This study aimed to determine the tensile strength, ductility and ultimate tensile stress to yield stress (TS/YS) ratio of 12mmØ, 25mmØ and 36mmØ GR 415W TEMPCORE weldable steel bars based on the specifications provided by the Philippines National Standard (PNS 49-2002) and the American Society for Testing and Materials (ASTM A706M), once these steel bars are subjected to butt welding. It also sought to determine if these steel bars could be used safely in actual design. This study tested 3 pieces of 12mmØ, 3 pieces 25mmØ and 3 pieces of 36mmØ un-weld GR 415W TEMPCORE weldable steel bars for tensile strength and ductility. After V-grooves had been cut and the pieces welded together, the steel bars were subjected to tensile strength and ductility tests.
Findings showed that the tensile strength of butt-weld specimen was reduced by 12.8% or 22%. Ductility also diminished by 41.1% or 68.5%. The ultimate tensile stress to the yield stress (TS/YS) ratio was reduced by 7.5% or 12%. The reductions in tensile strength and ductility affected the compliance with the minimum requirements specified by the Philippines National Standard and American Standard for Testing Materials. This study found that the two (2) pieces of 25mmØ butt-weld rebars (YS = 402.09 Mpa) were safer to use than the two (2) pieces 36mmØ buttweld rebars (YS= 345.5 Mpa) when its average yield strength was applied to design the minimum required number of steel bars @ midspan of tension zone of a Singly Reinforced Concrete Beam (SRCB).