Wind-resistant Risk Analysis Of Long-span Rigid Frame Bridge During Construction Period

With good performance of mechanism, the rigid frame bridge is one of the most widely used types of bridge structure nowadays.With the increase of the span length, all kinds of uncertainty have been arisen, and the engineering construction is faced to unprecedented high risk. With the rapid growth of traffic vehicles and the circumstances that many large-span rigid frame bridge often to be situated in windy strip, the problem of Construction risk under the loads of wind is prominent. And the frequent changed loads will cause cycle stress and structures fatigue failure.This dissertation focuses on the Wind-resistant risk of long span rigid frame bridges, which includes the following aspects:Firstly, The theoretical skeleton in this part, the risk conception and its analysis principle are discussed.The definition of risk and the selection principle of risk analysis methods are put forward, the definition of structure risk of bridges during construction is given and the theoretical skeleton of construction risk analysis for bridges is built.Secondly, Due to the complicated characteristic of construction risk factors of bridges and the lack of practical data for construction accidents, the principle and the process of construction risk identification for bridges are discussed.A uniform risk loss model are defined, and a basic loss estimate method is also proposed.Basic mathematic format of bridge risk probability are studied, and a uniform risk probability estimate model are proposed,Risk probability estimation will be more accurate and practicable. Bridge Dynamic ANalysis System is discussed, which is ready for the construction Wind-resistant risk Analysis.Finally, Based on the construction Wind-resistant risk assessment method, the risk of BeiShan Bridge under the influence of wind in cantilever construction stage is taken as an example in the research, each method of this research is introduced and the finally consequences estimation is earned.Time-domain buffeting method was used to calculate buffeting-induced responses at the maximum double cantilever stage, damping coefficients were determined by measured damping ratio of aeroelastic model in the analysis. Because required damping ratio can not be achieved in the design of an aeroelastic model, a proper modification for the dynamic response was carried out and the influence of damping ratio on buffeting-induced responses was discussed.the risk of under the influence of wind and the influence of damping ratio on buffeting-induced responses is further studied and discussed based on the construction Wind-resistant risk assessment method.This study provides useful references for application and development of construction Wind-resistant risk analysis theories and methods in practical projects.