perhitungan beton
Post on 14-Apr-2016
217 Views
Preview:
DESCRIPTION
TRANSCRIPT
Diketahui :
Pelat berukuran 6 m x 4 m dibebani oleh beban terpusat,
dengan luas penyebaran 55 x 40 cm
tebal pelat = 30 cm
P = 7.5 ton
Mutu beton = K 225
Mutu baja = U 32 = 2,780
Berat sendiri pelat diperhitungkan
2 m 6 m
###
55 10 10 55
4 my =
12 -
140
2 2
Ditanyakan :
Tulangan pelat dan gambarkan tulangannya (dihitung dgn teori M. Pigeaud)
Jawab :
Akibat beban terpusat :
2 y
2 y
2 y+ + +
2 3
1 42 u
1) u = = 2 ( 0.55 + 0.1 ) = 1.30 m
v = = 2 ( 0.4 + 0.8 ) = 2.40 m
k = = 6.00 / 4.00 = 1.5 m
u=
1.30= 0.325
u=
2.40= 0.400
4 6
dari grafik diperoleh : = 13.5 = 6.3
harus dikalikan dengan
= 13.5 ( 0.55 + 0.1 ) ( 0.4 + 0.8 ) = 10.53
σ*au kg/cm2
2 ( u1 + x )
2 (
v1 +
y )
2 (
v1 +
y )
2 ( u1 + x )
2 ( u1 + x )
2 ( v1 + y )
ly / lx
lx ly
m1 . 10-2 m2 . 10-2
( u1 + x ) ( v1 + y )
m1 . 10-2 . 10-2
= 6.3 ( 0.55 + 0.1 ) ( 0.4 + 0.8 ) = 4.914
2) u = 2 x = 2 ( 0.1 ) = 0.20 m
v = 2 y = 2 ( 0.8 ) = 1.60 m
u=
0.20= 0.050
u=
1.60= 0.267
4 6
dari grafik diperoleh : = 23 = 10.4
harus dikalikan dengan x y
= 23 ( 0.1 ) ( 0.8 ) = 1.84
= 10.4 ( 0.1 ) ( 0.8 ) = 0.832
3) u = = 2 ( 0.55 + 0.1 ) = 1.30 m
v = 2 y = 2 ( 0.8 ) = 1.60 m
u=
1.30= 0.325
u=
1.60= 0.267
4 6
dari grafik diperoleh : = 14.8 = 9.5
harus dikalikan dengan
= 14.8 ( 0.55 + 0.1 ) ( 0.8 ) = 7.696
= 9.5 ( 0.55 + 0.1 ) ( 0.8 ) = 4.94
4) u = 2 x = 2 ( 0.1 ) = 0.20 m
v = = 2 ( 0.4 + 0.8 ) = 2.40 m
u=
0.20= 0.050
u=
2.40= 0.400
4 6
dari grafik diperoleh : = 19.2 = 6.8
harus dikalikan dengan
= 19.2 ( 0.4 + 0.8 ) ( 0.1 ) = 2.304
= 6.8 ( 0.4 + 0.8 ) ( 0.1 ) = 0.816
= ( 1 ) + ( 2 ) - ( 3 ) - ( 4 )
= ( 10.5 + 1.84 - 7.7 - 2.3 ) = 2.37
= ( 4.91 + 0.83 - 4.94 - 0.82 ) = -0.01
Momen lentur :
=4 P
=4 7,500
( 2.37 + 0.3 -0.01( 0.4 ) ( 0.55 )
= 3228 kgm
=4 P
=4 7,500
( -0.01 + 0.3 2.37( 0.4 ) ( 0.55 )
= 956 kgm
Akibat berat sendiri pelat :
berat sendiri = 0.3 x 2,400 = 720
jadi P = ( 6 ) ( 4 ) ( 720 ) = 17,280 kg
u= 1
untuk k = 1.5 ; diperoleh = 4.9
u= 1
= 1.5
m2 . 10-2 . 10-2
lx ly
m1 . 10-2 m2 . 10-2
m1 . 10-2 . 10-2
m2 . 10-2 . 10-2
2 ( u1 + x )
lx ly
m1 . 10-2 m2 . 10-2
( u1 + x ) . Y
m1 . 10-2 . 10-2
m2 . 10-2 . 10-2
2 ( v1 + y )
lx ly
m1 . 10-2 m2 . 10-2
( v1 + y ) . x
m1 . 10-2 . 10-2
m2 . 10-2 . 10-2
Harga m 1 dan m 2 total :
m1 10-2. . 10-2
m2 10-2. . 10-2
Mx ( m1 + 1,15 m2 ) . 10-2 . 10-2
u1 v1
My ( m2 + 1,15 m1 ) . 10-2 . 10-2
u1 v1
kg/m2
lxm1 . 10-2
m2 . 10-2
= 1
= 17,280 ( 4.9 + 0.3 1.5 ) = 924.48 kgm
= 17,280 ( 1.5 + 0.3 4.9 ) = 513.22 kgm
Momen total akibat berat sendiri + beban terpusat :
= 3,228 + 924.48 = 4,152.21 kgm
= 956 + 513.216 = 1,469.13 kgm
Penulangan : = 30 cm --> h = 28 cm
= 1.5 ( 4,152 ) = 6,228.31 kgm
Cu =28
= 5.326,228.31
2 ( 0.5 ) ( 1 ) ( 225 ) diperoleh q = 0.0365
(cari di tabel)
δ = 0
A = 0.0365 . 100 . 28 .2 ( 0.5 ) ( 225 )
= 8.272,780
( pakai 18 = ) Ø 14 - 36
= 1.5 ( 1,469 ) = 2,203.69 kgm
Cu =28
= 8.952,203.69
2 ( 0.5 ) ( 1 ) ( 225 )
pakai A minimum = 0.25% . 100 . 30 = 7.5 ( 15 = 7.54
Ø 12 - 30
Sketsa penulangan :
10
0
60
0
30
Ø 1
2 -
30
Ø 1
2 -
Ø 14 - 36
Ø 14 - 36
10
0
400
ly
Mx . 10-2 . 10-2
My . 10-2 . 10-2
Mx
My
ht
Mux
cm2
Ø 14 - cm2
Muy
cm2 Ø 12 - cm2
50 50
40
)
)
. 10-2
. 10-2
)
top related