Flexural behaviour of glass fibre-reinforced polymer and ultra-high-strength fibre-reinforced concrete composite beams subjected to elevated temperature

Abstract

Composite beams consisting of pultruded glass fibre-reinforced polymer (GFRP) I-beams and ultra-high-strength fibre-reinforced concrete (UFC) slabs have been developed for use in short-span bridges. Fibre-reinforced polymer bolts (fibre-reinforced polymer threaded rods) and epoxy adhesive were used to connect the UFC slab to the GFRP I-beam. The authors conducted material tests and large-scale static bending tests at room and elevated temperatures (less than 90°C) to investigate the flexural behaviour of GFRP-UFC composite beams subjected to elevated temperature. The test results demonstrated that the mechanical properties of the GFRP I-beams, fibre-reinforced polymer bolts and epoxy adhesive were significantly deteriorated at elevated temperatures due to the glass transition of their polymer resin matrices. As a result, the stiffness and ultimate flexural capacity of the GFRP-UFC composite beams under elevated temperatures were significantly reduced. More than 85% of the flexural capacity of the GFRP-UFC composite beams was retained up to 60°C but that was decreased to 50% at 90°C. Fibre model analysis results confirmed that the stiffness of the GFRP-UFC composite beams is not significantly affected by actual hot environments, where there is a moderate temperature gradient across the beam cross-section.

Mechanical Properties of Fibre Reinforced Polymers under Elevated Temperatures: An Overview

“…Wijayawardane et al [133] also studied the pultruded GFRP I-beams flexural properties under elevated temperatures. It was reported that beams lose only 15% of their flexural strength after exposure to elevated temperatures up to 60 • C. On the other hand, they showed that both stiffness and strength deterioration increase by increasing the temperature and the failure mode was related to the wall's delamination.…”

Compressive and Bonding Performance of GFRP-Reinforced Concrete Columns

“…Studies on concrete structures that are reinforced in the longitudinal and transversal direction using GFRP bars showed satisfactory performance in bending and shear [15][16][17][18]. Furthermore, other studies conducted experimental work on this type of reinforcement and reported the mechanical properties [19][20][21][22][23][24][25][26], physical properties [3], chemical properties [19,25,27], thermal characteristics [21,26,28], and durability properties [20,29]. These studies have been specified in CSA S807 [30], ASTM D7957 [31] material specification, and design codes to verify the quality, design, and safety of these reinforcing materials to be used as structural reinforcement.…”

Pultruded materials and structures: A review

“…Therefore, only the most remarkable works are listed here. General stress–strain analysis of the pultruded beams; 64,142,314,315,326,346,353,356–363 straightening and restoration of existing beams; 246,364–366 buckling instability; 247,310,342,367–379 thermal loading; 380,381 and web-flange junction strength 379 are just primary examples of what composite scholars are working on in regard to the flexural behavior of full-scale pultruded structures. Other types of structural elements were also widely studied: application of composite bars and strips for reinforcement; 382–389 space frame structures; 390–394 hybrid beams; 79,395–398 sandwich structures and bridge deck systems.…”