Analysis of Distortion-Induced Stress and Retrofitting Technique of Curved Twin I-Girder Composite Bridge
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Distortion-induced fatigue problem at the web–diaphragm connection plays a major role in both durability and serviceability of composite bridges. Out-plane bending of the girder’s web at the diaphragm-web connection of the plate girder is stated as a fundamental source of distortion stress. Also, the stress gets intensified by the presence of curvature at the diaphragm-web connection. Besides, the effect of slab thickness, web-gap depth and cross-frame stiffness on distortion stress is not considered in the existing process of stress calculation. This paper demonstrates the possible causes of distortion stress, factors affecting distortion stress and an appropriate, cost-effective countermeasure for mitigating distortion stress. For this purpose, a three-dimensional curved twin I-girder bridge model is developed and verified with existing work. The numerical problem formulation, model verification, retrofitting and analysis are performed using the ANSYS program. The validated model is used to investigate the effect of bridge curvature, slab thickness, cross-frame stiffness and web-gap depth on the differential deflection and the distortion-induced stress. A substantial effect of curvature is noticed on girder differential deflection which proportionally affects the distortion-induced stress. Lastly, this study proposed two retrofitting techniques which are found efficient to extenuate the differential deflection and distortion stress about 50–60%.
KeywordsDistortion stress Curved twin I-girder bridge Finite element analysis Out-plane bending Differential deflection Retrofitting
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