b'THE OFFICIAL NFBA MAGAZINETECHNOLOGY & RESEARCH Example 1 Figure 3: Exterior of buildingthe building code does allow exceptions, mostis more challenging for warehouses that use the of which are dependent upon occupant loadsecond floor area for warehouse-type storage.The and egress.A story is that portion of a buildingIBC separates warehouse storage loads into heavy included between the upper surface of a floor andand light categories with minimum live loading of the upper surface of the floor or roof next above.250 psf and 125 psf, respectively (see also additional A second floor system is designed to satisfy therequirementforconcentratedpointloads). strengthanddeflectionrequirementsoftheTheoutsideperimeterofthesecondfloor International Building Code (IBC).In post- framing can be supported by the side and end frame buildings, the second floor framing consistswall columns.The most common detail for this generally of dimensional lumber or manufacturedtype of support includes a single or doubled joists (i-joists, floor trusses), dimensional lumber,ledger board fastened to the wood columns with glulam, laminated veneer lumber (LVL) or steelnails or structural screws.A support below the girders, and dimensional lumber or LVL ledgers.ledger may be required if the ledger cannot fit the The girders are supported by wood or steel columnsrequired quantity of fasteners.The floor joists are on a thickened concrete slab, spread footings belowattached to the ledger board with joist hangers. the slab, or a round shallow post foundation.The designer should also consider the effects The design of wood framing and connections isof the second floor system on the lateral force governed by the National Design Specificationresisting system of the building.The effects may be for Wood Construction (NDS).The design ofnegligible, positive or negative.If the floor system steel and concrete components is governed by theis a small mezzanine near the end of a building, Specification for Structural Steel Buildings (ANSI/ the effects are likely negligible.However, if the AISC 360) and Building Code Requirementsfloor system takes up all or most of the building for Structural Concrete (ACI 318), respectively.footprint, the effects on the lateral force resisting The loading on the floor framing is determined bysystem are likely significant.The floor system in the intended use of the space.For example, thethe latter case is a diaphragm located somewhere live load for office use is 50 psf.Structural designbetween the main floor below and the ceiling or 24 / FRAME BUILDER -JAN2020'