Study On Durability Influencing Factors Of Deck-Type CFST Arch Bridge

Although the history of the concrete filled steel tube(CFST)arch-bridge is not longer,CFST arch bridge has great competition in mountain bridges with span between 200 m to 500 m because of its advantages.In the past 20 years,the span and amount of this type of bridge have been greatly increasing.Compared with the design theoriest and practice,the research of durability index of CFST arch bridge is relatively backward and cannot be applied in the operation maintenance.Based on “The study on Durability Index of Deck-Type CFST Arch-Bridge”,which is the item of Guizhou Department of Transportation Science and Technology Project “The research of strategy on main arch structure,concrete infusion and maintenance of deck-type CFST arch-bridge”(contractNo.215-122-052),the following researches have been completed:1.According to the material and force of structure,the influence factors of durability of deck-type CFST arch bridge have been analyzed.The cause and the harm of the influence factors have also been discussed.Based on the atmospheric environment and operation conditions of Xianghuoyan Bridge,tube corrosion,high-strength bolt failure,weld cracking,concrete crack and reinforcement corrosion are considered to be the durability index of Xianghuoyan Bridge.2.Aiming at the tube corrosion,the effects of corrosion on stress and deformation of arch ring have been analyzed.Furthermore,ultimate bearing capacity of the CFST arch bridge which has been rusted uniformly is discussed.Based on the analysis results of confining parameter,stress of arch ring and the ultimate bearing capacity,the permissible value of corrosion rate is proposed.3.Based on the existing corrosion model,a new model which can be used to predict the corrosion rate of the reinforcement in concrete has been derived.Aiming at the continuous beam structure,influence in internal force of girder caused by temperature effect and Core concrete shrinkage and creep has been discussed.