Approximate ponding analysis by amplified first-order analysis

Abstract When water accumulates on the roof of a building, the resulting loads and deflections mutually depend on each other. This nonlinear effect, known as ponding, can cause collapse of insufficiently stiff and strong structures. There is a growing recognition of the limitations of current design methodologies for ponding. Newer methods of design have been proposed that overcome the limitations of the existing methodologies. These newer methods rely on the ability of the engineer to perform a nonlinear ponding analysis. Several methods exist for performing this type of analysis accurately. However, many design situations do not require full accuracy and an approximate method would be useful to practicing structural engineers. This work addresses this need by presenting an approximate ponding analysis method in which nonlinear results are obtained through amplification of first-order analysis results. Development of the methodology is described, an example is presented, and the accuracy of the method is discussed along with suggestions for future improvements. The availability of this method of analysis will allow wider adoption of newer and more rigorous methods of design for ponding.