Study On Seismic Behavior Of Precast Confined High-strength Concrete Columns Under Various Axial-compression Ratios

In recent years,the advantages of high-efficiency construction,good overall performance,and sustainable development of fabricated concrete structures have become more prominent.At the same time,high-strength and high-performance concrete can reduce the problem of "fat beams and fat columns" and reduce costs.In this paper,with prefabricated constrained high-strength concrete columns as the main research objects,five full-scale assembled welded ring-shaped stirrup-constrained high-strength concrete columns and one cast-in-place contrast column were designed and fabricated,and the prefabricated joint connection was a semi-grouting sleeve Connection,using a combination of pseudo-static test research and finite element analysis,comprehensively studied the effect of different axial compression ratios on the seismic and deformation performance of assembled constrained high-strength concrete columns.The main research results are as follows:Through the failure form and hysteresis characteristics of 5 assembled constrained high-strength concrete columns and 1 cast-in-place contrast under low-cycle cyclic reciprocating load,the skeleton curve,ductility and consumption of different axial compression ratios(n = 0.19 ~ 0.34)were analyzed.The influence law of seismic performance such as energy capacity,stiffness and bearing capacity degradation.The research results show that:(1)the assembled constrained high-strength concrete column has the same seismic performance as the cast-in-place column;(2)the assembled joint performance and construction technology directly affect the ultimate deformability and seismic level of the precast structure.The sleeve joint has good performance,and the construction process has reference significance;(3)With the increase of the axial compression ratio,the peak horizontal bearing capacity of the specimen is significantly improved,the rigidity and strength attenuation is accelerated,the ductility is reduced,and the energy consumption performance is slightly increased.The impact is smaller.The bearing capacity of the specimen with a larger axial compression ratio is increased by 31% than the minimum axial compression ratio,but on the contrary,the deformability is getting worse and the seismic performance is unstable.The finite element model under the same conditions was established using ABAQUS software.The simulated load-displacement hysteresis curve was compared with the test results to verify the accuracy of the model,and the parameters were designed to expand the design of 19 prefabricated column models.The ultimate bearing capacity has a greater influence,and the design axial pressure ratio limit within 0.51 can achieve relatively good deformation requirements.Based on the experimental research and finite element analysis of the assembled constrained high-strength concrete column,a rational three-line restoring force model with varying axial compression ratio parameters is proposed from the skeleton curve,and the key features are derived through the empirical formulas and regression analysis of previous studies The theoretical value of the point is verified to have a good fit,and the hysteresis rule is determined.Provide a basis for the calculation of the deformation capacity of the assembled constrained high-strength concrete column and the establishment of the element model.