Seismic Response Analysis In The Infilled Wall Framework With Buckling-restrained Braces

Collaborative work between the filling wall and the frame has a very big impact on the seismic behavior of infilled frame structures. The current code for structural design does not calculate the contribution of filling wall lateral stiffness to frame structure, just by reducing framework cycle to consider the role of infilled frame structures. In order to fully exploit the commercial value of the framework along the street, usually the bottom two are used for commercial, the upper floors for residential or office. At this time, the bottom two floors height is generally higher and almost no filling wall, while other floors height shorter with many filling wall, easy to form a weak layer in the bottom floor frame, make the structure first in the weak layer damage or even collapse when an earthquake occurs, left a security risk for the use of the structure. In order to study the influence of filling wall on the seismic performance of frame structure with large space at the bottom and the method to eliminate the structural weak layer. This paper has done the following work:1)According to the equivalent bracing section width formula of infill wall proposed by scholars before, using the finite element software SAP2000 establish filling wall-frame model and pure frame model for the structure that the bottom two layer is large space(no infill walls) and other layer have filling wall. By comparing the period of the two models, this paper attained fitting curve cycle reduction factor of this kind of structure, to provide a reference for this kind of structure.2)Use modal response spectrum method, time history analysis method to find thedifference between cycle reduction framework model and filling wall frame model in terms of side column shear, storey drift of and other, description current standard design method has unreasonable. In addition through Pushover analysis find that there is a big difference between the two structure models in terms of inter story displacement and the plastic hinge distribution of the structure, proof of that want to get more accurate analysis results of frame structure the bottom floor is weak layer, should establish the infilled frame analysis model.3) According to the "stiffness compensation" concept, a simplified design method of BRB eliminate structurally weak layer and select BRB model and number is proposed, and in this way the BRB arranged in the weak layer. In practical engineering background, use SAP2000 finite element software to establish a pure framework model,infilled frame model, infilled frame-BRB model, conducted a response spectrum analysis, modal analysis, linear time history analysis, nonlinear time history analysis,comparative of the pure framework model and infilled frame models in the interlayer displacement, vertex displacement,acceleration apex, base shear, energy distribution,hysteresis curve terms vary greatly. Description infill walls have a non-negligible effect on the frame structure seismic response. Comparative of the infilled frame-BRB model and two models aforementioned,found that under frequently occurred earthquake BRB provides lateral stiffness for the structure, under rare earthquake BRB by its hysteretic seismic energy dissipation, played eliminate vibration energy dissipation effect,reducing the seismic response of the structure, improve the seismic performance.Verified herein BRB Press "stiffness compensation" principle to eliminate structural weak layer design method is correct. Description BRB has a very good value for the elimination of structural design and strengthening the weak layer.