A Study on Toughness Contribution to Structural Capacity of Reinforced Concrete Beam

Abstract

The term of toughness is one of the fracture parameters which describes the ability of structures to remain deformed while collapsing. Toughness can be expressed as both, strain energy release rate G or as stress intensity factor K. This study deals with how reinforcement influences toughness K to divert rapid to gradual failure. Wedge forces developed by cohesiveness between rebars and concrete are the main concern in transforming elastic to plastic behavior by means reducing the value of stress intensity factor K. Three-point bend beam as a specimen with mode I fracture of (150 × 300) mm dimension with 100 mm initial crack was conducted in the analytical processing. The specimen was reinforced by 4#12mm steel bars. Wedge forces ‘p’ due to reinforcement tensile T developed by composite action between concrete and reinforcement prevailed KIP=441.613Nmm−1.5 whereas stress intensity factor due to load for beam without reinforcement KIP=482.7Nmm−1.5. Hence, the stress intensity factor due to the contribution of reinforcement KIR=41.087Nmm−1.5 which is greater than the critical toughness KIc = 22.136Nmm−1.5. By applying the term strain energy release rate G in conjunction with stress intensity factor K through the relationship K=EG, resulting in G is close to 35 N/m, a value under which normal plain concrete would fail.