Innovative Applications of Steel Fibres in Concrete Flange of Composite Beam Subjected to Combined Negative Bending and High Axial Tension

Abstract

The steel-concrete composite beam has become very popular these days and deterioration of the composite beam and its ultimate limit state are often reported in the subjection of combined negative bending and axial tension. Due to the presence of high axial loads, it was given a guideline in a previous research study by experimental investigation such that the failure modes were reinforcement fracture and shear connection failure in limiting the ultimate limit state of the composite beam subjected to combined negative bending and high axial tension rather than concrete failure. Thus, it is important to study in order to implement the strengthening methods with innovative material applications to overcome this problem. It was assumed that the application of steel fibres in the concrete flange will be an excellent contender owing to its in-service and mechanical properties, which is the hypothesis of this research. In order to evaluate this concept, the finite element (FE) models of a composite beam subjected to negative bending and high axial tension, and steel fibre reinforced concrete (SFRC) slab were developed with non-linear material components and validated with relevant experimental studies. Consequently, the plain concrete flange of composite beam was replaced by SFRC flange and studied the failure behaviour of the composite beam subjected to combined negative bending and high axial tension. It was predicted that an improvement in the ultimate limit state and in initial cracking load due to the postponing the failure modes, which are extensively discussed and suggested as it will be a strengthening method of the concrete flange on the composite beam in such cases.