Sensitivity analysis of seismic performance of portfolio of bridge supports for multiple qualitative limit states

Abstract

The seismic performance of bridges is of primary importance for the durability and functionality of these structures. Several numerical methods have arisen in order to evaluate this performance and one is generally led to define the most significant input parameters in the seismic response. Thus, the sensitivity analyses are practical tools to achieve this objective. In this study, a sensitivity study was carried out on the seismic performance of 88 supports of a road network located in a low to moderate seismic zone. A preliminary visual inspection of these structures was carried out and showed the degree of advanced degradation that the structure had undergone during its lifetime. This visual inspection was completed by a set of non-destructive and destructive tests in order to characterize the geometric and mechanical parameters of the materials that compose these supports. The data collected is directly inserted into the finite element model on OpenSees, which describes the nonlinear fibered behavior with distributed plasticity of these supports. The seismic capacity is thus described through the nonlinear static analysis which provides the shear force curves at the base as a function of the displacement at the head of the pile. This curve will be idealized into a bilinear curve in order to integrate it into the equivalent linear system composed of both the supports and the elastomers that serve as seismic isolators. The sensitivity study is carried out on the basis of the analysis of variance, which evaluates the part of the variance of the input parameters in the output responses that characterize the seismic behavior of these structures. The input parameters are vertical loads, geometric and material properties, and output responses are the deck and top pier displacements, in addition to the shear force at the base of the supports and the distortion of the elastomers. The results of the sensitivity study allowed to prioritize the most significant parameters in the seismic responses for different limit states. The most significant parameters are the ratio of longitudinal and transverse reinforcement, followed by the diameter of the piles and the applied vertical loads.