Abstract

RC double-column medium height bents (DCMBs) are widely applied in the mountain areas as the substructure of highway bridges, and the two columns are normally connected by RC link beams to enhance the lateral stability. However, serious damage and/or large residual displacement were repeatedly observed in the DCMBs after many major earthquakes, which may make the bridges lose functionality and have to be demolished and rebuilt. In order to improve the seismic performance of the bridges, a novel self-centering variable friction dissipation brace (SCVFB) using SMA plates is developed to replace the traditional RC link beams in the DCMBs in this study. The mechanical properties of the shape memory alloy (SMA) plate were investigated experimentally. Then, the analytical model of the DCMBs with inverted-V SCVFBs (DCMB-SVFB) is built, and the corresponding design philosophies of the SCVFB in the DCMB are proposed based on the concept of structural fuse. Subsequently, the hysteretic behaviors of the DCMB-SCVFB in the transverse direction are analyzed, and the dynamic responses of the whole bridge under near-field ground motions are also investigated. For comparison, the seismic behaviors of the bridges with original bents (the bridges with and without link beams) and the bridges retrofitted with buckling restrained braces (BRBs) are also presented. The results show that the SCVFB has stable energy dissipation capability and excellent self-centering ability, even without the need of prestressing. Compared with the original bridge, the bridges with SCVFBs and BRBs are featured by higher strength, larger stiffness, better energy dissipation capacity, and less damage. In particular, the SCVFB can effectively reduce the residual displacement of the bridge and quickly restore the traffic capacity.

中文翻译：

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近场地震动下SCEB加固双柱中高弯RC桥的抗震性能

摘要

RC双柱中高排架（DCMB）作为公路桥梁的下部结构广泛应用于山区，两柱通常采用RC连接梁连接，以增强横向稳定性。然而，在多次大地震后，DCMB 多次出现严重损坏和/或较大残余位移，这可能导致桥梁丧失功能，不得不拆除和重建。为了提高桥梁的抗震性能，本研究开发了一种使用 SMA 板的新型自定心可变摩擦耗散支撑（SCVFB）来取代 DCMB 中的传统 RC 连接梁。对形状记忆合金（SMA）板的力学性能进行了实验研究。然后，建立了带有倒V型SCVFB的DCMB（DCMB-SVFB）的分析模型，并基于结构熔丝的概念提出了DCMB中SCVFB的相应设计思想。随后，分析了DCMB-SCVFB横向的滞回行为，并研究了近场地震动下全桥的动力响应。为了进行比较，还给出了具有原始弯曲的桥梁（有和没有连接梁的桥梁）和用屈曲约束支撑（BRB）改造的桥梁的地震性能。结果表明，即使不需要预应力，SCVFB也具有稳定的耗能能力和优异的自定心能力。与原桥相比，采用SCVFB和BRB的桥梁具有强度更高、刚度更大、耗能能力更好、损伤更小的特点。特别是SCVFB可以有效减少桥梁残余位移，快速恢复通行能力。