Study On Wind-Resistant Performance Of Riding-Cable Crane In Long Span Suspension Bridge

Riding-cable crane which is a kind of efficient carrying equipment for the erection of steel girder, plays an important role in the construction of suspension bridge. Riding-cable crane located at high altitude where the wind speed is much higher than that of deck, will frequently suffer the action of strong wind, so its parameters of wind resistant design are much greater than that of main girder. Due to the safety of riding-cable crane is directly related to the schedule and safety of the construction, it is necessary to check and evaluate its wind-resistant performance through wind tunnel tests and calculating analysis.In this paper, taking Xihoumen suspension bridge as the enginnering background, the wind-resistant performance of riding-cable crane under the condition of strong wind was evaluated through wind tunnel tests and calculating analysis. The main jobs as follows:(1) In order to study the wind loads endured by riding-cable crane, rigid model wind tunnel tests were conducted, which measured forces with four point-bar balances simultaneously. The shape coefficients of three directions in various operating conditions(different wind directions and wind attack angles) were obtained through tests, the three directions are respcetively cross direction of bridge, axial direction of bridge and vertical direction.The change rules of wind loads and the most dangerous operating conditions was also known by analysing the experimental data.(2) The turbulent wind field of design wind speed was simulated through user-defined programme using WAWS. It was based on Davenport's quasi-steady theory to build dynamic wind forces model of riding-cable crane. Dynamic time domain analysis of most unfavorable loads combination were computed by finite element program.(3) The specefication method was that the determination of static gust loads was based on shape coefficients measured in wind tunnel tests and static gust load factor obtained from "Wind-resistent Design Specefication for Highway Bridges"(JTG/T the D60-01-2004). After static gust loads of riding-cable crane had been determined, the response analysis was also computed by finite element program. And then the results of the specefication method were compared with that of time domain analysis.(4) According to the concept of equivalent static wind loads, practical method on equivalent static wind load of linear-elastic structure was proposed in this paper. When adopting this method, the peak value of target response was either calculated by frequence domain method or time domain method. Equivalent static wind loads of riding-cable crane under design wind speed were respectively caculated by practical method and gust factor method.(5) Finally, structure strength and overturn stability of riding-cable crane were analysed, its wind-resistant performance under the condition of strong wind was evaluated to be fine.