车辆荷载作用下大跨度斜拉桥钢和CFRP拉索的非线性振动

NONLINEAR VIBRATION OF STEEL AND CFRP CABLES OF LONG SPAN CABLE-STAYED BRIDGE UNDER VEHICULAR LOADS

  • 摘要: 采用非线性有限元方法,评价了大跨度斜拉桥在车辆荷载作用下发生索桥耦合振动的可能性。以跨度为1400m的斜拉桥模型为例,通过车桥耦合振动分析获得主梁和桥塔的振动响应,将其作为拉索在支点处受到的激励,分别计算得到钢索和碳纤维(CFRP)索的振动响应。结果表明:不论是钢索还是CFRP索,其位移响应振幅均不大。由于较大跨度钢索的自振频率低且接近于桥梁的主要自振频率,此类钢索在车辆荷载作用下容易发生局部振动。相比较而言,CFRP索由于刚度较大随桥梁整体发生小幅振动。另外,激励持续时间长度对拉索的振幅影响不大。在拉索的主要固有频率范围内,梁、塔和拉索的固有频率之间没有明显的相关性,大跨斜拉桥在车辆荷载作用下发生索桥耦合振动的可能性不大。

     

    Abstract: The nonlinear finite element method is adopted to analyze the possibility of coupling vibrations of cables and the bridge of long span cable-stayed bridges due to vehicles. A cable-stayed bridge with span of 1400 m is studied as a case. Results show that the dynamic responses of cable supports due to vehicles are obtained through vehicle-bridge coupling vibration analyses, and are taken as stimulations in nonlinear vibration calculation of steel and CFRP cables. Results show that the displacement amplitudes of both steel and CFRP cables are not big; the local vibration of a long-span steel cable due to the action of vehicle is observed because its frequency is close to the main frequencies of the bridge; but the CFRP cables vibrate with the bridge because its stiffness is greater. Besides, the influence of lasting time on the amplitude of cables is not obvious. The predominant frequencies of the dynamic responses of the bridge have no obvious relation with that of cables in the primary frequency range of cables. The large amplitude cable-bridge coupling vibration due to vehicular loads is not possible to occur.

     

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