Research On Performance-based Seismic Evaluation And Design Method For RC Frame Strucrure

Although casualties caused by earthquake is reduced,damage losses has been increasing in recent years with the economic development and increasing population density. For the losses of building function and the time and cost of rebuilding after earthquake have greatly exceeded the limits that the society and the owners can bear, the deficiencies of existing codes have been pointed out by many scholars. Under such circumstances, the performance-based seismic design was firstly proposed by scholars from the United States in the early 20th century 90, which attracted wide attention from various countries and became the mainstream for amendment of seismic design code in the 21 st century. In this paper, reasearches foused on capacity spectrum method which is simple and effective seismic-resisting analysement are carried out according to the seismic evaluation and design theory based on performance /displacement.(1) The enormous losses caused by earthquake in recent years illustrats the shortcomings of the seismic design method in current code. Herein the general situation of performance-based seismic design research, the purpose, content and method of seismic design are introduced as well as summarized performance-based seismic design issues.(2) The relationships between static pushover analysis (Pushover Analysis) and the performance-based seismic design are described. The main functions, advantages and disadvantages of the Pushover analysis, along with the theory development, implementation steps and lateral load distribution, are also represented.(3) In some extent, capacity spectrum method is based on the combination of Pushover analysis and response spectrum. The basic theory of capacity spectrum method as well as implementation steps and the problems is described here. According to inter-story drift limit in each performance level, capacity spectrum method is improved in order to evaluate the various performance levels more conveniently and combine with performance levels more closely. The method provided in this paper is proved by Examples and the results from the method are very closed to the ones from the nonlinear dynamic analysis.(4) Displacement-based seismic design is an effective means to achieve performance-based seismic design,which can use the story drift limit to design the structure directly. On the basis of the capacity spectrum method proposed in this paper, the structure can be redesigned to achieve targeted performance level according to displacement by assessment results if the structure can't meet certain performance standards after an assessment. In this paper, two examples is put forward using displacement-based seismic design and nonlinear dynamic analysis, and the nonlinear dynamic analysis results verified the method provided is efficient and reasonable.(5) According to more common "strong beam and weak column" failure mode of the frame from Wenchuan earthquake, the slab effection should be considered. One entire cast reinforced concrete frame example is done under nonlinear static push-over analysis in two ways, one is to consider slab effection and the other is no slab effection. And the structural performance is checked through the lateral carrying capability, ductility and the order of plastic hinge. Finally, role of the slab should be paid much attention in performance-based seismic design studies in future.