Numerical Study on Yield and Ultimate Resistance of T-Stub Joints with Four Bolts per Row

Abstract Because the Japanese construction industry faces a decreasing skilled workforce, connection details that reduce the number of bolts and shorten field assembly are increasingly required for temporary bridge structures. High-strength bolted tension joints can satisfy this requirement because they generally require fewer bolts than friction-type joints. However, when large sectional forces must be transmitted, tension joints may require larger-diameter bolts, such as M24 bolts, larger flange plates, or multiple bolts per row. In such cases, especially when high-strength flange plates are adopted to increase joint resistance, the applicability of existing design formulas becomes less clear. This study focuses on T-stub joints with four bolts per row, for which several strength formulas have already been proposed. Although previous studies have investigated the effects of various structural parameters, the applicability of existing formulas has not been fully clarified for tension joints using relatively large-diameter bolts, such as those used in bridge members, or for joints with high-strength flange plates. Therefore, this study conducts parametric FEM analysis to examine the applicability of existing yield and ultimate resistance formulas. The parametric FEM results confirmed that the existing formulas can reasonably evaluate the yield and ultimate strengths of four-bolt-per-row T-stub joints with M24 bolts, even when major geometric parameters are varied within the range examined in this study. However, when high-yield-strength steel such as SBHS700 is used for the joint flange, the existing formulas may provide unconservative strength predictions, indicating the need for further refinement for high-strength flange materials.