Research On Theory And Application Of Performance Based Aseismic Design Method To R.C. Buildings

The performance based aseismic design theory is a new concept in the civil engineering field since 1990's. Much attention has been paid to study it. Aiming at improving the target performance level of structures, the theory requires that the performance of structures designed using it should be predictable. In China, the study on it is in its first stage, so the systemic research is of great theoretical significance and practical value to the development of aseismic design theory.The paper firstly devotes to the structural performance levels and the safety index of the designed performance. The damage states are described in detail in terms of structural members and the relationship between the damage degree and the four types of performance limit states is built. The concept of the structural performance safety index is put forward and its calculation method is derived based on the structural deformation limit state equation.The deformation control design method is studied. In this method, the inter-story displacements and the mode of the structural vibration are postulated. The MDOF system is transferred into an equivalent SDOF system and the interior forces can be calculated. The design can be done after the structural earthquake response is got based on the distribution of lateral forces of the prototype. Many factors should be considered when the target displacements are selected.The distribution formats of the horizontal lateral forces are mainly studied when the static pushover analysis method of the R.C. buildings is discussed. An improved distribution method of the horizontal lateral forces to the planar structures and a new one to the structures with torsional responses are presented. The example of the pushover analysis testifies the validity and feasibility ofthe studied distribution method, and the potentiality of the use of static pushover analysis method to irregular structures is also proved.The capacity spectrum method of the structural performance evaluation is discussed in this paper. The concept of the equivalent mode and the modal participation coefficient is introduced when the regulation structures are studied. As to the vertical irregular structural systems, the inter-story capacity spectrum method is used and the strength reduction coefficient 77 is put forward when the capacity method is used to evaluate the performance of the torsional irregular structures. The calculation result shows that the capacity spectrum method can also be used to evaluate the performance of the irregular structures.The comprehensive aseismic design method to R.C. buildings is studied at last in this paper. The study objects of the paper are used in different stage of the design process in the design method. It is to say that after the target performance level is selected, the deformation control design method is used as the structural design method; the static push-over analysis method is used as the structural nonlinear calculation method and the capacity spectrum method is used as the structural performance evaluation method. So the unified structural design method of the performance based aseismic design can be formed and the aseismic performances of the structures can be controlled in every step of the design process. This design method embodies fully the concept of the "performance based".