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10. Signalling
In accordance with the ICAO (International Civil Aviation Organisation), the sec-
tions must be assembled in alternating aeronautic colours, white and red, the
latter being the colour of choice for the end sections, so it is easily identified
during the day.
The sections can be mounted using more than one structure of the same colour
after another, always maintaining the same proportion of colours (red/white –
red, red/white, white – etc).
On towers which are more than 45m high, a night beacon system must also be
fixed to it; this consists of three double lights in red, every 45m.
11. Important advice
Although the tower is intended for temporary use and not as a permanent
structure in a set location, a periodic control of the brace tension and to tighten
the screws is required. We recommend doing this each year between the 1st of
October and the 1st of January (for example).
We also recommend an inspection of the whole structure after strong wind or
ice storms or any other extreme conditions.
Similarly, we also recommend a periodic inspection of the structure in areas
with a high salt concentration (coastal areas) and in corrosive environments.
Dispose of sections which may have been damaged in transit, whilst assem-
bling, whilst disassembling or throughout the lifespan of the tower.
Annual inspections and maintenance work where necessary must be carried
out in the following instances.
- Desalinations and deformities.
- Welding inspection.
- Paint inspection.
- Inspections of the cable connections.
- Cable inspection.
- Tension of the cables (measure*).
* LThe tension of the measuring cables is subject to small variations depending
on wind and temperature.
Do not measure or adjust cables in strong-wind conditions.
12. Measuring guy tensions (Normative)
This paragraph provides guidelines for field measuring guy tensions. There are
two basic methods for measuring guy initial tensions in the field: the direct
method and the indirect method.
The Direct Method (see figure 6)
A dynamometer (load cell) with a length adjustment device, such as a come-
along, Is attached to the guy system by clamping onto the guy Just above the
turnbuckle and onto the anchor shaft below the turnbuckle.
The come-along is then tightened until the original turnbuckle begins to slac-
ken. At this point the dynamometer cerries all of the guy load to the anchor, and
the guy tension may be read diredly off the dynamometer dial.
One mey use this method to set the correct tension by adjusting the come-
along until the proper tension is read on the dynamometer. The control points
are marked, one above the clamping point on the guy and one on the anchor
shaft, and the control length is measured. The dynamometer and come-along
are then removed, and the original turnbuckle is adjusted to maintain the con-
trol length previously measured.
The Indirect Methode
There are two common techniques for the indirect measurements of guy initial
tensions; the pulse or swing method (vibration) and the tengent intercept or
sag method (geometry).
1. The Pulse Method (see figures 6 and 8)
One sharp jerk is applied to the guy cable near its connection to the anchor
causing a pulse or wave to travel up and down the cable. On the first return of
the pulse to the lower end of the guy cable the stopwatch is started. A number
of returns of the pulse to the anchor are then timed, and the guy tension is
calculated from the followin equations:
2
W L N
T
=
M
2
5.94P
2
W L N
T
=
M
2
5.94P
2
W V
W H
T
=
T
-
+
A
M
2L
2L
2
W V
W H
T
=
T
-
+
A
M
2L
2L
Where:
TA = Guy tension at anchor, in Newton.
TM = Guy tension at mid-guy, in Newton.
W = Total weight of guy, including insulators, etc., in Newton.
L = Guy chord length, in m.
L=
2
2
H
+ V
2
2
L=
H
+ V
H = Horizontal distance from guy attachment on tower to guy attachment at
anchor, in m.
2
2
V = Vertical distance from guy attachment on tower to guy attachment at
WC
H
+ (V-I)
2
W L N
T
=
T
=
A
HI
anchor, in m.
M
2
5.94P
N = Number of complete pulses or swings counted in P seconds.
2
2
WC
H
+ (V-I)
T
=
A
P = Period of time measured for N pulses or swings, seconds.
HI
2
Instead of creating a pulse that travels up and down the guy, one may achieve
W V
W H
T
=
T
-
+
A
M
2 L
2L
the same result by causing the guy cable to swing freely from side to side while
2
2
H
+ (V-I)
S
T
=
A
timing N complete swings. The formulas given above will also apply for this
HI
approach.
2
2
S
H
+ (V-I)
T
=
A
2
W L N
HI
T
=
M
2
2
W L N
5.94P
T
=
N
M
2
5.94 P
S=
W
C
i
i
2. The Tangent Intercept Method (see figure 7)
i=1
N
2
2
L=
H
+ V
A line if sight is established which is tangential to the guy cable near the anchor
S=
W
C
2
W V
W H
T
=
i
i
T
-
+
A
i=1
M
end and which intersects the tower leg a distance (tangent intercept) below
2
2 L
2L
W V
W H
T
=
T
-
+
A
M
the guy attachment point on the mast. This tangent Intercept distance is either
2L
2L
2
WC
1+tan
T
=
measured or estimated and the tension is calculaled from the following equa-
A
(V- H t an )
tion:
2
WC
1+tan
T
=
A
( V-H tan )
2
2
H
+ (V-I)
WC
T
=
A
2
2
HI
H
+ (V-I)
2
=
1+tan
2
2
L=
H
+ V
H
2
2
L=
H
2
+ V
2
H
+ (V-I)
Where:
=
2
1+tan
H
C = Distance from guy attachment on tower to the center of gravity of the
2
2
weight W, in m.
S
H
+ (V-I)
T
=
A
HI
I = Tangent intercept, in m.
2
2
H
+ (V-I)
WC
If the weight is uniformly distributed along the guy cable, C will be approxima-
T
=
A
2
HI
2
H
+ (V-I)
WC
tely equal to H/2. If the weight is not
T
=
N
A
HI
S=
W
C
uniformly distributed, the guy may be subdivided into n segments and the fo-
i
i
i=1
llowing equation may be used:
2
2
S
H
+ (V-I)
T
=
A
2
HI
2
2
S
H
+ (V-I)
1+tan
WC
T
=
T
=
A
A
HI
(V- H tan )
Where:
N
S=
W
C
i
i
N
2
i=1
2
H
+ (V-I)
S=
W
C
2
i
i
=
1+tan
i=1
H
2
WC
1+tan
T
=
A
(V- H tan )
2
1+tan
WC
T
=
A
(V- H t an )
2
2
2
2
2
23
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