Time-dependent Reliability Estimation with Risk Mitigation Strategies for Early-age Thermal Cracking in Concrete Dam Structures

Mass concrete structures encounter a significant challenge with heat dissipation during hydration, often leading to thermal cracks due to non-uniform temperature distribution. Accurate reliability estimation concerning thermal cracking is essential for mitigating failure risks. Given that concrete gains strength over time through hydration, this reliability assessment must be inherently time-dependent. In this context, a case study on dam construction was undertaken to evaluate the probability of structural failure over time. A finite element (FE) model, parameterized with critical factors such as lift height, pouring temperature, time-dependent material properties (thermal and mechanical), and heat generation due to hydration under thermal and mechanical constraints, was developed. These parameters were treated probabilistically, following appropriate distributions considering the material uncertainty to assess the risks of thermal cracking and its progression. A data-based surrogate model using a Long Short-Term Memory (LSTM) framework was created to evaluate failure probabilities with acceptable accuracy. The results of this study can inform the development of effective risk-mitigation strategies to prevent thermal cracking in freshly poured concrete.