Influence Of Different Parameter Variables On The Seismic Performance Of SRC Column-H Steel Beam Composite Joints

As an important construction form and carrier of construction industrialization,prefabricated building.The development of prefabrication is an effective way to solve the disconnection between architectural design,production and construction management.It is also of great significance to alleviate the current domestic labor supply and demand imbalance,rising labor costs and aging population and other practical problems.As the core part of prefabricated structure system,the seismic performance of joint connection has always been the focus of scholars at home and abroad.This paper uses pseudo-static tests to study the seismic performance of three steel reinforced concrete column-H steel beam composite joints.Based on the experimental study,the effective model is established by using the finite element software ABAQUS,and the seismic performance of the joint is analyzed systematically.The main research contents and achievements are as follows:(1)Pseudo-static tests were carried out on three joint specimens,study the influence of different joint cover length on the seismic performance of joints.It mainly analyzes the seismic performance indicators such as the failure form,bearing capacity,energy consumption and stiffness of the joint.The result shows: the three joint test pieces are all beam hinge failure mechanisms,which conform to the seismic design principle of "strong column and weak beam";The hysteresis curves of the test pieces are all shuttle-shaped,relatively full,and the equivalent viscous damping coefficients are all greater than 0.3,and the energy consumption capacity is relatively excellent;The increase in the length of the joint cover can effectively improve the bearing capacity of the joint,but the ductility is slightly reduced.(2)Based on the pseudo-static tests research,the finite element software ABAQUS is used to simulate and analyze the seismic performance of the joint specimens.The results shows: the final finite element model is the beam hinge failure mechanism,which is basically the same as the failure mode of the test piece.The simulated hysteresis curve,skeleton curve and test piece curve are in good agreement.The feature point value extracted from the skeleton curve is compared with the result of the test piece,and the error is basically within5%.The feasibility and reliability of the finite element model are verified,and the stress distribution of the joint is determined.It lays a theoretical foundation for further exploring the influence law of different parameter variables on the seismic performance of the joint.(3)Based on the effective model established by ABAQUS.The influence of the length of the joint cover plate,the weakening form of the steel beam and the axial compression ratio of the column on the mechanical behavior of the joint under monotonic loading is studied.The results shows: The ultimate failure of models with different joint cover length(150 mm ～350 mm)occurred at the flange connecting plate,which was consistent with the failure mode of joint test pieces.The bearing capacity of the joint increases with the increase of the cover plate length,but the ductility decreases.Different weakening forms of steel beams have great influence on the mechanical performance of the joints.The failure mechanism of each model is beam hinge,which conforms to the seismic design principle of joints;The weakening form of steel beam flange can significantly improve the bearing capacity and ductility of the joint;The weakened form of the steel beam web has little effect on the mechanical performance of the joint.It is recommended to appropriately increase the weakened diameter of the web in the later stage and set up annular stiffeners for in-depth study;The ductility performance of the steel beam flange plus web weakened model is relatively excellent,but when the weakened web diameter of this form exceeds 70 mm,the joint bearing capacity decreases.The increase of the column axial compression ratio(0.15～0.5)makes the joint yield higher and accelerates the failure speed of the joint.It is recommended that the axial compression ratio be controlled within 0.3 to ensure the stability of the joint connection.(4)Based on the effective model established by ABAQUS,the influence of the length of the joint cover plate,the weakening form of the steel beam and the axial compression ratio of the column on the seismic performance of the joint under reciprocating loading is further explored.The results show that the failure mechanism of different joint slab lengths is beam hinge failure,and the increase of joint slab length can effectively improve the bearing capacity of the joint,but when the joint slab length is greater than 300 mm,the ductility and energy consumption of the joint decrease significantly,especially when the joint slab length is350 mm,the bending failure occurs in the core area of the column joint,which is not conducive to the stability of the joint,This should be avoided in seismic design.The results show that the ultimate failure position of the model with flange weakening form and flange plus web weakening diameter of 70 mm occurs at the flange connecting plate,and the hysteretic behavior and bearing capacity of the weakened model are slightly different from those of the non weakened model,which proves the stability of the weakened joint model;The ultimate failure position of the model with 80 mm and 90 mm weakening diameter of steel beam flange and web is at the weakening position of steel beam.The energy dissipation capacity is greatly improved,but the ductility performance is significantly reduced.It is suggested that the weakening diameter of web of this model should be controlled within 70 mm.The column axial compression ratio model is the failure mechanism of beam hinge,which is in line with the original intention of joint design.With the increase of axial compression ratio,the yield degree of the joint is higher and the energy consumption is increased obviously.However,the ductility of the joint decreases more when the axial compression ratio is too large.It is suggested that the axial compression ratio should be controlled within 0.3.The research results of this paper can provide some references for the engineering application of prefabricated steel reinforced concrete composite structures.