Welded hybrid steel box-section girders subjected to pure bending and bending-shear interaction

Abstract

In civil engineering, high-strength steel materials, namely steel grades ranging from S500 up to S960, are increasingly gaining recognition, particularly in the construction of large-span bridges and high-rise buildings. When it comes to bridges, a cost-effective and efficient solution involves using hybrid girders that incorporate both low-strength and high-strength steel materials. Typically, these hybrid girders feature low-strength steel webs and high-strength steel flanges. In Europe, aside from some limited practical applications and research outcomes in Sweden and Spain, these types of structures are pioneering solutions in bridge engineering. Notably, the current European design standards lack the theoretical background and practical guide for their strength and stability design. To determine the theoretical background of this girder type and to develop the design theories for application purposes a large-scale experimental research program is designed and carried out focusing on the bending and bending-shear interaction resistance of hybrid steel box-sections. 14 welded hybrid steel box-section beams are tested with varying geometry, six of them against pure bending and eight against combination of bending and shear. The flanges of the examined hybrid girders are made of S700 or S500, the web of the specimens consists of S355 steel grade. Two control specimens were homogenous girders made of S355 and S700. The details of the experiments and the results such as resistances, failure modes, stress- and displacement curves are presented and discussed in this paper.