RAFT FOUNDATION DESIGN
1 - GENERAL Ultimate strength design method is used for reinforced concrete design. For the stability check of foundation earth cone method is used.It is assumed that sides of the cone make an angle (frustrum angle) with vertical. Foundation design is checked according to overturning and compression.
2 - MATERIAL CHARACTERISTICS Concrete : BS20 (C20) Characteristic compressive strength of concrete Design compressive strength of concrete Design tensile strength of concrete Shear stregth of concrete Specific weigth of concrete Reinforcing steel bar : St IIIa Yield strength of steel Max.Allowable Design Stress St I Yield strength of steel Max.Allowable Design Stress
160 130 10,0 10 2400
kg/cm2 kg/cm2 kg/cm2 kg/cm2 kg/m3
4200 3.652 2500 2.174
kg/cm2 kg/cm2 kg/cm2 kg/cm2
3 - LOADING Loads are taken from Structural analysis/foundation loads sheets. Moments at base are calculated according to these loads. (At both X and Y direction.)
4 - FOUNDATION TYPE Raft type foundation are used for this antenna type of tower.
5 - SOIL PARAMETERS Soil parameters are on the calculation sheets for each type of antenna tower.
ANTENNA TOWER
HT- 40 GSM TOWERS
REVISION a b c
Page No 1
RAFT FOUNDATION DESIGN
SOIL PARAMETERS : Unit Weight of Soil : Soil Bearing Capacity : Frustrum Angle :
1800 kg/m3 1 kg/cm2 20 °
Moments At Base 1)x-x Direction :
Mxx overturning = S.F.
= =
Hy horizontal
=
V tension
= = =
Vcompres
= = = = =
696406 kgm 1,3 696406 kgm with safet factor 38 3874 3874 566 57696 75005 610 62181 80836
kN kg kg kN kg kg kN kg kg
Max H=
40 KN 4077,472 kg 5300,714 kg
2) y-y Direction : Myy overturning = = = =
S.F.
Hy horizontal
= = =
0 kNm 0 kgm 1,3 0 kgm with safet factor
0 kN 0 kg 0 kg
Symetrical
ANTENNA TOWER
HT- 40 GSM TOWERS
REVISION a b c
Page No 2
RAFT FOUNDATION DESIGN
A 0,65
A 0,65
2tanD= Stup Type foundat
0,06
4,504 HK
0,30
D
2,00
D
0,6
H
4,642
0,6
0,50 T
4,672 6,492
Overturning Check = B=
Mtotal overturning =
535697 kgm
without safety factor
Mtotal overturning =
696406 kgm
with safety factor
Vconcrete
= =
B² * T + 4 * H* A² 25,0 m3
Vsoil
= = = = =
H / 3 ( B² + E² + B * E ) - Vchimney 101,2 m3 7,948 m Vcon*2400+Vsoil*1700 231992 kg
E W foundation
6N
=
e M resisting
= =
243654 kg 0,39 m
=
OK
%0RY61
6N*B/2
=
F.S
=(Vten^2+Vcom^2)+Wfoun
790900 kgm
M resisting / Mtotal overturning
=
1,1 overturning is not critical
OK
Base Pressure Check =
V Vmax Vmin
=
6N / B2 (1+- 6e/B)
=
0,79 <
=
0,37
ANTENNA TOWER
1,00
OK
HT- 40 GSM TOWERS
REVISION a b c
Page No 3
RAFT FOUNDATION DESIGN
Reinforcement Calculation = a ) Raft Reinforcement =
a
a M a-a
=
M a-a Vaa
= =
As
= =
(( Vaa * L² ) / 2 + ( Vmax - Vaa ) * L² ) / 3 ) * B 902788 kgcm 0,75 kg/cm2 M a-a / fyd * j * d 10 cm2
Min. reinforcement Area = B * T * 0.003 Use St IIIa in both directUse St IIIa for one level TOTAL Reinforcement……………… b ) Chimney Reinforcement =
46
91 cm2 I 16
92
I 16
Unit weigh
I 16
M
= =
Hx,z * (H+HK) 1219164 kgcm
As
= =
M / fyd * j * d 9,94 cm2 Use St IIIa Total Reinf: Unit weight
Ast=
92
Enough Reinf. OK.
10
Enough Reinf. OK.
1,58
( At one side )1.25 safety 5 16 I 16
I 16
Ast= 1,58 5 13,8 13,8 13,8 5
c) Stirrups
I 8/ every 20 cm Use St I
Unit weigh
I8
6) Chair
I 16 every 1 m2 Use St I
Unit weigh
I 16
unit weghts unit weghts unit weghts unit weghts unit weghts unit weghts unit weghts
0,39
1,58
unit weghts unit weghts
ANTENNA TOWER
HT- 40 GSM TOWERS
I I I I I I I I
8 10 14 16 18 20 24
I 26 I 30 REVISION a b c
kg/m 0,39 0,61 1,21 1,58 2 2,47 3,55 4,17 5,55 Page No 4
RAFT FOUNDATION DESIGN
PUNCHING CHECK A
Hn
Hn=A+2*((T-5)tan(45))/2 Apunc=Hn*(T-5)*4 Tp=Fcomp/Apunc =
ANTENNA TOWER
110,00 CM 19800 CM2 4,1 kg/cm2
T-5
<
HT- 40 GSM TOWERS
10
kg/cm2
REVISION a b c
OK
Page No 5
280
H
H3
H2
30
200
G
649
Slope of chimney
A
60
=
0,06
chairs
D
65
60
stub
B
ground level
For stup foundation
D
plane concrete min 10 cm
H1 50
4
399
2
3
strips
F
529
1-L
65
B
lower reinf.
637
669
450
column reinf.
=
upper 1-U reinf.
D
EX -1 =
E
C
A
60
A 60
D
669 EX - 2
A
290 EX - 3
450
R5
R3
R1
23 + kg
cm
R2
23
R4
23 + kg
cm 23
LENGTH = TYPE= QUANTITY= WEIGHT=
290 16 64 293
5
R6
kg
cm
25
R8
2
3
30
CHAIRS
4
4
R7
STRIPS
16 x
COLUMN REINFORCMENT
LENGTH = 689 TYPE= 16 46 QUANTITY= 501 WEIGHT=
BASE REINFORCMENT
LENGTH = 689 TYPE= 16 QUANTITY= 46 501 WEIGHT=
LENGTH = TYPE= QUANTITY= WEIGHT=
25
230 8
cm
140 16
cm
4
B 65
C 399
450
E 637
R4
501
629 16 46 457
REINFORCMENT TOTAL
G.KIRGIZ G.KIRGIZ
SCALE
DIMENSIONS IN CM
D.KOSE
G 649
1
KG
M3
M3
kg/cm2 DATE
50
DRW.NO
60
STRIPS R7 230 8 67 60
H1
HT- 40 GSM TOWERS
NOTES
293
COLON REINFORC. R5 R6 30 260 16 16 64 64 30 263
TOWER TYPE :
SOIL TYPE BEARING CAPACITY
DESIGN DRAWN
529
200 Kg/cm2 42 Kg/mm2 YIELDING . 25 Kg/mm2 YIELDING . 1 KG/CM2
FOUNDATION DESIG CALCULATIONS
DATE
APPROVE
PROJECT:
REVISION
1- ALL DIMENSIONS ARE IN CM. 2- CONRETE 28 DAYS STRENGTH 3- FORMED IRON BARS STRENGTH 4- FORMED IRON BARS STRENGTH 5- SOIL BEARING CAPACITY
1.448
25
30 16 92 44
130
FOUNDATION TOTALS
501
BASE REINFORCMENT R1 R2 R3 30 629 16 16 92 46 44 457
CONCRETE TOTAL
NOTES
F
FOUNDATION REINFORCMENT DIMENSIONS (cm)
D
EXCAVATION TOTAL
TOTAL W.
LENGHT BAR SIZE QUANTITY WEIGHT
1/1 m2 42 93 kg
67 17 x 60 kg
LENGTH = TYPE= QUANTITY= WEIGHT=
LOWER LEVEL
1-L
1-U
UPPER LEVEL
60
EXCAVATION DIMENSIONS (cm) EX - 1 EX - 2 EX - 3 669 669 290
A
FOUNDATION GEOMETRICAL DIMENSIONS (cm)
93
CHAIRS R8 140 16 42 93
H2 200
DRW.
H3 30
APPR.
H 280
