Analytical Algorithm for Calculating the Lateral Load Distribution of Skewed Adjacent Box Beam Bridges

Skewed adjacent box bridges are favored over square ones in many circumstances in that their oblique crossing can best fit the original terrain. However, the current calculations of lateral load distribution for skewed adjacent box beam bridges only consider a skew correction factor on the basis of the square adjacent box beam bridge. In this paper, an analytical algorithm based on the transfer matrix method is developed to calculate the lateral load distribution of skewed adjacent box beam bridges. The transfer matrices for transverse end nodes of each beam are established from the derived flexibility factors of a single skewed adjacent box beam. The global transfer equation is derived based on the lateral connection characteristics between the beams. Then, the lateral load distribution of beams is computed through introducing boundary conditions of free nodes. Taking a precast adjacent box beam bridge of span length 20 m and skew angle 30° as an example, the good accuracy and efficiency of the proposed method are verified by comparing with the results of the finite element method. And it is more rational than the semi-empirical equations in Load and Resistance Factor Design (LRFD) Bridge Design Specifications released by the American Association of State Highway and Transportation Officials (AASHTO). Furthermore, the effects of skew angle, span lengths and relative flexibility factor for beams on the lateral load distribution for skewed adjacent box beam bridges are examined through the parametric study.