مويد نوروزي

With the expansion of the use of concrete slab tracks in railway transportation systems, especially bridges and tunnels, the safety eva‎luation of these structures during their operating lifetime and their timely and appropriate maintenance and repair has become very important. The existence of uncertainty in structural load and resistance variables and concrete deterioration over time has made the use of probabilistic approaches inevitable. An example of a common concrete slab track and its loading was selected. In order to analyze the reliability, the limit state functions were determined, the resistance part of which was obtained from Eurocode and the load part was obtained by modeling and dynamic analysis. The effects of concrete deterioration due to corrosion on the statistical characteristics of random variables during the service life of the structure were considered using a number of time dependent deterioration functions and Monte Carlo simulation. The reliability index (β) was calculated over time and sensitivity analysis was performed in order to investigate the effect of a number of random variables on β. The results show that in the studied slab track, the most critical β is related to the limit state function of the lower longitudinal bending moment. β of all the limit state functions in the first year of operation is more than target β according to Eurocode, and in the fiftieth year, the β of the limit state function of the lower and upper longitudinal bending moment is slightly less than the target β according to Eurocode, and in other cases it is more than that. The cross sectional area of rebars, yield stress of steel, effective depth of slab section and axial load have the most effect have little effect on β of the limit state functions, while compressive strength of concrete and its modulus of elasticity have little effect on β. As concrete cover thickness of rebars increased, the corrosion initiation time increased exponentially and the corrosion rate and erosion depth decreased linearly and vice versa. This issue shows the importance of timely and appropriate maintenance and repair of failures that reduce the concrete cover thickness of rebars.

تحليل قابليت اعتماد وابسته به زمان , شبيه‌سازي مونت‌كارلو , روش قابليت اعتماد مرتبه اول , زوال بتن ناشي از خوردگي , تحليل حساسيت

Time-dependent reliability analysis , Monte Carlo simulation , First order reliability method , Concrete deterioration due to corrosion , Sensitivity analysis

Moayyed Norouzi

Dr. Saeed Mohammadzadeh