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32 Cards in this Set
- Front
- Back
2 most common steel structural systems
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beam and girder, open-web steel joist system
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Beam and girder
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-large members span between columns w/ smaller beams framed into them.
-beams span the longer distances/girders span shorter -framing is covered with steel decking, then concrete is poured to create floor slab -mid to high rises - very little space between the girders and the suspended ceiling (difficult to install new mechanical or large recessed fixtures. |
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Open-web steel joist system
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-joists span between beams or bearing walls
-spaced 2'-0" to 6'-0" o.c -flooring is poured the same way as beam and girder -1 story / low-rise buildings -easy to run mechanical/electrical and to hang suspended ceilings from |
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2 most common concrete systems
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cast-in-place, precast
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Cast-in-place concrete system
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-concrete is poured into forms
-mostly has mild steel reinforcement -can be post-tensioned - should not be penetrated for pipes or conduit |
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Precast concrete system
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-components are usually formed in a plant and shipped to the site
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5 types of cast-in-place concrete systems
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1. beam and girder - similar to steel system
2. concrete joist system - concrete member spaced 24-36" apart which frame into larger beams. more difficult to drill holes for pipes and conduit 3. flat plate construction - floor slab transfers loads directly onto columns. Used when floor-floor heights are at a minimum. Difficult to drill 4. flat Slab - similar to flat plate, except that drop slabs are used to increase strength. 5. waffle slab (2-way joist)- provides support for heavier loads. Often left exposed and lighting integrated into coffers. |
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3 types of precast concrete systems
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1. single tees - popular, along with double tees, because they can be used simulatneously as beam and floor decking and they are easy and fast to erect.
2. double tees - industrial buildings, 1 and 2 story commercial buildings and garages 3. hollow core slabs |
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Masonry
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-generally limited to load-bearing walls out of concrete block
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Concrete block (concrete masonry units or CMU)
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-units based on 4" modules - 3/4" less than nominal to allow for mortar joints - commonly 8"x8"x16"
-manufactured with 2 open cells which can be left open when load are light, or reinforced and filled with grout if more strength is needed. |
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Loadbearing walls
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-support loads from above
-live loads = people, furniture, etc... / dead loads = weight of structure -can only be cut for openings if framed with supporting lintel or beam -in residential - exterior walls; some interior -in commercial - mostly limited to core elements |
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Gravity loads
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-includes live and dead loads
-dead loads will generally stay the same. Live loads are limited by building codes by occupancy (reidential floor = 40 lbm/sf, office = 50lmb/sf) -concentrated loads cannot be more than 2-1/2 sf |
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Lateral loads
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-include wind loads and earthquake loads
-IBC makes seismic zones which may need more detailing |
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Dynamic loads
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-when a load is applied suddenly or changes rapidly (cars in a garage, elevators, helicopter on the roof)
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Building movement
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-partitions attached to perimeter or floor above need to have slip joint to allow movement
-joint cover in floors or at walls cannot be covered with finishes. |
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Core drill
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-2"-4" drilled into floor with hollow drill bit
-beam and girder and one-way pan slabs are easiest to drill (all are difficult) |
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Penetrations in cast-in-place floors
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-holes cannot be cut near beams or column intersections
-large openings require extra support -holes cannot be cut in tee sections. must be between them. -cannot penetrate post-tensioned concrete |
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Fire-resistive ratings
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-structural frame must be rated from 1-hour to 3-hour
-if protected beams or columns are changed, a designer is not allowed to specify or modify fire protection of structural systems |
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Residential and small commercial structural systems
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-mostly of wood and wood products as primary material (easy to work with, plentiful, inexpensive, strong)
-loadbearing walls are made with studs (2"x4", 16" o.c.) -joists are 2" thick wood placed horizontally to support the floor (depths are 3/4" less than nominal size) |
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Sheathing
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nailed to the exterior of the stud wall to stiffen the wall and provide a nailing base for the exterior finishing material
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Exterior penetrations (residential)
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doors/windows - framed at the top with lintels (headers); double 2x4 members oriented vertically to carry loads.
larger openings - laminated veneer lumber, glued laminated beams or small steel beams can be used |
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Joists (residential)
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can span about 20 feet; if more, steel or manufactures wood must be used
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2-story construction (platform framing)
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wood studs one story high are placed on a sole plate and spanned with a double top plate at the ceiling level. 2ns story joists bear on the top plate and serve as a platform for the 2nd story wall studs and roof.
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Glued laminated wood members (glulams)
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individual peices of lumber glued together, then finished
used when stronger wood is needed for heavier loads or long spans or when appearance is a factor can be manufactured in shapes like arches, etc... manufactured in fixed dimensions |
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Plywood web joist
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I-shaped joist, stronger and thicker thana standard wood joist
used in residential/light commercial does not have problems with warping splits, etc... |
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Laminated veneer lumber (LVL)
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layers of veneer glued together
used for headers over large openings stronger than solid lumber |
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Sole plate
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horizontal wood member that serves as a base for the studs in a stud partition
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Trimmer
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a wood member in a floor or roof used to support a header
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Wide-flange beam
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looks like an "H". Gives the column/beam equal strength in both directions
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Lintel
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horizontal structural member over an opening that carries the weight of the wall above it
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Cripple stud
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a stud above a door opening or below a window sill
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Purlin
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a piece of timber laid horizontally
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