| Prefabricated assembly structure is assembled on site by various mainly forced member.It is vigorously promoted in China,due to its short construction period,energy saving,clean production and other advantages.In prefabricated constructions,prefabricated reinforced concrete columns are the main vertical bearing member in the structural system,it is particularly important to study the seismic performance of precast columns connected with foundation.At present,domestic and foreign scholars have done many researches on the seismic performance of precast column and foundation beam,but less considered the seismic performance of the connection between precast column and independent foundation in low-rise buildings as well as the minimum anchorage length of precast column longitudinal bars in actual structures.Meanwhile,the grouted corrugated sleeves connection are gradually used on the assembly vertical component connection for its convenience in construction.In order to further promote the application of grouting corrugated sleeve connection between prefabricated columns and prefabricated independent foundations in low-rise buildings in urbanization.In this paper,experimental and theoretical analysis are used as the main research means to study the seismic performance of prefabricated columns and prefabricated independent foundations connected with grouted corrugated sleeve with the parameter of longitudinal reinforcements.The main work and research results are as follows:(1)Six prefabricated colums and one cast-in-place column were fabricated on site,and the pseudo-static tests of seven test columns were carried out.The test results showed that no sleeves were pulled out from the prefabricated independent foundation,and no longitudinal bars of the column were pulled out from the sleeves.The grouted sleeve connection can transfer stress effectively,which indicates that the pre-embedded grouted sleeve grouting connection can be used between the prefabricated column and the prefabricated independent foundation.(2)The influence of three parameters on seismic performance of prefabricated columns,namely,the length of grouting rebar,the axial load index,the debonding of longitudinal reinforcement at the bottom of column(the way of bonding with concrete in the range of 5 times the diameter of longitudinal reinforcement at the bottom of column),is mainly studied.The failure mechanism,load-displacement curve,skeleton curve,strength and stiffness degradation curve,displacement ductility,energy dissipation and column foot curvation of all test columns were compared and analyzed.The results show that when the axial load index is constant,the length of longitudinal reinforcement grouting anchor of prefabricated column is not less than 20 times of its diameter in order to prevent the damage of prefabricated independent foundation under low cycle;When the axial load index is constant,debonding length of the column longitudinal reinforcement can postpone the oblique crack of the prefabricated column and increase the ductility,energy dissipation capacity and residual deformation of the component.when the longitudinal reinforcement of prefabricated column is anchored to the independent foundation with 20 times the diameter of longitudinal reinforcement,its failure mode,ductility,bearing capacity and energy dissipation capacity are close to that of cast-in-situ column,so the prefabricated column and independent foundation can be connected under the same working conditions.(3)Based on the analysis of the test data,the skeleton curve model of precast assembled column and precast independent foundation connected with grouted sleeve under low cyclic load is obtained by using the test fitting method,and the data regression of the unloading stiffness and strength degradation of the four test columns under different displacement ratios is carried out,and a restoring force model of the connection between prefabricated column and independent foundation grouting anchor is proposed. |
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