开口断面斜拉桥主梁动力特性的有限元简化计算

以1座双索面开口断面大跨径斜拉桥为例，探讨了采用3种主梁简化模型计算开口断面动力特性的差别。结果表明:对于纵飘、侧弯及竖弯各阶固有动力特性，采用单主梁模型、主梁壳单元模型、三主梁模型计算的结果基本一致，将3种模型的动力特性计算用于抗震分析时，结果相差不大；而采用单主梁模型会低估抗扭刚度，对桥梁结构扭转频率产生较大的误差；三主梁模型和主梁壳单元模型结果相近，桥梁抗风分析时不宜采用单主梁模型。

Finite Element Simplified Computation for Dynamic Characteristics of Cable-stayed Bridge Girder with Opening Section

Taking a large span cable-stayed bridge with opening section as example, comparing and analyzing three simplified models in computing differences of the dynamic characteristics in opening section, an appropriate computation model for them was recommended. The results show that for each order of the longitudinal drift, lateral bending and vertical bending inherent dynamic characteristics, the results of single-girder model, girder shell element model and triple-girder model are basically consistent. The calculation results of the dynamic characteristics of the three models for seismic analysis are little difference, but single-girder model will underestimate the torsional stiffness and will cause large errors of bridge torsional frequency. The results of triple-girder model and girder shell element model are similar, and single-girder model should not be used when analyzing wind-resistant design of bridges.