Experimental Research On Shear-Lag Effect In Box Girder Of Single Plane Cable-Stayed Bridge

The box beam had great ability of resisting flexure and torsion. Moreover, it was light and had great span and was convenient to construct. It was applied to all kinds of bridge structures and widely used in bridge engineering. However, it showed the shear lag effect when symmetry bending loads acted longitudinally. If the effect of shear lag was neglected, high risks might take place. As for most cable-stayed bridges, the main beam was usually wide thus those webs are sparse. As a result, the shear-lag effect especially for contagious region between beam and tower was obvious and important. Whereas, there was no massive and systematical reference data on big scale model tests.The conception of the shear lag effect about box girders and its disadvantage to structure were particularly expatiated in the thesis. Simultaneously the summary of a variety of theories and methods to solve the shear lag problem in engineering fields was mentioned. The applicability and limitation about above theories and methods were particularly commented and gave the research prospect. Sequentially the Jianbang Yellow River Highway Bridge as the engineering background was selected to perform the model experimental research. The experiment modeled seven segments which were closest to main tower with the scale of 1/5 and loaded different loading conditions. Through the experiment, shear-lag effect of different cross sections under different loading cases was tested. In the meanwhile, based on the finite element theory and the principle of structural simulation for structures, the finite element software ANSYS was adopted to establish the structural simulation model for the experimental model and relative results are obtained. The theoretical values and experimental values were compared and it showed that the two set of data match fairly well.According to the above-mentioned analysis of box girder of cable-stayed bridge, some valuable conclusions were obtained that could be referred to in practical designing and construction. The conclusions provided accurate and visible results and were valuable in bridge structure engineering.