If d is the diameter of a bar, f_t is allowable tensile stress and f_b, is allowable bond stress, the bond length is given by

ANS:A -

The bond length (lb​) of a reinforcing bar in concrete, considering allowable tensile stress (ft​) and allowable bond stress (fb​), can be determined using the following formula: lb​=fb​/ft​​×d Where:

• lb​ = Bond length
• ft​ = Allowable tensile stress
• fb​ = Allowable bond stress
• d = Diameter of the reinforcing bar

This formula represents the relationship between the allowable tensile stress and the allowable bond stress, scaled by the diameter of the reinforcing bar. The bond length is the distance along the surface of the reinforcing bar where the bond stress is transferred from the concrete to the bar. It ensures that the bond stress developed between the concrete and the reinforcing bar does not exceed the allowable bond stress, which can lead to bond failure. By using this formula, the appropriate bond length required for a specific reinforcing bar can be calculated based on the allowable tensile stress and the allowable bond stress specified for the given concrete and reinforcement materials.