Question

Investigate the adequacy of the beams shown below to resist bending moment. All indicated dead load does not include self weight:

WD 1.4 k/ft PL 20 kips each 21 ft 20" 2#6 fc 4,000 psi fy 60,000 psi 32" 4#5 Skin reinforcement 2#9+4#8 Not required by code

Answer 1

here 20kirs the keam Self hleight Unit u Volumme Convreta , Unit Weight Contrete 45 A wme Volume oConcrute 32 20 12 2 3. 33 Jt beam 1L5 X 93 33 Weight 3,533.33 b kips 13.533

the camtre at beam Sely Weigh (Ws) act ualy distribulad over ao1e Point hoads Given the Spam 20kjps 13-533kips zkipses 14K/st 5-25ft 5-25 t 5.25f 5.25t Moment due to vDL + Mmax du to Concetre hoaals Moment Wab Wab Wab 2 UDA 3-5332(4)(2)(20)(525) (157) 2. (20)(1o 5(D5) (20)( 15 75 ) (525) (21)2 kip- ft 358.22 358.22*! 2 20" kip - in 4298.64 2#6 hore 32 Skin uinsoame Not Consiler b = 20" Wlidth d 3" 2 H9+4 H8

TT 24 Ast prov Here Considned not anc 4 #5 bars erist iven conditions the gired o Nominal steed here do ksi B, 6.85 002) &D009 O54) O.O0 3 O.0030009 CO 1-2/ lor) 0 012 stal 2 X 100 20K 3 2 min 7. 7D Ast. futher naquired 7.70 6-G:013 1693 Sin the Troblen Replace 2 H9t 48 bars Overcome 2# 8 bars 4 #9 bar8 with Here, check dor Moment

bd Mu y- L here, b 20 d: 32 kir Mu 4298 64 1 D.9 3.5 y Coksi KSi bd rElE)9) 26, 480 in3 429 864 Mu (0-012)(60) Pty 0(0-012)(60) 4298 64 6579 3 7419 27 in 2 2 lemce 6k Sel weight inctuding ubficionemough Beam is all the Moment to resist the Sullicient