As per IS 456:2000 for M20 grade concrete and plain barsin tension the design bond stress τ_bd = 1.2 MPa. Further, IS 456:2000 permits this design bond stress value to be increased by 60% for HSD bars. The stress in the HSD reinforcing steel barsin tension, σ_s 360 MPa. Find the required development length, L_d, for HSD bars in terms of the bar diameter, Φ