| Structural vulnerability analysis is a key component of earthquake loss esti-mation. For the structural type lacking in earthquake damaging data, numerical method is a possible way to estimate structural vulnerability. Obtaining ana-lytical fragility curves with nonlinear dynamic method is computationally inten-sive and time-consuming, so carrying out the recearch of structural vulnerability analysis based on simplified sismic response analysis method is sifnificant for performance-based earthquake engineering.In this paper, structural vulnerability analysis method base on simplified structural seismic response calculation method is studied. A vulnerability anal-ysis method based on equivalent linearization method of SDOF system was es-tablished. To analyze its application, the fragility results of simplified method presented in this paper and finite element analysis are compared. Modeling the structures to obtain the the simplified SDOF system, calculateing the seismic re-sponse of structures with equivalent linearization method, then fragillity curves are established.In this paper, a simplified calculation method called equivalent linearization method based on SDOF systems was used to calculate the seismic response of RC frame structures. Then the fragility of structures is obtained based on the results of seismic response of RC frame structures. Compared with the results of OpenSees, the applicability on height of equivalent linearization method based on sdof system applying to analyze the vulnerability of RC frame structures is obtained.By modeling the structures of different height, the finite element models and quivalent SDOF systems are obtained. The equivalent SDOF systems are then simplified to bilinear patterns. The responses of structures with different height under different seismic intensity are calculated with IDA analysis using equiv-alent linearization methods and OpenSees program. After statistical analyzing the results of structural response, the fragility curves calculated with different linearization methods are obtained. The conclusions are as follows:1. The average maximum roof displacement computed by OpenSees is ranged between that computed by linearization methods. This shows that the estimation of maximum roof displacement is possible. As the height of structures and seismic intensity increase, the dispersion of results of lin-earization methods become lager.2. By contrasting the curves of maximum roof displacement and drift angle of a5-story structure, we can see the curves are almost identical, which indicates that the response is domained by the first mode. As the height of structures increase, the curves of maximum drift angle ralated to that of maximum roof displacement become larger. The error of maximum drift angle between linearization methods and OpenSees program of5-story and10-story structures is small, but the error of15-story structure is very large except the L&M method.3. As the height and the damage state of structures increase, the fragility results varies among different linearization methods. For5-story and10-story structures, the fragility error of Iwan and L&M methods is minimum; For15-story structure, all the fragility results estimated by linearization methods are obviously smaller than that by OpenSees. Despite the average maximum drift angle of L&M method is closed to that of OpenSees, the fragility results vary greatly due to the impact of dispersion.4. The comparison of results between OpenSees and linearization methods shows:for10-story RC frame structures and below, the error of fragility re-sults between linearization methods is small, fragility analysis using equiv-alent linearization method is applicable. Howerver not all equivalent lin-earization method is applicable. For15-story RC frame structures and above, due to the impacts of higher modes and the dispersion of struc-tural response, the error of fragility results between linearization methods is large, fragility analysis using equivalent linearization method is no longer applicable. |
