Study On Seismic Performance Of Frame-rocking Wall Structure And Development Of Its Connection

Traditional frame structure tends to form storey collapse at the soft storey subjectto strong ground motion. Rocking walls are added to the structure in order to improveits seismic performance. Rocking wall is a concrete wall or steel truss pinned at thebottom which is expected to make the structure a better seismic performance than theconventional frame structure refer to the collapse prevention because the rocking wallcan control the structure’s deformation mode, preventing the occurrence of soft storeymechanism.The bearing capacity demand of rocking wall is a key point of the design of framerocking wall. This paper obtains the demand of rocking wall via certain seismic forceand capacity of frame. This job assists the design of rocking wall structure. In addition,the effect of nature period of structure is less than10%caused by the rocking wall isfind out by theoretical derivation.A series of finite element analyses (FEA) were carried out to study the seismicperformances of the frame-rocking wall system. A6-story RC frame following currentChinese design practice was taken as the example. Elastic-plastic model was established,and pushover analyses were conducted by a general FEA program called Abaqus6.9. Inaddition, time history analyses were also carried out using22ground motions suggestedby ATC63. Analysis results suggest that the rocking wall can significantly improve thestrength and ductility of the frame structure. The inter-story drifts become moreuniformly distributed and the soft story failure mechanism was prevented, although therocking wall did not contribute much to avoid the ‘Strong beam weak column’ yieldingmechanism.A new kind of connection between the frame and the rocking wall was devised forthe frame rocking wall structure system and physical tests were conducted mainly toinvestigate the performance of the rocking wall equipped with the connection. Theperformances focused are the rotational capacity, the stiffness added to the frame, thecontrolling effect of the wall and the gaps in the connections, and the overall stiffnessand the story drift concentration factor (DCF) were adopted as indexes. The resultssuggest the connection ensure the rocking wall a0.05rad rotation capacity both in planeand out of plane without significantly increase of the structure’s overall stiffness, and the gaps in the connection are small enough. The rocking wall can effectively controlthe story drift concentration and making the structure present a uniform deformationwhen subjected to various loading cases. In addition, the rocking wall with verticalplaced post tension (PT) bars inside was also tested, and it showed a flag-shapedhysteretic curve, providing the structure with self-centering capacity.