Inelastic Seismic Analysis of Reinforced Concrete Viaducts

Using modern seismic codes designers face the problem, which model and which procedure to choose in the case of the inelastic analysis of bridge structures? In this paper, general recommendations are formulated. A case study of a typical Slovene viaduct is presented. Regarding the choice between different models, a simple-lumped plasticity beam element is recommended for practical applications. The inelastic time-history analysis is found to be the best procedure for the analysis of bridges. A simplified inelastic pushover procedure is nowadays a popular alternative. However, it should be used with care, particularly in the case of irregular bridges. In general, no equivalent single mode static procedure (elastic or inelastic) can be used for torsionally flexible viaducts or viaducts with individual short and stiff columns. Additionally, an 'irregularity index' has been proposed as a global numerical measure to help designers decide about the suitability of the pushover analysis for bridges. This index is based on the relative difference of the results of two iterations of the simplified methods.