框架-摇摆墙结构受力特点分析及其在抗震加固中的应用

摇摆结构是一种新型抗震结构体系。摇摆结构通过释放某些部位的约束,允许结构相应位置发生相对位移,从而改变构件的受力状态,改善结构的抗震性能。框架-摇摆墙结构是摇摆结构的一种,其中摇摆墙能够绕着墙底连接件发生面内转动。墙体底部约束的释放降低了对基础的承载力需求,同时能有效避免地震作用下墙体的损伤。具有较大刚度的摇摆墙能有效地控制结构的变形模式,防止出现变形和损伤集中。在框架-摇摆墙结构中增设阻尼器和预应力钢筋可分别增加其耗能能力并减少震后残余变形。该文提出了框架-摇摆墙结构的分布参数模型,利用该模型分析了摇摆墙刚度对结构侧移分布、摇摆墙和框架承载力需求的影响。研究了摇摆墙在国内某工程抗震加固改造中的应用,提出了摇摆墙加固的具体方法以及连接的局部构造。采用动力弹塑性时程分析的方法,对比了原结构与摇摆墙加固后结构的抗震性能。分析结果表明,摇摆墙加固方案能使塑性铰的分布更加均匀,增设预应力钢筋和金属屈服型阻尼器显著提高了结构耗能能力,减小了结构的残余变形。

CHARACTERISTICS OF FRAME ROCKING WALL STRUCTURE AND ITS APPLICATION IN ASEISMIC RETROFIT

A rocking structure is a novel seismic resistance structure system. By releasing constraints in some parts of a structure, relative displacements at specific locations are allowed, the stress states of structural components are changed, and seismic performance is improved. A frame rocking wall structure is a kind of rocking structure, in which the rocking walls can rotate in plane around the connectors at the respective bottom. The releasing of the constraints at the bottom of the walls reduces the strength demand, and the damage of the walls under earthquakes can be avoided. Rocking walls with relative large stiffness can control deformation pattern effectively, avoiding concentration of deformation and damage. A distributed parameter model of a frame rocking wall was developed, and the effects of the wall stiffness on the displacement distribution, the capacity of the wall and the frame were investigated based on the model. An application of the rocking wall on seismic retrofit of a structure was studied. The retrofit construction and connection details are presented. The original structure and the rocking wall retrofitted models are compared based on time history analysis. The comparison results show that the retrofit by the rocking wall can effectively realize a uniform distribution of plastic hinges, and the prestressed tendon and application of metal damper significantly increase the energy dissipation ability and decrease the residual deformation of a structure.