Seismic Performance and Soil Structure Ineteraction effects of Earth quake Response of Cable-Stayed Bridge Towers

采用考虑土-结构相互作用的非线性动力分析方法，研究了土-结构相互作用对斜拉桥钢塔地震反应和动力性能的影响。数值结果表明，考虑地基相互作用和土体非线性可以减小塔模型的响应。基础下方土体的屈服和接触面上抬对基础摇摆响应有显著影响，被动控制技术的目的是通过在桥塔中插入特殊装置，使桥墩基础产生更灵活的摇摆或上抬，从而减小甚至消除结构在强震作用下的塑性变形。数值结果表明，允许有限的摇摆可以减少对桥梁结构的要求，有效地作为一种隔离机制。考虑摇摆作为一种可接受的响应模式可以通过减少所需的基脚尺寸来影响设计成本。此外，适当设计的基础的同时摇摆和加固柱的弯曲变形有望消除或大大减少大地震后柱的损坏和桥梁的残余位移。地震工程界面临的一个新挑战是开发能够改善桥梁抗震性能的新技术。这些新技术包括新的建筑材料（智能材料）和保护系统。通过在塔底设置垫板锚栓，提出了形状记忆合金材料的概念，以提高桥梁的抗震性能。计算结果表明，形状记忆合金螺栓在减小杆件内力和控制塔位移方面是有效的。

A nonlinear dynamic analysis including soil structure interaction is developed to assess the effects of soil-structure interaction on the seismic response and dynamic performance of the cable-stayed bridge steel towers. Numerical results indicate that considering soil foundation interaction and soil nonlinearlities can reduce response of the tower model. The soil yielding below the foundation and uplift at the interface have significantly contribution to foundation rocking response.Passive control techniques are aimed at reducing and possibly eliminating plastic deformations of structures under strong earthquakes, by exploiting a predetermined favorable behavior of special devices inserted in the tower to provide a more flexible rocking or uplift of the bridge pier foundation. The numerical results show that allowing of limited rocking can reduce demands on the bridge structure, effectively acting as an isolation mechanism. The consideration of rocking as an acceptable mode of response can impact design costs by reducing the required footing size. In addition the simultaneous rocking of a properly designed foundation and flexural deformation of the supported-column is expected to eliminate or substantially reduce damage in the column and residual displacements in the bridge following a major earthquake.Anew challenge to the earthquake engineering community is to develop new technologies that could improve the seismic performance of bridges. These new technologies consist of new construction materials (smart materials) and protective system. Shape memory alloy material concepts to improve the bridges seismic performance, are suggested by providing base plate anchor bolts at the tower base. The calculated results prove the effectiveness of using shape; memory alloy bolts in reducing structural element forces and control tower displacement for seismic design.