Dissertation Defence: Seismic Behaviour of Reinforced Concrete Columns Retrofitted with Fabric-Reinforced Cementitious Matrix
December 18 at 9:00 am - 1:00 pm
Moustafa Mansour, supervised by Dr. Ahmad Rteil, will defend their dissertation titled “Seismic Behaviour of Reinforced Concrete Columns Retrofitted with Fabric-Reinforced Cementitious Matrix” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Civil Engineering.
An abstract for Moustafa Mansour’s dissertation is included below.
Examinations are open to all members of the campus community as well as the general public. Please email ahmad.rteil@ubc.ca to receive the Zoom link for this exam.
Abstract
Many old reinforced concrete (RC) structures are inadequately designed against earthquakes, which could result in catastrophic consequences. Fabric-reinforced cementitious matrix (FRCM) is a relatively new composite material offering unique advantages, making it a viable alternative to other conventional materials for strengthening existing concrete structures. However, a comprehensive understanding of this material’s impact on retrofitting reinforced concrete columns under seismic loads has yet to be explored. The objectives of this study were to experimentally and numerically investigate the seismic behaviour of RC columns retrofitted with carbon FRCM jackets and to identify their vulnerability to earthquakes. In the experimental program, four large-scale RC columns were tested. The columns had a 300 mm diameter circular cross-section and a 1720 mm height. The columns had deficiency in their seismic reinforcement detailing in the plastic hinge region. The studied parameters included the longitudinal reinforcement ratios (1.1% and 2.6%) and the area of the FRCM strengthening system (0, 1 or 2 layers). The columns were subjected to a quasi-static lateral cyclic loading, and the seismic performance was evaluated in terms of the failure mode, load capacity, ductility, stiffness degradation, and energy dissipation. In the numerical study, a fibre-based model was developed using OpenSees framework and was validated against the experimental results. The developed numerical model incorporated nonlinear constitutive laws for concrete, steel reinforcement, and the FRCM system. The model also included the effect of the FRCM confinement and its matrix as well as the bond–slip interaction. The developed numerical model was utilized to conduct a seismic fragility assessment, aiming to predict the performance of the columns under real earthquake events. The results of this study revealed that the retrofitted columns had an enhanced overall seismic response where the lateral confinement action of the FRCM jacket either delayed or prevented rebar buckling. In addition, the experimental observations highlighted the progressive failure of the FRCM system and the association of this behaviour with the structural performance of the retrofitted columns. The numerical analysis revealed that FRCM jacketing is an effective retrofitting technique for improving the seismic fragility of seismically deficient RC columns.
