On the boundary conditions of the geometrically nonlinear Kirchhoff–Love shell theory

•Geometrically exact Kirchhoff–Love 3 parameters shell model is derived.•The initial geometry is exactly represented by means of a mapping procedure.•Several kinematic quantities are proposed to describe the boundary rotation.•Need of pointwise corner kinematic restraints is reasoned and numerically assessed.•Hybrid weak form is suitable for interpolative and non-interpolative approximations.