Computational Mode Number Research in Seismic Response Spectrum Analysis of Long-Span Cable-Stayed Bridge

On the basis of Guidelines for Seismic Design of Highway Bridges,the vibration mode number considered in mode-decomposition response spectrum analysis should get more than 90% of the effective mass in the calculation direction.To study the applicability of this standard in long-span cable-stayed bridges,three physical quantities on modal participation were introduced and compared.Then,a computational model of Sutong Bridge was set up to identify the different calculating vibration mode number in terms of the modal participation mass radio reaching 0.9 in different direction,so as to conduct response spectrum analysis and analyze the error.The result shows that,to conduct response spectrum analysis for a long-span cable-stayed bridge under both horizontal and vertical seismic excitation,the vibration mode number derived from the vertical moda participation mass radio reaching 0.9 should be taken as the calculating vibration mode number.