Research On R.C. Frame Structure With Staircase Based On Performance-Based Seismic Design

After the Wenchuan earthquake, staircase damages in the reinforced concrete frame structures exposed.The traditional treatment of staircase structure can not meet the seismic design requirements. Seismic code clearly put forward on the design requirements of the staircase, while it is proposed staircase as a safe island in the performance-based seismic design recommendations。This paper analysis the seismic performance of the concrete frame structures with board type staircase, based on the requirements of the performance-based seismic design.Five calculation models under different conceptual design that reduce the role of bracing, which based on performance-based seismic design, were compared and analyzed with SAP2000. The comparison research on seismic performance of the overall framework, and of the structure system of staircase including stairway columns, stairway beams, stairway flight and rest platform, were conducted.The comparison research on modal analysis and time history analysis of joints displacement reflect that the overall Stiffness and the uneven level of stiffness are differently reduced based on the different conceptual designs that reduce the role of bracing, as well as the torsion effects of the structure under earthquake.It is reflected different seismic performance of the components based on different design of reducing the role of bracing in the structure system of staircase.The components of stairway columns, stairway beams, stairway flight and rest platform in the common staircase without bracing reduced have complex and huge internal force. The performance of the staircases with bracing reduced are improved differently. Some new character of internal force is reflected in some components. A conception of deformation transfer based on stratified deformation is concluded in the structure system of staircase which can explain the complex seismic mechanism of the staircase system.At the end, it is compared and concluded about the design of bracing reduced in the staircase system. Some valuable advices are given about the design of reinforced concrete frame structure with board type staircase.