The use of Fiber Reinforced Polymer reinforcement in concrete columns and bridge piers has gained significant momentum as a sustainable and corrosion-resistant alternative to traditional steel reinforcement. This special session invites high-quality contributions that address recent advances in the behavior, design methodologies, numerical modeling, experimental validation, and construction practices of FRP-reinforced concrete columns and piers under various loading scenarios, including axial, lateral, seismic, and environmental conditions.
Learning Objectives:
(1) Recognize and understand the differences between conventional and FRP RC columns/piers;
(2) Identify issues related to the modeling, analysis, design, construction and performance of FRP RC columns/piers (performance through analysis, experimentation, field observation);
(3) Report on current research and construction practices related to FRP RC columns;
(4) Recognize existing codes and standards for the design and construction of FRP RC columns.
This session has been approved by AIA and ICC for 1 PDH (0.1 CEU). Please note: You must attend the live session for the entire duration to receive credit. On-demand sessions do not qualify for PDH/CEU credit.
Design of FRP Reinforced Concrete Columns for Earthquake-Resistant Buildings - the Canadian Perspective
Presented By: Murat Saatcioglu
Affiliation: University of Ottawa
Description: Lack of ductility and linear stress-strain characteristics of fibre-reinforced polymer (FRP) reinforcement creates challenges when used as internal reinforcement for buildings in seismically active regions, hindering widespread use of FRP reinforcement. The current National Building Code of Canada defines four seismic design categories (SC1 through SC4, where SC4 represents the highest seismic force and deformation demands) based on the building importance category and the seismicity of the region. The design requirements for each seismic design category call for different levels of stringency in design and corresponding inelastic deformability in members. The most recent Canadian Standard S806 for “Design and construction of building structures with fibre-reinforced polymers” includes different applications of FRP reinforcement for different seismic design categories. The use of transverse FRP reinforcement as buckling restraining hoops or confinement reinforcement in columns with steel longitudinal reinforcement is permitted for all seismic design categories, whereas the use of FRP longitudinal reinforcement in seismic force resisting systems (SFRS) is only permitted in the lowest seismic design category (SC1). However, members of concrete frames that are not part of SFRS, serving only as gravity load carrying systems, are permitted to be reinforced entirely with FRP reinforcement in seismic design categories SC1 through SC3. These members must be designed only if they fulfill the drift requirements associated with the attached SFRS members as they go for the ride during seismic response. The design requirements for FRP reinforced concrete columns will be presented and discussed while providing appropriate background information.
Lateral Cyclic Behavior of Hybrid (GFRP–Steel) Reinforced Concrete Columns: Implications for Performance-Based Design
Presented By: Sherif Osman
Affiliation: University of British Columbia
Description: This study investigates the seismic performance of innovative reinforced concrete (RC) bridge piers incorporating double confinement and hybrid reinforcement systems, compared with conventional RC piers, under quasi-static cyclic loading. Two advanced configurations were examined: Hybrid Glass Fiber Reinforced Polymer–Steel RC Bridge Piers (HRCBPs), which utilize an external GFRP cage to protect inner steel reinforcement, and Double-Confined Steel (DCS) piers, featuring dual spiral layers to provide varying confinement zones within the concrete core. Large-scale specimens were tested following ACI 374.2R-13 protocols to evaluate drift ratio thresholds, lateral load capacity, stiffness degradation, strain distribution, and energy dissipation. Experimental results highlighted distinct material responses: GFRP’s linear-elastic behavior facilitated broad strain distribution, while steel exhibited nonlinear localized strain concentrations. HRCBPs showed enhanced corrosion resistance and reliable drift capacity, whereas DCS piers demonstrated superior ductility, confinement efficiency, and post-yield stiffness. Comparisons across hybrid and steel systems revealed unique hysteretic behaviors, plastic hinge development, and damage progression, with both systems surpassing conventional RC in seismic resilience. Performance-based damage states—ranging from minor to local collapse—were defined using engineering demand parameters such as strain, ductility, and displacement. Predictive models, including fiber-based simulations and moment-curvature analyses, validated experimental observations and generated practical design charts. Four distinct performance levels were established, aligning with CSA S6-19 and PBD frameworks. Overall, hybrid and double-confined systems offer promising alternatives to conventional RC piers by improving ductility, durability, and resilience, thereby advancing seismic design practices for critical infrastructure.
Seismic Performance of GFRP-RC Bridge Columns under Combined Loading – Design Recommendations
Presented By: Ehab El-Salakawy
Affiliation: University of Manitoba
Description: Seismic excitation can result in complex flexural, shear, and torsion failure of reinforced concrete (RC) bridge columns for curved and skewed bridges. Glass fiber-reinforced polymers (GFRPs) have been recognized as internal flexural and shear reinforcement for concrete structures. However, the seismic behaviour of GFRP-RC bridge columns under combined loading including axial, flexural, shear, and torsion has not yet been investigated. This presentation introduces experimental and numerical investigations on the behaviour of circular GFRP-RC columns subjected to combined cyclic loads. Several full-scale specimens were constructed and tested under a constant axial load and variable torsion-to-bending moment ratios (T/M). The effects of T/M ratios, confinement, reinforcement ratio and concrete strength on the mode of failure, hysteretic behavior, bearing capacity, and plastic hinge characteristics of the GFRP-RC circular columns were discussed. In addition to offering design recommendations, it was concluded that the additional torsional moment had the tendency to cause the damaged zone to shift upward from the typical flexural plastic hinge zone.
Seismic Design of FRP-Reinforced Circular and Rectangular Concrete Columns – Canadian Code Approaches
Presented By: Shamim Sheikh
Affiliation: University of Toronto
Description: Use of internal FRP reinforcement in concrete structures is rapidly gaining acceptance but it is still limited mostly for flexural purpose in components such as bridge decks, beams, slabs, foundations, and in some cases as transverse reinforcement in columns and shear walls. FRP bars as compression reinforcement is not allowed in most codes. However, in 2019, the Canadian Highway Bridge Design Code, CHBDC (CSA S6-19), started allowing accounting for compression resistance of GFRP bars. This raised a possibility of using columns with longitudinal GFRP bars for seismic resistance. Over the last two decades, a number of studies have been carried out especially in Canada to evaluate this aspect of earthquake design. In this presentation, experimental and analytical results will be presented to evaluate the performance of GFRP reinforced columns for seismic resistance. Effects of changing one variable such as steel vs GFRP longitudinal reinforcement, steel vs GFRP transverse reinforcement are discussed by comparing otherwise similar columns from a data base of over 200 columns of varied sizes and configurations tested in a similar fashion. Detailed design guidelines developed in consultation with the designers and manufacturers (CSA S6-25 and CSA S806-2026) will be presented. A brief discussion on hybrid reinforced concrete columns with both GFRP and steel reinforcement will be included to address concerns raised in some of the ACI440 meeting.