Arch Beam Buckling Constitutive Law Continuum Mechanics Critical Point Curved Beam Eigenvalue Elastic Stiffness Element Quality Test Finite element Framed Structures Generalized Displacement Control Method Geometric Nonlinear Analysis Incremental-iterative Procedure Lagrangian Formulation Limit Point Nonlinear Analysis Nonlinear Solution Method Plane Frame Plate Postbuckling Rigid Body Rule Shell Snap-back Point Space Frame Stability Stiffness Matrix Truss Variational Method Virtual Work Principle