Performance of CFRP-strengthened concrete beams fastened with distributed CFRP dowel and fiber anchors

Abstract

This paper presents the results for three full-scale T beams and three full-scale rectangular beams that were tested while strengthened with CFRP sheets and anchored using two types of CFRP spike anchors. For each beam type, the first specimen was loaded to failure as a control beam whereas the other two beams were strengthened with identical CFRP sheets and anchored along the shear spans. Same designs were used on both series to perform comparisons between the behavior of T and rectangular beams. The required number of CFRP anchors were established using a newly developed design procedure presented in this paper. Experimental testing and nonlinear analysis confirmed the performance of the anchored beams, which attained full flexural capacity that was controlled by FRP rupture for T beams and concrete crushing for rectangular beams. The results prove that the design and the arrangement of CFRP anchors offer an effective solution against premature debonding failure. The effect of anchors is accounted for using a multiplier proposed here to augment the ACI 440.2R-17 effective design strain. This multiplier is based on the ratio of the CFRP strain at failure of anchored beams to the debonding strain. Comparisons are made with beams of comparable CFRP sheets and U-wrap anchorage system tested in a previous study.