RC U-shaped walls subjected to in-plane, diagonal, and torsional loading: New experimental findings

•Longitudinal strain profiles showed a yielding length of approximately 1200 mm.•Equivalent plastic hinge lengths were approximately half of the yielding length.•The longitudinal strains at the base of these walls showed some shear lag effects.•Strains correlated with theory for a section governed by warping torsion.•Out-of-plane deformations were observed to be concentrated within a small region.