Study On The Influences Of Steel Stairs On Seismic Performance Of Steel Frame Structures

When the earthquake occurs, a number of houses crack or even collapse under strong earthquake and the stairs become an important channel for people to escape. So the capability of earthquake resistance and disaster prevention of stairs should be higher than the main structure. So far there have been many studies on the concrete stairs, and the stairs can be directly considered in the design software of concrete structure. However, there are few researches on the steel frame structure, and the traditional design method is still used in the design of the steel structure stairs. The structure of steel stairs is quite different from the concrete stairs. And the application of steel frame structure is very extensive. So it is necessary to make a systematic analysis.According to the actual projects, three steel frame structures with different structure characteristics are selected, which are as follows:the residential, plant and office buildings. By using the finite element software Midas Gen, this article builds six structure models which differ in whether the stairs is taken into account.Firstly, after the response spectrum analysis of the six models under the frequently occurred earthquake, this article compared and analyzed the difference between the two kinds of models in periodic, modal mass participation coefficient, interlayer displacement angle, base shear and so on. It is concluded that the deformation of the frame-staircase structure under earthquake action is reduced.Secondly, this article compared and analyzed the difference between the two kinds of models in internal force and stress ratio of structural members. The conclusions are as follows:For the models which are considered the stairs, it’s advantageous to the seismic performance of the beams which in the stairwell, it’s disadvantageous to the seismic performance of the columns which in the stairwell. There are few influences on the members which are far away from the stairwell.Finally, by using the pushover analysis and time history analysis under the rare earthquake, analyzed the yield mechanism of structures. It is concluded that the failures of the beams and the columns which in the stairwell happened earlier, and the plastic hinges appeared in these members.