چكيده به لاتين
Reinforced concrete is one of the most used building materials in civil engineering and construction industry. Concrete under different loading for different reasons, behaves unlike what is expected. One of the reasons for these behaviors is the build-up of corrosion in the concrete and the rebar. Corrosion of rebar is known as the most important factor in the failure of RC structures. Concrete is generally thought to be a very durable material, but the history of concrete performance in marine environments suggests that in the face of seawater, as one of the most corrosive natural environments in the world, concrete is exposed to serious problems in terms of durability. In recent years, due to the severe damage to concrete structures in the Persian Gulf, we see repair and reconstruction operations in many of these structures.
In this research, the reduction of loading capacity of the berth piles due to the corrosion of reinforced concrete and rebars in different environmental conditions has been investigated. In the first part of the study, a comparison was made between the approach of different codes in considering different environmental conditions for estimating the start time of corrosion. Then, using the results of the first part, reduction of the loading capacity of the berth piles under chlorine-induced corrosion by numerical modeling has been investigated. Corrosion as a function of time, has been measured based on factors such as amount of chlorine ion in water, critical chloride concentration, chlorine ion emission factor, member positioning conditions (submerged, tidal and splash conditions), position of the berth, start time of corrosion, rebar cross-section, rebar yielding stress, compressive strength of concrete, water to cement ratio and concrete cover amount. Finally, using coding in the MATLAB program, the interaction charts for concrete berth pile has been sketched. During 40, 60, 80 and 100 years after the construction of the berth, the rate of reduction in the loading capacity of the berth piles was discussed and reviewed. The results showed that corrosion and reduced loading capacity in splash conditions were more than tidal and submerged mode, respectively. For example, in a berth with a surface chloride level of 3, a critical chloride level, a water to cement ratio, and a concrete coating of rebar are 0.9, 0.4 and 60mm respectively, and during 60 years after the construction of the berth, the percentage reduction in the bending capacity of the piles at splash, tidal and submerged conditions, are 11.56, 13.26 and 7.14. In the third part of this research, a modeling to estimate the start time of corrosion using fuzzy logic is done in the MATLAB program. The fuzzy modeling results are acceptable with slight difference in comparison with the computational results.
