Nonlinear Behavior of the Main Beams of Butterfly-Shaped Arch Bridges and Its Influencing Factors

Abstract

Given the unique pattern of butterfly-shaped arch bridges, the nonlinear behavior rules of the main girders are difficult to determined compared with those of ordinary arch bridges. The traditional design method that does not fully consider nonlinear influences is unsuitable for such investigation. The nonlinear behavior of the main girders was analyzed by considering various nonlinear factors using a self-compiled program. The influences and rules of different design parameters such as depression angle, rise/span ratio, steel ratio, and so on, were studied. The following results were obtained. (1) The beam-column effect of arch rib elements has unfavorable influences on the main beam moment, but the beam-column effect of the main beam elements can effectively prevent such unfavorable effects. (2) The nonlinear behavior rules of the main beam moment are more complicated than the rules of deformation. (3) The distance of the eccentric load has a significant effect on the influence coefficients of the boundary beams at the unloading side. (4) The influence coefficients of the mid-span deformation and moment increase as the depression angle increases. (5) The influence of the steel ratio and the angle between the cable plane and the arch plane on the nonlinear behavior of the main beams can be neglected.