47.5 MB - The Whole Building Design Guide

Table 3-8: Checklist for Building Vulnerability of Critical Facilities Exposed to High Winds (continued)Vulnerability Sections Guidance ObservationsStructural Systems Section 3.3.2Is a pre-engineered building beingconsidered?Is precast concrete being considered?Are exterior load-bearing walls beingconsidered?If yes, ensure the structure is not vulnerableto progressive collapse. If a pre-engineeredbuilding exists, evaluate to determine if it isvulnerable to progressive collapse.If yes, design the connections to resist windloads. If precast concrete elements exist, verifythat the connections are adequate to resist thewind loads.If yes, design as MWFRS and C&C.Is an FM Global-rated roof assemblyspecified?Is there a covered walkway orcanopy?Is the site in a hurricane-proneregion?Is the site in a tornado-prone region?Do portions of the existing facilityhave long-span roof structures (e.g.,a gymnasium)?Is there adequate uplift resistanceof the existing roof deck and decksupport structure?If yes, comply with FM Global deck criteria.If yes, use “free roof” pressure coefficientsfrom ASCE 7.Canopy decks and canopyframing members on older buildings often haveinadequate wind resistance. Wind-borne debrisfrom canopies can damage adjacent buildingsand cause injury.A reinforced cast-in-place concrete structuralsystem, and reinforced concrete or fully groutedand reinforced CMU walls, are recommended(Section 3.4.2).If yes, provide occupant protection. See FEMA361.Evaluate structural strength, since olderlong-span structures often have limited upliftresistance.The 1979 (and earlier) SBC and UBC,and 1984 (and earlier) BOCA/NBC, didnot prescribe increased wind loads at roofperimeters and corners. Decks (except cast-inplaceconcrete) and deck support structuresdesigned in accordance with these older codesare quite vulnerable.The strengthening of thedeck attachment and deck support structure isrecommended for older buildings.MAKING CRITICAL FACILITIES SAFE FROM High Wind3-149