결정론 및 확률론적 방법에 따라 시간의존성 염화물 확산계수 및 외부 영향인자가 내구수명에 미치는 영향
Effect of Time-dependent Diffusion and Exterior Conditions on Service Life Considering Deterministic and Probabilistic Method
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초록
염해에 콘크리트 구조물의 내구수명 평가는 매우 중요한데, 결정론적 방법 및 확률론적 방법에서 평가된 결과는 큰 차이를 보이고있다. 본 연구에서는 시간의존형 확산계수와 고정 확산계수를 고려하여 내구수명을 모사하였다. 기본확산계수, 콘크리트 피복두께, 표면염화물량을 3조건으로 분류하여 각 평가방법에 따라 변화하는 내구적 파괴확률과 내구수명을 평가하였다. 시간의존형 확산계수의 도입을 통하여두 방법 간의 차이를 감소시킬 수 있었으며, 합리적인 해석결과를 유도할 수 있었다. 염화물 확산계수가 2.5×10-12m2/sec에서 7.5×10-12m2/sec으로 증가할 때 내구수명은 25.5~35.6%수준으로 감소하였으며, 피복두께가 75 mm에서 125 mm로 증가할 경우, 267~311%로 내구수명은 증가하였다. 또한 표면염화물량이 5.0 kg/m3에서 15.0 kg/m3으로 변화할 때, 내구수명은 40.9~54.5% 수준으로 감소하였다. 피복두께의 변화에 따른내구수명의 변화는 기본확산계수 및 표면염화물에 비하여 8~10배정도 크게 평가되었으며 내구수명 확보를 위한 중요한 인자임을 알 수 있다.
Abstract
Service life evaluation for RC Structures exposed to chloride attack is very important, however the previous two methods(deterministic andprobabilistic method) show a big difference. The paper presents a service life simulation using deterministic and probabilistic method with timedependentdiffusion coefficient. Three different cases are considered for diffusion coefficient, concrete cover depth, and surface chloride contentrespectively, and then the PDF(probability of durability failure) and the related service life are obtained. Through adopting time-dependent diffusion,the discrepancy between the two methods can be reduced, which yields reasonable service life. When diffusion coefficient increases from 2.5×10-12m2/secto 7.5×10-12m2/sec, the service life decreases to 25.5~35.6% level, and cover depth does from 75 mm to 125 mm, it increases to 267~311% levelas well. In the case of surface chloride content from 5.0 kg/m3 to 15.0 kg/m3, it changes to 40.9~54.5%. The effect of cover depth is higher than theothers by 8~10 times and also implies it is a key parameter to service life extension.
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