Method to improve seismic provisions for nonstructural components in buildings

The purpose of this paper is to propose a procedure to determine in a rational but simple way equivalent static lateral forces for the seismic design of nonstructural components attached to buildings. The procedure is derived using concepts from a previously developed dynamic theory for secondary systems mounted on a primary structure and by introducing into this theory some simplifying assumptions. It takes into account the dynamic interaction between a nonstructural component and its supporting structure, the level above the base of the structure of the point or points where the nonstructural component is attached to the structure, the number of such attachment points, and the nonlinear behavior of the structure. In addition, it uses the design spectra specified by building codes for the design of the structure as the earthquake input to the nonstructural component. Presented also is a numerical example that illustrates the simplicity of the procedure and a numerical comparative study with three nonstructural components attached to a multistory frame building to verify its adequacy. Based on the simplicity and rationality of the proposed formulas and the results from this comparative study, it is concluded that the procedure is adequately simple and accurate enough for design purposes, represents an improvement over the pertinent design recommendations in current code provisions, and a suitable replacement for these recommendations.