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

)