Shear Resistance Of New Perforated Shaped Steel Engineered Cementitious Composite(ECC)Connector

In recent years,prefabricated structure has become an indispensable structural form because of its fast construction in the actual project and environmental protection in the construction process.However,the joint connection of traditional prefabricated structure is weak and easy to be damaged.In view of this situation,some scholars have proposed the dry connection of steel joints to precast beams and columns,but the transition between shape steel and concrete structures has become a sudden change in stiffness,which leads to damage near the area.Engineered Cementitious Composite(ECC)has better ductility and energy consumption capacity.Therefore,ECC material with high ductility is used in this transition area and a new shear connector is proposed.Aiming at the combination of ECC and the new shear connector,the main research contents and conclusions of this paper are as follows:(1)Experimental study on the performance of the perforated shape steel ECC /concrete connectors.In the test design,it is considered to change the type of material(ECC or ordinary concrete),the compressive strength of ECC,whether there is perforated shape steel ECC connector,and the number of rows of the holes.Through comparative test,the failure mode and bearing capacity of perforated shape steel ECC connector and perforated shape steel concrete connector are analyzed.Among them,the failure mode of the perforated shape steel ECC/concrete connector is the splitting failure of the external ECC/concrete.In addition,the ductility of ECC specimen is obviously better than that of ordinary concrete specimen.the bearing capacity of perforated shape steel ECC connector about 5.3-8.8 times to the steel reinforced ECC,and the existence of reinforcement in the hole increases the bearing capacity of the perforated shape steel ECC/concrete connector by about 1.6 times.The load slip curve of the perforated shape steel ECC/concrete connector can be roughly divided into five stages: no slip stage,slip stage,yield stage,descent stage and stable stage.(2)The nonlinear finite element analysis of the perforated shape steel ECC/concrete connector.Based on the finite element software ABAQUS,the finite element model of the perforated shape steel ECC/concrete connector is established.The parameters such as the thickness of the protective layer,the diameter of the perforated steel bar,the volume stirrup ratio,the length of the perforated steel bar,the position of the perforated steel bar,and the thickness of the perforated shape steel are calculated.Among them,the change of parameters has no effect on the failure mode of the model,the volume stirrup ratio,the length of the perforated steel bar outside the section steel and the position of the perforated steel bar have no effect on the bearing capacity of the shear piece;the ultimate bearing capacity of the shear piece is independent of the thickness of the flange of the section steel without yield failure of the section steel;the ultimate bearing capacity is dependent on the thickness of the protective layer and the diameter of the perforated steel bar outside the section steel ECC Increase with increase.(3)Theoretical study and formula derivation of the perforated shape steel ECC connector.This paper sums up the theoretical research and the formula of the former in the perforated plate connector.According to the failure mode and ultimate bearing capacity of the perforated shape steel ECC connector in the process of experimental research and finite element calculation,based on the conventional perforated plate connector,the stress analysis model of the new perforated shape steel ECC connector is obtained,and the calculation formula of the ultimate bearing capacity of the new perforated shape steel ECC connector is derived.