RESEARCH ON A MODEL OF THE INFLUENCE COEFFICIENT FOR PRE-FREEZE-THAWING FATIGUE LIFE

To explore working mechanism and life of prestressed structure under pre-freeze-thawing environment which includes freeze-thaw and dynamic fatigue，this paper searched the main factors of fatigue life and the relative relations. On the basis of test and statistical theory，this paper deduced multivariate curve relation，with effective variables. A model about pre-freeze-thawing coefficient C was built using many test data of members that had undergone different freeze-thaw times T and had different pre-stressed grade S，whose fatigue lives were measured and analyzed. The results show that with the increase of freeze-thawing times T，the fatigue life influence coefficient C decreases，but when the times T reach a certain value，the coefficient C has a complicated relation with pre-stressed grade S. More freeze-thaw times has more influence on higher grade pre-stressed members than the lower ones. This papers model can get the influence coefficient and fatigue lifes predicted value when the survival probability is given.