Rotation capacity of continuous reinforced concrete slab strips revisited

Abstract

Rotation capacity is a key characteristic of statically indeterminate reinforced concrete structures, as it (i) enables bending moment redistributions, whether intentionally introduced through optimized reinforcement layouts or arising from unforeseen self‐equilibrated stress states, and (ii) promotes large rotations at failure load, thereby providing a clear and reliable warning prior to failure. This paper synthesizes existing modeling approaches for rotation capacity and benchmarks them against the recently introduced provision in the EN 1992‐1‐1:2023. The rotation capacity of a new experimental campaign of 12 continuous slab strips is evaluated using Digital Image Correlation and Distributed Fiber Optic Sensing Data, and the predictions of the presented modeling approaches are validated against these results, as well as a database comprising 130 experiments from the literature. The new formulation in EN 1992‐1‐1:2023 is found to give safe predictions when failure is governed by reinforcement rupture, but to be unconservative if failure is governed by concrete crushing, as the ultimate concrete strain tends to be overestimated in structures with shear reinforcement. Thus, it is recommended to disregard the influence of the shear reinforcement ratio in the EN 1992‐1‐1:2023 formula for the ultimate concrete compressive strain, or adopt a simplified model proposed by Sigrist and Marti.