Experimental Study On Seismic Behavior Of Prefabricated Concrete Columns With Longitudinal Reinforcement Lap Connection

With the advantages of saving resources,reducing energy consumption and high industrialization,the prefabricated concrete structure has become the direction of future building development.The main factor restricting the development of prefabricated concrete structures is the connection of joints.As an important mechanical component in building structure,the seismic performance of column will directly affect the safety and stability of the structure.Longitudinal bar overlapping is a common connection form of prefabricated concrete columns.The overlapping length and the concrete performance in the overlapping area have a great impact on the seismic performance of prefabricated concrete columns.Steel fiber reinforced concrete has high tensile and flexural strength,which can significantly improve the seismic performance of members.In this paper,the effect of longitudinal reinforcement overlapping length and pouring high content steel fiber reinforced concrete in the overlapping area on the seismic performance of prefabricated concrete columns is studied.The main research contents are as follows:(1)Four concrete columns were designed and fabricated,including three fabricated concrete columns and one cast-in-situ concrete column.The prefabricated concrete column adopts the lap connection method of longitudinal bars,and the lap lengths of the longitudinal bars are 100mm,200mm and 300mm respectively.The quasi-static tests of four specimens under axial compression ratio of 0.15 were completed.By analyzing the failure mode,hysteretic curve,skeleton curve,strength and stiffness degradation curve,ductility and energy dissipation performance of the specimens,the influence of the lap length of longitudinal reinforcement on the seismic performance of fabricated concrete columns is studied.(2)The longer the lap length of longitudinal reinforcement is,the fuller the hysteretic curve of fabricated concrete column is,but it is not as full as cast-in-situ concrete column.The peak load of all fabricated concrete columns is lower than that of cast-in-situ columns,but the fabricated concrete columns with a lap length of 300mm basically reach the peak load of cast-in-situ concrete columns.(3)The overlapping length of longitudinal reinforcement has a great influence on the energy dissipation capacity and ductility of prefabricated concrete columns,The cumulative energy dissipation,energy dissipation coefficient and ductility coefficient of fabricated concrete columns with an overlapping length of 300 mm reach the corresponding values of cast-in-situ concrete columns.(4)The cracks of cast-in-situ concrete columns develop more fully and distribute more evenly,and the cracks of prefabricated concrete columns are less and mainly concentrated in the joint of new and old concrete.The lap length of longitudinal reinforcement affects the development and distribution of cracks.The longer the lap length is,the more fully the cracks develop.