Research

Finite Element Analysis of CFT Columns Exposed to Fires

This study compares two material models in Eurocode and AISC 360-22, showing that the AISC-based model provides a higher safety margin under fire conditions. In addition, the influence of initial geometric imperfections on the fire resistance of CFT columns is analyzed, revealing that greater imperfection amplitudes result in lower fire resistance times. Based on these findings and the limitations noted in Appendix 4 of AISC 360-22, an improved fire resistance (FR) rating equation is proposed and validated through experiments and numerical simulations.

Design Curves of EV Fires for Structural Fire Design

This study statistically analyzes 20 EV fire test datasets to propose a design fire curve. Key parameters such as HRR, peak HRR, THR, curb weight, and battery capacity were examined. A large portion of EVs reached peak HRR rapidly, and analysis showed that battery capacity is generally associated with vehicle weight and peak HRR. A quadratic growth–plateau–linear decay fire curve was proposed. Results show ISO 834 underestimates EV fire temperatures, and EN 1991-1-2’s 900°C limit should be reconsidered for modern EV scenarios.

Structural Fire Performance of Modular Steel Buildings

This study evaluates the structural fire performance of modular steel buildings through full-scale fire tests and coupled CFD-FEM analysis. Experimental and numerical approaches capture thermal responses of modules and steel frames, supporting both prescriptive and performance-based fire design. By assessing critical temperatures and load-dependent criteria, the study provides a framework for optimizing structural fire resistance design in modular construction.

FR Design Equation of Square CFT Columns

This study evaluates the fire resistance of rectangular CFT columns and improves the safety of the FR prediction in AISC 360-22. Due to non-uniform heat transfer in rectangular sections, the AISC equation can be unconservative. Using FEM-based thermal-structural analysis, 160 simulation cases were conducted. Results showed that aspect ratio and load ratio have high sensitivity to FR. A new equation including aspect ratio improved the safe prediction rate from 49% to 90%. Full-scale fire tests are planned to further validate the equation and model confinement effects more accurately in FEM.

Structural Fire Design Guideline of Steel-plate Composite Wall

This research aims to establish a practical fire design approach for SC in Korea, where no specific design standards currently exist. Based on international guidelines, numerical modeling and fire testing are conducted to provide temperature distribution data, prediction equations, and resistance charts, forming the basis for a proposed guideline that facilitates practical and efficient application of SC Wall in domestic buildings.

Progressive Collapse and Failure Criteria under Fire Conditions

This study aims to establish step-by-step failure criteria for structural elements subjected to fire and to analyze their residual performance. Numerical simulations are conducted to assess structural response, considering material deterioration, thermal effects, load redistribution, and fire-induced damage progression. A quantitative evaluation is performed to determine failure thresholds, identify critical structural components, and examine collapse sequences under varying fire scenarios. By conducting numerical analysis, this research contributes to the development of fire-resilient design approaches and improved safety guidelines for steel structures subjected to extreme fire events.

Damage Index and Residual Capacity under Fire Conditions

This study defined the performance level for progressive collapse of steel structures under fire conditions and proposed the damage index. The behavior of the structural system at elevated temperature was analyzed, and the damage index was calculated based on the residual strain of the yielded members. The proposed damage index framework is ultimately expected to serve as quantitative tool for assessing the performance level of steel structures exposed to fire and predicting the collapse.

Mechanical Properties At and After Elevated Temperatures

The high-temperature behavior and post-fire mechanical properties of carbon steel, fire-resistant steel, and structural timber were experimentally investigated. Variables include temperature, load ratio, and fire duration. Steel specimens were preloaded and heated to induce thermal creep, followed by tensile tests after cooling. Timber was tested under elevated temperatures to observe degradation and thermal sensitivity through tension and compression tests. The results support performance-based fire and resilience design.

Structural Fire Behavior of Composite Beams

This study investigates the structural fire behavior of composite cellular beams with web openings in the steel section. Fire resistance tests are conducted to examine the structural behavior, deflection, and failure modes. By comparing with conventional composite beams at elevated temperatures, this study reveals that web openings help mitigate thermal expansion and improve the load-bearing capacity of the concrete slab. Based on the experimental results, a finite element model is proposed to simulate the behavior under fire conditions and conduct a parametric study.

Time Equivalent Approach for Assessing Fire Resistance

Most furnaces cannot accurately reproduce the standard fire curve, causing discrepancies when comparing experimental results under varying conditions. To overcome this, the furnace temperature is controlled to align precisely with the standard curve, ensuring consistent input for reliable analysis and development of a performance evaluation formula. Since traditional time-equivalent methods do not reflect the complex behavior of concrete-filled steel tube (CFT) columns, this study applies an energy-based time-equivalent method. Ultimately, this provides a robust framework for evaluating structural fire resistance under diverse fire conditions.

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