Study On Seismic Performance Of New Type Precast Concrete Composite Pipe Columns

In order to promote the transformation and upgrading of the construction industry,our country is actively developing prefabricated buildings.Prefabricated concrete structures have been widely used in the new buildings in various prefectures and cities.In the current reinforced concrete precast columns,there are too few types of precast columns to choose from,and the cost is too high,and the construction is more complex.Therefore,this paper puts forward a new type of precast concrete column,which is made of precast concrete pipe pile as external precast pipe,which is transported to the construction site and filled with ordinary concrete in the core area of the pipe.A new type of precast concrete composite pipe column is connected with the joint by inserting longitudinal bars in the pipe.In this paper,the seismic performance of the pipe column is studied by means of experimental research and numerical simulation.The main research contents are as follows:1.Through the low-cycle reciprocating tests on two groups of six new prefabricated concrete composite pipe-column beam-column joints,the test results show that the seismic performance of the two groups of specimens is good,but the joints are not reinforced because of the high concrete strength of the pile.Finally,the joint is destroyed due to local compression.2.According to the above test results,an improved scheme is proposed,and two groups of new precast concrete composite pipe column-foundation joint specimens are designed.Before the test,the beam-column joint test model is established by using ABAQUS software,and the model is in good agreement with the test results.Then the relevant parameters of the model are applied to the pipe-column-foundation joint test model,and the preliminary analysis results of bearing capacity and failure mode are obtained.3.According to the test scheme,the low cycle reciprocating test of a new type of precast concrete composite pipe column-foundation joint is carried out,and the test results show that the effect of the improved scheme is good,and the seismic performance of the pipe column with rear longitudinal sleeve rubber tube and rear inserted longitudinal steel bar is good,and the ductility coefficients are all greater than 4.0,which all meet the relevant requirements of the current code.The ductility of the specimen with back-inserted longitudinal bar and rubber tube is better than that of the other group.the installation of rubber tube can effectively reduce the lateral stiffness and improve its ductility,but it will not reduce the bearing capacity and energy dissipation capacity of the member.4.After verifying the high reliability of the finite element model,the relevant factors are analyzed parameterized.The results show that the axial pressure has a great influence on the seismic performance of the pipe string,and it is suggested that the design axial compression ratio should be controlled within 0.55.Increasing the effective precompression stress of pipe pile concrete or reducing the spacing of pipe pile spiral stirrups can improve the ductility of pipe columns.Increasing the number or diameter of post-inserted longitudinal bars can improve the ultimate horizontal bearing capacity of pipe columns to a certain extent.