Probabilistic Model for Degradation of Concrete Strength of Bridges

This paper investigates the degradation mechanism and tendency of concrete strength of existing bridges. Concrete strength is a time-variant property which usually increases rapidly during the first few years but more slowly as it approaches a nearly uniform level. For bridges sUbjected to environmental attack, the concrete strength can decrease with time. More than 700 concrete strength data have been obtained on dozens of existing bridges by resilience method, ultrasonic method and core-drilling method in south of China. And a non­ stationary random process is proposed to describe the time-variant concrete strength, in which mean value function, variance function, and autocorrelation coefficient function of the random process are established. The results can be used to better perform service-life assessment of concrete bridges and acts as the basis for time-dependent reliability analysis.