C. PERENCANAAN BALOK MEMANJANG

1. Perencanaan Dimensi

Kedua ujung menerus

Baja mutu U32 = 320 Mpa

= 22.5 Mpa

Bentang L = 6000 mm

Beban Hidup = 250 kg/m2

maka

hmin = .L

= 244.89796 mm

direncanakan ukuran balok h = 0.50 m = 500 mm

b = 0.25 m = 250 mm

2. Pembebanan

a. Beban Mati (qD)

- Berat sendiri = 0.5 x 0.25 x 2400 = 300 kg/m

- Dinding = 1700 x 4 x 0.15 = 1020 kg/m

- Beban PLAT TYPE D= (2 x 396 ) x 2 = 1,584 kg/m

Total qD = 2,904 kg/m

b. Beban Hidup (qL)

qL = 250 x 2 x 2 = 3,200 kg/m

c. Beban terfaktor

qu = ( 1.2 x qDL + 1.6 x qL)

= 8,605 kg/m

3. Perhitungan penulangan

8,605 kg/m

4.5 m5 m 5 m

Mtumpuan = 1/10 x qu x L2 = 30,977 kgm

Mlapangan = 1/11 x qu x L2 = 28,161 kgm

5m

Mutu Beton K 200 ;fc’

5 m

700

fy4,0

21

1

Penulangan Tumpuan

rmin = 1.4 / fy = 0.0044

rmaks = =

Mu = 30,977 kgm = mpa

b = 250 mm

d = 450 mm

f = 0.8

Rn = = 0.76

w = = 0.035

ρ = w x fc’ / fy = 0.0024

Sehingga ρ < ρ min dipakai ρµιν =

Luas tulangan yang digunakan

As = ρ min x b x d = 492.19 mm2

dipakai tulangan 16 A = 200.96 mm2

Jumlah n = 2.45

dipakai tulangan 3 D 16

Penulangan Lapangan

rmin = 1.4 / fy = 0.0044

rmaks = =

Mu = 28,161 kgm = 2.8E+07 mpa

b = 250 mm

d = 450 mm

f = 0.8

Rn = = 3.52

w = 0.174

ρ = w x fc’ / fy = 0.0123

Sehingga ρ < ρ min dipakai ρµιν =

Luas tulangan yang digunakan

As = rmin x b x d = 492.19 mm2

dipakai tulangan 16 A = 200.96 mm2

Jumlah n = 2.45

dipakai tulangan 3 D 16

0.0044

0.02

0.0044

0.02

3.10E+07

2xbxd

Mu

'

353,21185,0

fc

xRnx

fy

xxfy

xfcx

600

60085,0

'85,075,0

'

353,21185,0

fc

xRnx

fy

xxfy

xfcx

600

60085,0

'85,075,0

2xbxd

Mu

Tulangan Geser

Vu = 51628.8 kg = 516 kN

b = 250 mm

d = 450 mm

j = 0.6

f'c = 22.5 mpa

fy = 240 mpa

Kapasitas Geser Pada Balok

Vc = 1/6 x 22,5 x 250 x 450 x 10^3= 88.94 kN

Gaya geser nominal yang bekerja (Vn)

Vn = 516.3 kN > Vc Perlu Tulangan Geser

Vs ada = Vn - Vc

= 427.35 kN

Dicoba Sengkang Diameter = 8 mm

Av = 100.48 mm

Periksa jarak sengkang maksimum :

S < 1/2 x d = 225 mm

S < 200 mm = 200 mm

So < = = 25 mm

dipakai Jarak 200 mm

Jadi dipakai tulangan sengkang dia. 8 dengan jarak 200 mm

cek Gaya yang terjadi

Vs = 542.6 > (OK)Vs ada

Vu

Vn

Vs

d.fy.Av