Abstract
A method for evaluation of the horizontal ultimate strength and displacements of steel piers or frames with box sections is proposed. The concept of plastic deteriorating hinge is introduced to the versatile a-e model so that it can be used to study local buckling in pushover analyses. A hardening-softening stress-strain relation is used in a beam element, which has the maximum compressive stress calculated as the buckling stress of a stiffened plate under uniaxial compression. The horizontal ultimate strength and displacement of steel frames will be predicted by finite displacement analyses with linear Timoshenko beams, which give a good approximation of the strain distribution in the beam section.
