Evaluation of a minimum flexural reinforcement ratio using fracturebased modelling

摘要

Minimum reinforcement ratios are specified for reinforced concrete structures to provide enoughrnductility. The aims are to control cracking in the serviceability limit state and to prevent suddenrnfailure by ensuring sufficient ductility after the loss of tensile stress in concrete due to cracking.rnThis can provide a warning before collapse and time to take preventive or remedial measures. Arnreview of past research reveals that there are large variations, and sometimes contradictions, inrnproposed minimum reinforcement requirements for flexural members. In this paper, a fracturernmechanics-based model is used to study different local phenomena such as tensile andrncompressive concrete softening to more precisely describe the behaviour of reinforced concreternbeams. The findings show a decrease in the minimum reinforcement ratio with increasing beamrnsize. This contradicts the provisions of prevailing codes and standards which suggest no change inrnthe minimum reinforcement ratio with size. Therefore, there is a need to review the minimumrnreinforcement provisions.