Tower Crane Stability Check

PROJECT

CP-5

DESIGN CALCULATION

DESIGN BY

TOWER CRANE STABILITY CHECK

CHECKED BY

SHAIKH

Tower Crane Stability Checks As per manufacturers load data sheet for Tower Crane in service and out of service condition they considered 150KM/h wind speed and To Void the toppling counter weight of 72 ton at the baseand 17.1 ton at the top is provided.(Please refer the attached load data sheet) we checked the stabilty of tower crane considering wind load and counter weight of 17.1 ton.

5.6 m

F2

16.8 m

60 m

F4 Counter weight 171 KN Please refer method statement Of Potain Tower Crane F3 = Load due to wind for Tower Crane Height = 45.5 m

F3

45.5 m

Tower Crane Base

Tower Crane Mast 1.6 m x3xm Total 14 Nos of Mast use

Lifting Load F1 = 0

Load Details Maximum Counter weight (Concrete block) F4 = 171 KN (Please refer method statement) Maximum wind Speed considered = 150 Km/h Maximum Dynamic wind Pressure = 3.33 KN/m2

Refer the attached wind calculation

Total Height of Tower Crane = 45.5 m Tower crane Windward face of area = 1.6 x45.5 m Total Height of Counter weight Concrete block = 3 m Concrete block Windward face area = 0.65 x3 m One Mast Windward face area = 1.6mx3.1m = 4.96 m2 No of Mast install =15 Nos Total Height of Mast = 15x3.1 =46.5 m (Actual Height is 45.5) Say = 45.5 Total area of Opening in one mast = 2mx 1.64 m2 = 3.28 m2 Effective area for wind= 4.96 – 3.28 = 1.68 m2 Counter weight Concrete block Height = 3 m Effective Height of tower crane for wind =45.5-3 = 42.5 m No of Mast required for 42.5m tower crane height = 42.5/3.1 = 13.7 Say = 14 Maximum Dynamic wind Pressure = 3.33 KN/m2

Refer the attached wind calculation

Total effective area of wind for tower crane height = 14x1.68 = 23.52 m2 Load due to wind for tower Crane height (F3) = 3.33x23.52 = 78.33 KN Maximum Wind Load due to concrete block Height (F2) = 3.33X3X0.65 =6.5 KN

Check for Overturning Total Restoring Moment = F4 X 16.8 = 171X16.8 =2872.8 KNm Total Overturning Moment F3X 22.75 + F2x39.9

78.33X22.75 + 6.5X39.9 = 2042 KNm Safety factored for overturning =

Total Restoring Moment /overturning Moment

= 2872.8/2042 = 1.4

PROJECT :

CP-5

DESIGN CALCULATION

WIND LOAD CALCULATION

Effective Building height above 1) ground level

Design By

Checked By

Shaikh 45.5

=

Hr

2) Type of Building

m

WELDED STEEL UNCLAD FRAMES

3) Building type factor Kb

=

( As Per BS 6399 - 2 1997 From table -1)

4

As Per BS 6399-2 1997 From Figure 3 Cr can be interpolated 4) Dynamic Augmentation factor Cr

=

0.18

Since Cr < 0.25 & H < 300 m , BS 6399 Apply. 5) Basic wind speed Vb

=

41.67 m/sec

6) Calculation of Site Wind Speed (Vs)

= Vb * Sa * Sd * Ss * Sp

As Per BS 6399-2 1997 From Figure 3 Cr can be interpolated = 1+ 0.001 ∆s

Sa

Use ∆s conservatively = 10 m =

1.010 (Section 2.2.2.2)

Sd

=

1.000 (Section 2.2.2.3)

Ss

=

1.000 (Section 2.2.2.4)

Sp

=

1.000 (Section 2.2.2.5)

Vs

=

Ve

= Vs * Sb

42.0867

m/sec

As Per BS 6399-2 1997 Table -4 Factor for Sb shall be for the worst case Sb

=

2.1

Ve

=

88.38

7) Calculation of Dynamic Pressure (qs)

= 0.613 * Ve

m/sec

2

=

4788.382

=

4.788

N/m

2 2

KN/m

Calculation External Pressure co-efficient CPe WIND X

B

D H

=

45.5 m

D

=

1.6 m

B

=

1.6 m

H>B

Ratio

= D/H =

0.04

H

=

45.5 m

D

=

1.6 m

B

=

1.6 m

WIND Z

D

B

Ratio

H>B

= D/H =

0.04

As Per BS 6399-2 1997 From Table 5 Cpe can be interpolated WIND WARD (FRONT FACE)

=

0.8 (Worst case)

LEE WARD (REAR FACE)

=

-0.3 (Worst case)

45.5

Calculation External Pressure co-efficient Ca From Figure - 4 Area Zone = A a (Diagonal Length) = 45.52812

1.6 Ca

=

External Pressures "Pe"

=

qs * Cpe * Ca

Wind ward Wall

=

3.33

0.87

2

KN/m

Tower Crane Height

Counter Weight

Crane Height

Counter weight