Summary

This paper describes a consistent incremental tangent stiffness matrix for geometrically ninlinear analysis of space beam element. In this refined finite element formulation, two deformation matrices due to axial force and moment, which represent the higher order effects of the deformations in element, are derived. These matrices are the functions of element deformations and incorporated with the coupling among axial, lateral and torsional deformations. These proposed matrices are used together with linear and geometric stiffness for beam elements to analyze deflection behavior of space frames comprising members with negligible sectorial warping. Numerical examples show that the proposed element is accurate and efficient in predicting the nonlinear behavior, such as axial-torsional and lateral-torsional buckling of space frame even when less elements are used to model a member.