The Effect Of P-Δ And Structural Damping To The Dynamic Performance Of Semi-rigid Connection Of Steel Framework

In the 1994 USA Northridge Earthquake and the 1995 Japan Hyogoken-Nanbu Earthquake, most of the welded beam-to-column connections of steel frames were heavily damaged, which aroused widespread notice of academic circles. Since the two earthquakes, the overall performance of semi-rigid steel frames in earthquake becomes an important issue.In the traditional analysis and design of the steel frame, beam-to-column connections are usually assumed as ideal hinged or completely rigid. Although it simplifies the analysis and design process of steel frame, the ideal connection model is unreasonable, and it dosen't reflect the actual behavior of the structure and the calculation error is large. Therefore, the simplification of the steel frame is bad for the seismic design.In this paper, the dynamic behavior of semi-rigid connections of steel frame structures are discussed by using ANSYS to analyse the example of three floors high building. In the example, there are three kinds of dynamic loading are considered, such as cyclic loading, ground acceleration, seismic load. As the effect of P-A and structural damping to the dynamic performance of steel frames varies with the kinds of beam-to-column connections, the effect to semi-rigid connection of steel framework has been studied particularly, and the results of the semi-rigid connection are compared with the results of the rigid connection steel frames.The analysis results of this paper show that:1,The influence of P-Δeffect to the dynamic behavior of semi-rigid steel frames is greater than the rigid steel frames. As a result, the deformation of the semi-rigid steel frames can be controlled effectively by restricting the P-Δeffect.2,The influence of structure damping to the dynamic behavior of semi-rigid frames is greater than the rigid steel frames, especially the lateral sway of the steel frames. Because of semi-rigid connections, the steel frames have more capacity of energy dissipation and more capacity of ductility. Therefore, the semi-rigid steel frames have extra damping ratio of structure. 3,The structure damping prefer to effect the amplitude of dynamic response time-travel curves, rather than the time of amplitude and the number of back-and-forth swinging of the structures. It is believed that with rational damping ratio of the structure, the lateral sway of semi-rigid steel frames can be decreased so effectively that the sway of semi-rigid steel frames is close to the rigid steel frames. It is good for the seismic resistance of semi-rigid steel frames.Finally, this article is put forward some of the issues which need to be resolved or improved.