Load Path Effect on the Response of Slender Lightly Reinforced Square RC Columns under Biaxial Bending

This paper presents an experimental investigation of the effect of load path on force-displacement response, damage patterns, and failure modes of slender lightly reinforced concrete (RC) columns. A review of available experimental tests, which include columns subjected to multiaxial loading protocols, is first presented. Next, a new experimental campaign on 18 column specimens tested under constant axial load and lateral displacement-controlled load paths is described. The results of the tests performed confirm that the response under biaxial load paths is qualitatively and quantitatively different from that observed for uniaxial load paths. The first and foremost qualitative difference is that the damage mechanisms change and the failure mode can change as a result. This, in turn, leads to quantitative differences in ultimate and collapse deformation, and therefore ductility and hysteretic dissipation capacity.