Wind-Induced Fatigue Analysis Of Temporary Connection On Girder Of Suspension Bridges

Streamlined steel box girder is widely used in long-span suspension bridges. This type of stiffening box girder has good wind resistance performance. Girders are connected by temporary connection during the girder erection process. Stiffening girders are welded on-site when a part or all of them are erected.Bridge alignment adjustment should be taken before welding.The wind tunnel experiment of Xihoumen Suspension Bridge shows that buffeting occurs under turbulent flow in each bridge construction stage. Internal forces of girder due to wind are composed of static wind forces and buffeting forces.This two kinds of forces are assigned to tempotary connections according to stiffnesses of bolts. Buffeting forces are random, so axial forces of bolts change with time. And that can easily lead to fatigue failure. It will endanger worker's safety, at the same time change the bridge alignment of construction phase, or even damage the bridge if fatigue failure of temporary connection happens.Static wind forces are calculated by FEM using mean aerodynamic force coefficient, which is got by wind tunnel test of Xihoumen Suspension Bridge. While buffeting forces of typical contraction phase are calculated by FEM and SRSS method using buffeting response displacements obtained from wind tunnel test. Constant amplitude loadings of different construction phase are established. Then stress of temperary connection is calculated by finite element analysis software. And then its fatigue dangerous position is determined. Crack lengths in bolt and fillet weld are analysised using fatigue crack propagation theory in fracture mechanics.Fatigue design method is proposed. Fatigue tests are introduced in this thesis.