Experimental Research On Masonry Walls Retrofitted With CFRP After Severe Damaged

Masonry building system is used for the key construction material of the wall, is one of the most used types of structures in the world. Since structural performance of masonry wall is comparatively brittle, so the cracks are easily to appear. The earthquake investigation shows that the masonry walls are the worst damaged. Some walls in the buildings need to be repaired and retrofitted due to earthquake, especially the important or history building that can't be rebuilded, a new requirement for retrofitting the masonry wall is needed. And CFRP has great merits, such as high strength, light weight, thin thickness, a possible method is provided. In order to testify the effectiveness of retrofitting the severe damaged masonry wall with CFRP, and provide a technical support for the engineering. The following work were done:â‘ Experimental investigation of retrofitting the severe damaged masonry walls with CFRPFour severe damaged masonry walls retrofitted with carbon fiber reinforcement polymer (CFRP) and injected glue are provided, two walls with opening and two walls without opening. According to the failure situation, the"X","#", and"X#"retrofitting style are adopted respectively. All specimens were designed and tested under combined uniformly distributed constant vertical load and cyclic lateral load. The main purpose is investigating the failure model and failure characteristic, and analyzing the strength, ductility, and the energy dissipation. The test data indicate that, 1) Injected the glue and CFRP for retrofitting the severe damaged masonry wall is effectively. The maximum horizontal load of retrofitted wall is increased remarkably, compared with the original masonry wall. The displacement capacity and energy dissipation capacity of masonry walls are improved when retrofitted with CFRP. On the other hand, use of CFRP can't delay the appearance of the cracks clearly, but can restrict cracks\ development in the masonry walls. 2) Confining effect of different CFRP style is different, the best style should be decide according to the original damaged wall (before retrofitted). For the retrofitting style"X", the action of composite strips is similar to that of the diagonal braces in the truss analytical model. And the shear force contributed by CFRP strips is mainly coming from the action of tension bars in the analytical model; for the retrofitting style"#", the action of composite strips is similar to that of the stirrup in the frame column; for the retrofitting style"X#", the action of horizontal composite strips is similar to that of the stirrup in the frame column and the action of cross composite strips is like he diagonal braces in the truss. 3) The compression debonding and the shear impair are the main reasons for CFRP damage. And the CFRP strain of broken wall is far more less than the CFRP ultimate strain. Therefore, the higher strength CFRP shouldn't be considered, except the stronger elastic modulus CFRP.â‘¡Shear strength prediction after retrofitting the damaged masonry wallsBased on experiments and studies, a simplified calculated schematic of CFRP retrofitted the severe damaged masonry walls and the coefficient caused by injected the glue is provided. The coefficient may be tentatively used in predicting the shear strength of retrofitting damaged masonry walls, made of shale bricks.