Unified Poisson‐constrained radial ( PCR ) no‐slip–bond–slip model

Reliable crack‐width prediction is critical for liquid‐retaining structures. Popular codes notably over‐predict crack widths (EC2 and AS 3600 in tension) or under‐predict them (BS 8007, EC2, AS 3600, MC 2010, and ACI 318 in flexure); none are simultaneously safe and economical across the full spectrum of conditions, including long‐term effects. This paper presents a new unified semi‐empirical model that provides a mechanics‐based formulation for the no‐slip contribution via axial‐lateral equilibrium induced by Poisson coupling around the bar (restraining radial contraction), while retaining the classical bond–slip term. Unification is achieved through strain partitioning. The formulation satisfies equilibrium and compatibility from crack initiation to stabilization. Calibrated and validated on 580 crack widths from 18 independent studies, the model delivers low coefficients of variation (19%–35% vs. 22%–103% for the codes), limited under‐prediction extremes (1.15–1.56 vs. 1.21–10.45), conservative‐to‐balanced bias (means 0.60–1.01 vs. 0.59–1.58), and superior stability in wide beams (>600 mm), varying cover thicknesses, and the critical low‐crack‐width regime () that governs serviceability in liquid‐retaining structures.