【摘要】 《公路桥梁抗震设计细则》规定:进行多振型反应谱分析时,所考虑的振型数应在计算方向上获得90%以上的有效质量。为了研究这条规定在大跨度斜拉桥中的适用性,在介绍推导振型参与系数、振型参与质量系数和振型贡献系数的表达式并比较物理意义的基础上,建立了苏通大桥模型,对上述三个物理量在振型中的分布规律进行了对比分析,同时,根据不同方向的振型参与质量系数达到90%确定不同的计算振型数,进行反应谱分析并分析误差。结果表明:上述规定是合理的,并且对于受水平向与竖向地震联合激励的大跨度斜拉桥,应以竖向振型参与质量系数达到90%所确定的振型数作为计算振型数进行反应谱分析。更多还原

【Abstract】 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.更多还原