Development of Reliability-Based Design Tools to Determine Toughness Requirements for Canadian Steel Highway Bridges

The current toughness provisions in CSA S6 lack a probabilistic basis and do not allow the influences on brittle fracture risk of several important factors to be explicitly considered in design. To address these shortcomings, this paper demonstrates how Monte Carlo simulation, fracture mechanics, and the master curve approach can be used establish reliability-based toughness requirements for Canadian steel highway bridges. The performance of a typical bridge designed to meet the current requirements is taken as a reference point to establish equivalent required toughness levels for a broad range of yield strengths, plate thicknesses, and demand-to-capacity ratios. The results are fitted to two-degree surfaces, allowing the Charpy V-notch test temperature and impact energy to be established for a specified reliability index. The resulting design tools may be of interest to engineers and owners endeavouring to improve the economy of steel highway bridges while ensuring consistent and acceptable levels of risk.