Analytical derivation of rib bearing angle of reinforcing bar subject to axial loading

This paper documents a study carried out to formulate the rib bearing angle in initial bond stress–slip for deformed reinforcing bars under axial loading. An analytical approach is proposed that utilises the conventional Mohr–Coulomb material properties. A universal maximum rib stress bearing angle is formulated as the complementary angle of the internal friction angle of surrounding concrete. For a given bar, the rib bearing angle can be narrowed down further. An equation for the estimation of the most possible rib bearing angle is formulated as a function of the material properties and the confinement level. The analytical results presented in this paper indicate that the most likely rib bearing angle is around 25° for an unconfined reinforced concrete structure. The validity of the proposed theory is established by comparing the analytical results to the experimental data in the literature.