Out-of-plane buckling of roller bent wide flange arches - imperfections and finite element modeling

Steel arches are used more and more in contemporary architecture, combining structural efficiency with architectural merits. If lateral supports are absent, these arches are prone to out-of-plane buckling. Arches are often made by cold bending wide flange beams at ambient temperature. This manufacturing technique, also known as the roller bending process, induces changes in residual stresses, mechanical properties and geometric imperfections. This paper addresses the out-of-plane buckling of freestanding roller bent wide flange arches. A shell model is created with the commercial finite element code ANSYS v.11.0, incorporating material non-linearities, residual stresses and geometric imperfections to investigate the out-of-plane elastic-plastic buckling response. The finite element model is validated against earlier performed experimental tests on freestanding arches. Sensitivity analyses are performed to assess the influence of the imperfections. The results were plotted in column curve graphs to show the influence of imperfections with respect to the non-dimensional slenderness of the arch. It is shown that the residual stresses have a limited influence, but the presence of geometric imperfections and altered non-linear material properties have significant influence on the elastic-plastic buckling load. In addition it was concluded that the current column curves in EC3 can be adapted to include the elastic-plastic buckling behavior of freestanding roller bent arches.