Question

The short cantilever below carries a heavy concentrated load near the end of the beam. Three number 8 bars are used in tension and you can assume they are adequately anchored in the supporting column. There is at least 2 in. cover from the end of the bars to the end of the beams. Detemine if hooks are needed to fully develop the number 8 bars. If they are needed, calculate the development length of the hook and provide a sketch of the required details including if confining transverse reinforcement is needed. fy = 60 ksi, fe-4 ks, normal-weight concrete. 40 in. 2 in, cover in. clear 8 318bars b-10 in.

no need to draw sketch

Answer 1

#8 bar top reinforcement f_c = 4000 psi, f_y = 60000 psi Development Length (Ld) Ld = 3/40[f_y/squareroot f_c min(psi_t psi_r,1.7)psi_s lambda/min((cb + ktr/d_b),2.5)]db d_b = dia of bar = 1 in c_b = radius of bar = 0.5 in psi_t = location modifier = 1.3 (top rein forcement) psi_e = epoxy modifier = 1.0 (non-epoxy) psi_t psi_e = 1.3 psi_s = size modifier = 1.0 (#7 and larger) lambda = 1.0 (norml weight) K-b = not given as no transverse reinforcement. Ld = 3/40 times 60000/squareroot 4000 times 1.3/2.5 times 1 in Ld = 36.998 in Ld = 37 in Length of beam = 40 in Cover of reinforcement = 2 in Development length provided = (40-2)in Ld, provided = 38 in provided Ld > required Ld No holes required.