Research On The Behaviors Of Vertical Prestress Spacing To Composite Masonry Walls With Holes On The Aspect Of Eccentrically Compress

The intention of this test is to research the behaviors of prestresse spacing to composite masonry walls with holes on the aspect of eccentrically compress. This paper, firstly, reviews the tests and researches about the composite masonry walls at home and abroad, and find out that despite a number of researches have been done,and gained some useful results, yet most of these were focused on the even layed loads and lateral forces or aseismatic performance, specification is also too brief involved in this part.Chongqing university has done a series of tests on composite of single-wall without upper load and composite multi-wall with the upper eccentric load. So this test designs 4 pieces of walls with same structure,but Prestresse varying degrees to study composite masonry walls with holes which are eccentrically compressed under the upper loads. the influences of holes on the coordination of columns,ring beams and masonry walls under upper floors and concentrated loading out-of-plane are discussed, the transfer and distribution of section stresses in the vertical direction of the walls affected by Vertical prestress, emergence and development of cracks , deformation and failure mechanism of members are revealed , the reasons and rules influencing the behaviors of the composite masonry walls are discovered, some meaningful conclusions are concluded as follows:①Concentrated prestressing effectively improve the capacity of composite masonry walls which are out-of-plane and eccentrically compress. Within a certain range,the greater of concentrated prestress,the higher of the capacity.②Concentrated prestressing effcetively improve the overall space performance, development of cracks and stiffness degradation are delayed, stress concentration are slowed down, the transfer and distribution of section stresses in the vertical direction are changed;③Same with no hole composite masonry walls,the greater the stiffness of beams are, the better the cracking-resistance, loading bearing and deformation capacity are. The influence of beams'stiffness is very important for the ultimate carrying capacity;④Same with no hole composite masonry walls,the higher of material strength,the greater ultimate anti-bend capacity are;⑤Same with no hole composite masonry walls,the smaller space berween columns,greater the stiffness of structural columns'cross-section is and higher of reinforcement ratio,the greater ultimate anti-bend capacity of composite masonry walls;⑥The vertical loads could reduce eccentric compression obviously,and minish the horizontal distortion of the walls with holes.⑦Although the composite masonry wall has obvious special effects under out-of-plane eccentric compression, its deformation is harmonious; masonry, structure concrete columns and ring beams bear the load together, and some stress re-distribution happens during the loading process;⑧To analyze the performance of composite walls under out-of-plane eccentric compression, the composite frame model may be used.Although this study for the effect of prestresse on composite masonry wall is on the basis of the previous, further study such as spacing of columns and transverse bracing, stiffness of ring beams and structure concrete columns , size of holes, wall layers and horizontal load is needed to know the influence rules of the aspects above, put forward effective calculation method and appropriate structure measures, and provide enough testing and academic foundation for the present code of masonry structure.