Perhitungan Sambungan

Dipakai WF 250x125x6x9
- Mmax = 3005,202 kgm
- Q = 6677,672 kg
- N = 4747,518 kg
- D = Q x cos α + N x sin α
= 6677,672x cos 30° + 4747,518 x sin 30° = 8156,793 kg



Sambungan menggunakan baut dan las.
Pelat penyambung tebal 10 mm.
Dipakai baut Ø19 mm.
Panjang profil = 250/cos 30° = 216,506 mm
Jarak baut :
Tepi = 2 – 3 d → 2Ø = 2 x 19 = 38 ~ 40 mm
Tengah = 10– 3 d → 3Ø = 7x 19 = 133 ~ 100 mm
N1 = 42 = 16 cm2
N2 = 142 = 196 cm2
N3 = 242 = 576 cm2
N4 = 342 = 1156 cm2
N5 = 442 = 1936 cm2
Σy2 = 1344 cm2

N1 =
Untuk 1 baut = ½ x 3880 = 1940 kg
tarik baut =
=
= 684,25 kg/cm2 < 0,7 x 1600 = 1120 kg/cm2 PPBBI 87 pasal 8.2 ayat 1:68

Akibat Gaya Lintang dan Gaya Normal
Maka sambungan iris tunggal
0,393d = 0,393 x 1,9
= 0,747 < 1,0
Geser menentukan
τ =
= 287,83 kg/cm2< 0,6 x σ ijin = 960 kg/cm2(PPBBI 87 pasal 8.2 ayat 1:68)
σi =
=
= 772,943 kg/cm2 ≤ σ ijin = 1600 kg/cm2 ……………………… (OK)


Perhitungan Las
Tebal las badan = 1/2 x 5,5 = 3,89 ~ 3 mm = 0,3 cm
Tebal las sayap = 1/2 x 8= 5.65 ~ 5 mm = 0,5 cm
Statis momen las terhadap las bagian bawah;
S2 = 2 (5,95x 0,6) x (1,5) = 7,04 cm3
S3 = 2 (18,2 x 0,4) x (10,3) = 149,968 cm3
S4 = 2 (5,95x 0,6) x (19,1) = 136,374 cm3
S5 = 2 (5,975x 0,6) x (20,6) = 147,084 cm3
S6 = 2 (27,1 x 0,4) x (29,2) = 633,056 cm3
S7 = 2 (5,95x 0,6) x (47,4) = 338,436 cm3
S8 = 12,5 x 0,6 x (48,6) = 364,50 cm3
S total = 1776,558 cm3

Luas Las = S1+S2+S3+S4+S5+S6+S7+S8
Luas las = (12,5X0,6) + 2(5,95X0,6) + 2(18,2X0,4) + 2(5,95X0,6) + 2(5,95X0,6) + (27,1X0,4) + 2(5,95X0,6) + (12,5X0,6)
= 79,8 cm2
Yb = cm
Momen Inersia Las terhadap titik berat las;
1/12bh2 + FA2
Ix1 = (1/12 x 10 x 0,63) + 5(15,40)2 = 1185,98 cm4
Ix2 = 2 (1/12 x 4,7x 0,63) + 4,7(13,90)2 = 1029,24 cm4
Ix3 = 2 (1/12 x 0,4 x 14,63) + 11,2(6,7)2 = 908,26 cm4
Ix4 = 2 (1/12 x 4,7 x 0,63) + 4,7(1,697)2 = 23,14 cm4
Ix5 = 2 (1/12 x 4,7 x 0,63) + 4,7(0,197)2 = 1,10 cm4
Ix6 = 2 (1/12 x 0,4 x 14,7) + 11,76(8,45)2 = 1051,46 cm4
Ix7 = 2 (1/12 x 4,7x 0,63) + 4,7(15,7)2 = 1158,67 cm4
Ix8 = (1/12 x 10 x 0,63) + 5 (17,20)2 = 1479,38 cm4
Ix total = 6837,23 cm4

Wb = Ix/yb
Wb = 6837,23/17,20 = 397,51 cm3
Wa = Ix/ya
Wa = 6837,23/15,41 = 443,98 cm3

Kontrol Tegangan
- Akibat Momen

- Akibat Gaya Normal

- Akibat Gaya Geser

(PPBBI ’87 Pasal 8.5 : 75)
=
= 305,68 kg/cm2 < 0,7 x 1600 = 1120 kg/cm2 …………. (OK)
(PPBBI 87 pasal 8.2 ayat 1:68)