Equivalent stabilizing force of members parabolically compressed by longitudinally variable axial force

Wrocław University of Science and Technology, Faculty of Civil Engineering, 27 Wybrzeże Wyspiańskiego st., 50-370 Wrocław, Poland

^* Corresponding author: dariusz.czepizak@pwr.edu.pl

Abstract

The EN 1993-1-1 model of equivalent stabilizing force q_d and R_d of bracings conservatively assumes that the braced member is compressed with a force constant along its length. This assumption is incorrect since the axial force distribution varies along the length of the braced member. As a result, the braced member generates equivalent stabilizing forces different from equivalent force q_d and R_d acc. to EN 1993-1-1. This paper presents parametric studies of the equivalent stabilizing forces of the braced, compression top chord of roof trusses. The girder’s top chord is compressed parabolically by a variable axial force. The values of the axial compressive forces is: N_supp in the support zone of truss and N_span in the central zone of truss. Parametric analyses of the equivalent stabilizing force and the stress of the purlins and the bracings depending on axial forces N_supp and N_span in the braced member were carried out. The investigated problem is illustrated with exemplary calculations of the equivalent force in trusses.