Evaluation of the Mechanical Properties of Reinforcing Steel Bars from Collapsed Building Sites

Abstract

Mechanical properties of reinforcing steel bars obtained from three different collapsed building sites in Lagos, Nigeria were examined. An optical emission spectrometer was used for chemical composition analysis while the tensile test was carried out using a Universal Testing Machine. The yield strength of the steel bars was found to be higher than BS4449 (GRADE 460B), Nst.65-Mn, and ASTM A706 standards, while their percentage elongations were lower than most of the standards. The steel bars used at the Sango collapse site have higher UTS compared with the standards, while those used at Ilesanmi and Ewuntun collapse sites have UTS values that are in close range with the standards. The reinforcing bar obtained from Ilesanmi collapsed site has higher percentage elongation than ASTM A706 standard but lower than Nst.65-Mn and BS4449 (GRADE 460B) standards. The bars obtained from Sango and Ewuntun collapse sites displayed lower percentage elongation compared with that from Ilesanmi site. All the investigated reinforcing bars possessed reasonably high strength with low ductility. Thus, these bars are susceptible to brittle fracture, which might have contributed to the collapse of the building structures.