Efficient analysis of simple secondary structures in large buildings under earthquake excitation

Time history analysis of secondary structures like machinery or piping systems in large buildings under earthquake excitation is in general very costly. The procedure proposed in this study is based on the modal synthesis method. Then the addition of a secondary structure with a single degree of freedom results in a rank-one modification of the original eigenvalue problem. This simple form allows the efficient analysis of simple secondary structures with arbitrary mass and stiffness at arbitrary locations. By applying the response spectrum method together with a special superposition rule interaction between eigenmodes with closely spaced and tuned eigenfrequencies can be considered. (orig.)