pandeo

Pandeo, commonly referred to in English as buckling, is the instability phenomenon that occurs in structures under compressive load when a member deforms laterally due to loss of stiffness, rather than yielding. Buckling can lead to sudden reductions in load-carrying capacity and premature collapse if not controlled. The onset and mode of pandeo depend on geometry, material properties, boundary conditions, and imperfections in manufacturing and assembly.

Several buckling modes are recognized: flexural buckling of columns, lateral-torsional buckling of beams, and torsional buckling of slender members. For an ideal column with pinned ends, Euler's critical load is Pcr = π^2 EI / L^2, where E is the modulus of elasticity, I is the second moment of area, and L is the unsupported length. Real members require adjustments for end restraints, imperfections, and nonlinear behavior, often expressed via an effective length or slenderness ratio.

Prevention and mitigation focus on increasing stability: shortening unsupported lengths, providing lateral bracing, choosing cross-sections with higher stiffness, adding stiffeners, ensuring proper end conditions, and designing with redundancy. Structural codes supply stability criteria and interaction equations to account for combined loading and buckling effects.

Applications cover columns in buildings and bridges, slender aerospace components, and other load-bearing members where compressive stability is critical. Analysis methods range from classical Euler theory to finite-element simulations that incorporate imperfections and nonlinear behavior.