ATCS4010/6140: Structural Systems
Performance of Structural Framing System
Lecture 3: Steel Frame Construction
:--:"-':":-
"-* :
DESIGN CRITERIAFORTHE SELECTION
SYSTEMS
OF ST"RUCTURAT
If you wish to create a huilding with
a highly i!rcguLa ! Iom:
| '. If you wish to leave the stuclure
exrosed while rctaining a high
rcsktance rating:
20
Choose systems with simple floor and roof ftaming thai are lab cated
mostly on-site,such as
Sitecas tconcret e using any slab system wilhoul beams or ribs
(pages107-12 3)
Liqrht gauge steel framing (paqes 88-9 t)
Platform toame(Pages49-65)
Masonr y constru ction with either concret e slab or wood light floo!
lraming (pages 71 85)
Choose structural sYslems that are inherently resistant to fire and heat'
including
All concret e sYstem s (althoug h ribbed systems may require added
thickne ss in the ribs or slalr, or an applied fireploo fing) @ages
107-l3s )
Heavy timber flame (Pages49-69)
MiU consiru ction bages 7l-85)
Structu ral steel is higNy suscepl ible to loss of strength in a fte and usually must be protected with a fire-resistive finishing system For further
informa iion on the fire resistan ceofvariou s suuctur al systemsand uses
for which they are permiited, see pages 304-3 15
ll yau wish to allow column Placemenls that deviate [rom a regDlar
grid:
Use sysiefis thal do nol include beams orjoists in the floor androof struc-
ff you wish Io minimize floor thick
ne to reduce total building heiqht
The thinnest floor sYstems are conclete slabs s,ithotlt ribs, preferably p!estresse d such as
Sitecas tconcret e two-way flat plate or flat slab (pages ll8-I2l)
Metal space tuame
.xl
Fire Resistance Directory: Underwriters Laboratories Inc.
Modern methods for protection of the steel framing.
Spray-on Fire proofing
grid:
Sitecas tconcret e two-way flat plate or flat slab (pages ll8-I2l)
Metal space tuame
ff you wish Io minimize floor thick
ness to reduce total building heiqht
or ta reduce lloor sqandrel dePth
an the building tacade:
The thinnest floor sYstems are conclete slabs s,ithotlt ribs, preferably p!estresse d,such as
Sitecas tconcret e two-way fla1plate or flat slab, especia lly when Pos!
lensione d (Paqresll8-l2l)
Precastpresires sed hollow core or solid slab (pages 132-133 )
Postten sionedone-wa y solid slab (paqes I l4-ll5)
If you wish to minimize the area
occupied by columns or bearing
Conside r long-sp an structd: al systems ,such as
Heaw wood tusses (Pages 66-6?)
Clue larRinat edwood beams (pages 62-63)
Clue laminaie d wood arches Gaqes 68-69)
Conven tional steel frame (paqes 87-105)
Open-w eb steel joisls Gages I00-I0l)
Single-s iory rigid sleel ftame (pages I02-103 )
steet tusses (Pages I04-105 )
Sitecas tconclete walfle slab, particul arly when poslten sioned (pages
r22-r23)
Precastconcret e single or double lees (pages I34-135 )
You may also wish to conside r othel long-sp an systems ,such as sPecial ly
fabricai ed steel beams, suspend ed systems ,arches,vaults, and shells'
What is the purpose of Building Structure?
Building Structure:
System of members
integrated to support various
loads (forces) generated
through creation of sheltered
space and to redistribute
these loads safely into the
ground to achieve
equilibrium as a whole.
Structural Framing:
Matrix of members to collect
(concentrate) various loads
and transfer them into
foundation.
Foundation:
Spreads (dilutes) the
concentrated load down to
soils bearing capacity so the
“ground” can safely support
the entire load of the building
structure and reach
equilibrium.
Loading and Load Paths
in Steel Frame Construction
Steel Frame Construction
What kind of loads are
being collected and
transferred by the
framing?
Gravitational Loads / Lateral Load
Gravitational Loads:
Dead Load: The vertical load due to the weight of all
permanent structural and non structural components of
the building, such as walls, floors, roofs and fixed
service equipment.
Live Load: The vertical load superimposed by the use
and occupancy of the building usually assigned per
code.
Lateral Loads:
Wind load
Load induced by the wind
pressure on building
facades and roofs.
Seismic load:
Inertial force induced by
sudden movement of earth.
Both generally given as per
code.
Gravitational Loads
Load on Roof Slab (Decking)
Roof Live Load:
Loads that are produced during the life
of the structure by movable objects.
Loads that are produced during
maintenance by workers, equipment, and
materials.
Rain Water (flat roof parapet if ponding is
anticipated), soil, plants, water on green
roof. Snow Load
Dead Load:
Weight of the roof system (membrane,
insulation, roof decking, ballast, traffic
decking etc.)
Permanent Mechanical Equipment
Dead Load:
Interior ceiling system
Mechanical Load - mechanical pipes and ducts, plumbing pipes
conduits etc.
Load on Roof Framing
Load on Roof Framing
Loads on the Roof Slab (Decking) are collected by Beams and
transferred into Girders and then, transferred into columns
Load on Floor Slab (Decking)
Load on Floor Slab (Decking)
Live: Load of occupants, furniture,
movable fixtures and equipments,
stored items (transient and moving)
Special provision for library (books
and shelving), Garage (cars), interior
partitions (office space) etc.
Dead: Load of the floor (Finish
Flooring, Sub-flooring or Decking),
Permanent Interior walls, Permanent
Mechanical Equipment, Interior
ceiling system (hanging below),
Mechanical ducts, conduits (hanging
below)
Load on Floor Framing
Load on Floor Framing
Loads on the Floor Slab (Decking) are collected by Beams and
transferred into Girders and then transferred into columns
Loads directly carried by permitter girders and beams:
Gravitational loads of Building Envelope
Load on Columns
Load on Columns
The Columns collects loads from Girders (and Beams), then,
transfer them into Foundation
Load Tracing
Live Load
(by code)
Roof
Occupancy
Int. Partition
Gravitational
Dead Load
Loads on the structure
Lateral
Live Load
(by code)
Decking/Slab
Mechanical
Ceiling
Etc
Wind Load
Seismic Load
Determine the reaction forces
(end-shear) for beams B-1, B-2,
B-3 and Girder G-1 + the load
carried by column C-1 (12’ H)
Assume the following loads:
LL = 50 psf
DL:
Concrete = 150 pcf
Steel Decking = 5 psf
Mech. Equip = 10 psf
Sus. Ceiling = 5 psf
Steel Beam: W8x24
Steel Girders: W18x35
Tributary Area:
Area of roof or floor (walls if lateral load is in
consideration) contributing to loading of individual
structural member - beams (joist /rafters), girders,
columns, bearing walls and foundations etc.