Strength of Bridge High-Strength Concrete Slender Compression Members Reinforced with GFRP Bars and Spirals: Experiments and Second-Order Analysis

Abstract

Design for slender high-strength concrete (HSC) bridge compression members (columns, piers, and piles) reinforced with glass fiber-reinforced polymer (GFRP) has yet to be addressed in the relevant American and Canadian codes and guidelines. Including such provisions undoubtedly requires a comprehensive assessment of the structural performance of such members, as well as a definition for the slenderness limit below which second-order responses can be discarded. Consequently, full-scale slender GFRP-HSC columns with a concrete compressive strength of 80 MPa and measuring 2,500 mm in height and 305 mm in diameter were prepared and tested at four eccentricity levels (0%, 16%, 33%, and 66% of the column size). The influence of HSC on the behavior of slender GFRP-HSC columns was also assessed with respect to reference normal-strength concrete (NSC) counterparts. Moreover, the effect of two different longitudinal GFRP-reinforcement ratios (3.28% and 4.66%) on the performance of the test specimens was investigated. The test results herein indicate the ability of HSC and GFRP reinforcement to improve column strength and to maintain stability at various loading stages. An analytical second-order model was then developed to extend the research program to include a wide range of parametric studies. The developed model was validated against the test results for 47 FRP-HSC columns selected from the current study and the literature. Lastly, the applicability of the current slenderness limit to HSC columns was verified and a modified slenderness limit was proposed to account for HSC columns with compressive strengths up to 125 MPa.