摘要
拟建的九江长江公路大桥为双塔双索面钢箱梁斜拉桥,全长1432m,主跨长达768m,应对其进行地震动多点激励分析。首先针对当前被普遍认可的适用于多点激励的位移输入模型中存在的容易但不容忽视的问题介绍了提出的无质量刚性元法,然后基于拟合《公路工程抗震设计规范》反应谱方法生成桥位区的随机非平稳空间地震动场,最后对此大桥进行了多点激励下的地震反应分析。结果表明:纵向激励下,考虑多点输入减小了索塔的底部剪力、底部弯矩和塔顶的节点位移;三向激励下,考虑多点输入可增加也可降低索塔的底部剪力和底部弯矩,剪力最大增加近10%;考虑多点输入增加了塔顶的节点位移,最大增加近100%;考虑多维激励均比仅考虑纵向激励的反应大。由此可看出,对于大跨度斜拉桥地震反应分析,须考虑地震动的多维多点激励。
The earthquake-induced ground motion is characteristized by complicated variation in space and time and may be different at dissimilar supports of structures. Relevant sdudies have shown that it is necessary to consider the effects of multi-support excitations for structures,especially for large span structures. The JIUJIANG Yangtze River highway bridge is a double-tower double-cable-side steel-box-beam cable stayed bridge,with 1432 m full length and 768m main span length. Here,the presented spring impedance method for a current displacement input model was firstly introduced. Spatially variable ground motion time histories were generated by the method of the reponse-spectrum-compatible artificial ground,then the responses of the highway bridge under uniform excitation and multiple support excitations were studied by adopting the time history analysis method. From the analysis results,it was found that considering multi-support could decrease the seismic response of the cable tower’s shear force,moment and displacement under longitudinal excitation,and the seismic design was favorable for cable stayed bridge;considering multi-support could increase or decrease the seismic response of the cable tower’s shear force and moment under multi-dimensional excitation,the maximum of shear force might be increased about 10%;considering multi-support could increase the seismic response of the cable tower’s displacement under multi-dimensional excitation,the maximum of displacement might be increased about 100%;the response of considering multi-dimensional excitation was larger than that considering longitudinal one only. A conclusion was given that the multi-support and multi-dimensional earthquake excitations must be considered in the seismic analysis of the long-span cable stayed bridge.
出处
《振动与冲击》
EI
CSCD
北大核心
2009年第9期204-209,共6页
Journal of Vibration and Shock
基金
国家自然科学基金重大研究计划重点项目(90815026)
高等学校学科创新引智计划(B08014)
教育部创新团队(IRT0518)资助项目
关键词
地震
差动
斜拉桥
多点激励
规范反应谱
earthquake
cable stayed bridge
multiple support excitation
code response spectrum
