Experimental Study On The Influence Of Steel Plate Restraint On Autogenous Shrinkage Of High Strength Concrete

The early non-load stress cracking of steel-concrete composite shear wall may have an important influence on the overall mechanical performance and durability of the structure.In order to solve the cracking problems of shear wall,a number of scholars have made all kinds of research and exploration,including material shrinkage deformation of concrete and the reinforced shrinkage deformation properties by the various constraints,but little research about the influence of the plate constraint on the shrinkage performance of high strength concrete.At the same time,it has been shown that the autogenous shrinkage of high strength concrete can reach more than 50% of the total shrinkage.Based on this,the paper studied the influence of the plate constraint on the autogenous shrinkage performance of high strength concrete from the aspects of the autogenous shrinkage of high strength concrete,deducing the calculation model,autogenous shrinkage test of high-strength concrete and autogenous shrinkage stress simulation of high-strength concrete.Choosing the shrinkage characteristics of concrete as the research object,based on the coordinate deformation of the specimen cross section,the deformation of concrete constrained by steel consolidation and the relationship between macro deformation and mechanism,the calculation model of the deformation and stress of the concrete section for different situations is derived in theory.Based on the autogenous shrinkage test of plain concrete specimens,the autogenous shrinkage test of high strength concrete under different constraints and the basic mechanical properties tests of high strength concrete were designed and implemented.Through the test and analysis,the main conclusion showed: the higher the rate of steel,the constraint ability of steel plate on concrete was stronger,but the increase was not linear;constraint ability of center steel plate was higher than separate ways;influence of the rust on constraint ability of the steel plate was little;the constraint ability on concrete of steel plate was stronger than reinforcing bar;the strongest constrained regions were the constraints configuration area and the center of the specimen for the center configuration constraints and separate configuration constraints;the restraining effect decreased with the distance from the constraint configuration;no matter what kind of constraints,the concrete shrinkage stress and cracking tendency of the constrained region was strongest;test data,multiple autogenous shrinkage prediction model and theoretical model of restrained shrinkage were analyzed.The results showed that the models had limitations,needing further amendment.Using finite element analysis software ABAQUS,the autogenous shrinkage stress of high strength concrete was simulated.The results showed that the internal constrained stress was large for the configuration of steel plate and reinforcing bar,the cracking tendency of the concrete close to steel plate and reinforced bar was obvious;the restraint stress distribution in the concrete was not even,close to the central region of the concrete,the constraint stress was large,and it's tensile stress,the stress decreased with the distance from the central region,the regional concrete was compressive.The stress concentration phenomenon at the reinforced end was found with high cracking risk;by comparing the simulation results of software data and the calculated stress value,the value calculated by restrained shrinkage test was small,so the influence of non axial constraint stress component should be considered when juding the concrete cracking or not,and the finite element simulation of the specimen should be carried out to estimate the concrete shrinkage stress.