Seismic Emperical Fragility Curves of Bridges Considering Composite Inherent Randomness

There are a few methods for seismic vulnerability assessment of bridge structural systems. The development of vulnerability information in the form of fragility curves is an approach when the information is to be developed accounting for a multitude of uncertain sources involved، such as، structural characteristics، estimation of seismic hazard and site condition. Inherent randomness is involved to these uncertain factors. The major effort of this study is placed on the development of empirical fragility functions by utilizing the damage data from past earthquakes considering composite inherent randomness of the uncertain factors. The introduced procedure is suitable for the development of fragility curves under the assumption that they can be presented by two-parameter lognormal distributions. The empirical fragility curves are developed using 768 bridge damage data obtained from the 1994 Northridge and the 1995 Kobe earthquakes، which could be used as reference curves for seismic risk assessment studies of the similar bridges in Iran.