Design of Base Plate :
Grade of steel used fy = 250 MPa
Grade of concrete
used,
For M25 fck = 25
MPa Bearing strength of concrete,=0.45 x fck
As per Cl.34.4 of IS :456:20000
=0.45 x 25 = 11.25 N/mm2
Max. bearing pressure should not exceed the
bearing strength equal to 0.6 x fc as per Cl.7.4.1 of IS 800 :2007
0.6 x 25 = 15 N/mm2
partial safety factor γm0 = 1.1
Sectional Properties of column 2 NB TUBE 150 x 4.85 THIK.
b = 168 mm
A = 24.90 cm2
d = 150 mm
d = 150 mm
Maximum support reaction at each leg = 316 KN
(Ref : " Design of Trestles" in design notes ) = 316000 N
Required area of slab Base
= 316000 X /
11.25
=28088.89 mm^2
provide size of base plate more than = 28088.9 mm^2 =167.5974012 mm^2
proposed section for Base plate 280 x 280 mm
Thickness of plate provided = 22 mm
Thickness of plate provided = 22 mm
Length of the base plate = 280 mm
Width of the base plate =280 mm
Area of base plate
Abp = 280 x 280
= 78400 mm^2
Hence Safe/ Design Ok
Stress on base plate w = 4.031 N/mm2
Check for Base
plate thickness
Depth of column section = 168 mm
Total width column section =150 mm
Smaller projection b = ( 280 - 150) / 2 =65
mm
Larger projection a = (280 - 168)/ 2 = 55.85 mm
Thickness of the base plate required, T = 2.5 x 4.03
x (65 x 65
- 0.3 x ( 5.85 x 55.85 )
x 1.1/250
T = 12.0762 m
HENCE SAFE
