Finite element-based reliability analysis of RC bridge piers subjected to the combination of barge impact and blast loads

In this paper, the reliability analysis of a girder bridge pier is presented when exposed to the combinations of barge collision and blast loads based on the finite element (FE) simulations performed in LS-DYNA and the Monte Carlo algorithm performed in MATLAB. An improved reliability analysis approach is proposed for the bridge pier under combined loads using the residual dynamic resistance capacities of the impacted bridge pier when sub-jected to sequential blast loading rather than utilizing the static resistance capacities of the pier columns which are commonly employed by conventional fault tree analysis. In the first step of the proposed framework, the response surface method (RSM) using the Box-Behnken design (BBD) method is employed for fitting the struc-tural response surfaces and the internal forces of the pier columns obtained from the FE simulations. Then, the reliability analysis results including the failure probability (Pf) and corresponding reliability index (beta) are calculated using the Monte Carlo algorithm in MATLAB. Finally, the sensitivities of Pf and beta to various barge collision and blast loading parameters are assessed, and fragility curves are plotted for the reliability analysis results. From the reliability analysis of the pier under combined loads, it is found that the failure probabilities of the pier resulting from the proposed method are greater than those from the conventional method based on the static capacities of the pier. Therefore, the conventional static-based method provides an unconservative approach and the residual dynamic capacities of the impacted and damaged pier should be considered under the sequential blast loading for reliability analysis of the pier under combined loads.