Experimental Study On Axial Compression Of Block Masonry Wallettes Confined With Spirals In Core Columns

In recent years,reinforced concrete masonry shear wall structure(RCMSWS)has been widely used and made great developments as a kind of structural system in middle-rise and high-rise buildings.However,the limits of its constructional process result in less reinforcement in boundary elements of RCMSWS.The less reinforcement in boundary elements has become a common concern in concrete masonry wall structural design and caused engineers' doubt for structure ductility,which restricts the development of RCMSWS.Therefore,it has become to a key issue on how to improve structural ductility of RCMSWS by using a proper reinforcement plan.In this thesis,spiral reinforcement,which is placed in the holes of concrete blocks,is used for confining boundary elements of concrete masonry walls.An experimental study was carried out by simplify the boundary elements into concrete block masonry wallettes.The experiments under axial compression included 23 fully grouted concrete block masonry wallettes confined by spiral reinforcement.Design of the experiment and construction of specimens were directed by the standard for test method of basic mechanics properties of masonry(GB/T 50129-2011).There were two methods used to investigate,namely performance analysis and experiment data analysis.(1)The failure modes and the typical stress process of the specimens were studied by the method of performance analysis.In addition,failure characteristics such as horizontal mortar crushing,block web failure and concrete failure between spirals were found.The result of performance analysis showed that the failure mode of spiral confined block masonry wallettes were three types,and the three failure modes reflected their own stress states respectively.The specimens with spiral and horizontal reinforcement gave the most ideal failure mode.(2)By using experiment data analysis,the mechanical properties of specimens under axial compression were studied.The experimental performance was verified by analyzing the confine mechanism of spiral reinforcement.Experiment data showed that reducing the spacing,enlarging the diameter and increasing the strength of spirals had positive effects on mechanical properties of specimens.The deformability of specimens with spirals was significantly enhanced than specimens without reinforcement.The failure mode of specimens was effectively improved by using spiral and horizontal reinforcement together,also the peak load and ultimate deformation were significantly improved.