Block shear strength for stainless steel bolted connections under post fire condition

초록

High temperatures during a fire can cause severe damage not only to structural members but also to connections; however, current fire-resistance design codes in Korea do not provide explicit provisions for connection behavior. Although international standards present the mechanical properties of steel materials and strength reduction of structural members at elevated temperatures, post-fire material models for stainless steel have not been clearly defined, and related research remains limited. In this study, the post-fire structural performance of austenitic stainless steel (STS304) double-shear bolted connections with a 2 × 2 bolt arrangement was evaluated through experimental testing and numerical analysis. Specimens were heated to room temperature, 600 °C, and 800 °C and then cooled in air. End distances of 24, 32, and 48 mm were used as variables to investigate block shear failure behavior of connected plate under post fire conditions. Test results showed that STS304 bolted connections exhibited almost no reduction in strength after high-temperature exposure, and all specimens failed by block shear fracture. A material damage model was developed based on the test results and applied to finite element (FE) analysis. The FE predicted ultimate strengths matched the test results within a 2% error. Finally, reduction factors were recommended from the experimental and analysis results, and a block-shear fracture strength equation for post-fire STS304 bolted connections was proposed. © 2026 Elsevier Ltd.

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