Comparison for Calculation Methods of Long span Structure under Multi support Seismic Excitation

Abstract:

Four calculation methods for the seismic response analysis of the long span structure under the multi support seismic excitation, such as direct method, displacement input method, relative motion method and large mass method, are compared. Based on a practical project in Shanghai, an illustrative example using these four methods respectively is presented. Results indicate that the direct method, displacement input method and relative motion method are high fidelity calculation methods and are recommended to use. The acceleration response calculated by large mass method is accurate enough. However, the displacement response and internal force response calculated by large mass method are seriously distorted. Main reason of the distortion is produced by the numerical integration in the calculation procedure and the seismic displacement input during the analysis in large mass method can not be equal to the true seismic displacement excitation surely.

Key words:multi support seismic excitation; direct method; displacement input method; relative motion method; large mass method; seismic response