Study On Axial Compressive Behavior Of Recycled Concrete T-shaped Steel Tube Stub Columns With Tie Bars

The application and development of recycled concrete technology can effectively reduce the waste of building materials in my country,improve the recycling rate of waste concrete,and reduce construction waste,thereby beautifying people’s ecological environment and improving the quality of life.The combination of recycled concrete and outer steel pipe overcomes the defect that recycled concrete has a certain degree of deterioration compared with ordinary concrete.However,most of the current research on recycled concrete columns with steel tubes focuses on circular,square and other cross-sections.There are fewer studies on concrete columns.Therefore,it is of great significance to carry out research on the axial compression performance of such components to promote engineering practice and application.In this paper,the axial compression performance of T-shaped steel tube recycled concrete short column is studied by the method of combining experiment and numerical simulation.The main work carried out and the conclusions reached are as follows:（1）The axial compression performance test of 14 T-shaped steel tube recycled concrete short columns was carried out.The variable factors considered include the wall thick Ness of the steel pipe,the replacement rate of recycled coarse aggregate,the presence or absence of tie rods,the spacing between tie rods,etc.Through the test,the whole stress process and failure mode of the specimen were observed and analyzed,the load-displacement relationship curve and the load-strain relationship curve were obtained and explored,and the bearing capacity,ductility,stiffness degradation and axial compression loss of the specimen were analyzed.ability.The results show that: 1)The specimen undergoes elastic,plastic and failure stages under stress,and manifests as obvious bulging failure;2)The increase in the replacement rate of recycled concrete will affect the bearing capacity of the specimen to a certain extent;3)The tie rod is strengthened The constraining effect of the steel pipe on the core recycled concrete makes the bearing capacity,ductility,energy dissipation capacity,and stiffness of the tie-rod specimen with restraint all better than those of the unconstrained tie-rod specimen.Among them,the bearing capacity is 17% higher than that of unrestrained tie rod;4)The increase in the wall thick Ness of the steel pipe can increase the T-shape Bearing capacity,initial stiffness and displacement under peak load of recycled concrete-filled steel tubular columns.（2）The ABAQUS finite element software is used to establish the model,and the load-displacement curve of the specimen under different parameters is obtained through numerical simulation,and the stress distribution of the specimen at different parts and different loading times is analyzed.By comparing the simulation results with the experimental results,the results are in good agreement,and the feasibility and effectiveness of the model are verified.On this basis,the parameter analysis is carried out,and the results show that the bearing capacity of the specimen is mainly affected by the presence or absence of tie rods and the spacing between the tie rods,which is effectively improved after the tie rods are added.It increases with the increase of recycled coarse aggregate and decreases with the increase of the replacement rate of recycled coarse aggregate.