Description
A Master of Science thesis in Civil Engineering by Reem Talo entitled, “Finite Element Modelling of FRCM-Confined RC Columns Exposed to Fire”, submitted in June 2023. Thesis advisor is Dr. Farid Abed and thesis co-advisor is Dr. Ahmed El Refai. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Abstract
Externally bonded fiber-reinforced polymers (FRP) have been widely used for strengthening and retrofitting applications. However, their efficacy is hindered by the poor resistance of epoxy resins to elevated temperature and their limited compatibility with concrete substrates. To address these limitations, fabric-reinforced cementitious matrix (FRCM), also known as textile reinforced mortar (TRM), systems have emerged as an alternative solution. This thesis presents the development of three-dimensional (3D) finite element (FE) models using ABAQUS software to investigate the performance of FRCM-confined RC columns exposed to fire. A parametric study was conducted to examine the behavior of confined columns under various conditions. The parameters studied include the concrete clear cover (40, 50, and 60 mm), the number of poly-paraphenylene benzobisoxazole (PBO) FRCM layers (0, 1, and 2 layers), the presence of a 30 mm thick insulation layer, and axial preloading. Numerical analysis revealed key findings. Increasing the concrete clear cover from 40 to 50 and 60 mm resulted in reductions of steel reinforcing bar temperatures by 14 and 27%, respectively, after 1 hour of fire exposure. Moreover, the inclusion of a 30 mm insulation layer reduced steel bar temperatures by 70% compared to uninsulated columns. Increasing the number of FRCM layers did not significantly affect load resistance duration, but increasing the preloading level significantly reduced the duration of load resistance. In addition to the numerical study, preliminary experimental tests were performed on PBO-FRCM confined cylinders subjected to different target temperatures (100, 400 and 800 °C) with different concrete strengths (30, 45, and 70 MPa) and number of FRCM layers (0,1, and 2). The experimental results highlighted the confinement effect of FRCM, particularly in cylinders with lower concrete compressive strength. Cylinders exposed to 100 °C exhibited a slight increase in strength, while no specific trend was observed in the variation of the compressive strength for cylinders heated to 400 °C. Specimens heated up to 800 °C experienced a significant reduction in strength, reaching up to 82%.
