Curved composite I-girder bridges are often used in advanced highway systems, but the open sections of I-girders mean that the structures have low torsional stiffness, especially in construction stage. This paper presents a detailed investigation of the torsional warping normal stress in horizontally curved composite I-girder bridges during construction. Firstly, based on Vlasov’s theory, the constrained torsion differential equation of curved I-beam under uniform load is established, and the torsion effect of curved I-beam is solved by the initial parameter method. The relationship between torsion warping normal stress and transverse stiffeners spacing is established by considering the influence of transverse stiffeners by continuation method. The bending stress of curved beam under uniform load is solved and the expression of torsional stress ratio is obtained. Then, ABAQUS finite element method is used to analyze the influence of intermediate diaphragm spacing on the torsion warping normal stress of simply supported double girder bridges. Analysis results indicate that the torsion effect obtained by the continuous method is reliable, and the method is simple and practical. With the decrease of curvature radius, the torsion warping normal stress increases gradually. However, When the radius of curve is larger than 16000m, the warping effect can be ignored. When the radius of curve is between 14000m and 16000m, the ratio of the warping normal stress to the bending normal stress can be limited effectively to 0.05 by using a small number of transverse stiffeners. However, when the radius of curve is less than 14000m, intermediate diaphragms are more effective in controlling the torsional warping stress. An empirical formula is developed to provide a preliminary design limit for the intermediate diaphragm spacing. Suggestions for selection of warping stress control under different radius of curve are given.

CICTP