STRATEGIES FOR PREDICTING THE SERVICE LIFE OF CONCRETE MATERIALS AND STRUCTURES

摘要

Service life of reinforced concrete(RC)structures is important to durability design,repair and strengthening works of RC structures.Durability of RC in natural environment is difficult to predict as there are various influence factors.Therefore,the research about strategies for predicting the service life of RC structures is necessary.To improve the accuracy of predicting the service life of concrete materials and structures,the whole process of service life was analyzed first.There are some key periods in the whole process,including the time when initial corrosion of steel bar in concrete occurs(T0),the time from when steel bar corrosion occurs to when the cracking of concrete caused by corrosion happens(Tcr),and the time that the cracking develops to the certain width(Tw).Related calculation models of the service life in different phases are given respectively.Then based on the action spectra of nature environment,response spectra of micro-environment in concrete and the time-varying model of the steel bar corrosion rate,the strategy for predicting the service life in the durability design of new concrete structures is proposed,and a numerical example is also illustrated.The accelerated aging factor(φ)of durability test is presented.The method of predicting the service life of the RC structures based on the durability tests in the artificial climate environment is initially proposed.