Experimental Study On Axial Compression Performance Of Partial Prefabricated Steel Reinforced Concrete Columns

Partially Prefabricated Steel Reinforced Concrete(PPSRC)structure refers to a new composite structure in which the outer part of the Steel Reinforced Concrete structure is prefabricated and the core part is cast in place.It has the advantages of high bearing capacity and good seismic performance of Steel Reinforced Concrete structure.The internal and external concrete materials can be selected differently,rationally configured,and economical.In this paper,the experimental research and numerical simulation analysis of the axial compression performance of PPSRC columns are carried out,and the calculation formula of axial bearing capacity is proposed.The main research contents of this paper are as follows:Firstly,eight PPSRC solid columns and two PPSRC hollow columns were designed for axial compression test.The failure modes,strain development and load-axial deformation curves were studied.The effects of the core concrete strength,rectangular spiral stirrup spacing,cross-shaped steel flange welding shear on the axial compression performance of PPSRC columns were analyzed.The influence of parameters such as welding shear studs on the axial compression performance of the PPSRC column.The results show that all the columns destroyed due to material damage when the load capacity limit state is reached,and the failure modes are basically the same.As the core concrete strength increases,the axial bearing capacity and its increments all increase.As the rectangular spiral stirrup spacing decreases,the axial bearing capacity and its increments all increase.In these three factors,the core concrete strength has the greatest influence on the axial bearing capacity of PPSRC columns,followed by the spacing of the stirrups.And the studs has little effect on the improvement of the axial bearing capacity.Secondly,the software ABAQUS is used to simulate the axial compression performance of the PPSRC columns.The calculation results of the ultimate load and load-relative displacement curves of each models are in good agreement with the experimental results.Based on the validity of the model,the influencing parameter expansion analysis is carried out to study the influence of section steel ratio?_s,section reinforcement ratio?_r and section size(scale factor?)on axial bearing capacity.The results show that the axial bearing capacity of PPSRC columns increases with the increase of?_s,?_r and section size,so do the increment of the axial bearing capacity and the ductility.And the increment of the axial bearing capacity is approximately linear with?_s and?_r.Compared with the hollow columns,the solid columns exhibits better ductility,higher peak load and later bearing capacity.The stress cloud diagram of the column section concrete under the failure state of all columns shows obvious distribution law.In the strong confinement zone,the stress around the steel flange and web is the largest,and the stress peak distribution appears as a distinct cross shape.The stress value gradually decreases with the increase of the distance from the steel.Finally,the four corners in the core octagonal region show a distinct parabola shape.In the weakly constrained zone,the longitudinal ribs and the surrounding areas exhibit high stress values.Finally,based on the results of experimental research and numerical simulation,the effective lateral compressive stress of concrete with rectangular spiral stirrups and cross-shaped steel for different confinement areas is analyzed,and the calculation method of axial concrete compressive strength in different confinement areas is explored.Based on the existing theory,a simplified calculation method for the axial compressive strength of concrete in strong confinement area is proposed.The strength superposition method is used to establish the calculation formula of the axial bearing capacity of the PPSRC columns,and compared with the experimental results and the simulation results to verify the reliability of the formula.