Keywords: concrete beams, microcomposite multistructural formable steel, MMFX steel rebars, beam failure mode, concrete crushing, bending ductile failure, reinforced concrete, structural behaviour, structural performance, tensile stress, deflection, crack width, elastic modulus, stiffness, strain
Experimental investigation of the bending behaviour of concrete beams reinforced with microcomposite multistructural formable steel rebars
This paper discusses on bending behaviour of concrete beams reinforced with microcomposite multistructural formable (MMFX) steel rebars. MMFX steel provides non corrosion, high tensile strength, good ductility and toughness comparing with conventional steel. To evaluate structural behaviour and performance, a series of four concrete beam tests were conducted under static four point bending. All concrete beams were tested to failure. The service applied load corresponding to a tensile stress level of about 277 MPa in the MMFX steel rebars satisfies both deflection (span/360) and crack-width (0.406 mm) criteria. The deflection results calculated from concrete theory using effective moment of inertia (ACI) with the elastic modulus of a steel rebar presents different values than the experimental values. However, the deflection values can be well approximated up to a stress level of 517 MPa using actual stiffness of the steel rebar and also by accounting the corresponding increase in strain as compared to elastic modulus of a steel rebar. For beam failure mode, it was observed that tension strains in the steel rebars were excessive the ACI minimum strain for tension controlled when concrete crushing in the compression zone of the beam section occurred. The failure mode was classified as bending ductile failure.