Time-dependent advanced analysis method for steel truss bridges under atmospheric corrosion

Abstract Atmospheric corrosion is one of the major factors leading to the deterioration of steel truss bridges. In order to overcome this problem, protective coatings are generally applied to steel members. Since coatings also can deteriorate over time, investigating the time-dependent structural performance becomes essential. In this paper, a method was developed for the time-dependent advanced analysis of steel truss bridges with and without coatings. To achieve this goal, material and geometric nonlinearity were accounted for evaluating the structural load capacity of the bridges, and consequently, the whole structural behavior was monitored. The effect of atmospheric corrosion was modelled using a relationship based on ISO 9224 for members without coating. Besides, two different coating degradation models were applied for the members with coating. For the evaluation of the proposed method, four steel truss bridges from the literature were accounted and time-dependent structural load capacities were calculated under atmospheric corrosion exposure for 100 years. In order to represent the effects of different environments, each steel truss bridge type was assumed to be built in different countries, and atmospheric corrosion data for each case was acquired from international corrosion databases. Numerical analysis results revealed the importance of detrimental atmospheric corrosion effects in terms of structural load capacity in steel truss bridges. In some cases, reductions in structural capacities were significant and even unexpected failures occurred in aggressive environments. Besides, when coatings were applied to steel truss bridges under atmospheric corrosion, a satisfactory delay in the decrease in load-carrying capacity was achieved throughout the structural lifetime.