Sessions & Events


All sessions and events take place in Central Daylight Time (CDT).
All events take place at the Hyatt Regency New Orleans.

On-demand sessions will be available for viewing in the convention platform/event app under "On-Demand Content" within 24-48 hours of the session premiere. Please note, on-demand sessions are not available for CEU credit. *Denotes on-demand content.

FRP Use in Column Applications, FRPRCS-16 Symposium, Part 11 of 14

Sunday, March 24, 2024  10:30 AM - 12:30 PM, Strand 12B

This session is one of 14 sessions that form the 16th Fiber Reinforced Polymer Reinforced Concrete Structures (FRPRCS-16) Symposium. It is co-sponsored by ACI Committee 440 and the International Institute for FRP in Construction (IIFC) for the purpose of advancing the understanding and application of FRP composites in civil infrastructure to serve the engineering profession and society. FRPRCS was first held in conjunction with the ACI 1993 Spring convention in Vancouver, British Columbia, Canada. Since 1993, FRPRCS has evolved into a prestigious and reputable international conference that has been held 15 times including 5 times in conjunction with ACI: British Columbia, Canada (1993); Baltimore (1999); Kansas City (2005); Tampa (2011); and Anaheim (2017).

This session will focus on the use of FRP as reinforcement of concrete columns and walls.

Learning Objectives:
(1) Describe the behavior of elliptical concrete columns reinforced with GFRP bars under biaxial bending;
(2) Analyze alternative solutions for strengthening of concrete columns where adjacent elements prevent FRP wrapping;
(3) Examine the stress-strain behavior of concrete confined by FRP laminate and spike anchors;
(4) Develop knowledge about the failure characterization of GFRP-reinforced concrete walls.

This session has been approved by AIA and ICC for 2 PDHs (0.2 CEUs). 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.

Biaxial Interaction Diagrams of Elliptical Concrete Column Sections Reinforced with GFRP Bars

Presented By: Ahmad Ghadban
Affiliation: AEDA LLC
Description: The release of ACI 440.11-22 building design code for concrete structures reinforced with GFRP bars comes with several challenges at various fronts. One such challenge is tackled in this paper which is the development of limit interaction diagrams for elliptical bridge columns reinforced with GFRP bars under biaxial bending plus axial compression/tension. This type of columns requires special considerations at all levels. This paper depicts the various formulations encountered herein in a detailed treatment highlighting the critical steps to build an efficient analysis algorithm. The formulation is implemented into a user-friendly software developed using object-oriented programming, namely the C# programming language. The robustness of the formulation is tested by comparing interaction diagrams of elliptical sections to those of corresponding rectangular sections. The significance of an ACI code comment requiring bar orientation being considered for circular sections with less than 8 bars is also examined in this paper. This paper also tests the ACI recommendation to neglect GFRP action in compression. Results indicate reasonable similarity among interaction diagrams of elliptical and rectangular sections leading to the conclusion that the formulation presented herein provides an accurate tool to analyze elliptical sections.

Stress-Strain Model of Concrete Confined by FRP Laminate and Spike Anchors

Presented By: Enrique del Rey Castillo
Affiliation: University of Auckland
Description: The application of fiber-reinforced polymer (FRP) jacketing for confinement may not always be feasible, particularly in cases where adjacent elements obstruct the structural member and prevent wrapping. To address this issue, the utilization of FRP laminate and spike anchors has been proven as an alternative solution. This study focuses on proposing a design methodology for this particular application. A stress-strain model was developed to assess the behavior of concrete prisms confined with FRP laminates and spike anchors under axial compression. The model adopts a bi-parabola stress-strain curve, with the coefficients derived from previously published experimental data on concrete prisms confined using this solution. The comparison between the analytical and tested stress-strain curves yielded a coefficient of determination (R2) averaging at 0.96, demonstrating the effectiveness of the bi-parabola model in describing the tested stress-strain responses.

Failure Characterization of GFRP-Reinforced Concrete Walls

Presented By: Jimmy Kim Yail
Affiliation: North Dakota State University
Description: This paper presents a new methodology for characterizing the failure mode of structural walls reinforced with glass fiber reinforced polymer (GFRP) bars. An analytical model is used to derive a non-dimensional failure determinant function, which is validated against existing test results. The function involves geometric attributes (wall length, wall height, and boundary element size), reinforcement ratios (horizontal and vertical), and material properties (compressive strength of concrete and tensile strength of GFRP bars). According to the determinant function, structural walls fail in flexure when a high aspect ratio is associated with a relatively low reinforcement ratio in the boundary element. The proposed methodology and design recommendations provide valuable guidance for practitioners dealing with GFRP-reinforced concrete walls.

Evaluation of Hysteretic Energy and Damping Capacity of GFRP-RC Columns Under Cyclic Loading

Presented By: Ehab El-Salakawy
Affiliation: University of Manitoba
Description: The seismic performance of reinforced concrete (RC) structures relies on their ability to dissipate earthquake-induced energy through hysteric behavior. Ductility, energy dissipation, and viscous damping are commonly used as performance indicators for steel-RC seismic force-resisting systems (SFRSs). However, while several previous studies have proposed energy-based indices to assess energy dissipation and damping of steel-RC SFRSs, there is a lack of research on fiber-reinforced polymer (FRP)-RC structures. This study examines the applicability of the existing energy dissipation and damping models developed for steel-RC columns to glass FRP (GFRP)-RC ones, where the relationships between energy indices and equivalent viscous damping versus displacement ductility were analyzed for GFRP-RC circular columns from the literature. In addition, prediction models were derived to estimate energy dissipation, viscous damping, and stiffness degradation of such types of columns. It was concluded that similar lower limit values for energy-based ductility parameters of steel-RC columns can be applied to GFRP-RC circular columns, whereas the minimum value and analytical models for the equivalent viscous damping ratio developed for steel-RC columns are not applicable. The derived models for energy indices, viscous damping, and stiffness degradation had an R2 factor of up to 0.99, 0.7, and 0.83, respectively. These findings contribute to the development of seismic design provisions for GFRP-RC structures, addressing the limitations in current codes and standards.

Strengthening of Rectangular Reinforced Concrete Columns Using CFRP

Presented By: Salah Aly
Affiliation: Housing and Building National Research Center, Egy
Description: Rectangular reinforced concrete (RC) columns with aspect ratio up to one-to-five are commonly used in residential buildings. Wrapping rectangular RC columns with external carbon fiber reinforced polymer (CFRP) are introduced in this research to increase its axial capacity as well as the ductility. The strength enhancement of these columns arises from two sources. First, the confinement effect of transverse fiber sheets leads to an increase in the uniaxial compressive strength of the confined concrete resulting subsequently in an increase in the contribution of concrete to the load-carrying capacity of the column. Second, the longitudinal fiber sheets contribute directly to the load-carrying capacity of the column. Wrapping circular column with CFRP has been proven to be a very effective method to increase both the axial capacity and ductility of columns. However, it is less effective for square columns and much less effective for rectangular columns. This is attributed to less confinement of the columns due to the out-of plane deformation of the laminates, induced by the axial loads on columns. A total of 8 half-scale, short columns were fabricated and tested to failure under a concentric load to investigate the effect of CFRP configuration on the strength enhancement of the columns, and a simple analytical approach is used to evaluate the axial load carrying capacity of the strengthened columns. Each column had across-sectional dimension measuring 120 by 480 mm, with an aspect ratio of 4.0, overall height of 1940 mm, and a clear height of 1500 mm. The study revealed that the strengthening technique is expected to effectively enhance the efficiency of the CFRP strengthening technique, especially for columns with rectangular sections as the area of the well-known dead zone of these columns is reduced using the proposed technique.

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