RESEARCH ON THE AXIAL PERFORMANCE OF THE X-JOINT IN OBLIQUE GRID STRUCTURES SUBJECT TO RECIPROCATING LOADS

Based on the prototype of diagrid X-joint, the Finite Element Analysis software package ABAQUS was used to establish an analytic model. Subsequently, the nonlinear analysis was conducted to study the behavior of the X-joint under the axial tension-compression cyclic loading. The stress distribution of the steel and the concrete of the connection were analyzed. The hysteretic characteristics and stiffness degradation were also studied. The effects of the intersecting angle, thickness of the vertical connecting plate and lining plate, the width-thickness ratio of steel tubes, the thickness of stiffening ring and concrete strength on the axial performance of the X-joint were analyzed. Results show that the confinement effect of concrete is improved with vertical connecting plate, lining plate and stiffening ring of joint. The connection exhibits good seismic performance with plump hysteretic curves, large initial stiffness and slow stiffness degradation. Various thickness of vertical connecting plate, width-thickness ratio of steel tube and concrete strength have a great impact on the bearing capacity, hysteretic characteristics and stiffness degradation of the connection, while the intersecting angle, thickness of lining plate and stiffening ring have little influence on the bearing capacity, hysteretic characteristics and stiffness degradation of the X-joint.