Reliability analysis of a historical bridge against ship impact with ANSYS optiSLang
Ship impact against bridges crossing waterways may damage the structure and in some unlikely case may cause a failure with dramatical consequences. The contribution shows a practical example for determining the failure probability of a historical bridge against ship impact. For this purpose, a parametric, automatized workflow was generated with ANSYS optiSLang using a nonlinear dynamic finiteelement analysis of a 3 dimensional bridge model. In the ANSYS FE model nonlinear material models for concrete, historical masonry and the soil have been considered. The applied calculation method allowed a realistic calculation of the bridge by utilizing the available reserves of the load bearing capacity due to cracking and due to the load redistributions in the structure. In preparation of the probabilistic assessment of the bridge ultimate load calculations have been applied to identify the critical impact scenario, the failure mechanism and the ultimate load capacity of the bridge. Based on these results, different damage criteria had been derived, which are considered in a first variation and sensitivity analysis for the decisive impact scenario. With this sensitivity evaluation the most relevant parameters for the load behavior and for the evaluation criteria had been identified and only a small number of important input parameters could be identified. In the following reliability analysis the most suitable evaluation criterion was used to estimate the failure probability. The estimate was validated by using two different types of reliability analysis techniques within an automated workflow, an Adaptive Response Surface Approach in the significant parameter subspace and a Global Response Surface in the full parameter space combined with directional sampling. With the presented strategy a confident estimate of the failure probability could be achieved and the safety of the historical bridge against ship impact could be proven.