Time-Dependent Reliability of Concrete Structure in Chloride Environment

Abstract

In this paper, the age factor of chloride diffusion coefficient of concrete is considered, as well as the randomness of the chloride diffusion coefficient, concrete cover depth, surface concentration, threshold concentration and age factor. Based on the First Order Reliability Method, a time-dependent reliability analysis model for concrete structures under chloride conditions is established. The results show that the time-dependent reliability model is in good agreement with the Monte Carlo sampling method. The results of example show that the corner region of the concrete structure must be designed and calculated based on the two-dimensional diffusion model, and the attenuation characteristics and randomness must be considered for the concrete structures in chloride environment.

Risk-Cost Optimized Maintenance Strategy for Steel Bridge Subjected to Deterioration

“…The coefficient followed lognormal distribution with COV of 0.20. The cover thickness of slab reinforcement c was 30 mm, which followed normal distribution and had a COV of 0.02 [38]. Surface chloride content C 0 was 0.8% with COV of 0.5, following lognormal distribution [38].…”

“…It is essential to make sure that the chloride concentration within the concrete bridge is below the threshold value, so that the deteriora-tion of reinforcement can be avoided. The relevant limit state can thus be established as follows [38]:…”

“…where C(t) is the chloride concentration at the position of the steel reinforcement (%, the percentage of chloride in the mass of concrete is used as the unit of chloride concentration in this paper). C 0 is the critical threshold chloride concentration that initiates the corrosion of reinforcement, which is 0.05% [38]. The chloride concentration C(t) at time t is as follows [38]:…”

“…C 0 is the critical threshold chloride concentration that initiates the corrosion of reinforcement, which is 0.05% [38]. The chloride concentration C(t) at time t is as follows [38]:…”

“…Reinforcing steel was Grade 40. Diffusion coefficient D f for chloride was determined as 31.5 mm 2 /year [38]. The coefficient followed lognormal distribution with COV of 0.20.…”