Shear Capacity Prediction of Reinforced Concrete Beams without Stirrups Using Fracture Mechanics Approach

This study presents an analytical shear strength prediction equation for lightly reinforced slender concrete beams without stirrups based on the phenomenological experiment observations. The concept of the loss of bond performance between concrete and longitudinal reinforcement was used in these beams to explain the potential cause for the sudden release of longitudinal reinforcement from wrapping concrete. In the proposed equation, shear capacity was related to bond fracture resistance by introducing a new parameter: Mode II fracture toughness KIIc. The equation showed the size effect with effective depth to the power of -1/2 and was evaluated using test data published in other sources. Comparisons between the proposed formula and other prediction equations indicated that, for lightly reinforced slender concrete beams without stirrups, this developed formula can estimate the shear strength of beams with varying concrete strengths, shear span-depth ratios (a s/d), longitudinal reinforcement ratios, and beam depths with reasonable accuracy.

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