Study On The Axial Compression Performance Of A New Prefabricated Steel Reinforced Concrete Column-Column Joint

Prefabricated Steel Reinforced Concrete(PSRC)Column is a prefabricated structural member that connects industrial prefabricated components mechanically.This structural member has the advantages of simple and efficient construction method,small amount of concrete grouting,and reliable quality,which can solve the problems of large amount of concrete grouting and poor seismic resistance of precast concrete structures.At present,there are few studies on the effect of different steel structures inside the PSRC structure on the mechanical performance,as well as the mechanical performance during the assembly stage.Therefore,this thesis conducts experimental research and numerical simulation on the axial compression performance of a new type of prefabricated steel reinforced concrete column-column joint and proposes a formula for calculating the axial compression bearing capacity of the member.The main research results are as follows:Four new types of column-column joint specimens with different steel structures were designed and subjected to axial compression tests.The failure modes,strain-axial displacement curves,and load-axial displacement curves were studied to analyze the effects of the shear studs and the bottom plates on the axial compression performance of the new column-column joint.The results show that the bottom plate is the most important component that can change the stress mechanism of the column-column joint and avoid stress concentration at the end of the embedded section steel.The failure modes of the specimens with the bottom plates include buckling deformation of the flange plate of the external section steel,and slight cracking of the concrete column.The concrete column of the specimen without the bottom plates shows severe cracking.The bottom plates can significantly improve the axial compression bearing capacity,stiffness,and ductility of the specimen.The shear studs can improve the initial stiffness of the specimen and reduce the yield displacement.The finite element software ABAQUS was used to establish a numerical analysis model of the new type of column-column joint under axial compression.The simulation results of the axial compression bearing capacity,failure mode,and stress distribution of the steel structures of the models with bottom plates are in good agreement with the experimental results.The stress distribution in the cross-sectional concrete of the specimens with bottom plates was analyzed.The parametric analysis was conducted by the axial compression ratio,anchorage length,stud spacing,and size of the bottom plate.The results showed that within the range of the parameters,the axial compression bearing capacity of the new column-column joint increases with the increase of the axial compression ratio,anchorage length,and thickness of the bottom plate,and the effect of the anchorage length showed an attenuation trend.As the size of the bottom plate increases,the axial compression bearing capacity first increases and then decreases,indicating that there is an optimal parameter.The change of stud spacing has a significant effect on the stress distribution of the flange of the embedded section steel,but its effect on the axial compression bearing capacity is relatively limited.Based on the current standards in China and considering the interaction between the bottom plates and concrete,and between the shear studs and concrete.A formula for calculating the axial compression bearing capacity of the new column-column joint is proposed,and the rationality of the formula is verified by experimental and numerical simulation results.