Reliability assessment of anchor bolt resistance in column base connection of pre-engineered steel frames considering metal corrosion in marine environment

Anchor bolts of the column base are important in ensuring the stability and safety of pre-engineered steel frames. The reliability of anchor bolts is influenced by various random factors, including geometric dimensions, material properties, loads, and particularly the corrosion status. This study aims to evaluate the reliability of steel column anchor bolts in marine environments where metal corrosion is a dominant factor. A deterministic model for calculating the safety condition of anchor bolts is built and then developed into a stochastic model by considering geometric dimensions, material properties, loads, and corrosion status as random variables. The safety probability (reliability) of the anchor bolts is evaluated through Latin hypercube sampling and Monte Carlo simulation. The research results indicate that the safety probability of anchor bolts in a marine atmospheric environment tends to decrease over time. Specifically, for Model 1, the safety probability decreases from 94.26% after 10 years, 87.96% after 15 years, 63.66% after 25 years, and only 6.78% after 50 years. Model 2 exhibits a slower decline, with the safety probability decreasing from 96.2% after 10 years to 92.4% after 15 years, 80.46% after 25 years, and 33.25% after 50 years. Meanwhile, Model 3 shows a higher probability of maintaining safety, with a likelihood of decreasing from 96.82% after 10 years, 94.11% after 15 years, 86.29% after 25 years, and 52.14% after 50 years. Although the structure met the safety requirements according to the initial model, the results of the random analysis showed that the risk of damage increased due to the influence of random variables, especially metal corrosion in the marine environment.