Nonlinear Analysis and Ultimate Strength of Multi-Cell Reinforced Concrete Box Girder Bridges

摘要

A numerical method of analysis is developed to trace the nonlinear response of multi-cell reinforced concrete box girder bridges under stepwise increasing static loads. Nonlinearities considered are material nonlinearities inherent in reinforced concrete structural members under short term loading, such as cracking of the concrete, yielding of the reinforcement and formation of plastic hinges due to flexure and shear. The analytical model, based on a three-dimensional grillage, is developed for multi-cellular structures of arbitrary plan geometry and constant height. The analytical method can trace the complex nonlinear behavior of the bridge beyond the working stress range all the way up to the ultimate failure and collapse of the structure. Both collapse machanisms and failure loads can be determined. The proposed analytical scheme which is based on a mixed model formulation is demonstrated and tested on a series of numerical examples. The results are compared with experimental results obtained from large scale tests on multi-cell RC box girder bridge models.