9. Concrete Prestressing Applications Using SMAs

There is a growing interest in using shape memory alloy’s (SMA) thermal stressing features in various concrete prestressing applications. The primary advantage is the ease of application and time savings due to eliminating the mechanical tensioning process required for prestressing. Thermally stressed SMA systems are easily configured to apply prestressing forces at any direction and at target locations where prestressing force is needed the most (i.e., local prestressing). Studies presented in this chapter show that SMA local prestressing will help with time and material savings and prevent common types of damages associated with conventional prestressing such as end-splitting cracks. This chapter highlights the application of SMA using different configurations in developing internal and external prestressing systems for new construction and strengthening existing structures. Precast concrete railroad crosstie is discussed as a potential candidate component that could benefit from such a versatile prestressing system. The chapter also provides the reader with a fundamental idea of how merging SMA prestressing with computational topology optimization techniques could significantly reduce concrete usage in bridge construction.