Formulation and Implementation of General Thin-Walled Open-Section Beam-Column Elements in Opensees (No. R961)

Abstract

The formulation and implementation of beam-column finite elements for the general thin-walled open cross-sections within the OpenSees framework is presented. To account for the non-coincident location of shear centre and centroid as is the case in non-symmetric sections, a local cross-section transformation matrix is derived relating the axial force acting through the centroid and the shear centre. The stiffness relations are derived based on the Green-Lagrange strain for the displacement based beam-column element while the Wagner effect is incorporated in the torsional rigidity term for the elastic beam-column element. The beam-column elements are then implemented within the corotational framework of OpenSees. The performance of developed beam-column elements are demonstrated through the use of monosymmetric, doubly-symmetric and asymmetric sections in a series of numerical examples. The solutions obtained are verified with the results from the beam and shell element models in ABAQUS software.