Model Updating for the Selection of an Ancient Bridge Retrofitting Method in Almeria, Spain

Abstract

In this paper we analyse a case study where a finite element model (FEM) was updated on the basis of the experimental modal parameters recorded for a reinforced concrete truss bridge built in Almeria (Spain) in 1927. The final aim of this study is to help understand the actual state of structural conservation of the bridge, in order to select an appropriate retrofitting technique for its reinforcement before a planned widening of its deck. At present, the two most widely used methods for retrofitting are either reinforcing the structure with external prestressing or increasing its flexural strength by adhering carbon fibre reinforced polymer (CFRP) laminates. The first method is especially advantageous if the structure has deteriorated to such an extent that the strengthening needs to focus not only on increasing the flexural strength of the bridge, but also on avoiding the deflection problems associated with the reduced inertia of the structure. If this were not the case, strengthening with CFRP would be an adequate option. To this end, and given the monumental character of this ancient construction, it is not possible to apply destructive or static load tests directly to determine the properties of its constituent materials, so that it becomes necessary to estimate its deterioration state indirectly with the use of non-destructive techniques. For this purpose, in this study, a FEM is updated based on experimental modal parameters, which allows for checking of its service condition through the estimation of the value of several physical parameters of the bridge. The resulting updated model constitutes a valuable tool to help establish the most adequate retrofitting method.