TYPICAL DESIGN CALCULATION FOR BRIDGE MAST BASE PLATE & HOLDING DOWN BOLT
BRIDGE MAST B-200 MAST DESIGN CALCULATION
LEGEND DESCRIPTION UNIT FACTOR REMARK
1 Safety factor for wire 0.75
2 Safey factor for mast 1.90
Basic Data
Weight of OHE Kg/m 1.60
Weight of Bracket Assembly Kg 60.00
Weight of Man Kg 60.00
Tension in Each Coductor Kgf 1000.00
Dia Cartenary wire m 0.0105
Dia of Contact wire m 0.0122
Spans
At "A" m 50.40
At "B" m 53.60
Basic wind Pressure Kgf/m2 216.00
SL NO. DESCRIPTION UNIT CALCULATION REFRENCE
1 Type of Mast B-200
Length Of Mast m 9.50
Unit weight of Mast(2 nos of ISMC-200) Kg/m 44.20 22.1*2
As per SP-6, TABLE-II, Page No-06
2 A Total Weight of Mast Kg 419.90
B Additional Height of Super Mast m 0
Total A+B m 419.90
C Intensity of Wind Kg/m2 216.00
D Depth of Construction(Pier top to Rail Level) m 2.45
E Height of contact wire from Rail Level m 5.80
F Height of contact wire from base plate m 8.25
G Encumbrance 1.40
H Height of catenary wire from base plate m 9.65
3 OHE Span on either side of Mast
Avg Span C m 52.00
4 Degree Of Curve
5 Radial Pull(Due to Staggering) of Contact wire
Stagger A m 0.40
Stagger B m 0.40
((Stagger A + Stagger B)/Ave. Span)x1000 Kg 15.38
Say Kg 15.4
6 VERTICAL LOAD
A Wight of OHE(Avg. Span x Weight of OHE) Kg 83.20
B Weight of Bracket Kg 60.00
C Weight of man on the Bracket Kg 60.00
D Weight of Mast Kg 419.90
E Weight of Super mast@ 40kg/m Kg 0.00
F Weight of super mast cantilever arm Kg 0.00
G Weight of RC Wire Kg 0.00
H Weight of Base Plate(0.7x0.7x0.025x7850) Kg 96.16
Kg 150 APPROX
TOTAL VERTICAL LOAD Kg 869.26
7 WIND LOAD
A On catenary wire(including 5% wind load on dropper)
0.75xDia of catenary wirex Wpx Avg spanx1.05 Kg 92.87
B On contact wire( Including 5% wind load on dropper)
0.75xDia of contact wirexWpxAvg spanx1.05 Kg 107.91
C On RC Wire Kg 0
D On Bracket Kg 40.00
E On mast and super mast(0.2xWpxLenght of mastx1.9) Kg 779.76
8 A VERTICAL LOAD AND BENDING MOMENT
Weight
1 Wight of OHE(Avg. Span x Weight of OHE) Kg 83.20
2 Weight of Bracket Kg 60.00
3 Weight of man on the Bracket Kg 60.00
4 Weight of Mast Kg 419.90
5 Weight of Super mast@ 40kg/m Kg 0.00
6 Weight of super mast cantilever arm Kg 0.00
7 Weight of RC Wire Kg 0.00
8 Weight of Base Plate(0.7x0.7x0.025x7850) Kg 96.16
Kg 150 APPROX
TOTAL WEIGHT Kg 869.26
LEVER ARM
1 Wight of OHE(Avg. Span x Weight of OHE) m 3.55
2 Weight of Bracket m 1.78
3 Weight of man on the Bracket m 3.55
4 Weight of Mast m 0.00
5 Weight of Super mast@ 40kg/m m 0.00
6 Weight of super mast cantilever arm m 0.00
7 Weight of RC Wire m 0.00
8 Weight of Base Plate(0.7x0.7x0.025x7850) m 0.00
MOMENT
1 Wight of OHE Kg-m 295.36
2 Weight of Bracket Kg-m 106.5
3 Weight of man on the Bracket Kg-m 213
4 Weight of Mast Kg-m 0
5 Weight of Super mast@ 40kg/m Kg-m 0
6 Weight of super mast cantilever arm Kg-m 0
7 Weight of RC Wire Kg-m 0
8 Weight of Base Plate(0.7x0.7x0.025x7850) Kg-m 0
TOTAL MOMENT Kg-m 614.86
B HORIZONTAL FORCES AND MOMENTS(PERPENDICULAR
TO TRACK)
1 Wind load on catenary wire Kg 92.87
2 Wind load on contact wire Kg 107.91
3 Wind load on mast Kg 779.76
4 Wind on radial pull contact Kg 15.38
5 RC Kg 0.00
LIVER ARM
1 Wind load on catenary wire m 9.65
2 Wind load on contact wire m 8.25
3 Wind load on mast m 9.50
4 Wind on Radial pull contact m 8.25
5 RC m 0.00
MOMENT
1 Wind load on catenary wire Kg-m 896.24
2 Wind load on contact wire Kg-m 890.27
3 Wind load on mast Kg-m 7407.72
4 Wind on Radial pull contact Kg-m 126.92
5 Kg-m 0
TOTAL Kg-m 9321.15
9 TOTAL BENDING MOMENT(Perpendicular to the track) Kg-m 9936.01
Parallel to track= 5% of perpendicular to track bending Kg-m 496.80
moment
say Kg-m 497
A Properties of channel, ISMC-200X75
A cm2 39.00 As per
Ixx cm4 3880.00 RDSO
Guideline
Iyy cm4 211.00 for bridge
Zxx cm3 307.00 mast
Zyy cm3 38.50 calculation
B Moement of inertia of combined section
Ixx=(2x1819.30) cm4 7760
Iyy=(2x(144+(22.10x(20.5+2.17)^2))) cm4 40969.52
C Section modulous of combined section
Zxx=(3638.60/12.50) cm3 620.8
D Actual benading stress Kg/m2 1501.47428269
HOLDING DOWN BOLT CALCULATION
Max Bending moment at X-X Kg-m 9936.01
Kg-cm 993601.23
Compressive force on column Kg 869.26
Spacing between bolt cm 55
Total tension in bolt Kg 18065.48
Using no. of bolt on oneside Nos. 3
Both side Nos. 8
Axial compression force in one bolt Kg 108.66
Tensile Force in each bolt Kg 5913.17
As per
RDSO
Guideline
Kg/cm2 1224
for bridge
mast
Permissible tension in each bolt calculation
Area required cm2 4.83
Provided diameter of holding down bolt mm 28.00
As per
RDSO
Guideline
cm2 4.83 <6.15
for bridge
mast
Provided area calculation
Hence safe
As per
RDSO
Embedded Length of Bolt( Design bond stress, M-20 as Guideline
cm 62.05
per 26.2.1 of IS456-2000-8.15Kg/cm2 for bridge
mast
calculation
Permitted stress increased by 33.33% when wind load is considered as per annexure
B 2.3,IS456:200
Total Length of Bolt cm 104.55
(Length of bolt extended by thickness of base plate =2.5
cm, Depth of channel=25 cm, and extra margin15 cm
Hence embedment length to be provided cm 125
DESIGN OF BASE PLATE CALCULATION
Max. Tension in each bolt Kg 5913.17
Bending moment at critical section x-x(3x5913.17x9.5) Kg-cm 168525.29
As per
RDSO
Guideline
Permissible bending stress in plate(1650x1.33) Kg/cm2 2195
for bridge
mast
calculation
Thickness required cm 2.47
mm 24.7
Thickness provided mm 25
Hence Base plate size= 750mmx750mmx25mm
