Research On Mechanical Performance And Failure Mechanism Of Masonry-infilled RC Frames

Masonry-infilled reinforce concrete(RC) frames are made of frame columns,frame beams,slab and infilled walls,which are used widely in tall buildings and multi-story RC frames. During Wenchuan earthquake occurred in 2008 with a richter magnitude of 8.0, numerious masonry-infilled RC frames failed due to strong beam weak column,obvious weak story and short column effect,while the ductile failure mechanisms specified by seismic design codes were rarely realized.However,theoretical analysis and experimental study of infilled RC frame are still quiet insuficient,and investigations on interaction mechanism between infill wall and bounding frame are particularly rare. Therefore,it is of critical importance to gain insight into and improve the seismic performance of the masonry-infilled RC frames.In the present study, a micro finite element(FE)method was used to analyze the effect of infilled wall on seismic performance of RC frames. The main contents are as follows:(1) A two-dimensional(2D) micro FE model of the masonry-infilled RC frames was developed based on the DIANA platform and then varified by avilable experimental results. The pushover curves obtained with this micro-model were in good agreement with the corresponding test data.(2) Based on the above study,the influences of the aspect rato of the infills on the seismic performance of the structure were investigated. Analyze results showed that with the aspect ratio increased, the initial stiffness of structures incresed too, and the peak capacity of structures decreased at first but then increased while the aspect ratio exceeded an certain threshold value.(3) The influences of opening configurations and locations on the seismic performance of the structure are analyzed deeply. It was shown that partial-height infill, door and window decrease the advantage of masonry-infilled wall and increase the risk of damage. Hense, windows and doors should be placed in the middle as far as possible, thus avoiding partial-height infill wall.(4) Some flexible connecting structural measures which can improve the seismic performance of masonry-infilled RC frames in solid and opening infill wall are analyzed.