Moment‐curvature behavior of continuous reinforced concrete slab strips—Experimental determination and modeling

Abstract With the market introduction of new reinforcing materials, such as corrosion‐resistant steel, the effect of their stress–strain relationship on the ductility of reinforced concrete structures needs to be evaluated. Their moment‐curvature behavior significantly influences bending moment redistributions, rotation capacity, and deformation at failure of reinforced concrete elements. This article presents 12 experiments on continuous slab strips reinforced with five types of reinforcing steel exhibiting different stress–strain relationships. It proposes new ways to determine curvatures using Digital Image Correlation measurements, with results differing by only 3% between the methods. Among the three introduced approaches, a novel method that deduces crack element rotations from the best fit of the deformation gradient was identified as the most generally applicable. The article discusses modeling approaches for moment‐curvature relationships, focusing on bond shear stresses, crack spacings, steel stress–strain relationships, and the concrete ultimate strain. The curvature at the ultimate state is accurately determined using a bilinear approximation of the steel stress–strain relationship, which proves advantageous since it avoids overestimating tension stiffening at low hardening ratios close to failure while requiring the least amount of prior knowledge.