Durability Damage In The Atmospheric Environment Of Existing Structure-based Dynamic Reliability Assessment

Under the action of load, environment and interior factors of materials etc, there sistance of the members or structures varies and structural behavior degrades of reinforced concrete structures with time, as a result the probability of failure increases. A number of civil, industrial and hydrodynamic structures perform so insecurely thatendangers wealth and life within their design working life. More and more economicloss caused by durability damages is being paid close attention worldwide. It is urgent to improve the research on regularity of durability damages, reliability evaluating on existing structures, in order to provide scientific basis for re-service, repairing or backout. Aiming at the urgent demanding, some fundamental problems of reliability evaluation of existing structures were researched in this paper . Firstly, according to the characteristic of different types of load, evaluating methods and probability distribution of dead load and live load has been minutelydeduced based on equal exceeding probability principle. And some concise tables are given for practical use. Especially, some daring try for evaluating seismic action of existing structures in different re-service term is given as to get some positive result. Secondly, based on the comparisons of existing research findings of durability damages, the reason, the process and the rule of resistance varying, as well as destruction forms of structural members has been minutely exposited. The Three-stage Resistance Varying Model is put forward, together with computing formula of damaged members. Thirdly, the evaluating methods of load and resistance given above has been directly used to evaluating structural members. An improved mathematical model for reliability evaluation of existing structure is put forward, with detailed example. Such results combined with safety classification can be used in reliability evaluation of structural system. In this way, the current reliability evaluation criterion take a step from applied method to probabilistic method. Lastly, according to actual insufficient and development trend, some innovative suggestion is put forward for further thinking, expecting that throw out a minnow to catch a whale.