Deflection and Ponding of Steel Joists

The techniques of discrete field analysis are utilized to investigate the response of steel joists (idealized as warren trusses) to various static loading conditions. Deflection formulas for arbitrary static loads are presented in finite Fourier series form. These formulas are specialized for the case of a uniformly distributed loading and a highly accurate approximate formula obtained for vertical deflections. The effect of web strain for both short and long spans is accurately reflected and generally will result in less than 2% error. Deflection formulas in the form of finite Fourier series are also obtained for the case of rainwater ponding loads combined with static live and dead loads. For ponding with a uniformly distributed live or dead loading, highly accurate equivalent beam approximate formulas are presented which should be quite useful to the practitioner. In addition to providing insight into the parameters affecting joint behavior, heretofore unavailable analysis techniques are presented to aid designers in steel joist construction.