Global analysis of steel and composite highway bridges - Development of improved spatial beam models

Nowadays exact modelling of a complete steel or composite bridge structure - using Finite Elements (FE) - is possible, because of the rapid development of computer power. Nevertheless this leads in general to nonacceptable costs in practical work, due to the fact of the enormous amount of data - caused e.g. by a lot of traffic load cases in complex structures. Therefore simple beam models for the whole bridge structure are useful combined with local FE - models if necessary. In the paper a simple spatial beam model of bridge decks built with two webs (open or box section) is shown, allowing for effects of section distortion and local bending between deformable intermediate diaphragms. Two examples show the accuracy and efficiency of the model, by comparing the stresses with results of more refined FE models.