深厚黄土高地震区斜拉桥桥塔抗震性能研究

Research on Seismic Performance of Cable-stayed Bridge Towers in Deep Loess and High Intensity Seismic Areas

以某深厚黄土高地震区斜拉桥为工程依托,根据钢-混结合梁斜拉桥的结构特点,采用有限元分析方法,对纵向阻尼器设计参数、布置方式进行分析,针对不同的设计方案分析对抗震性能的影响,确定最优方案。通过分析弯矩-轴力时程曲线与截面轴力-等效抗弯屈服弯矩曲线(P-M曲线),对桥塔塔底及其桩基抗震性能进行研究。研究结果表明,斜拉桥设置纵向阻尼器,能有效降低塔底内力,减小梁端位移;当斜拉桥桥面以下墩塔较高时,可采用在主塔+桥台设置阻尼器的方式来降低主梁梁端位移和阻尼器行程。桥塔塔底薄弱截面外包钢板方案、内设钢管混凝土骨架+外包钢板方案均可满足高桥塔抗震要求。

Based on the structural characteristics of a cable-stayed bridge with steel-concrete composite beams in a deep loess high seismic area,finite element analysis method is adopted to analyze the design parameters and arrangement of longitudinal dampers.The impact of different design schemes on their seismic performance is analyzed to determine the optimal scheme.By analyzing the bending moment axial force time history curve and section axial force equivalent bending yield moment curve(P-M curve),the seismic performance of the bridge tower bottom and its pile foundation is studied.The research results indicate that the installation of longitudinal dampers in cable-stayed bridges can effectively reduce the internal forces at the bottom of the tower and the displacement at the beam;When the piers and towers below the deck of a cable-stayed bridge are higher,dampers can be installed on the main tower and bridge abutment to reduce the displacement of the beam and the stroke of dampers.The weak section at the bottom of the bridge tower can be wrapped with steel plates,and both the internal steel pipe concrete skeleton and wrapped with steel plates can meet the seismic requirements of high bridge towers.