Research is currently being conducted on the stability of open web steel joists subjected to wind uplift. The experimental phase includes testing of full size joist speciments. A unique testing apparatus was constructed to apply a series of closely speced upward point loads along the top chord of a joist, thereby simulating uniform wind uplift. Bracing members are emulated by adjustable kinfe plates which provide lateral restraint to the lower chord at prescribed locations. Joist specimens are loaded under various support configurations to investiate lower chordbuckjling. While maintaining this critical load, the buckled chord is pulled back into its original straight alignment with an instrumented steel cable which allows load and deflection data to be gathered.
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