Nonlinear Analysis Of Large Span Arch Bridge

According to the present state of the study of the arch nonlinear characteristics, concrete-filled steel tube arch bridges with box cross-section, which adopt the stiffening frames construction method, is chosen to be analyzed in this paper. In order to compare the linear and nonlinear behaviors of arch bridges, more than 1,000 models were built with different designing parameters. After the study, the rule of the nonlinear influence coefficient is obtained, which help to make the preliminary design of the main arch rib.Some main conclusions are listed as following:1) The nonlinear influence on deflection is positive and comparatively stable in the region between about 1/2 and 1/4 point of main span, but is negative and unstable in the region between arch spring and 1/4 point. The influence is always more stable in the region near the 1/4 point where the flexural moment is zero. However, as to the arch bridges with relatively small rigidity, if the arch axial coefficient is small and the rise-span ratio is big, the nonlinear influence changes to be positive between arch spring and 1/4 point, and negative in between about 1/2 and 1/4 point. The influence degree of positive is always less than 20%, but that of negative sometimes exceeds 100%.2) The nonlinear influence on inner force is reversed from top to bottom of the cross section along the span direction. In the region of positive influence, for both top and bottom part, the nonlinear influence coefficient is comparatively stable and the difference is not bigger than 15%; while in region of negative, the coefficient is not stable and its difference may exceed 200%(this phenomenon is caused by the change of the force direction, which makes the components change from small to big eccentricity pressing).3) When the arch axial coefficient increases, the absolute of the nonlinear influence coefficient decrease. The coefficient function is linear type in the region of positive influence, while it is exponential type in the region of negative.4) When the rise-span ratio increases, the absolute of the nonlinear influence...