Post-buckling Ultimate Bearing Aerostatic Performance of the Long-Span Bridge

Abstract

Calculating on aerostatic stability for long span cable-supported bridges, the Newton-Raphson method can obtain the critical wind speed of aerostatic instability accurately. When the wind speed exceeds the critical extreme wind speed, the structural whole stiffness matrix exists the stagnation effect depends on the large deformation Displacement, Newton-Raphson method has been unable to carry out the iterative calculation after initial structural instability. In order to study the development and change of the later stage of the structural global instability, explore the morphological transition and the stiffness enhancement effect of the structural instability, the iterative search algorithm of the arc length method is introduced in the analysis of the aerostatic stability of the long span bridge, then analyze the similarities and differences of Newton-Raphson Method and Arc-Length Method in solving leaping-type extreme value instability. Aiming at the typical large span bridge, the whole process of aerostatic instability of the long span bridge is obtained by arc-length method, and the post-buckling behavior of the bridge is explored. The research shows that the long-span bridges’ static stability has the characteristics of the leaping-type extreme value instability, When the large deformation development caused by wind for the first time approach the structural whole stiffness’ stagnation point, the sudden change of the main beam’s position makes the cable force decrease sharply and then the gravity of the main beam dominates, the main beam occurs step change under the gravity and cable tension, forming the re-strengthening effect of the whole stiffness. Along with the continuing increase of wind speed, the main beam will appear the reciprocating “step-enhanced” cycle effect under the lift force and lift moment.