大跨下承式连续梁拱组合式桥自振特性研究.docVIP

大跨下承式连续梁拱组合式桥自振特性研究 李青山 （中铁第五勘察设计院集团有限公司桥梁设计院，北京102600） 摘要：为准确掌握结构的动力特性，以（82+172+82）m连续梁拱组合式桥为工程背景，建立空间结构有限元模型。对桥梁自振频率、振型进行了计算分析，研究了拱肋刚度、横、斜撑刚度及其布置形式和矢跨比对连续梁拱组合式桥动力特性的影响。分析结果表明，结构面外振型较面内振型先出现，面内刚度大于面外刚度；拱肋刚度对结构自振特性影响较小；横、斜撑刚度及布置形式对结构面外基频影响较为显著，对面内基频影响不明显；结构面外基频随矢高的增加而减小。 关键词：连续梁拱组合式桥；自振特性；拱肋；横、斜撑；矢跨比 Self-vibration Characteristics Research of Long-span Continuous Through Type Composite Arch Bridge Li Qing-shan (Bridge Department of China Railway Fifth Survey And Design Institute Group Co., Ltd., Beijing 102600) Abstract: In order to obtain the dynamic characteristics of the structure exactly, the (82+172+82) m continuous through type composite arch bridge was simulated by using MIDAS. Self-vibration frequencies, mode shapes were calculated and analyzed. Impacting on the self-vibration characteristics, more factors were researched, such as arch rib stiffness, arranging and the stiffness of the transverse and inclined brace, rises-pan ratio. The results indicated that out-plane vibration mode of the structure appeared earlier than in-plane vibration mode and the dynamic characteristics of the structure were influenced by the arc rib stiffness slightly. It also suggested that the stiffness and arranging of the transverse and inclined brace impacted on the out-plane frequency obviously and on the in-plane frequency slightly. At the same time, the out-plane frequency decreased with increasing of the rise of arch. Key words: continuous composite arch bridge; self-vibration characteristics; arch rib; transverse and inclined brace；rises-pan ratio 梁拱组合式桥梁是将主要承受压力的拱肋和主要承受弯矩的梁体组合起来共同承受荷载，可以是刚性拱及柔性拉杆，也可以是柔性拱及刚性梁，它同时具有梁的受弯和拱的承压特点，利用梁部受拉来承受和抵消在竖直荷载下产生的水平推力，便可以在一般地基条件下修建。钢管混凝土拱桥利用钢管的套箍作用，使混凝土处于三向受力状态，使其承载能力大大提高，同时也能提高混凝土的塑性性能。另一方面，混凝土内填于钢管之内，增强了钢管的管壁稳定性，刚度也大于钢结构，使其稳定性也有了极大的提高[1]。 为了准确掌握结构的动力特性，为结构设计、车振及抗震分析提供有力的支持，在总结以往动力分析方法的基础上，本文以（82+172+82）m连续梁拱组合式桥为研究对象，采用通用有限元软件Midas建立本桥的空间结构有限元模型,计算了桥梁自振特性，详细探讨了拱肋刚度、横、斜撑刚度及其布置形式和矢跨比对该类桥梁自振特性的影响。 1 工程概况 广元嘉陵江双线特大桥（82+172+82）m连续梁拱组合式桥全长337.8