Experimental behaviour and numerical modelling of smooth steel bars under compression

Many existing reinforced concrete buildings located in seismic regions are characterised by internal steel reinforcement made of smooth bars and stirrups with inadequate spacing. These bars could be subjected to significant compression and eventually buckle. This paper deals with a comprehensive experimental campaign investigating the compressive behaviour of smooth bars for different values of the ratio L/D, L being the restraints distance and D the bar diameter. The stress-strain relationship is then modelled ranging from an elastic-plastic behaviour identical to that in tension (L/D = 5) to the elastic buckling behaviour (L/D > 20). The comparison between the experimental results and the outcomes of the model confirms the accuracy of the proposed stress-strain relationship.