Study On Seismic Performance Of Pre-stressed Connection With Angle And Shear Key

The fabricated integral frame connection has a good prospect for its high efficiency,environmental protection and labor saving,but it needs secondary pouring on the site,so there is still room for improvement in the construction speed.In order to improve the construction speed of the structure and make the structure have good seismic performance,a new self-centering PC frame connection is proposed in this paper.The prestressing steel strands can improve the self-centering ability of joints,and the additional energy dissipation elements can also improve the energy dissipation capacity of joints.Therefore,this will be an important development direction for the rapid construction of prefabricated concrete structures in seismic fortification areas.In order to further clarify the failure mode,bearing capacity,displacement ductility,energy dissipation capacity and self-centering ability of the new self-centering PC frame connection,the work accomplished in this paper is as follows:(1)A full-scale pseudostatic test of a new self-centering PC frame connection model and an assembly integral frame joint comparison model is designed and completed.The experimental results of crack development and hysteretic curves of two kinds of joints are obtained.The test results show that the grouting material of the beam end of the self-centering connection appears crack first,then the longitudinal steel bar and angle steel yield of the beam,so a plastic hinge mode of beam end of angle steel yield appears in the self-centering connection.The common plastic hinge mode of beam appears in the assembled connection.The ultimate bearing capacity of the assembled joints is 131.6kN,and that of the self-centering connection is 186.5kN,which is 29.4%higher than that of the prefabricated connection.(2)The seismic behavior of the two connection is compared.The skeleton curve,stiffness change,displacement ductility and energy dissipation of two kinds of connection are analyzed.The results show that:the end of the beam from yield to the structural failure,the stiffness of the self-centering connection was reduced by 8.6kN/mm,31.2%smaller than the 12.5kN/mm of the assembled connection.The displacement ductility factor ?=6.203 of self-centering connection is 19.1%larger than that of assembly connection ?=5.021,which indicates that the self-centering connection has good yield stiffness and better ductility.The maximum energy consumption of the self-centering connection is lower than that of the assembled joint 1025.3kN·mm before the angle steel yield.However,with the yield energy of angle steel,the energy consumption of angle steel will increase from 20%to 80%.With the angle steel yielding energy consumption,the energy consumption of the self-centering connection increases,and the total energy consumption of the self-centering connection exceeds that of the assembled connection at the maximum of 1974.71 kN·mm,which indicates that the self-centering connection has a good energy dissipation capacity.(3)The residual deformation and self-centering ability of two kinds of connection are analyzed.The results are as follows:when the prefabricated beam with self-centering connection is elastic,the maximum residual displacement at the end of the beam is only 9.5 mm,and the maximum residual deformation rate Rrd at the end of the beam remains below 0.2 mm.The residual displacement at the beam end of the assembled connection is 24.8 mm,which is 2.6 times of that of the self-centering connection,and the maximum residual deformation rate Rrd of the beam end is 0.55,which is 2.75 times of that of the self-centering connection,which indicates that the self-centering connection has smaller residual deformation and better self-centering ability.(4)Using the design value of beam end moment of energy-dissipation angle steel Mba and the design value of Mbp of prestressed steel strand beam end moment balance principle of beam end moment balance,Tensile strength Fa and post tensioned strand area Ap are got.The dimension of angle steel and the amount of high strength bolt are obtained by the bilinear ideal model of angle steel force-displacement.The design theory and calculation method of a new self-centering PC frame connection are obtained.