CONTOH PERHITUNGAN PENULANGAN TANGGA

  
Contoh hasil analisa dari ETABS didapat :

Pada pelat tangga :
M11 = -311,6979 Kgm = -3116979 Nmm
M22 = -1582,6438 Kgm = -15826438 Nmm

Pada bordes :
M11 = -879,6493 Kgm = -8796493 Nmm
M22 = 1863,7989 Kgm = 18637989 Nmm

Tebal pelat t = 15 cm = 150 mm

PADA PELAT TANGGA  
ARAH 1-1 
d = 150 -25 = 125 mm
As = 86,58 mm2
As min = 0,0020 x b x d = 0,0020 x 1000 x 125 = 250 mm2
250 mm2 > 86,58 mm2
Maka As perlu = 250 mm2
Pakai tulangan diameter 8 mm
A = ¼ x Π x d2 = ¼ x Π x 82 = 50,265 mm2
A = 50,265 x 5 = 253,125 mm2
Jarak tulangan 1000/5 = 200 mm maka Ø8-200 mm

a = 4,765
ØMn = Øx As x fy x (d-a/2) = 0,8 x 253,125 x 400 x (125-(4,765/2))
= 9932017,5 Nmm
ØMn > Mu
 9932017,5 Nmm > 3116979 Nmm …………..(OK)
Maka dipakai tulangan pembagi Ø8-200 (arah pendek)

ARAH 2-2
d = 150 -25 = 125 mm
As = 439,62 mm2
As min = 0,0020 x b x d = 0,0020 x 2500 x 125 =
625 mm2 625 mm2 > 439,62 mm2
Maka As perlu = 625 mm2
Pakai tulangan diameter 8 mm
A = ¼ x Π x d2 = ¼ x Π x 82 = 50,265 mm2
A = 50,265 x 13 = 653,445 mm2
Jarak tulangan 2500/13 = 192 mm maka Ø8-192 mm

 a = 4,920
ØMn = x As x fy x (d-a/2) = 0,8 x 653,445x 400 x (125-(4,920/2))
= 25623408,1 Nmm
ØMn > Mu
25623408,1 Nmm > 15826438 Nmm …………..(OK)
Maka dipakai tulangan pembagi Ø8-192 (arah panjang)


PADA PELAT BORDES
ARAH 1-1
d = 150 -25 = 125 mm
As = 244,347 mm2
As min = 0,0020 x b x d = 0,0020 x 1000 x 125 = 250 mm2 250 mm2 > 244,347 mm2
Maka As perlu = 250 mm2
Pakai tulangan diameter 8 mm
A = ¼ x Π x d2 = ¼ x Π x 82 = 50,265 mm2
A = 50,265 x 5 = 253,125 mm2
Jarak tulangan 1000/5 = 200 mm maka Ø8-200 mm

 a = 4,765
ØMn = Ø x As x fy x (d-a/2) = 0,8 x 253,125x 400 x (125-(4,765/2))
= 9932017,5 Nmm
ØMn > Mu
9932017,5 1 Nmm > 8796493 Nmm …………..(OK)
Maka dipakai tulangan pembagi Ø8-200 (arah pendek)

ARAH 2-2
d = 150 -25 = 125 mm
As = 517,722 mm2
As min = 0,0020 x b x d = 0,0020 x 1000 x 125 = 250 mm2
517,722 mm2 > 250 mm2
Maka As perlu = 517,722 mm2
Pakai tulangan diameter 8 mm
A = ¼ x Π x d2 = ¼ x Π x 82 = 50,265 mm2
A = 50,265 x 11 = 552,915 mm2
Jarak tulangan 1000/11 = 90,909 mm ≈ 90 mm maka Ø8-90 mm

a = 10,408
ØMn = Øx As x fy x (d-a/2) = 0,8 x 552,915x 400 x (125-(10,408/2))
= 21195841,71 Nmm  
ØMn > Mu 21195841,71 Nmm > 18637989 Nmm
 Maka dipakai tulangan pembagi Ø8-90 (arah panjang)