N62473-10-D-5403-X066
P-565 E-2C/D Hangar & Apron Alterations
Naval Base Ventura County
Point Mugu, CA
Basis of Design
4.0
STRUCTURAL
4.1
General Project Description
The project scope involves three new controlled facility addition to the existing hangars.
In addition to the new additions, the new 5 ton crane is installed under the existing
hangar roof frame.
Seismic retrofit of the existing building is not included in the scope.
4.2
Structural Systems
4.2.1
The Gravity System
Concrete filled roof metal deck over steel wide flange beams. CMU bearing walls
are designed to support steel beams
4.2.2
The Lateral Load Resisting System
The lateral load resisting system for the new one story building addition consists of
a one-story special reinforced masonry shear wall system. Since each building has
only three side walls, the roof diaphragm is assumed to be rigid diaphragm by using
concrete filled metal deck system. Torsional effect is checked with Code allowed
limit.
4.2.3
Slab on Grade
The concrete floor slab for the addition shall be a 6-inch thick slab reinforced with
#5 rebar at 16-inches on center, each way. The interior slab on grade shall be
underlain by a 2-inch thick sand blanket over a ten mil PVC or polyethylene
membrane over a 4-inch clean gravel layer under the membrane to prevent
moisture migration.
4.2.4
Foundations
The foundation design is provided based on the soils report prepared for nearby site
(P-900 Triton Maintenance Training Facility, dated Oct 2013 and prepared by GeoLogic Associates, San Diego, CA.) The foundation for the single-story masonry
building addition is a 2’-0” wide x 2’-0” deep continuous wall footing.
Estimated allowable bearing pressure:
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a. 1,500psf: Dead plus live load (for shallow continuous footings)
b. Pressure is allowed 33% increase for wind and seismic load
Passive pressure of 300pcf
Coefficient of sliding resistance – 0.32
For Retaining Walls:
a. 35 pcf: Lateral earth pressure (active)
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N62473-10-D-5403-X066
P-565 E-2C/D Hangar & Apron Alterations
Naval Base Ventura County
Point Mugu, CA
Basis of Design
b. 55 pcf: Lateral earth pressure (at rest)
c. Surcharge shall be applied as uniform (rectangular) pressure
distribution by Pressure = 0.5 x surcharge load
 Liquefaction potential at the site is considered to be low to moderate
 10 mil PVC or polyethylene membrane with a two-inch sand blanket on top
and a 4-inch clean gravel barrier on the underside of the membrane is
required under any new slab-on-grade.
** Existing steel columns are supported by either concrete piles with pile cap or steel
piles with pile cap. The compressive and tensile capacity of the foundation system is
available in the existing drawings.
4.3
Design Code and Criteria Reference
The project will comply with applicable Federal and local regulations and shall be
designed primarily in accordance with UFC Criteria and industry standards as modified
by the UFC. The following references, codes and standards shall be used for structural
design:
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UFC 1-200-01, General Building Requirements, 01 July 2013 with Change 1, 01
September 2013
UFC 3-301-01, Structural Engineering, 01 June 2013
UFC 3-310-04, Seismic Design of Buildings, 01 June 2013
UFC 4-010-01, DoD Minimum Antiterrorism Standards for Buildings, 09 February
2012 with Change 1, 01 October 2013
UFC 4-211-01N, Aircraft Maintenance Hangars: Type 1, Type II, and Type III,
dated 25 October 2004 including Change 3, 16 December 2009
International Building Code 2012 (IBC 2012)
ASCE 7-10, Minimum Design Loads for Buildings and Other Structures including
Supplements No. 1 and No. 2, 2010 Edition
ACI 318-11, Building Code Requirements for Structural Concrete and
Commentary
AISC Steel Construction Manual, 14th Edition
AISC 360-10, Specification for Structural Steel Buildings
AISC 341-10,Seismic Provisions for Structural Steel Buildings
TMS 402-11 / ACI 530-11 / ASCE 5-11,Building Code Requirements for Masonry
Structures
TMS 602-08 / ACI 530.1-08 / ASCE6-08, Specification for Masonry Structures
SDI Steel Deck Institute Design Manual – Code of Recommended Standard
Practice for Metal Deck Construction
AWS D1.1-10, Structural Welding Code – Steel
AWS D1.8-09, Structural Welding Code – Seismic Supplement
AWS D1.3-08, Structural Welding Code – Sheet Steel
AWS D1.4-11, Structural Welding Code – Reinforcing Steel
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Section 4│2
N62473-10-D-5403-X066
P-565 E-2C/D Hangar & Apron Alterations
Naval Base Ventura County
Point Mugu, CA
Basis of Design
4.3.1
Design Loads
Dead Loads
As calculated actual weight of permanent building materials.
Live Loads
Roof 20 PSF (Reducible)
2nd Floor at Elevator:
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Typical .................................................................. 80 PSF
* Note that as built drawing, roof live load is 20 psf when tributary area is less than
200 sqft and 15 psf when tributary area is larger than 200 sqft.
Lateral Loads
Risk Category ………………………………………..…………II
Wind Loads:
Ultimate Design Wind Speed (3 Second Gust) ........ 110 MPH
Exposure ............................................................................. C
Note that design wind speed was 20 MPH per record drawings.
Seismic Loads:
Site Class D
Mapped Spectral Acceleration for Short Periods: SS=2.170g
Mapped Spectral Acceleration for 1-s Period:
S1= 0.909g
Site Coefficients: Fa = 1.00 and Fv = 1.5
Design Spectral Response Acceleration at Short Periods:
SDS= 1.447g
Design Spectral Response Acceleration at 1-second Period: SD1= 0.909g
Seismic Design Category = E
* Note that existing building design seismic zone was 3 per record drawings.
4.3.2
Structural Materials
Reinforced Concrete:
All new concrete shall be normal weight concrete (145 lb/cu. ft) with aggregate
conforming to ASTM-C33. Cement conforming to requirements of ASTM-C150,
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N62473-10-D-5403-X066
P-565 E-2C/D Hangar & Apron Alterations
Naval Base Ventura County
Point Mugu, CA
Basis of Design
with type II or V cement for concrete in contact with soil, and type I/II low alkali
elsewhere.
Reinforced Masonry:
Concrete masonry units shall be medium weight ASTM C-90, with a 28-day design
compressive strength of f’m = 1,500 psi. Mortar shall be type S, with a minimum
compressive strength of 1800 psi at 28 days, and the grout strength shall be a 2000
psi. All masonry construction shall be laid in running bond and grouted solid.
 It is noted that the existing CMU compressive strength used is f’m=1200 psi,
which does not meet the current minimum code requirement.
Reinforcing Steel:
All new reinforcing steel used for this project shall conform to requirements of
ASTM-A615 Grade 60 deformed steel bars and ASTM A706 Grade 60 welded rebar
for concrete and masonry reinforcement, fabricated and detailed to conform to the
requirements of ACI 318/318R-11 and ACI 315-04.
 The reinforcing steel used in the existing building confirms ASTM A15-54,
with fs=24,000psi (Allowable). All bars are deformed per ASTM305-53
Structural Steel:
For all new Structural steel:
W or WT sections:
Other rolled shapes, plates,
Bars and sheets:
Pipes:
Hollow Structural Sections (HSS):
Slip Critical or Friction Bolts:
Bolts, typical unless noted otherwise
Bolts marked MB or A-307:
Nuts:
Anchor Rods:
Grating:
Welding:
ASTM A 992 Grade 50.
ASTM A 36, unless otherwise noted
ASTM A 53, Grade B, Fy = 35ksi.
ASTM A 500, Grade B, Fy = 46 ksi.
ASTM A 325SC or A 325F at
braced frames.
ASTM A 325N
ASTM A 307 or F 1554, Grade 36.
ASTM A 563, Hot forged
ASTM F 1554, Gr. 50
Welded steel grating conform to
NAAMM, Metal Bar Grating Manual.
AWS D1.1, Performed by certified welders.
As-Built/ Existing building
All Steel sections
fb = 20,000psi (Allowable)
Structural Light-Gage Steel:
All structural metal decking shall be galvanized steel conforming to ASTM A653 SS
Grade 40 or ASTM A1003-12 ST40H. Structural metal deck shall meet all
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N62473-10-D-5403-X066
P-565 E-2C/D Hangar & Apron Alterations
Naval Base Ventura County
Point Mugu, CA
Basis of Design
requirements of the UFC as well as the Steel Deck Institute Design Manual. Deck
units shall span 3-span continuous wherever possible and a minimum of 2-spans.
Exterior Light-gage structural cold formed steel studs shall meet all AT/FP
requirements as discussed in Section 9.0, in addition to the requirements of the
UFC and the Steel Stud Manufacturers Association. Exterior studs shall be
galvanized and shall have a minimum thickness of 12 gage. Connections shall meet
the design requirements from forces discussed in Section 9.0.
For non-structural cold formed steel stud framing, the design shall meet UFC
requirements in conjunction with the ASTM C645.
*Note that the material/ specification of the as-built roof deck is unknown.
4.3.3
Deflection Criteria
Roof:
Live Load:
Total Load:
L/360
L/240
Fabricate new steel beams with natural camber up. Remove dead load deflections
in excess of ⅟₂-inch by cambering unless otherwise noted on drawings.
4.3.4
New Crane Addition
Proposed new 5 ton capacity crane system adds more dead/ live loads to the
existing roof frames. Since crane contractor is not available at the time of this
design, we assumed weight of the runway track and girder is 150 lb/ft (wide flange
section.)
5 ton crane live load and roof live load will not be combined for the evaluation of the
current framing system, analysis and design for possible strengthening of the
existing frames.
FOR OFFICIAL USE ONLY
Section 4│5