EFFICIENT ANALYSIS OF SIMPLE SECONDARY STRUCTURES IN LARGE BUILDINGS UNDER EARTHQUAKE EXCITATION

Time history analysis of secondary structures such as 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. Using this method, 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 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 the interaction between the eigenmodes with closely spaced and tuned eigenfrequencies can be taken into account.