Assessment Of The Magarola Arch Bridge. ACase Study

Abstract

The Magarola bridge is a masonry arch bridge located near Barcelona in one of the busiest highways in Spain, connecting the city with the capital Madrid. The structure is a multi-span arch bridge with 5 arches of 20 m each. In order to check the feasibility of the bridge to carry the overloaded special trucks present in the Spanish Network, the Road Directorate of the Spanish Ministry of Public Works decided to perform the structural evaluation and assessment of the existing structure in face of the actual existing traffic and the expected overload permits as well. Because any documentation is not available, the evaluation process is based on the Structural Reliability Theory, starting with the experimental testing program in order to get information about the geometric dimensions and the strength characteristics of the materials. Two different models were used in the carrying capacity analysis: 1) the arches behave linearelastic and failure is reached when only one single section of the bridge reaches the Ultimate Limit State, 2) a theoretical model that takes into account the nonlinear behaviour of the arches in the stage close to failure, as well as the system and redundancy behaviour of the structure. In this case, the failure is due to either a material collapse or a mechanism with 4 hinges in the arch. The safety of the bridge is obtained in terms of the probability of failure (reliability index). The safety level is evaluated both for the actual existing traffic which data is available from the traffic surveys, as well as for the special permits as outlined in Eurocode 1-Part 3. The results show that the actual carrying capacity is large enough to safely support the expected maximum permits. Other conclusions are related to the most suitable theoretical models of failure analysis of multi-span arch bridges. Transactions on the Built Environment vol 39 © 1999 WIT Press, www.witpress.com, ISSN 1743-3509