Specifications and Performance Standards

Contribution to the 2017 Specifications for highway bridges
The "Specifications for highway bridges and its commentary" (by Japan Road Association) was revised in 2017. In the revised Road Bridges Specifications, partial safety factor design method was adopted to clarify the relation between the action and resistance assumed in the design, as well as the meaning of the safety margins. In the past, CAESAR engaged in the research on variation in material strength, which is considered a premise for design, as well as the variation in the formula of load-bearing capacity (e.g., the shear bearing capacity of concrete members). Both are required in to provide partial safety factor in the specification. We also studied the influence of uncertainty of the soil reaction coefficient in the calculation of the response and bearing capacity of pile foundation and researched the performance evaluation of new materials, such as the high-strength bolt S14T. The revised Road Bridges Specifications also specifies partial coefficients that consider these analysis results, as well as new inspection standards for a few new materials.
Moreover, based on the results and expertise accumulated from planned inspections across the country, the Specifications determines that structural designs should, to the extent possible, avoid parts that are difficult to be inspected and repaired/reinforced. It also states that the method of renewal and repair reinforcement needs to be studied in advance, and that the structures should be designed to reduce uncertainty in design such as local stress concentrations and stagnant water.