strain in the bolt. According causes Joints, Structural Bolted and Riveted Research council on the nut is considered to be snug when impacting first begins as it or being tightened by an impact wrench. Although snugness is the of condition the to due vary can tightness initial surfaces being tightened, this variation is not significant. inadequate wonder whether there is danger of having may One load; proof if the pretension exceeds the strength reserve when it approaches 90 percent of the ultimate strength. i.e., with 60 shows the effect of various turns of the nut Figure wrench calibrated the safety indicated. If of margin the the with factor, strength is the critical used is method of possibility The shown in Fig 60 margin safety typical a considered not is wrenches overtorquing the bolts with power bolts the fractures usually such overtorquing since problem the In installation. during replaced are they and factor critical the is deformation method, turn-of-the-nut either For typical safety margin shown in Fig 60. the with turns one can expect a minimum of 21/4 process installation from snug to fracture. When the turn-of-the-nut used and bolts are tensioned using 1/8 turn increments, frequently as many as The fracture. to snug from obtained be may turns four method is the cheapest, is more reliable, and turn-of-the-nut is generally the preferred method. method requirements, as approved by AISC-1.23.5,are given The the Research Council 1966 specifications. The approved nut by rotations are indicated in Table 61 Friction-Type and Bearing -Type Connections 1969 provides for two categories of high-strength bolted AISC in Bolts bearing-type. and the friction-type the joints, either type of joint are installed by the same process so that bolted the pretension is provided. Performance of same the load service identical; is loads service under joints the between difference The friction. by is transmission friction-type and bearing-type connection lies entirely in the factor of safety provided against slip under overloads. higher the has so called because it is friction-type The stress when suitable thus and slip safety against of factor of or cyclical loading may occur. The higher factor reversal safety provides good fatigue resistance. not is is so named for use when it joint bearing-type The to overload occasional under occurs slip if critical deemed hole. the bolt shank into contact with the side of the bring by transfered is the stress loading, subsequent any For in combination with bearing on the plate. As long as friction once; only occur will slip such static is loading the 149 thereafter the bolt is already bearing against the material the side of the hole. at %Turn 60 Safety margin for strength (calibrated wrench tensioning method) 50 .9. ~4a 40 30 0 20 10 0.05 0.20 0.15 0.10 Bolt elongation, inches Fig. 0.25 60 Nut Rotation" from Snug Tight Condition (from Ref. 7) Disposition of Outer Faces of Bolted Parts Both faces normal to bolt axis, or one face normal to axis and other face sloped not more than I : 20 (bevel washer not used) Bolt length b not exceeding 8 diameters or 8 inches Bolt length bexceeding 8 diameters or 8 inches Both faces sloped not more than I : 20 from normal to bolt axis (bevel washers not used) For all length of bolts 3/4turn 2/3 turn 1/s turn a Nut rotation is rotation relative to bolt regardless of the element (nut or bolt) being turned. Tolerance on rotation: 30' over or under. For coarse thread heavy hex structural bolts of all sizes and lengthband heavy hex semi-finished nuts. Bolt length is measured from underside of head to extreme end of point. Fig. 61 150 BI BL IOGRAPHY 151 Evans Inc., Gerw ick, Wiley & Construction of Prestressed Sons, Inc., 1971. Concrete of Prestressed Concrete Structural Analysis, Magne I, 1954. Prestressed Rud. Structu res, in Bechtold Publishers, & Sons, Publications, Architecture, Ltd., Watson-Guphill Parker, Simplified Design of Rei nforced Concrete, John Sons Inc., 1976. Institute, Architectural Concrete Precast Precast Concrete Institute, 1973. & John W & Sons Housing, John Wiley Concrete, Concrete Concrete Precast Morris, Publications, 1978. &3, 1,2 Intext Educational Hollard, Nachman, Yackev, Macsai, Inc., 1976. John Concrete Structures, Koncz, Manual of Precast Concrete, vol Company, 1971. Design 1955. Hall, Nostrand Van Engineering, of Handbook Co., 1974. Mc Cormac, 1975. and Bennett, Prestressed Concrete, Chapman and 1958. Fintel , Reinhold Lin, Inc., Concrete, Prestressed of Theory 1963. Chi & Biberstein, Prentice-Hall, Inc., & Drewett Concrete, Knapp, Reinforced Prestressed Billig, Sons, Ltd., 1944. Wiley & Concrete, Precast Concrete Institute, Precast Concre te Institute Design Precast Concrete Precast Prestressed Concrete, Precast Handbook Institute, 1978. Sollenberger, & Preston Graw-Hill Inc., 1967. & Johnson, Salmon 1971. Inc., Large Sebestyen, Academy Hungarian Walley, Steel Modern Prestressed Concrete, Structures, Harper & Row, Panel Buildings, Publishing of Sciences, 1965 Mc Publishers House Prestressed Concrete Design and Construction, of the London: 152 Her Majesty's The Stationery Office, following are manufacturers 1953. published catalogs: Flexicore Northeast Schokbeton San-Ve I Spancrete 153