Compressive Bond Behavior of Shape Memory Alloy (SMA) Rebar in Concrete

Presented by AHM Billah, Lakehead University Shape memory alloys (SMAs) are special materials with distinct thermomechanical properties that allow them to ‘memorize’ or retain their original shape when subjected to load or temperature. In recent years, SMAs have drawn significant attention and interests among researchers and structural engineers for diverse civil engineering applications. Due to the fact that SMA reinforcement has significantly different properties than conventional steel, structures reinforced with SMA will behave differently. The design equations used for steel reinforced concrete structures are not applicable while using SMA as reinforcement in concrete. This study investigated the bond behavior of SMA rebars in concrete using 56 pushout specimens. The test results are explored to evaluate the influence of concrete strength, bar diameter, embedment length, and surface condition. Surface modification using sand coating notably improved the bond strength of SMA rebar. Finally, empirical equation based on statistical analyses is presented to predict the maximum average bond strength. The proposed equations appear to be reasonable for calculating the average bond strength of SMA reinforcing bars in concrete.