EFFECT OF FUSSINESS AT LIMIT STATES ON SEISMIC FRAGILITY ANALYSIS: REINFORCED CONCRETE FRAME CASES

Abstract

It is a key step to determine the structural capacity at different limit states for a seismic fragility assessment. However, limit state definition is highly dependent on engineering practices, which includes strong fuzziness. Therefore, it is necessary to conduct a comprehensive study on the influence of fuzziness at limit states in a seismic fragility assessment. This study performs a seismic fragility assessment by considering fuzziness at limit states, where ten types of membership functions are considered with varying fuzziness levels. Four reinforced concrete frame structures with varying heights and fortification levels are taken as the study cases. The fuzziness-probability integration is adopted to derive seismic fragility functions corresponding to different types of membership functions. The seismic fragility results with and without considering fuzziness at limit states are compared to extract the effect of limit state fuzziness with considering varying membership functions and different fuzziness levels. Moreover, the modified seismic fragility function considering limit state fuzziness is derived. The analysis results show that different membership functions show a significant effect on seismic fragility results considering limit state fuzziness. As the promotion of fuzziness level, the difference in seismic fragility results considering limit state fuzziness is growing accordingly. The proposed modified fragility function considering limit state fuzziness can well represent the effect of fuzziness at limit states on the seismic fragility analysis.