Influence of residual stresses on innovative composite column sections using high strength steel

Current developments in steel and steel concrete composite constructions lead to an increasing use of high strength steel grades. Especially in structural members under compressive load, imperfections determine the load bearing behavior significantly. In detail, geometric imperfections can be influenced by the manufacturing process of the columns, whereas structural imperfections such as residual stresses result from the steel’s production. In several research projects, innovative composite columns using steels with yield strengths up to 960 MPa with new section designs are being developed. Bundled high strength reinforcement bars are deployed as core within steel tubes and confined with concrete. As there is little knowledge about the residual stress distribution in sections of such steel grades, investigations for each section were carried out. Preliminary results of such examinations will further be used as input parameters for numerical simulations. Comparing calculations with and without consideration of residual stresses of the steel sections are made and their results are presented.