Probability Analysis Of Mutiple Hazard Action On Bridges In Life-span Service Period

Bridges basically serve as an essential section of road transportation,playing an very important role in transportation system.Due to the long life-span of middle and major bridges,which is usually not less than 100 years,they often face the threats of multitudes of extreme hazard unavoidably.Hence,the method of life-span period has been proposed.During latest several decades,the concept of life-span design upon brdiges has been proposed and got profoundly great evolution in the field of bridge enginnering.Large amouts of researchers have done a lot of work upon the responding characterstics and damage states of bridge structure under the effect of double or more hazard and made some achievements.However,there are still little researches aiming at the hazard anysis and fortification of multiple hazards.This thesis,which is aiming at the problem above,mainly executive the following work:(1)Primarily collects document literature both in China and aborad,and consequently conlude 8 typical hazards frequently occurring during servie period of bridges,then basically make a classification upon which.Besed on work above,the research on spatial and temporal domain of hazards are conducted and the foundamental hazard chains given.(2)Then we anlaysis and compare multiple bridge design codes worldwide,introducing the seciont related to extreme hazard lodas in which and drawing a conlusion that apparent difference on the forticfication criteria of different hazard are existent.So we establish a unified criterial method to standardize the fortification level for different hazard,along with a performance requirement,and set up performance matrix for each hazard,giving analysis example for parts of hazards consequently.(3)Several practical bridges with respective environmental condition located in China are given as examples to demonstrate the theory of hazard assessment proposed above,and the hazard analysis both single and multiple of several typically extreme hazard are obtained,attaining different fortification criterion for parts of hazard.