Experimental and Numerical Investigations on the Behavior and Failure Mechanism of RC Beams Strengthened with Near-Surface Mounted High-Strength Aluminum Alloy Bars

Abstract

This paper presents experimental and numerical investigations on the flexural behavior of reinforced concrete beams strengthened with near-surface mounted high-strength aluminum alloy (AA) bars subjected to four-point bending load. A total of five RC beams, including one control beam and four beams strengthened using near-surface mounted (NSM) AA bars with or without CFRP U-warp end anchorage, were constructed and tested monotonically up to failure. To get a better understanding of the flexural behavior and failure mechanism of the tested specimens, 3D finite element models were developed. A comparison between the finite element (FE) and experimental results was carried out and therefore confirmed the ability of the developed FE models to accurately predict the flexural performance of the RC beams strengthened with NSM AA bars. In addition, FE simulations provided an in-depth investigation of the intermediate crack-induced debonding (ICD) and concrete cover separation (CCS) failures. It is observed from the experimental and FE results that compared to the control specimen, more than 34% increase in the load-carrying capacity of the NSM strengthened specimens was achieved. In addition, the CFRP U-wrap end anchorage contributed to the prevention or delay of the CCS and ICD failures and hence increased the load-carrying capacity and enhanced the displacement ductility of the strengthened beam specimens. Furthermore, a FE parametric study was carried out to investigate the influence of different parameters on the performance of the RC beams strengthened with NSM AA bars, and recommendations based on the parametric study for efficient application of the NSM strengthening technique were given.