Assignment on Threaded jointsDue date:__________________ ___________________ ________________ Surname Given names IDA power line tower is erected to support a high-voltage power line (see figure below),which includes six phase conductors and three Earth shield wires. The tower isfabricated as a steel structure resting on four square supporting feet bolted to aconcrete foundation with four Anker bolts at each support (see figure below). Theresultant tension force FT from cables on each side of the tower is applied at point m,and can be at 60o to the horizontal plane (sagging downwards) if the tower is installedon a plane or at 30o to the horizontal plane pointed upwards if the tower is installed on ahilly landscape. The gusty wind load, which could be represented with a resultant forceof Fw is applied at the geometric centre of the tower n in any direction in the horizontalplane (see figure below) and tends to shift the tower sideways and topple it. In the caseof an accident when all cables on one side of the tower are torn, the tension force FT willbe applied only at one side of the tower. Each foot of the tower is bolted to the concretefoundation with four Anker bolts (see figure). Because of safety considerations, ISOGrade 8.8 steel bolts and a safety factor of 5 (based on proof strength) are to be used.Assume that the tension force in cables on each side of the tower is FT = 12,000N, theresultant wind load is Fw = 80,000N, and the weight of the tower is W = 120,000N.For the given data carry out the following design calculations:1. Discuss all possible combinations of external loads showing all sketches and identify theworst case. Consider additional loads that may appear, for example, if the tower isinstalled in seismic area subject to earthquakes.2. Discus whether the Anker bolts are equally loaded.3. Assess the frictional force in the flange on each foot created by the external forces.Assume frictional coefficient in the flange μ = 0.17.4. Determine an appropriate bolt size to secure the joint and prevent the tower displacement.5. Assess the tension force in a bolt under the maximum load for the worst case scenario.6. Assess the pretension force in a bolt required.7. Assess what torque T on the bolt head is required to develop this pretension force.8. Recommend locking method for the bolted joint taking into account operating conditions.Assessment:Criteria Mark out of 7 Weighted markA. Demonstrate and apply theoretical and practical Knowledge of mechanical design (55%)B. Demonstrate information retrieval skills (20%)C. Demonstrate written and graphical communication skills (25%)Total mark out of 7Final mark out of 10%(In block letters on your ID card)Dr Wiji Senadeera Phase conductorsEarth shield wires25m60o30oPointed in anydirectionFT13mFwmnFront view Side viewFeet attachment to the foundation5 x250x250mm350x350mm A A A - A 20mmPower line tow

EBK ELECTRICAL WIRING RESIDENTIAL
19th Edition
ISBN:9781337516549
Author:Simmons
Publisher:Simmons
Chapter27: Service-entrance Equipment
Section: Chapter Questions
Problem 17R
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Assignment on Threaded joints
Due date:
__________________ ___________________ ________________ Surname Given names ID
A power line tower is erected to support a high-voltage power line (see figure below),
which includes six phase conductors and three Earth shield wires. The tower is
fabricated as a steel structure resting on four square supporting feet bolted to a
concrete foundation with four Anker bolts at each support (see figure below). The
resultant tension force FT from cables on each side of the tower is applied at point m,
and can be at 60o to the horizontal plane (sagging downwards) if the tower is installed
on a plane or at 30o to the horizontal plane pointed upwards if the tower is installed on a
hilly landscape. The gusty wind load, which could be represented with a resultant force
of Fw is applied at the geometric centre of the tower n in any direction in the horizontal
plane (see figure below) and tends to shift the tower sideways and topple it. In the case
of an accident when all cables on one side of the tower are torn, the tension force FT will
be applied only at one side of the tower. Each foot of the tower is bolted to the concrete
foundation with four Anker bolts (see figure). Because of safety considerations, ISO
Grade 8.8 steel bolts and a safety factor of 5 (based on proof strength) are to be used.
Assume that the tension force in cables on each side of the tower is FT = 12,000N, the
resultant wind load is Fw = 80,000N, and the weight of the tower is W = 120,000N.
For the given data carry out the following design calculations:
1. Discuss all possible combinations of external loads showing all sketches and identify the
worst case. Consider additional loads that may appear, for example, if the tower is
installed in seismic area subject to earthquakes.
2. Discus whether the Anker bolts are equally loaded.
3. Assess the frictional force in the flange on each foot created by the external forces.
Assume frictional coefficient in the flange μ = 0.17.
4. Determine an appropriate bolt size to secure the joint and prevent the tower displacement.
5. Assess the tension force in a bolt under the maximum load for the worst case scenario.
6. Assess the pretension force in a bolt required.
7. Assess what torque T on the bolt head is required to develop this pretension force.
8. Recommend locking method for the bolted joint taking into account operating conditions.
Assessment:
Criteria Mark out of 7 Weighted mark
A. Demonstrate and apply theoretical and practical
 Knowledge of mechanical design (55%)
B. Demonstrate information retrieval skills (20%)
C. Demonstrate written and graphical communication skills (25%)
Total mark out of 7
Final mark out of 10%
(In block letters on your ID card)
Dr Wiji Senadeera Phase conductors
Earth shield wires
25m
60o
30o
Pointed in any
direction
FT
13
m
Fw
m
n
Front view Side view
Feet attachment to the foundation
5 x
250x250mm
350x350mm A A A - A 20mm
Power line tow

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