Experiment and numerical investigations of S700 high strength steel CHS beam-columns after exposure to fire

• Main Author: Koh, Alvin Zhan Wei
• Other Authors: Zhao Ou
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Civil engineering::Structures and design
• Online Access: https://hdl.handle.net/10356/149409
• Institution: Nanyang Technological University

This paper presents a comprehensive experimental investigation of S700 cold-formed high strength steel circular hollow section beam-columns after exposure to fire. The experimental investigation was performed on two series of S700 cold-formed high strength steel circular hollow section beam-columns specimens with two different dimensions (139.7 × 10 and 168.3 × 4) to study the structural performance of Class 1 and Class 4 structural members. Each series comprised five geometrically identical specimens, with four heated to different levels of high temperatures (namely 400 °C, 600 °C, 900 °C and 1100 °C) and one unheated to simulate ambient temperature. The heating and cooling procedure, material tests, initial global geometric imperfection measurements and eccentric compression tests were performed and fully reported. Due to the absence of codified post-fire design rules, the test and numerical results were employed to evaluate the applicability of codified interaction formulae for high strength steel circular hollow section beam-columns at ambient temperatures, as prescribed in European code, American specification and Australian standard, to the design of post-fire S700 high strength steel circular hollow section beam-columns. The results concluded that European code leads to safe but conservative and scattered failure load predictions, while American specification and Australian standard yield safe, accurate and consistent failure load predictions with the most accurate predictions obtained from the American specification.