Strengthening of steel I-section beams by wire arc additive manufacturing - Concept and experiments

An experimental investigation to assess the major-axis flexural behaviour of 10 hot-rolled steel I-section beams, strengthened by the addition of material through wire arc additive manufacturing (WAAM) and tested under either four-point or three-point bending conditions, is presented in this study. The ability of WAAM to pre- camber hot-rolled steel I-section beams, as well as to enhance their bending moment resistance and initial elastic stiffness, has been demonstrated. The geometry of the strengthened beam specimens, including the initial imperfections and pre-camber, were obtained by means of 3D laser scanning. Complementary material testing was conducted to obtain the mechanical properties of both the hot-rolled and WAAM steel under monotonic tensile loading. The experimental results showed that significant pre-cambers of approximately 1/200 of the span of the beam could be achieved with only a 2.6% increase in mass. Moreover, increases of between 11.5% and 33.2% in the ultimate bending moment resistance, and increases of between 8.7% and 35.9% in the initial stiffness, were achieved for increases in mass of between just 2.6% and 12.3%. The presented WAAM-strengthening approach can be employed for the strengthening, repair and retrofitting of steel beams in service, as well as for the fabrication of hybrid steel members with improved flexural behaviour in new structures.