Ductility and Seismic Suitability of Locally Sourced High Yield Rebars in Benin City

Abstract

Ductility is the ability of a system to sustain large deformations beyond its yield point without breaking or failing. Eurocode 8 makes allowance for receipt of seismic forces using the damping capacity of ductile members. This allows for the absorption of energy and helps increase the amount of energy absorbed by ductile structures before failure. This paper investigates the maximum ductility locally sourced steel rebars in Benin City structure can sustain without damage by establishing parameters that influence ductility. Tensile tests were conducted for rebar sizes of 10 mm, 12 mm, and 16 mm diameters, which were sourced from three different vendors within Benin City, Nigeria. The strain-hardening ratio Stu/Sty, i.e. the ratio of tensile strength Stu to yield strength Sty, and the elongation at maximum tensile force Agt were investigated in order to determine plastic deformation capacity and the degree of ductility of these rebars. A numerical model – the modified Ramberg- Osgood and Rasmussen equations – was modified in order to predict the experimentally obtained ductility parameters of these locally sourced rebars. The model collaborates well with experiments and could be used to establish ductility parameters of local rebars. Also, ductility test results showed that strain hardening ratios and elongation were relatively low (Recommended strain hardening ratio of rebar for seismic design is 1.15) and this could result in reinforced concrete structures made with these rebar exhibiting moderate ductility, i.e. a moderate plastic deformation capacity which might not have sufficient energy absorbing capacity in events of large earthquakes.