Analysis of the Interaction between Stair and Frame under Horizontal Earthquake Action Based on ETABS

Abstract

Two computer models of concrete frame with staircase were made and the seismic-performance of the models in elastic-phase was calculated by adopting base shear method, spectrum analysis by ETABS. The results show that including staircase into models will change the seismic performance of frame structure significantly. The paper proposes that the computer model with staircase and the response spectrum analysis should be used firstly in the seismic design of concrete frame with staircase. Introduction The conceptual design is always used to consider the impact of the stairs on the structural performance during the previous seismic design of buildings, for example, the short columns in stairwells should have more stirrups in its full-height, the asymmetrical layout of the stairwells could make a significant torsion effect to the whole structure[1, 2]. The damage survey in 5 • 12 Wenchuan earthquake indicates that a considerable number of stair risers fracture occurred in the earthquake zone, which shows that stairs as an integral part of the structure have a significant impact on the whole structure dynamic performance. Based on the above concepts and damage investigation, the newly revised GB 50011-2010 "Code for Seismic Design of Building Structures" begins to consider the impact on the overall structure seismic performance by the stairs[3]. As described in Section 3.6.6 "Calculation model, necessary simplified calculations should be in line with the actual working conditions; Stair component should be taken into consideration when doing the calculation." Several research have been taken about the interaction behavior between stair and frame in China, which indicates that stairs have a great influence on the structural layer stiffness. In this paper, analysis models of a 12 layers framework with or without stairs have been made by ETABS, relevant analysis has been made about the influence of stairs[4,5,6].