The column must support additional moment created by the column axial load acting on the deformed column, also known as second-order moments. There are two types of second-order moments related to the P-delta effects shown in the attached figure : 1 second-order moments due to translation of the column ends (p-δ) ; and 2) second order moments due to deflection along the member (p-δ). These second-order moments gradually increase due to this geometric nonlinearity until the column stabilizes. As a column becomes more slender, larger lateral deformations and deformation along the length occur due to the applied load. If the slenderness ratio is very high, the column becomes unstable and cannot resist the axial load.
