Question

3. Determine the beam's height, h, if the allowable bending stress is 1.50 ksi and the allowable shear stress is 50 psi. What is the maximum load P that the beam can then support? Use the shear and moment diagram to determine the maximum shear and moment. 7 in

Answer 1

h=0.45feet=5.4inch

P 2P 3. 3ft t5B 2 5 J - t Finch given allowable bending Stoess = 1.5ksi allowable Shear Shress : 50psi = 0.05 ksi RATRB = up EMA = 0 RBXl - 2PX6 - Px3 - Px 16 =0 AO taftst oft t 5ft R 5ft RBXl : 12p+3P+16P TRB = 311 RA= up - 31P - (44-31) US/IP 3Pp 11 BMP [PA = 13P Glazedene Bending moment AC COCALB) 2М - RAXR Atx=0 BPA = 0 x=3 = 1343P BMC = 39 p BM CD (BLUL6) -RAXX - px(x-3) at x=3 BPK 3 p n=6 BMD = 788 - P3 - 45P

BM DB (6 LALI) BAM= RAXX - P(x-3) - 2p(2-6) Bl at x = 6 8M = 13PX6 - P03) - 0 = 450 x=1, 8MB = 13px 11 - P(69) up gM BE ( исясть) BM- Raxn- pla-3) -2P12-6) +R$(x-11) B Mat += 11 Boat x = 16 = Up = 13x16P-P(13) –2P(10) + px (5) Shear for Bending moment SF B CAC COLNL3)

Maximum BM= u5p maximum SF - - 20p ĐI use 11 xh = 1.5 2 b 7x53 12 = USP x 12 x h = 15 1173 = USP x 12 = 15 0 J = Vu bd + 0.055 7xh 7h: -400P a ain 45xp x 12 = 1400) ² ph 77X2 45X12 ps on placing ③ in a&o we get h = 0.45 77x2x15 X 14oo. 22 p = 0.086625 ksi -> ☺ = 5.4 inch