Abstract The effects of flexibility and eccentricity in the nodal connections of plane frames due to static loading are considered in this paper. A numerical model that includes both nonlinear connection behavior and geometric nonlinearity of the structure is developed. Two types of geometric nonlinear analysis are considered: with and without the bowing effect influence. The stiffness matrix for the beam with flexible eccentric connections is developed based on the analytical solution of the second-order analysis equations. The numerical model presented has the same number of degrees of freedom as the corresponding model in the conventional analysis used for the frames with fully rigid connections.