Flexural Testing of Reinforced Concrete Beams Strengthened with Near-Surface Mounted Titanium-Alloy Hooked Bars to Evaluate Member and Bond Strength

Strengthening reinforced concrete (RC) members using near-surface mounted (NSM) titanium-alloy bars (TiAB) has recently emerged as a feasible option to provide an alternative to NSM with fiber-reinforced polymers. An experimental study is presented in this paper that investigates: (i) the flexural strength and behavior of RC members strengthened using NSM TiAB with hooked ends; and (ii) the applicability of the calculation methods and guidance provided in the AASHTO NSM Guide on the flexural strength and TiAB development length. Five specimens with varying TiAB bonded lengths and one control specimen were constructed and tested for these purposes. The test results indicate that the flexural resistance of the RC members can be significantly increased using NSM TiAB if adequate TiAB bonded length is provided. The results suggest that the AASHTO NSM Guide provides accurate flexural-strength predictions and ductile response can be achieved with TiAB yielding if the TiAB development length provisions are followed. The paper also provides recommendations and detailed guidance on the installation of the NSM TiAB for practical applications.