Experimental Study On Seismic And Crack-Resistance Behavior Of Prestressed Masonry

Along with the basic national policies that protect the land resource and farmland are executed, the small-sized concrete hollow block have replaced the clay block, and become one of the predominant wall material in the reformation of wall material. In recently years, the small-sized concrete hollow block is wildly used in urban buildings. For the shear strength of the concrete hollow block masonry is low, it is a question for in-depth discussion that how to improve masonry's crack-resistance and seismic behavior by effective technical measure.Prestress the masonry wall can change its material property, improve masonry's crack-resistance , shear strength-resistance and seismic behavior, and also expand masonry's application scope, fulfill the requires of masonry development for tall-building , anti-seismic and environmental protection. Based on domestic and international researches, this paper have experimental researched on crack-resistance and seismic behaviors of prestressed small-sized concrete hollow block masonry, and below is the concrete contents of research:Adopt a finite element analysis soft, and proceed nonlinear finite element analysis to different type and different structure measure of walls. The result expresses that the walls which have window, have stress concentration at the window cape, and easily appear the cracks, the same type walls' carrying capacity of crack-resistance are greatly improved after being prestressed, and compare the different type walls, a problem is discovered that window or hole is consumedly lowered the carrying capacity of crack-resistance and stiffness of wall. And these are accord with the result of experimentation.we designed five walls for simulate both sides of the top floor. Proceeded to add unilateral horizontal static loading experiment to 4 pieces of prestressed small-sized concrete hollow block masonry models and 1 piece of normal concrete hollow block masonry model. Crack-resistance behaviors were analyzed, and we have proceeded prestressing loss survey for 25 days, and discussed the reasons of prestressing loss. Experiment results show that prestressing force can greatly improve masonry crack-resistance behavior and the carrying capacity of crack-resistance is greatly improved after being prestressed.In addition, 4 pieces of prestressed small-sized concrete hollow block masonry models and 1 piece of normal concrete hollow block masonry model are tested under frequency low-cyclic static load. Some seismic behaviors such as strain-stress curve and ductility of the prestressed masonry were analyzed. The results of the tests show clearly that the carrying capacity ofshear-resistance and deformation property and ductility of the masonry walls were increased after being prestressed, and the prestressed walls are forced more uniform and material property can be completely developed. Cracks are more slightness and more dense, and will be closed after being unloaded, and the walls will not fall apart with cracks, which indicate that such walls may retain the entirety well and have good resistance of collapse.The failure mechanism and the pattern of damage are analyzed in this paper. On the grounds of experimental results and theoretical analysis, the formula of ultimate shear capacity of prestressed masonry wall is established.According to the research results, some recommendations of design method and construction details of prestressed masonry are simply introduced in this paper.