Influence of the Strengthening Configuration on the Shear Capacity of Reinforced Concrete Beams Strengthened with SRG (Steel-Reinforced Grout) Composites

Abstract

In this paper, the influence of the strengthening configuration on the structural response of U-wrapped SRG (Steel-Reinforced Grout) shear-strengthened reinforced concrete beams was analyzed both experimentally and theoretically. The parameters varied were the ratio sf/wf, sf being the distance between two consecutive U-shaped strips and wf the width of the strips, and the number of steel fabric layers (one and two). Two series of real-scale beams, eleven beams in total with one un-strengthened and ten strengthened, were tested up to failure (the results obtained in the first series of tests were reported in a previously published paper). The obtained results highlighted that the debonding phenomena, which occurred for all the examined strengthening configurations, strongly affected the shear capacity of strengthened beams. An analytical model found based on the “effective strain” of the SRG strips was developed to predict the shear capacity of SRG shear-strengthened reinforced concrete beams. Two analytical relationships were proposed to evaluate the “effective strain” of the SRG strips: The first one was based on a statistical analysis of results obtained by tests on FRCM (Fabric-Reinforced Cementitious Mortar) and SRG shear-strengthened reinforced concrete beams, while the second was developed through the results of single lap direct shear tests performed on SRG-to-concrete joints. The effectiveness of the proposed analytical methods was evaluated through the comparison of their predictions and available experimental results.

Simplified Procedure to Determine the Cohesive Material Law of Fiber-Reinforced Cementitious Matrix (FRCM)–Substrate Joints

“…The textile can be made of various types of fiber, e.g., carbon, basalt, glass, and polyparaphenylene benzobisoxazole (PBO), whereas the matrix is usually a cement-or a lime-based mortar. FRCMs are externally bonded (EB) to existing concrete and masonry members and can be used to improve bending [1][2][3][4] and shear strengths [5][6][7][8], as well as the axial compressive capacity of predominantly axially-loaded members [9][10][11][12]. EB FRCM reinforcement generally fails due to debonding of the composite at the FRCM-substrate interface, with or without damage of the substrate, or at the matrix-fiber interface [13].…”

Delaying the Occurrence of Bar Buckling in RC Columns Confined with SRG Jacketing

“…Steel-reinforced grout (SRG) jacketing presents an alternative composite system that combines high-strength steel-reinforced fabric with cementitious grout [14], appropriate for strengthening techniques of RC deficient structures [15][16][17][18]. Previous studies focusing on uniaxial compression of SRG-confined plain and reinforced concrete have provided evidence of the system's effectiveness in enhancing both axial strength and associated deformation capacity [19][20][21][22].…”