Study on Load Transfer Mechanism and Simplified Design Method for Skewed T-Girder Bridges

This study investigates the vehicle load transfer mechanism and proposes a simplified design method for simply supported reinforced concrete skewed T-girder bridges. Skewed bridges are often necessary due to obstacles in route selection, yet their mechanical behavior under existing design specifications remains inadequately addressed. Theoretical analysis reveals that skewed bridges exhibit a pronounced bending–torsional coupling effect and a rotation trend within the plane, resulting in the maximum bending moment shifting toward the obtuse-angle side and midspan moments decreasing. A refined numerical model utilizing the grillage method is established to validate the theoretical analysis results, demonstrating that load transfer paths deviate perpendicularly from the free edge as the skew angle increases. The bearing force of the skewed bridge with a skew angle of 30° is about 1.35 times that of the straight bridge. To address the lack of practical design methods, a mixed influence line method is proposed. This approach combines the lever principal method and the rigid plate girder method, interpolating transverse distribution coefficients along the span based on the skew angle. The proposed method accounts for the lateral stiffness and skew effects of skewed bridges, and the accuracy is confirmed by field load experimental and numerical validations. It is found that the mid-span bending moment of the straight bridge can be approximately adopted when the skew angle is less than 30°. The reduction coefficient of the bending moment with skew angles of 30° to 45 ° can be safely taken as 0.85 to 0.95.