Exploration of novel NSM methods to achieve stronger FRPs with minimal epoxy

Abstract

Conventional NSM methods require a significant amount of epoxy to achieve the desired bond strength, leading to substantial material costs and carbon emissions. Anchorages offer an opportunity to fully develop the tensile strength of NSM FRPs and reduce epoxy consumption. However, there is a lack of comprehensive studies to guide the application of this promising technology. Unlike conventional pull-off tests, a series of bending experiments were carried out to investigate the direct impacts of groove arrangement, bond condition, anchorage, and FRP cross-sectional area on the failure modes and load capacities of flexural elements. The findings were then utilized to calibrate numerical models, which could be directly integrated into equilibrium equations to predict the load-deflection responses for the concrete elements strengthened with NSM methods. FRP models were developed to capture the softening behavior caused by slip. Cracking models that incorporated the tensile contributions of filler material and cracked concrete was proposed to describe the post-cracking behavior. Failure modes such as FRP debonding and rupture related to specific FRP arrangements were employed to determine the ultimate load capacities. The outcomes indicate that anchored NSM methods improve FRP utilization and flexural strength in comparison to traditional NSM techniques, while also reducing epoxy consumption.

Keywords

• Minimal epoxy
• Anchorage
• Bending experiments
• Numerical models
• Optimizing NSM