FRP THIN-WALLED STRUCTURES. BEHAVIOUR AT ELEVATED TEMPERATURE AND UNDER FIRE EXPOSURE
This paper addresses one of the most critical issues regarding the use of fibre reinforced polymer (FRP) thin-walled structures in civil engineering applications: the behaviour at elevated temperature and under fire exposure. The first part of the paper presents an overview of the research activities on pultruded FRP structures at IST-University of Lisbon, focusing on different aspects and at different scales of analysis: short-term mechanical behaviour, creep behaviour and durability of the material; mechanical behaviour of structural members – beams and columns; connection technology (bolting, bonding); dynamic and seismic behaviour of frame structures. Examples of applied research projects, developed in collaboration with the industry, are also presented, namely the first two hybrid pedestrian bridges in Portugal and the modular emergency Clickhouse. The second part of the paper presents a review of the fire performance of pultruded glass-FRP (GFRP) thin-walled structures. First, the effects of elevated temperature on the thermo-physical and mechanical properties of the GFRP material are addressed. Subsequently, the fire reaction behaviour of the GFRP material and the effects of using different types of fire protection on such behaviour are discussed. Next, the available fire resistance tests on pultruded GFRP elements, including slabs, beams and columns, are reviewed and discussed, as well as the simulation studies that aimed at predicting their thermal and mechanical responses at elevated temperatures. Finally, international guidance for the fire design of pultruded FRP structures is summarized, and the most relevant research needs in this field are identified.