The Research On The Seismic Behavior Of T Shaped Side Joints Strengthened With Post Anchorage Tendons

The joints are connected with beams,columns and slabs in the frame structure,which play the role of transmitting and distributing internal forces,coordinating the deformation between the components,and ensuring the integrity of the structure.Under the action of earthquake,the joint force is complex and the stress concentration occurs in the core area.The earthquake damage of Wenchuan earthquake and Tangshan earthquake showed that the joints are damaged.The stirrup in the core area of joint is seriously inadequate,and the shear failure is occured under seismic load.Therefore,it is necessary for scholars to pay enough attention to the shear strengthening of the existing low-stirrup frame joints.In China,most of the existing joint strengthening methods can not directly improve the shear strength of the concrete core area.In foreign countries,there is also a lot of research on the strengthening of joint.Scholars have found that the shear ability of the core area has been greatly improved with the inclining steel bar arranged at the core of the joint(along the diagonal direction).However,there are few studies on this method.In this paper,steel bars,prestressed tendons and carbon fiber reinforced polymer tendons are used to intersecting and anchoring in the core area of the joint,and the following research work has been carried out.First,use ABAQUS finite element software to establish the finite element model of the joint.The accuracy of the finite element model is verified by comparison with FEM data and experimental data.Some parameters such as diameter of anchor bat,forms(different combinations of anchorage reinforcement and stirrup level),the number of anchor bars,the position of the anchor bolt,type of anchorage bar are study.According to the results of ABAQUS simulation,the effects of the parameters on the seismic performance of the joints are compared.The damage characteristics,plastic damage strain,hysteretic curve,skeleton curve,ultimate bearing capacity and shear deformation of the core area of T shaped joints are analyzed.The mechanical mechanism of the joints is analyzed,and the reinforced concrete joints strengthened by post anchored bars are analyzed.The formula for shear capacity of T type side joints strengthened with post anchored bars is put forward.