13.07.2015 Views

47.5 MB - The Whole Building Design Guide

47.5 MB - The Whole Building Design Guide

47.5 MB - The Whole Building Design Guide

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As part of the detailed design effort, load path continuityshould be clearly indicated in the contract documents via illustrationof connection details. Load paths need to accommodatedesign uplift, racking, and overturning loads. Load path continuityobviously applies to MWFRS elements, but it also appliesto building envelope elements. Figure 3-20 shows a load pathdiscontinuity between a piece of HVAC equipment and itsequipment stand. <strong>The</strong> equipment on this new Federal courthouseblew away because it was resting on vibration isolatorsthat provided lateral resistance, but no uplift resistance (also seeFigure 3-75).Figure 3-20:Temporary coveringsplaced over two largeopenings in the roof thatwere left after the ductworkblew away. HurricaneKatrina (Mississippi, 2005)Figure 3-21 illustrates the load path concept. Members are sizedto accommodate the design loads. Connections are designed totransfer uplift loads applied to the roof, and the positive and negativeloads applied to the exterior bearing walls, down to thefoundation and into the ground. <strong>The</strong> roof covering (and wallcovering, if there is one) is also part of the load path. To avoidblow-off, the nonstructural elements must also be adequately attachedto the structure.MAKING CRITICAL FACILITIES SAFE FROM High Wind3-37

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