| Generally, the steel frame has high anti-seismic capacity. However, when foundation differential settlement occurs because of the disturbance, internal forces of the superstructure will be redistributed, and plastic rotation capacity of beam-column joints will be seriously damaged, thus producing more unfavorable effects on seismic performance of the structure.In order to study the influence of differential settlement on the internal force and seismic behavior of steel frame structures, a numerical model of steel frame was established by SAP2000 in this paper, selected the structural beam column section that meet the requirements of the specification by steel structure design, calculated the internal force of the model under the various kinds of settlement. And defined the plastic hinge on the beam column element of the structure according to the seismic evaluation method of FEMA-356 in the United States. The elastic plastic properties of the structure under seven degree rare earthquake are reflected by the plastic hinges. The main contents of this paper are as follows:1. The domestic and foreign research states of foundation differential settlement were investigated and surveyed. And information about the changing internal forces of the superstructure and seismic performance, which is caused by coupled settlement and earthquake coupling action, was collected and summarized. Then the specific research orientation and method was defined.2. Combined with the construction example, the finite element model of the steel frame structure was built. The design of the steel structure was in accordance with specifications. Proper sections of beams and columns is selected, and plastic hinges is defined on beams and columns.3. The model of representatively "incline-type" settlement and mid "basin-shaped" settlement of the steel frame structure were built, respectively. Internal forces were calculated under various conditions, and the change rule of internal forces of the steel frame structure under two kinds of typical settlement conditions is found by contrasting and analyzing.4. NS EL-Centro seismic wave is selected to input models of two kinds of settlement structures, respectively, and the elastoplastic time-history is analyzed. According to the emerging time, situs and the deformation of plastic hinges, the elastoplastic deformation of the structure under earthquake is analyzed, and the most vulnerable place of the steel frame structure under settlement and earthquake coupling action is ascertained. These provide a theoretical support for seismic strengthening of the sedimentary steel frame structures. |
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