Joint Effect of the Nonlinearity of Elastic Foundations and the Variation of the Inertia Ratio on Buckling Behavior of Prismatic and Nonprismatic Columns Using a GDQ Method

Table 3

Nondimensional critical buckling loads of nonuniform columns with parabolically varying stiffness distributions .

Boundary conditions	Buckling load
	Bleich [47]	Bert [36]	GDQ (N = 11) (Du et al. [48])	SBCGM (N = 11) (Abumandour et al. [21])	Present proposed technique (N = 11)
Simple-simple	20.7923	27.455	20.8047	20.7943	20.7943
Clamped-clamped	—	—	82.1043	81.9279	81.9279
Clamped-simple	—	—	41.9679	42.0828	42.0828