Design of base plate

Project/Client :-
S.No Calculations References
1 Design forces
Factored Axial load Pu = 1100 KN From analysis
Nature of axial load = Tension
Factored Shear force Fy = 300 KN
Dia of anchor bolts (HT bolts) = M 36 mm
No of bolts = 4 Nos
Grade of bolts = 8.8
Ultimate Tensile strength of bolt fu = 100 Mpa
Ultimate Tesile strength of plate fcu = 250 Mpa
Yield stress of plate fy = 250 Mpa
Yield stress of bolt fyb = 250 Mpa
Cube compressive strength of concrete fck = 25 Mpa
2 Geometric properties
Column section = PIPE
Depth of section = 400 mm
Width of flange = 300 mm
Clearence of holes = 2 mm
Dia of holes = Nominal dia of bolt + clearence = 38 mm
Minimum Edge distance = 57 mm Clause 10.2.4
Maximum edge distance = 12tε IS:800:2007
= 144 mm
ε = (250/fy) 1/2

= 1
Edge distance provided = 160 mm
Not OK

50 50

12
500
160 180 160
100

50
200

300

400
 200

300

400
400

100
500

Minimum spacing of bolts (2.5 d) = 90 mm Clause 10.2.2 &

Maximum spacing of bolts (lesser of 32t or 300) = 300 mm 10.2.3
Spacing of bolt provided = 180 mm IS:800:2007
O.K
3 Check for base pressure
Bearing pressure of plate w = Pu/Ap
= 5.5 Mpa
Allowable bearing pressure = 0.6fck
= 15 Mpa
Safe
4 Check for Minimum Thickness of base plate Clause 7.4.3.1
Thickness of plate required IS:800:2007

t s  2.5w(a 2  0.3b 2 ) mo / fy  tf
ts = 10.29 mm
Thickness of plate required = 12 mm
Safe
4 Check for shear capacity of bolts Clause 10.3.3
Design shear strength of bolt, Vdsb = Vnsb/‫ע‬mb IS:800:2007
Nominal shear capacity, Vnsb
Vnsb = 105.73 KN
Vdsb = 84.584 KN

Calculated shear force per bolt Vd = 75 KN

Safe
5 Check for bearing capacity of bolts Clause 10.3.4
Design bearing strength of bolts Vdpb = Vnpb/‫ע‬mb IS:800:2007
Vnpb = 2.5kb d t fu
kb = 0.4
Vnpb = 43.2 KN
Vdpb = 34.56 KN
Calculated bearing strength of bolt Vb = 275 KN
Unsafe
6 Check for tension capacity of bolts
 Design tension capacity of bolt Tdp = Tnp/‫ע‬mb

Nominal Tensile capacity of bolt

Tnp = 0.9fubAn<fybAsb(‫ע‬mb/‫ע‬mo)
0.9fubAn = 73.25 Mpa
fybAsb(‫ע‬mb/‫ע‬mo) = 289.02 Mpa
Nominal Tensile capacity of bolt Tnp = 73.25 Mpa
Design tension capacity of bolt Tdp = 58.6 Mpa
Calculated tension per bolt T = 275 Mpa
Unsafe
7 Check for combined shear and tension

75 275
+ = 6.86297 > 1.0
34.56 58.6
Unsafe
 Design of Base Plate
1 Design Data
Factored Axial load Pu = 1100 KN
Nature of axial load = Tension
Factored Shear force Fy = 300 KN
Dia of anchor bolts (HT bolts) = M 36 mm
No of bolts = 4 Nos
Grade of bolts = 8.8
Ultimate Tensile strength of bolt fu = 100 Mpa
Ultimate Tesile strength of plate fcu = 250 Mpa
Yield stress of plate fy = 250 Mpa
Yield stress of bolt fyb = 250 Mpa
Cube compressive strength of concrete fck = 25 Mpa

2 Geometric properties
Column section = PIPE
Depth of section = 400 mm
Width of flange = 300 mm
Clearence of holes = 2 mm
Dia of holes = Nominal dia of bolt + clearence = 38 mm
Minimum Edge distance = 57 mm
Maximum edge distance = 12tε
= 144 mm
= (250/fy) 1/2

= 1.0
Edge distance provided = 160 mm
Not OK

50 50

12
500
160 180 160
100

50

400
200

300

400
100

500

Minimum spacing of bolts (2.5 d) = 90 mm

Maximum spacing of bolts (lesser of 32t or 300) = 300 mm
Spacing of bolt provided = 180 mm
 O.K
3 Check for base pressure
Bearing pressure of plate = Pu/Ap
= 5.5 Mpa
Allowable bearing pressure = 0.6fck
= 15 Mpa
Safe
Check for Minimum Thickness of base plate Clause 7.4.3.1
Thickness of plate required

ts  2.5w(a 2  0.3b 2 ) mo / fy  tf
ts = 10.29 mm
Thickness of plate required = 12 mm
Safe
4 Check for shear capacity of bolts
Design shear strength of bolt, Vdsb = Vnsb/‫ע‬mb
Nominal shear capacity, Vnsb
Vnsb = 106 KN
Vdsb = 84.58 KN

Calculated shear force per bolt Vd = 75 KN

Safe
5 Check for bearing capacity of bolts
Design bearing strength of bolts Vdpb = Vnpb/‫ע‬mb
Vnpb = 2.5kb d t fu
kb = 0.4
Vnpb = 43.2 KN
Vdpb = 34.56 KN
Calculated bearing strength of bolt Vb = 275 KN
Unsafe
6 Check for tension capacity of bolts
Design tension capacity of bolt Tdp = Tnp/‫ע‬mb
Nominal Tensile capacity of bolt
Tnp = 0.9fubAn<fybAsb(‫ע‬mb/‫ע‬mo)
0.9fubAn = 73.25 Mpa
fybAsb(‫ע‬mb/‫ע‬mo) = 289.02 Mpa
Nominal Tensile capacity of bolt Tnp = 73.25 Mpa
Design tension capacity of bolt Tdp = 58.6 Mpa
Calculated tension per bolt T = 275 Mpa
Unsafe
7 Check for combined shear and tension
 75 275
+ = 6.8629717 > 1.0
34.56 58.6
Unsafe