Dowel action contribution in shear resistance of concrete beams longitudinally reinforced with composite bars- A state-of-the-art review

Articles in Press

Document Type : Research Paper

Authors

1 Dept. of Civil Engineering, Taft C., Islamic Azad University, Taft, Iran

2 Dept of Civil Engineering, Yazd Branch, Yazd, Iran

3 Dept. of Civil Engineering, Yazd University, Yazd, Iran

10.22124/jcr.2026.31511.1718

Abstract

Dowel action of longitudinal reinforcement constitutes a key shear transfer mechanism in reinforced concrete beams without transverse reinforcement. This study aims to quantitatively evaluate the contribution of dowel action to the shear strength of concrete beams reinforced with Fiber-Reinforced Polymer (FRP) bars and to validate existing design models. To this end, a comprehensive database comprising experimental results of 510 FRP-reinforced concrete beams was compiled from technical literature and compared with predictions from ACI 440, CSA S806 codes, and analytical models. The results indicate that the contribution of dowel action varies between 10% and 40% of the total shear strength, depending on the bar diameter and concrete cover. Model evaluation demonstrates that the CSA S806 code, by accounting for the axial stiffness of the reinforcement, offers the most accurate prediction with an appropriate safety margin. In contrast, the ACI 440.1R-15 code estimates shear capacity conservatively (20% to 30% lower than actual values). Furthermore, models based on evolutionary methods (such as the Kara model) exhibit estimation errors at high shear strengths (exceeding 400 kN). This research concludes that for optimal design, models that incorporate axial stiffness parameters and concrete cover interaction can be more accurate.

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Concrete Research

Articles in Press, Accepted Manuscript
Available Online from 23 February 2026

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