Research On The Rigid-zone Factor Of Steel Frame All-welded Joints

With the development of steel structure, more and more buildings use steel structure, and the sizes of the beams and columns are also larger, so at the joints will form a large panel zone. As constraints of the beam and column, stiffness of the panel zone is very large relative to beam stiffness or column stiffness. Therefore, the effective length of the beam or column will be reduced, which is equivalent to a region with infinite stiffness known as rigid-zone exists along the beams or columns. In structural analysis software, mostly use the line-element model to simplify and abstract the actual structure, length of the rigid-zone affects the effective length of the beam or column, thus affects the stiffness of the entire structure, while the structural stiffness has a great influence on the vibration response of the structure, so to accurately calculate the seismic response, the premise is to calculate the actual stiffness of the structure accurately, which is to set the rigid region accurately, too.Current researches on the steel frame joints are concentrated in the panel zone of the beam-column joints and the load carrying capacity, not involve the rigid region, so it is essential to research the rigid region of the joints.In this paper, the solid model of all-welded steel frame is constructed by the finite element analysis software ANSYS, then give the simulation analysis method and example of the rigid-zone factor, and compare the deformations of ANSYS solid model with SAP2000 line-element model which has set the rigid-zone factor, the top horizontal displacement of the frame shows good agreement and proves the method is an effective method.Parameters affecting the rigid-zone factor of joints of―╋‖type and―┣‖type have been analyzed, these parameters include the beam and column section sizes, the continuity plate size, the beam span and the storey height. Calculation and analysis show that the thickness of column web, the beam depth, the column depth is the main factor affecting the rigid-zone factor, the other sizes of beam and column has impact only on their own rigid-zone factor, the continuity plate size has obvious impact only on the rigid-zone factor of beam, little impact on the column. Finally, the influence trends of all the parameters are analyzed through the deformation of the panel zone.