An Analytical Study on Aerodynamic Stability of the Diagonal Arch Bridge

As a consequence of wind loads on the cable system bridges, a notable aspect in aerodynamic behavior is the occurrence of vortex-shedding phenomena that induce flutter behavior on the bridge deck. As an analytical reference or preliminary design consideration, to prevent flutter on bridges with the relatively small dimensions, the Mathivat coefficient is commonly used. This is the ratio of fundamental torsional frequency to the fundamental vertical bending frequency, and a minimum value of 2.5 is recommended. Diagonal arch bridge (DAB) is a bridge where the longitudinal direction of the deck forms an angle with the longitudinal direction of the arch as viewed from the crown of the bridge, resulting in an asymmetrical layout of hangers and unique behavior under wind loads. This study examines the aerodynamic behavior of the DAB, particularly to analyze the influence of the stiffness of the arch and deck section on the flutter behavior. The cross section of the stiffening girder is a trapezoidal steel box, an inverted T-shaped floor beam, and a closed trapezoidal cross-sectional rib, forming an orthotropic plate structure. Based on the simulation of cross-sectional dimensions, it can be concluded that the height of the box girder and the height of the floor beam play a significant role in preventing flutter instability. In contrast, increasing the wall thickness in the cross section of the steel arch box does not contribute significantly to achieving flutter stability.