Analisa Balok Anak As 7 Analisa Pembebanan Balok Anak As 9

d. Beban Hidup ql = 1 x 2 x 250 kgm = 500 kgm = 0,3355 kipft b. Beban berfaktor qu qu = 1,2 qd + 1,6 ql = 1,2 . 0,4609 + 1,6 . 0,3355 = 1,089 kipft L = 6 m = 19,68 ft Analisa awal menggunakan tumpuan sendi-roll M max = 8 1 . qu . L 2 + 18 q L = 8 1 . 1,089. 19,68 2 + 18 0,6196 . 19,68 = 52,72 kip-fit Z x = fy M  max = 36 . 9 , 72 , 52 = 1,627 ft 3 = 19,75 in 3 Dengan Z x = 19,75 in 3 , dari LRFD di dapat Profil W8 x 24 Dengan data – data sebagai berikut : A = 7,08 in 2 wt = 24 lbft ry = 1,61 in d = 7,93 in Ix = 82,8 in 4 x 1 = 3020 ksi tw = 0,245 in Zx = 23,2 in 3 x 2 = 1610 1 . 10 5 ksi 19,68 ft bf = 6,495 in Sx = 20,9 in 3 kr = 16 9 in tf = 0,4 in rx = 3,42 in Sy = 5,63 in3 T = 6 8 1 in Iy = 18,3 in 4 k = 8 7 in Zy = 8,57 in 3  Dengan Tumpuan Jepit – jepit qu = qu 1 + Berat Sendiri = 1,089 + 0,024 = 1,113 kipft M max = 12 1 . qu . L 2 = 12 1 . 1,113. 19, 68 2 = 35,92 kipft Ra = Rb = 2 1 . qu . L = 2 1 . 1,113. 19,68 = 10,95 kip M 1 = M 2 = 24 1 . qu . L 2 = 24 1 .1,113 . 19,68 2 = 17.96 kip-ft Mu = Mmax + 10 . 2 2 1 M M  = 35,92 + 0,1. 2 92 , 35 92 , 35  = 37,716 kip-ft 17.96 + 17.96 Mu M 1 37,716 17,716 Dipakai M u = 37,716 kip-ft Check: ØMn M u 12 . . 9 , fy Zx 37,716 kip-ft 12 36 . 2 , 23 . 9 , 37,716kip-ft 62,64 37,716kip- ft ……..Ok Didapatkan : Lb = 19,68 ft Lp = 6,7 ft Dari LRFD Tabel 4-20 Lr = 24,4 ft Dari LRFD Tabel 4-20 Jadi LpLbLr M U = 37,716 kip.ft Syarat  M n M U Profil W8 x 24 Mp = F Y .  X = 36 . 23,2 = 835,2 kip.in = 69,488 kip.ft Mr = fy – Fr . Sx = 36 – 10 . 20,9 = 543,4 kip in = 45,210 kip ft M n = C b                 L M - M - M [ b r P P P r P L L L = 1 .                 7 , 6 4 , 24 7 , 6 68 , 19 21 , 45 488 , 69 488 , 69 = 44,48 kip.ft dipakai Mn = Mp M n = 0,9 x 44,48 kip.ft M n = 40,032 kip.ft Mn Mu  1 40,032 21,552 = 0,53 1 .......ok

4.3.5. Kontrol Penampang Kompak

 Tekuk Badan 36 640 245 , 93 , 7 640    Fy tw d = 32,367  106,667  Penampang Kompak  Tekuk Sayap 36 65 4 , . 2 495 , 6 65 . 2    Fy tf bf 8,118  10,833  Penampang Kompak

3.4.5 Kontrol Geser

Fy tw h 418  36 418 8 , 25  25,8 69,667 Vn = 0,6.Fy.d.tw = 0,6.36. 7,93. 0,245 = 41,965 kip ø Vn = 0,9. 41,965 = 37,768 kip Vu = ½.q u .L = ½.1,113 .19,68 = 10,95 kip ø Vn = 37,768 Vu = 10,95 kip .............. aman terhadap geser

4.3.7. Kontrol Defleksi

∆maks = 360 L = 360 68 , 19 = 0,054 ft ∆ = Ix E L q . . . 384 4 4 = 8 , 82 . 29000 68 , 19 . 113 , 1 . 384 4 4 = 0,00072 ft ∆ = 0,00072 ∆maks = 0,054 ft.............. aman terhadap defleksi