Time-dependent reliability of corrosion-affected RC beams. Part 3: Effect of corrosion initiation time and its variability on time-dependent failure probability

This paper forms the third part of a study which addresses time-dependent reliability analyses of reinforced concrete (RC) beams affected by reinforcement corrosion. Parts 1 and 2 of the reliability study are presented in companion papers (Bhargava et al., 2010, 2011). Part 1 of the reliability study (Bhargava et al., 2010) presents evaluation of probabilistic descriptions for time-dependent strengths of a typical simply supported corrosion-affected RC beam. These probabilistic descriptions, i.e., mean and coefficient of variation (c.o.v.) for the time-dependent strengths are presented for two limit states: (a) flexural failure; and (b) shear failure. Part 2 of the reliability study (Bhargava et al., 2011) presents evaluation of time-dependent failure probability for the considered RC beam by utilizing the information on probabilistic descriptions for time-dependent strengths available in Part 1 (Bhargava et al., 2010). Evaluation of time-dependent failure probability considering the variability in time-dependent strengths and/or time-dependent degradation functions is also presented (Bhargava et al., 2011). This paper investigates the effects of time to corrosion initiation and its variability on failure probability of the same RC beam presented in companion papers (Bhargava et al., 2010, 2011). By considering variability in the identified variables that could affect the expected time of first corrosion, simple estimations are presented for mean time to corrosion initiation and variability associated with time to corrosion initiation. Evaluation of time-dependent failure probability for the beam is presented by considering estimated probabilistic descriptions, i.e., mean and c.o.v. for time to corrosion initiation. Parametric analyses show that failure probability for the beam is sensitive to the mode of strength degradation and time to corrosion initiation.