Building ConstructionStructural Systems1. Load-bearing wall construction2. Skeleton framing3. Combination of the twoBuilding ConstructionFactors governing type selection• Economics – not necessarily the one that requires the least structural materials• Architectural, mechanical, electrical, and other costs may be affectedBuilding ConstructionLoad-bearing walls serve as:•Facades•Enclosures•Separators•Fire barriers•Carry floor & roof loads to the foundationBuilding ConstructionLoad-bearing wood walls• One to three story buildings (houses)• 2” x 4” or 2” x 6” construction • Studs on 16” to 24” centers• Top & bottom plates• Headers• Max. wall ht. (unsupported) = 15’Balloon FramingPlatform FramingPost & Plank FramingBuilding ConstructionLoad-bearing masonry walls•10 stories or more•Thickness of walls vary depending on height•Trapezoidal cross section•Lintels or arches at openingsBuilding ConstructionLoad-bearing reinforced concrete walls• Thinner than masonry• Solid or cavityLoad-bearing walls are used for:• Exterior• Interior partitions• Wind bracing• Service core enclosureBuilding ConstructionLoad-bearing partitions:• Short intervals• Carry floor/ceiling loadsLoad-bearing walls:• Can serve as shear walls = resists wind & earthquake (seismic) loadsBuilding ConstructionService core• Enclosing stairs or elevators• Service/mechanical rooms• Duct/pipe chaseBuilding ConstructionSkeleton framing• Columns carry loads to foundation• Lateral forces resisted by columns and diagonal braces, or rigid frameBuilding ConstructionHorizontal structural slab or deck • Floor/ceiling/ducts• Flat-plate construction• Flat-slab reinforced concrete • Slab-band construction• Two way slabsBuilding ConstructionBeam-and-girder-construction• Wood joist or rafters on 16” to 24” centers w/lumber or plywood decking• Open web steel joist• Light, rolled-steel beams• Precast concrete planksBuilding ConstructionHeavier loads / longer spans• One-way ribbed concrete slabs• Two-way waffle slab• Prestressed concrete planks, tees, double tees, or girders• Laminated wood girders• Structural steel beams & girdersBuilding ConstructionLateral-force bracing• Low wood buildings• Rigid frames• Shear walls• Braced framesBuilding ConstructionLateral-force bracing• Tall buildings– Hollow tube cantilever–X –bracing– Knee bracing between columns & girders– Haunched-spandrels– Moment-resistant connections between columns & girderBuilding Construction• Curtain Wall: non-load-bearing, exterior wall, supported on girts• Spandrel Wall: curtain wall at the level of the outside floor beams in multi-story buildings• Pilaster: bonded or keyed column of masonry, uniform thicknessBuilding Construction• Buttress: bonded masonry column– integral part of wall– provides lateral stability– decreases in thickness from top to bottom• Curtain Walls: metal, plywood, stucco– stick systems– mullion-and-panel systems– panel systems• Glazing: various window systemsBuilding Construction• Roof styles– steep sloped > 1½ “ in 12”– low-slope ≤1½ “ in 12”• Sloped roof types– gable–hip– gambrel– shedBuilding Construction• Sloped roof components– rafter/truss/purlins– sheathing– underlayment–fascia–soffet– dripedgeeavesBuilding Construction• Sloped roof components– ridge or hip– valley– rake gable end– saddle– dormer– flashingBuilding Construction• Sloped roof materials– mineral fiber - cement shingles– asphalt (fiberglass)– wood shakes/shingles– slate shingles– clay (terra cotta)– concrete tile– metal roofing - corrugated or ribbed, aluminum, copper, or galvanized steelBuilding Construction• Low-sloped roof materials– built-up bituminous, roll-roofing, single-ply membrane– components include:• substrate• underlayment• insulation• waterproof membrane• ballastBuilding Construction• Bitumens include asphalt & coal tar• Single-ply roofing– vulcanized elastomers (EPDM, neoprene)– non-vulcanized elastomers (CSPE, CPE, PIB)– thermoplastics– polymer-modified