Experimental Performance On Seismic Behavior Of Small-sized Hollow Concrete Block Masonry Strengthened With High Ductile Concrete

Small-sized hollow concrete block is a new type of wall material with many advantages such as energy saving,soil saving and convenient construction.After the 1980 s,This material has been widely used with the support of national policies.However,the concrete hollow block wall has low strength and poor structural integrity.Especially in rural areas,the quality of used block and construction level are pool.And seismic performance cannot be guaranteed.During the Yushu earthquake in2010 and the Yaan earthquake in 2013,a large number of concrete hollow block structures were damaged or even collapsed to seriously affect the safety of people’s lives and property.Therefore,it is of great significance to study the economic and effective method of concrete hollow block structure reinforcement.High Ductile concrete(HDC)is a new structural material with high toughness and high damage resistance.It has the characteristics of multiple cracking and strain hardening under tension and shear load.Our task group have done some research on concrete structure reinforced with HDC.When used to reinforce small hollow concrete blocks,it can effectively improve the seismic performance of building structures.The main research contents of this paper are as follows:(1)This experiment produced 6 small concrete hollow block masonry walls with a height-to-width ratio of 0.63.The wall was reinforced with HDC for strip reinforcement,single-sided reinforcement,double-sided reinforcement,reinforced strip reinforcement and double-sided reinforcement.After the test,the specific failure form and corresponding data characteristics are analyzed and compared.Through the test,it can be seen that the ultimate bearing capacity of the reinforced wall is improved and the failure form is improved.In particular,the crcking load of walls extra-reinforced with HDC were greatly improved with full development of cracks and full hysteresis curve,greatly improving the capability of energy consumption.(2)According to the test results,the masonry walls with different failure modes are analyzed by different methods to calculate the shear capacity of the wall.For stripreinforced and double-sided reinforced specimens with shear failure,the HDC surface layer utilization rate is calculated by correcting the standard formula,according to the previous test data of the research group.For the reinforced specimens with shear slip failure,the shear friction theory is used to calculate the surface after considering the action of the surface layer.(3)To provide basis for quantitative evaluation of reinforced building with losses in earthquakes,two damage states,nameky the “simple repair” and “complexity repair”states,are defined for masonry infills based on their reparability.From the data of our task group’s previous experiments,this paper compared the properties of three different materials of hollow blocks,solid concrete blocks and clay bricks,and analyze the seismic fragility for different types of masonry infills at the aforementioned damage states by taking the form of lognormal cumulative distribution functions.The results show that the deformability of unreinforced clay brick infills is much larger than that of hollow or solid concrete block infills,and the HDC-reinforced wall has better deformation ability and better repair performance after earthquake.