Seismic Performance Evaluation Of Existing Steel Frame Buildings With Semi-rigid Connections

Existing structure is the being used structure. As the existing structures had been used for quite some time, under the natural environment and the using environment, existing structures that will inevitably produce some degree of damage and corrosion of materials and other unfavorable phenomena, these unfavorable phenomena will be had a greater impact on the seismic performance of the existing structures. In the traditional analysis and design of the steel frame, in order to simplify the analysis and design process, beam-column connection is recognized as the ideal articulated connection or completely rigid connections, but, this ideal link model will result in huge difference between theory and practice. Because all connections are rigid and fully articulated in between, Relative to the rigid connection, the semi-rigid connected steel frame has the larger rotation capability and energy dissipation capacity which can resist dynamic loads. Therefore, the study of the existing semi-rigid steel structures and their seismic performance evaluation method is more practical significance for the earthquake disaster mitigation.In this paper, firstly, the node performance of existing steel frame structure in different years is been analysed, and use the Solid92 in finite element analysis software ANSYS to establish the rigid connections'and the semi-rigid connections'solid element node models of corrosion in different years, respectively according to the characteristics of corrosion, then, the rigid and semi-rigid joints are conducted on monotonic loading and cyclic loading for nonlinear finite element analysis, then analyse the nodes'performance in different years and the impact of different corrosion on the node properties.To compare the semi-rigid connection with rigid connection on the performance of the steel frame, the elasto-plastic time-history analysis is performed on the 3-layer,6-layer, 10-layer semi-rigid steel frames and rigid steel frames with 3 actual earthquake acceleration records, the vertex displacement-time curves, base shear force-time curves and the story drift envelope diagram are established, in order to compare the reaction of semi-rigid steel frame with rigid steel frame from different angles, and the height of the structure impact on the reaction of the structure.Based on the semi-rigid connections, as the existing semi-rigid structures are been used for some time, the structures inevitably produce some degree of damage and corrosion of materials and other unfavorable phenomena, and with the structure of the growth of useful life, expected remaining useful life of the ground motion exceeding probability is been changed. It is necessary to take into account the characteristics of semi-rigid connections and the impact of corrosion. Some 5-layer exiting steel frames with different semi-rigid connections are established, that the pushover analysis is performed on. Under the frequent earthquake and the rare earthquake in different re-service term, with the reducing of the nodes'initial rotational stiffness, compare the performance points and the vulnerability curve of the rigid frame and different semi-rigid frame, and analyse the semi-rigid connections impact on the seismic performance of the structure. The seismic performance of the steel frame is discussed, under the resistance and seismic action with the change of the re-service term.