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Rumus Dasar

Rumus Dasar. Berdasarkan Kekuatan M M = 1/10. q.l 2 s = W W = 1/6 b.h 2. = tegangan lentur kayu M = Momen lentur yg terjadi W = Momen perlawanan dr penampang. Berdasar kekakuan. 5.q.l 4 f = perletakan di atas dua tumpuan

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Rumus Dasar

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  1. Rumus Dasar Berdasarkan Kekuatan M M = 1/10. q.l2 s = W W = 1/6 b.h2 • = tegangan lentur kayu M = Momen lentur yg terjadi W = Momen perlawanan dr penampang

  2. Berdasar kekakuan 5.q.l4 f = perletakan di atas dua tumpuan 384.E.I 2,5.q.l4 f = perletakan di atas tiga tumpuan 384.E.I

  3. Contoh perhitungan bekisting Lantai • Suatu lantai beton dengan ketebalan 150 mm, bahan cetakan dari multipleks sedang balok dan tiang memakai kayu kelas II, dengan ketentuan : • Multipleks tebal 15 mm, E = 95.000 kg/cm2 • Kayu Kls II : slt = 10 MPa (100 kg/cm2) ; E = 100.000 kg/cm2 stk = 2,5 MPa (25 kg/cm2) ; t = 12 kg/cm2 • Dimensi balok kayu 6/12 – 400 (cm) • Berat satuan volume beton = 2400 kg/m3 • Lendutan yg diijinkan 1/400 l • Beban pelaksanaan = 1,5 kN/m2

  4. Menentukan beban terbagi rata > berat lantai beton 0,15 x 24 = 3,6 kN/m2 > berat bekisting = 0,2 kN/m2 > Beban pelaksanan = 1,5 kN/m2 q = 5,3 kN/m2 = 530 kg/m2 Beban per cm’ adalah q’ = 530 kg/m2 x 100 cm = 5,3 kg/cm’ • Menentukan jarak l1 W = 1/6.b.h2 = 1/6 x 100 x 1,52 = 37, 5 cm3 M = 0,1.q.l2 = 0,1 x 5,3 x l2 = 0,53 l2 I = 1/12.b.h3 = 1/12 x 100 x 1,53 = 28,125 cm4

  5. 2,5.q.l4 • f ≥ • 384.E.I • 2,5 x 5,3 x l4 • 1/400.l ≥ • 384 x 95.000 x 28,125 • 5300 x l3 ≤ 10,26 x 108 • l3≤ 193584,91 • l ≤ 57,85 cm • Dipakai l yg paling kecil yaitu 55 cm M s ≥ W 0,53 l2 100 ≥ 37, 5 l2 ≤ 3750 : 0,53 l ≤ sqrt (7075,47) l ≤ 84,11 cm

  6. W = 1/6.b.h2 = 1/6 x 6 x 122 = 144 cm3 M = 0,1.q.l2 = 0,1 x 2,97 x l2 = 0,297. l2 I = 1/12.b.h3 = 1/12 x 6 x 123 = 864 cm4 • Menentukan l2 c-t-c 55 cm Beban terbagi rata q’ = 55 cm x 540 kg/m2 = 2,97 kg/cm M s ≥ W 0,297.l2 100 ≥ 144 0,297. l2 ≤ 14400 l2≤ 48484,85 l ≤ 220,2 cm • 2,5.q.l4 • f ≥ • 384.E.I • 2,5 x 2,97 x l4 • 1/400.l ≥ • 384 x 100.000 x 864 • 2970 x l3 ≤ 3,318 x 1010 • l3 ≤ 11170909,09 • l ≤ 223,54 cm

  7. Menentukan l3 c-t-c 200 cm Beban terbagi rata q’ = 200 cm x 550 kg/m2 = 10,8 kg/cm W = 1/6.b.h2 = 1/6 x 6 x 122 = 144 cm3 M = 0,1.q.l2 = 0,1 x 10,8 x l2 = 1,08.l2 I = 1/12.b.h3 = 1/12 x 6 x 123 = 864 cm4 M s ≥ W 1,08.l2 100 ≥ 144 1,08. l2 ≤ 14400 l2≤ 13333,33 l ≤ 115,5 cm • 2,5.q.l4 • f ≥ • 384.E.I • 2,5 x 10,8 x l4 • 1/400.l ≥ • 384 x 100.000 x 864 • 10800 x l3 ≤ 3,318 x 1010 • l3 ≤ 3072000 • l ≤ 145,37 cm

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