Stress block parameters for concrete flexural members reinforced with superelastic shape memory alloys

The unique properties of superelastic shape memory alloys (SMAs) have motivated researchers to explore their use as reinforcing bars. The capacity of a steel reinforced concrete (RC) section is calculated by assuming a maximum concrete strain εc-max and utilizing stress block parameters, α1 and β1, to simplify the non-linear stress–strain curve of concrete. Recommended values for εc-max, α1, and β1 are given in different design standards. However, these values are expected to be different for SMA RC sections. In this paper, the suitability of using sectional analysis to evaluate the monotonic moment–curvature relationship for SMA RC sections is investigated. A parametric study is then conducted to identify the characteristics of this relationship for steel and SMA RC sections. Specific mechanical properties are assumed for both steel and SMA. Results were used to evaluate εc-max, α1, and β1 values given in the Canadian standards and to propose equations to estimate their recommended values for steel and SMA RC sections.

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