自重初应力对格构柱高墩-连续板梁桥动力特性的影响

以宁波火车南站枢纽改造工程临时铁路桥(宁波桥)为研究对象,探讨自重初应力对格构柱高墩-连续板梁桥的全模态和缩聚模态的影响。在考虑自重初应力与不考虑自重初应力2种情况下,分别采用子空间法和缩聚模态法,求得宁波桥包含局部振动的全局模态和仅考虑整体振动的缩聚模态。分析结果表明:自重初应力对宁波桥动力特性的影响主要体现在影响轴向受力构件的局部模态,对整体振动模态几乎没有影响;2种情况下局部振动模态的频率差别很大,振型也有所差异;而整体振动模态的固有频率几乎是一一对应相等,振型也是一一对应相同。该结论对恒载自重初应力较大的桥梁动力特性分析有指导意义。

Influence of self-weight stress on dynamic characteristics of high latticed column pier-continuous plate girder bridge

Taking temporary bridge of the Ningbo South Station transportation junction project(Ningbo Bridge) as the research objective,the influences of self-weight stress on the global modes and reduced modes were studied.Under the two conditions that considering the effect of self-weight stress or not,the global modes(including local vibration) and reduced modes(only including whole vibration of Ningbo bridge) were obtained using subspace iteration method and reduced method respectively.The results show that self-weight stress mainly affects the dynamic characteristics of those components axially loaded,while the whole vibration modes is scarcely influedced.The frequencies of local vibration modes make a great difference in the two conditions,and the mode shapes are also somewhat different.The natural frequencies and mode shapes of whole vibration in the two conditions are corresponding equal to each other.These conclusions must have guiding meanings for the dynamic characteristics analysis of bridges with significant self-weight stress.