Simplified Seismic Analysis of Secondary Systems

Abstract

A procedure is introduced to compute the maximum response of light secondary systems attached to buildings subjected to earthquakes. The procedure is based on the application of the response spectrum technique to a combined building‐attachment system, but it is formulated in terms of the natural frequencies and mode shapes of the independent building and attachment components. Hence, it fully takes into account the interaction between the two components, avoids the solution of large eigenvalue problems, and facilitates the analysis of different secondary systems without the need to reanalyze the supporting building. The procedure is formulated by using Rayleigh's principle and Hurty's component mode synthesis technique. Linear systems with classical modes of vibration, small secondary‐ to primary‐mass ratios, and no more than one point of attachment are considered. In a comparative numerical study the proposed procedure predicts correct solutions with an average error of about 1%.