Safety Evaluation Of Long-span Bridge In The Melting Ice Flood Season

In recent years, with the development of express way construction gradually transform from plain-rolling terrain to mountain-hilly terrain, larger the span of bridges grew, higher the bridge piers rose and more flexible the bridge system developed, obviously it has raised many new issues to long-span bridges of Safety Research. Especially in these days, the Yichang-Wanzhou railway tunnel and the western Hunan phoenix bridge, the two major accident's occurrence brought bridge workers heavier pressure. The security problem is becoming more important. But the melting ice flood of the Yellow River is the world's most typical hydrological landscape, it is also the largest non-potential flood disaster. The melting ice flood is one of the most serious natural disasters in the Yellow River Valley, which once is famous for the frequently burst and difficulty to control and prevent. To this end, a comprehensive systematic study on the melting ice flood would be necessary. On the basis of the analysis of the melting ice flood at home and abroad, this article mainly researched on the ice pressure of the melting ice in flood seasons. The research is based on the field of river ice load calculation and the flood load calculation, especially on the static and dynamic security assessment of the long-span continuous bridge which carry on the elaboration in the melting ice flood seasons. Taking the construction of the Dengkou Yellow River grand bridge as the project background, the research exert itself to the long-span continuous bridge's security in the melting ice flood season, including the following several aspects.Firstly, research condition and the existence question of the present river ice load in the melting ice flood season was elaborated, through the summary reached the ice load formula that suited national ice condition and compared with the measured data, demonstrated that this ice load formula was feasible. At the same time, it put forward the response spectrum theory to the theoretical simulation of large-scale drift ice load.Secondly, by the main factors of flooding the formation in the melting ice flood season, the flood damage mechanism on the structure of the bridge and the damaged forms of a bridge under flood function, we couid infer the formula of the flood to the bridge horizontal action.Again, the self-vibration characteristics of the Dengkou Yellow River grand bridge in the melting ice flood season was analysis. The entire bridge structure was simulated by using general finite element software Midas \ Civil, which included the simulations of rubber support, the pile support, the pile and the soil function and so on.Finally, it illustrated the importance of evaluation's safety in the melting ice flood season, and introduced the static and dynamic safety evaluation separately of full-bridge operation phase of the Dengkou Yellow River Bridge. In the dynamic analysis, the use of the relevant transient dynamics principles, combined with the time-history analysis functions in general finite element software Midas \ Civil accurately simulated the flow of the ice load, melting ice flood, separately obtained the bridge response result under these kind of load function, which in order to prevent the harmful vibration and so on.At the end of the paper, the work in this paper was summarized and some conclusions about the study were drawn. Besides, the further research problems were indicated in the passage.