2. DIK : SUATU PLAT LANTAI TERLETAK DIATAS TIGA TUMPUAN A,B dan CPLAT
DIBEBANI BEBAN MATI (DL)/FINISHING = 0,5 kN/m² dan BEBAN HIDUP (LL) = 4 kN/m²
(Gbr) DATA PERHITUNGN : f’c = 25 Mpa (250 Kg/Cm²)
f’y = 400 Mpa (4.000 Kg/Cm²).
DIMINTA HITUNG : a. Pembesian Plat
PENYELESAIAN
:
= L/24 = 4800/24 = 200 mm diambil = 20 Cm
L = 4.560 + 2 x ½ 240 = 4.800 mm
1. Tentukan Lebar bentang
2. Tentukan tebal plat
24
0
24
0
4.560
h
GAMBAR PLAT
B
A
24
0
4.560
3. Wu= 1,2 x WD + 1,6 WL
WD = Berat sendiri Plat = 0,20 x 24 kN/m³ = 4,8 kN/m²
WD = Berat Finishing lantai = 0,5 kN/m²
JUMLAH WD = 5,3 kN/m²
Wu= 1,2 x 5,3 + 1,6 x 4 = 12,8 kN/m² ( 1.280 kg/m²)
3. HITUNG BEBAN
MA = MC = 1/24 x Wu x L²
MA = MC = 1/24 x 12,8 x (4,8)² = 12,3 kNm (1.230 kgm)
4. HITUNG MOMEN TUMPUAN
5. HITUNG M0MEN LAPANGAN
M lap AB = 1/11 x Wu x L²
Mlap AB= 1/11 x 12,8 x (4,8)² = 26,8 kNm (2.680 kgm)
MB = 1/9 x Wu x L²
MB = 1/9 x 12,8 x (4,8)² = 32,8 kNm (3.280 kgm)
4. Penutup beton Tabel = 20 mm = 2 Cm
diameter tulangan Ǿ = 12 mm = 1,2 Cm
6. Hitung Tulangan
d = h - a - 1/2 Ǿ = 200 - 20 - 1/2 x12 = 174 mm
Mu
bx d²
12,3
1,0 x (0,174 )²
= 406 kN/m² LIHAT TABEL SNI
7. MOMEN JEPIT TAK TERDUGA (MA = MC)
MA = MC = 12,3 kNm
Menurur Tabel di Interpolasi
400 = 0,0013
406 = ρ
500 = 0,0016
6
100 0,0003 6/100 x 0,0003 + 0,0013 = 0,0013
As = 0,0013 x1,0 x 0,174 x = 226 mm² ( 2,26Cm²)
PAKAI BESI Ǿ 8 – 200 mm = 251 mm² > 226 mm²
5. 8. MOMEN LAPANGAN BENTANG (MLapAB = Mlap BC)= 26,8 kNm
Mu
bx d²
26,8
1,0 x (0,174 )²
= 885 kN/m²
Menurur Tabel di Interpolasi
800 = 0,0026
885 = ρ
900 = 0,0029
85
100 0,0003 85/100 x 0,0003 + 0,0026 = 0,0029
ρ = 0,0029
ρ = 0,0029
ρmin = 0,0018
ρmak = 0,0203
Lihat Tabel 7
Lihat Tabel 8
ρmin < ρ< ρmak
As = ρ x b xd
As = 0,0029 x1,0 x 0,174 x = 505 mm² ( 5,05 Cm²)
PAKAI BESI Ǿ 10 – 250 mm = 515 mm² > 505 mm²
6. Tulangan Pembagi menurut SKSNI T15 – 1991-03 Pasal 3.16.12
= 400 Mpa : As =
As = = 360 mm (3,6 Cm²)
0,18 𝑥1000 𝑥 200
100
9. MOMEN TUMPUAN (MB = 32,8 kNm)
Mu
bx d²
32,8
1,0 x (0,174 )²
= 1.083 kN/m²
1.000 = 0,0032
1.083 = ρ
1.100 = 0,0036
83
100 0,0004 83/100 x 0,0004 + 0,0032 = 0,0035
ρ = 0,0035
As = 0,0035 x1,0 x 0,174 x = 609 mm² ( 6,1 Cm²)
PAKAI BESI Ǿ 10 – 125 mm = 628 mm² > 609 mm²