考虑梁端顺桥向阻力的结构竖弯等代阻尼比计算方法研究  

Calculation of Equivalent Damping Ratio of Beam Structures in Vertical Bending Mode Considering Longitudinal Girder-End Resistance

作　　者：秦竟熙 苑仁安[2] 张明金[3] QIN Jingxi;YUAN Renan;ZHANG Mingjin(University of California,Los Angeles 90077,California,USA;China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.,Wuhan 430056,China;Department of Bridge Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]加州大学洛杉矶分校,美国洛杉矶90077 [2]中铁大桥勘测设计院集团有限公司,湖北武汉430056 [3]西南交通大学土木工程学院,四川成都610031

出　　处：《桥梁建设》2023年第5期125-130,共6页Bridge Construction

基　　金：国家重点研发计划项目(2022YFB2602903);中国中铁股份有限公司科技研究开发计划项目(2021-专项-01,2022-专项-01)。

摘　　要：针对梁式结构竖弯振动未考虑梁端顺桥向阻力引起阻尼比计算不准确的问题,提出桥梁结构各模态竖弯等代阻尼比计算方法。该方法通过考虑主梁竖向弯曲变形和梁端顺桥向变形之间的关系,基于能量原理,建立结构系统考虑梁端阻力的竖向弯曲振动的广义单自由度动力方程,采用RKF45预估校正法对其进行数值求解,从而确定结构各模态的竖弯等代阻尼比。应用该方法对80 m跨等截面简支梁的竖弯等代阻尼比进行计算,并分析不同的梁端阻力装置对结构竖弯等代阻尼比的影响规律。结果表明:提出的结构竖弯等代阻尼比计算方法可应用于大跨度梁式结构竖弯振动中阻尼比的计算,梁端阻力装置可有效提高结构竖弯振动的等代阻尼比,梁端阻力装置对结构竖弯等代阻尼比的影响与结构广义质量、广义竖弯刚度、竖弯振型和装置阻力本身相关。To address the analytical inaccuracy from neglecting longitudinal resistance when calculating for the damping capability of beam structures vibrating in vertical bending modes,this study proposes a new calculation method for bridge effective damping ratios.The study first establishes the relationship between the vertical bending deformation of the girder and the longitudinal girder-end displacement,then proposes a generalized single-degree-of-freedom dynamic equation of motion considering the girder-end resistance of the bridge structure based on energy principle.The RKF45 predictor-corrector method is employed for numerical solutions to determine the equivalent damping ratio considering the girder-end resistance.The application of the generalized single-degree-of-freedom dynamic equation of motion is demonstrated through sample calculations on a simply-supported beam with a span of 80 m,and the influence of different girder-end resistance on the equivalent damping ratio of the structure is analyzed and compared.The results indicate that longitudinal girder-end resistance devices can effectively increase the equivalent damping ratio of beam structures for vertical bending mode vibration and that the proposed calculation method is applicable on long span beam structures.The effect of the longitudinal girder-end resistance devices is associated with the generalized mass,generalized stiffness,and the vertical bending mode shapes of the structure,as well as the resistance of the devices.

关 键 词：大跨度桥梁 等代阻尼比 能量原理 广义单自由度动力方程 RKF45预估校正法 计算方法 

分 类 号：U443.3[建筑科学—桥梁与隧道工程] U441.3[交通运输工程—道路与铁道工程]