Experimental Investigation And Finite Element Analysis On Bond Slip Mechanism Between Shape Steel And ECC

Engineered Cementitious Composite(ECC)is a kind of fiber reinforced cement matrix composite with high ductility,which is different from conventional concrete.ECC is designed to greatly improve the brittleness of conventional concrete material and has a good deformation coordination with steel.The steel reinforced ECC composite structure formed by using ECC instead of concrete can improve the brittle failure of steel reinforced concrete structure,enhance its ductility and durability,and then improve the service life of the structure.Nowadays,there is little research on the mechanism and performance of bond slip between steel and ECC.Therefore,in order to understand the basic characteristics of bond slip between shape steel and ECC and the influencing factors of bond slip behavior,this paper studies the bond slip performance between the steel and ECC by combining the experimental research and finite element analysis.14 specimens were designed by the control variable method and subjected to a push-out test.The effects of the volume fraction of PVA fiber,stirrup reinforcement ratio,ECC cover thickness and H-shaped steel embedded length on failure mode,crack development and bond stress were analyzed.The results show that the volume fraction of PVA fiber and the ECC cover thickness are the main parameters affecting the bond strength,while the bond strength decreases with the increase of steel embendded length,and the effect of stirrup reinforcement ratio on the bond stress is not obvious.Based on the measured datas,the load slip curves of these specimens were obtained,and their types and characteristics were described respectively.By analyzing the test datas,it is found that the strain distribution along the embedded length of shape steel under different loads is basically exponential.The steel develop inelastic behavior at the loaded end when the ECC cover thickness reaches 70 mm or the embedded length reaches 600 mm.According to the grey correlation theory,the calculation formula of bond stress is established.The bond stress-slip constitutive relation of specimen s was proposed,which can describe the bond slip behavior of H-shaped steel with ECC well.This paper takes ABAQUS to establish 3D nonlinear models of push out test specimens.The bond slip constitutive laws between the shape steel and ECC presented in this paper is used to consider the contact between them through nonlinear spring element.The analysis results show that the finite element simulation method used in this paper can accurately analyze the bond-slip behavior between shape steel and ECC.On this basis,the finite element analysis of the steel-ECC composite beam considering the bond-slip effect is carried out by ABAQUS.The results show that more accurate results can be obtained by considering the bondslip effect.