scope:

This guide provides design and construction recommendations for strengthening existing reinforced concrete (RC) structures with titanium alloy bars with 6 percent aluminum and 4 percent vanadium alloying elements (TiABs) using the near-surface mounted (NSM) construction method. The overall approach and organization of this guide are based on those presented in ACI 440.2R (ACI, 2017). Recommendations are provided for shear and flexural strengthening. The design approach is based on and adapted from the AASHTO LRFD Bridge Design Specifications (2017), hereafter referred to as "AASHTO LRFD Design." The recommendations are supported by experimental and analytical research as well as field experiences that have demonstrated the application of TiABs for strengthening full-scale specimens typical of bridge girders. The available experimental evidence includes the influences of combined high-cycle fatigue and environmental durability on the structural performance of NSM-TiAB-strengthened girders.

TiABs are not sensitive to environmental deterioration such as corrosion. Their use near the concrete surface will not be adversely affected by environmental degradation. Long-term durability of applications with TiABs will be controlled by the concrete substrate and bonding materials.

This guide does not address seismic strengthening applications.