Numerical Simulation of Bent Corner of FRP Stirrups with Rectangular Cross Sections
Publication: Journal of Structural Engineering
Volume 149, Issue 9
Abstract
Due to the strength reduction at the bent corners of fiber-reinforced polymer (FRP) stirrups, the high tensile strength of FRP reinforcement cannot be fully utilized in concrete structures. Although numerous experimental investigations have been conducted to study the reduced bent-corner strength, the mechanism of the strength reduction at bent corners has not been fully understood. This paper presents numerical research into the bent-corner strength of FRP stirrups with rectangular cross sections. Refined finite-element models are established based on Hashin’s failure criterion and their validities are verified against six groups of 18 FRP stirrup specimens. Analyses of stress concentration in the elastic range and damage accumulation afterward are conducted to explain the mechanism of strength reduction at the bent corners of FRP stirrups. Further parametric analyses are conducted to quantitatively evaluate the contributing factors to the bent-corner strength and an empirical prediction equation is proposed. This research shows that the bond, compressive stress from concrete, and FRP material anisotropy are the critical contributors to the tensile stress concentration in the elastic range at the bent corners, which accounts for 7%, 48%, and 45% of the tensile stress concentration, respectively. The parametric analyses show that better bonding at the bent corners could potentially result in lower strength; the concrete properties and FRP width have limited influence on the bent-corner strength; and the bent-corner strength has logarithmic relation with the bent radius and thickness ratio of (). This work reveals the critical mechanism of strength reduction of FRP stirrups at bent corners in concrete structures and potentially provides the opportunity for more efficient material use of FRP reinforcement.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
The authors acknowledge and are grateful for the support of the Key-Area Research and Development Program of Guangdong Province (2019B111107002) and the Zhejiang Provincial Natural Science Foundation (LQ21E080021), who funded and resulted in this work.
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Received: Aug 12, 2022
Accepted: Apr 24, 2023
Published online: Jun 24, 2023
Published in print: Sep 1, 2023
Discussion open until: Nov 24, 2023
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