To study the effects of near-fault ground motions on a long-span curved rigid bridge,an actual curved rigid bridge based on a scale of 1/40 model was employed to conduct shaking table tests.The typical near-fault and farfield ground motions recorded under the same earthquake were selected as the ground motion input,and then comparative tests on a multi-shaking table array system were carried out.During tests,the structure was subjected to synchronous and traveling wave excitations taken as longitudinal and transverse inputs,and the combination of transverse and longitudinal inputs,respectively.The results showed that the velocity pulse contained in near-fault ground motions has a significant influence on the dynamic response of the curved rigid bridge and the structural response amplification effect can be further elevated by traveling wave effect;near-fault effect is more obvious for the structure with a larger stiffness or a certain direction of the structure,whereas the influence of traveling wave effect on the structure is dependent primarily upon higher order asymmetric modes induced by mult-point excitations;compared with a straight line bridge,both near-fault effect and traveling wave effect cause more harmful influence on the dynamic response of the curved bridge due to a larger stiffness in horizontal direction caused by curvature radius;therefore,the curved bridge may be damaged more seriously than a straight bridges may under the same earthquake in near-fault zone.It was suggested that special attentions should be received for a curved rigid bridge close to fault zones.%为了研究近断层地震动对大跨度曲线刚构桥抗震性能的影响,以某一大跨度曲线刚构桥为原型,设计制作1/40缩尺比例模型,选取同一地震中的近断层地震动记录和远场地震动记录,利用多子台积木式模拟振动台台阵系统,完成了横向、纵向、横向+纵向一致输入及行波输入的对比试验.研究结果表明:近断层地震动中所含的速度脉冲会对曲线刚构桥的动力响应产生显著影响,并且行波效应会进一步提升其对结构响应的放大作用;近断层效应的放大作用对刚度较大的结构或者结构某一个方向更为明显,而行波效应对结构的影响主要取决于由多点激励所激发的高阶反对称模态;与直线桥相比较,曲率半径会增大曲线梁桥的水平刚度,从而使近断层效应和行波效应对曲线桥的动力响应产生更不利的影响.因此,在靠近断层的区域遭受同样的地震作用,曲线梁桥将产生更为严重的破坏,建议在抗震设计中应特别注意处于断层附近的曲线桥结构.
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