Numerical Simulation And Analysis Of Semi-rigid Self-centering Steel Frame

In the Northridge earthquake, researchers found that many connections failed in low plastic level or even elastic level due to fracture. Then some optimized approach had been proposed. However, mostly of the new structures have residual deformation after earthquake, and have potential security risks because of their plastic hinge which appeared in beams. Therefore a new type of connection and system, which not only for prevent connection from fracture, but for removing residual deformation for structures, has been proposed.The connection incorporates energy dissipating component that are able to yield in axial compression and tension along with post-tensioned steel elements running parallel to the beam to provide a self-centering response. The post-tensioned energy dissipating connection minimizes inelastic deformation to the beams and columns, requires no field welding with quality workmanship and proper inspection, is made with conventional materials and skills, confines significant damage to the energy dissipating bars which are easily replaced, and is self-centering without residual deformation. In addition a post-tensioned energy dissipating moment-resisting connection properly designed is capable of achieving strength characteristics and stiffness similar to a traditional welded moment-resisting connection.In this thesis, non-linear time-history analyses were performed on a three-story, four-bay steel Moment Resisting Frame with post-tensioned energy dissipating connections to study its response to the seismic environment of ground motions, for 10% probability of exceedance in 50 years. Compared with welded steel frame, the advantages of the new frame are: (1) the connection is self-centering, there is little residual deformation after earthquake.(2) the connection has an initial stiffness similar to that of welded connection;(3) during earthquake, significant damage is confined to the energy dissipating component of connection(such as angles),the connection is easily repaired by replaced the energy component after earthquake.