UNDERSTANDING THE DYNAMICS OF MULTI-DEGREE-OF FREEDOM STRUCTURES SUBJECT TO MULTIPLE SUPPORT EARTHQUAKE EXCITATION

摘要

Multiple support excitation during earthquakes is a significant hazard for structures with large distances between ground support points. Typically this applies to long-span bridges, but the hazard may also be significant for buildings and other structures with a large plan area, particularly if the geological/soil conditions under the structure are non-uniform. The current approach for modelling multiple support excitation of structures uses a linear superposition method based on response spectrum techniques. Little experimental testing has been carried out in order to verify the theory and to test the nonlinear behaviour of these types of structures under extreme loading cases. In this paper we present results for a series of experimental tests on a two degree of freedom system. There is good agreement between the experimental data and a simple numerical model analysed using direct integration methods. The results also show that, for a two degree of freedom model, if multiple support excitation is ignored and only synchronous load cases are considered, the peak response of the system may be significantly underestimated.