考虑弯曲空间效应影响的箱梁强迫振动分析  

Analysis on Forced Vibration of Box Girders Considering the Effect of Bending Space

作　　者：张玉元[1] 张元海[1] 张慧[1] 王晨光[1] 余剑搏 ZHANG Yuyuan;ZHANG Yuanhai;ZHANG Hui;WANG Chenguang;YU Jianbo(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学土木工程学院,甘肃兰州730070

出　　处：《铁道学报》2024年第9期174-181,共8页Journal of the China Railway Society

基　　金：国家自然科学基金(52368020);甘肃省高校青年博士支持项目(2024QB-047)。

摘　　要：选取附加挠度为剪力滞广义位移,箱梁体系总动能中计入剪力滞附加变形的影响,综合运用薄壁结构弹性理论和Hamilton原理,建立考虑弯曲空间效应影响的箱梁强迫振动控制微分方程及边界条件,并给出任意简谐荷载作用下简支和连续箱梁的强迫振动解析解。引入振动频率影响的应力和挠度放大系数,详细分析简支、连续箱梁剪切剪力滞效应在初等梁结果中的占比及放大系数分布规律。算例分析表明:考虑弯曲空间效应影响的箱梁截面纵向动应力与有限元结果吻合良好;振动频率越大,应力和挠度放大系数、剪切效应占比越大,剪力滞效应占比越小;同频率振动时,简支箱梁放大系数远大于两跨连续箱梁(单跨长等于简支跨长),且频率越高,差值比越大;基频内振动时,箱梁纵向应力计算可忽略剪力滞效应,挠度计算需考虑剪切变形的影响。In this paper,by selecting the additional deflection as the generalized displacement of shear lag and taking into account the influence of shear lag additional deformation in the total kinetic energy of box girder system,a differenti-al equation and boundary conditions were established for the forced vibration considering the influence of bending space effect based on the theory of thin-walled structural elasticity and Hamilton’s principle.Analytical solutions for forced vi-bration of simply supported and continuous box girders were provided under arbitrary harmonic loads.By introducing the stress and deflection amplification factors influenced by vibration frequency,this paper analyzed the proportion of the shear deformation and shear lag in the elementary beam results and the amplification factor distribution for simply suppor-ted and continuous box girders.The results show that the longitudinal dynamic stress considering the bending space effect is in good agreement with the finite element numerical solution.The greater the vibration frequency,the greater the stress and deflection amplification factor,the proportion of shear deformation effect,and the smaller the proportion of shear lag effect.The amplification factor of the simply supported box girder is much greater than that of the continuous box girder,and the higher the frequency,the greater the difference ratio between the two when vibrating at the same frequency.In the case of fundamental frequency vibration,the influence of shear lag can be neglected in the calculation of longitudinal stress of box girder,and the influence of shear deformation should be considered in the calculation of deflection.

关 键 词：箱梁 强迫振动 弯曲空间效应 剪翘正应力 附加挠度 放大系数 

分 类 号：U448.213[建筑科学—桥梁与隧道工程]