Experimental behaviour of diagonally stiffened steel I-girders

Abstract

This paper reports on the experimental investigation carried out at the University of Coimbra, in which the behaviour of diagonally stiffened steel I-girders dominantly subject to shear is assessed. The experimental program consists of four specimens: one reference I-girder without a diagonal stiffener, and three specimens with different stiffener geometrical and materials characteristics, placed along the diagonal of the girder web to increase their stability and load-carrying capacity in shear. Moreover, two different stiffener joining techniques are explored, namely welding and bonding-bolting. The principal objective of this research is twofold: i) to qualitatively assess and compare the effects of these different diagonal stiffening strategies in terms of the shear capacity of I-girders, and ii) to critically assess currently available methodologies from the literature for the calculation of the shear resistance of diagonally stiffened I-girders. Regardless of the stiffener properties and joining technique, in all tested specimens the inclusion of a stiffener along the compression diagonal significantly increases the shear resistance when compared to the girder without diagonal stiffeners. However, the tests performed with bonded-bolted cold-formed stiffeners seem to show less ductile behaviour than those with a welded stiffener. Finally, a comparison of the experimental results with the available calculation methods was made and the conclusion is that they do not adequately predict the shear bearing capacity of the tested girders with the diagonal stiffeners, giving a large scatter of results.