1st Croatian Conference on Earthquake Engineering 1CroCEE 2021

Generation of Fragility Curves (FCs) forms the primary basis for seismic vulnerability assessment of structures within a probabilistic framework, which can effectively aid in seismic damage mitigation. This paper presents the system-level FCs generated for a class of reinforced concrete integral abutment bridges, in succession to the component-level FCs developed for the damageable components of the bridge class, namely piers, elastomeric bearings with dowel bars, abutment-backfill system and pile-soil system. System-level FCs have not been studied extensively and while incorporating explicitly the contributions of different components. From the evaluated probabilistic component-level seismic demand data, demand correlation coefficient between every two components at the respective ith Damage State (DS) rank is computed. The joint demand cumulative probability distribution surface is derived using the correlation matrix and the demand distributions at each DS, while the evaluated probabilistic seismic DS capacities of the individual components are considered to be mutually independent. Using Latin Hypercube sampling technique on the joint demand surface and the individual component capacities, the generated sample values for the Joint Demands (JDs) are randomly paired with those for the Capacity Quartets (CQs). Probability of failure of the Bridge System (BS) is computed as the ratio of the cases (JD-CQ pairs) wherein the BS DS is reached (if at least one of the capacity values is exceeded by one or all the demand values in a pair) to the total cases. Computation is repeated at each increasing value of the adopted earthquake Intensity Measure (IM) and for all the DSs to obtain the BS FCs. BS at a DS rank is found more vulnerable than the individual components at the respective same DS ranks. BS at DSs of higher ranks than those of the individual components shows more or less vulnerabilities upto certain IM ranges and vice versa beyond as compared to the individual components.