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American Journal of Environmental Engineering and Science 2014; 1(5): 104-109
Published online November 30, 2014 (http://www.openscienceonline.com/journal/ajees)
Initial tension forces in guys of steel industrial chimneys at adjustment phase
Bernard Wichtowski, Janusz Hołowaty
Faculty of Civil Engineering and Architecture, West Pomeranian University of Technology Szczecin, Szczecin, Poland
Email address
[email protected] (J. Hołowaty)
To cite this article Bernard Wichtowski, Janusz Hołowaty. Initial Tension Forces in Guys of Steel Industrial Chimneys at Adjustment Phase. American Journal
of Environmental Engineering and Science. Vol. 1, No. 5, 2014, pp. 104-109.
Abstract
The free standing and guyed industrial chimneys are the most typical steel chimney structures. Structural system of guyed
chimneys is very similar to masts, in particular, to tube masts. Sometimes steel chimneys with too loose guys are in risk to
collapse. In the paper, the presented results relate to initial tension force adjustments in 10 steel chimneys. The chimneys range
is from 25,0 to 60,5 m of height. Two ways of determining the initial tension forces are described. The measured values of
initial tension forces are presented. Analyses of performance in service conditions are also carried out. All the presented
chimneys required adjustments because they had deviations from verticality and their guys were hanging loosely. The initial
forces in guys at adjustment stages were calibrated to receive adequate horizontal rigidity of the chimney shaft in order to
avoid high normal force in the shaft and to prevent guy vibration. The method of initial tension force regulation in chimney
guys can be adopted for the assessments and adjustments of technical condition in similar structures.
Keywords
Chimneys, Guys, Tension Forces, Adjustment Phase
1. Introduction
The most popular types of steel chimneys are free-standing
chimneys and those with guys. As to the structural scheme and
forms of structure, a guyed chimney corresponds, to a
significant extent, to calculation requirements defined for
masts, in particular, with reference to masts with a tabular
shaft [1-3]. Sometimes guys insufficiently tensioned are the
reason of steel chimney collapses.
Usually initial tension forces in guyed chimneys are
selected so as to:
• obtain a proper initial horizontal rigidity of the shaft
elastic support,
• avoid of too large axial forces in the shaft, resulted from
vertical components of the tension forces,
• avoid vibration of guys.
In the paper, based on the example of the structure of ten
guyed steel chimneys in which adjustments were made, the
results of measurement of initial tension values in guy ropes
are presented. The analyses of the initial guys tension forces
may be useful when evaluating the technical condition of
similar structures and at their adjustment [4, 5].
2. Characteristics of Chimneys and
Guy Ropes Examined
General construction data of the discussed ten steel
chimneys with guys are presented in Fig. 1 and in Table 1. The
chimneys have single flue pipes without thermal insulation of
differentiated construction and height, ranging from 25,0 to
60,5 m. In seven cases, they are rigidly attached constructions
on a foundation with one level of guys, however, three
chimneys with two levels of guys and the height of 46,2 and
2×41,0 m („b”, „d1” and „d2” chimneys) based in an
articulated way on brick pedestals („b”), 7,1 m and 6,0 m high
reinforced concrete pedestals („d1” and „d2”). All chimneys
have single-flue pipe welded of structural carbon steels St3SY
and St3S of diameters ranging from 720 to 1520 mm. Former
Polish steel grades (St3SY and St3S) are similar to European
steel grade S235.
105 Bernard Wichtowski and Janusz Hołowaty: Initial Tension Forces in Guys of Steel Industrial Chimneys at Adjustment Phase
Chimneys were used in a continued way or in season. Each
of them served an independent boiler, using fine coal and the
boilers were not operating simultaneously but in turns. This
had it that each chimney was turned off and cooled in turns.
Chimneys marked with letter and number were of identical
structure.
Differentiated types of ropes were used for guys in the
discussed chimneys. They are steel ropes from tinned wire of
identical diameter of six strands with double or three layer
construction of strands T6×19 („b”, „g1”, „g2”) and T6×37
(„a”, „c”) with organic chord A and ropes W-S6×36+A („d1”,
„d2”, „e”, f”, „h”). The parameters of these ropes, according to
the Polish standards are given in Table 2. In all chimneys,
three guys were applied on every level, placed every 120°.
The angles of inclination from the horizontal level of the guy
chords υ were differentiated and fluctuated from 31,95° to
77,20° (Fig. 1).
At the bottom, the guys were attached in reinforced
concrete anchorage blocks through bolts (Fig. 2) put into the
ropes. Only in the ropes of „a” chimney near the anchorage
block were the tensioning devices assembled which were
adjusted to the connection of a dynamometer. In „b”, „d1” and
„d2” chimneys, the guys of two levels were anchored in one
block (Fig. 2).
In the analyzed ten chimneys, the overhanging sag of guys’
ropes was clearly visible and in some chimneys, deflection of
the shaft axis from the vertical (Fig. 3). For example, the
deflection of „d1” and „d2” chimneys’ tops amounted to 510
and 528 mm, or else was 4,4 and 4,5 times larger than
admitted standard assembling deflection δ = H/300, where H
constitutes the height of the chimney over the foundation.
The occurring rope sag was the proof of a too small value of
initial tension forces in the guys. This was confirmed by
executed field measurements. For example, in the ropes of „c”
chimney, the values of initial tension forces amounted to
2×5,83 and 14,11 kN. This means that the stresses in ropes had
only the values of 25,5; 25,5 and 61,6 MPa.
Table 1. Technical data of the chimney structures
Chimney
(Fig. 1)
Height
[m]
Level of guys
[m]
Shaft parameters Length of rope chord [m]
Diameter[mm] Plate thickness [mm]
1 2 3 4 5 6
„a” 60,50 47,50 1520 7,9÷16,3 56,35
„b” 46,20 38,50; 21,90 720 6,1÷9,8 45,67; 25,97
„c” 45,00 35,00 1016 7,8÷9,6 43,01
„d1”, „d2” 41,00 36,00; 26,00 800 9,1÷9,4; 9,0÷9,4 39,31÷55,07; 30,42÷49,13
„e” 40,00 25,20 920 9,1÷10,02 35,18; 35,60; 18,55 1)
„f” 31,00 22,30 1000 6,7÷7,4 22,86; 25,59; 30,54
„g1”, „g2” 30,00 19,70 820 5,1÷11,8
5,0÷12,1
24,32; 27,02; 25,60 1)
23,85; 24,00; 24,14
„h” 25,00 16,30 820; 1250 8,7÷9,2; 7,4÷7,8 22,50
1) – guys attached on the roof of a boiler house
Fig. 1. General construction data for ten steel chimneys
American Journal of Environmental Engineering and Science 2014;
Chimney
(Fig. 1)
Height
[m] Number of
levels Type
1 2 3 4
„a” 60,50 1 T6×37+A
„b” 46,20 2 T6×19+A
„c” 45,00 1 T6×37+A
„d1” 41,00 2 W-S6
„d2” 41,00 2 W-S6
„e” 40,00 1 W-S6
„f” 31,00 1 W-S6
„g1” 30,00 1 T6×19+A
„g2” 30,00 1 T6×19+A
„h” 25,00 1 W-S6
Chimney Level
(Fig. 1)
Height
[m]
1 2 3
„a” 1 47,5
„b” 2
1
38,5
21,9
„c” 1 35,0
„d1” 2
1
36,0
26,0
„d2” 2
1
36,0
26,0
„e” 1 25,2
„f” 1 22,3
„g1” 1 19,7
„g2” 1 19,7
„h” 1 16,3
a)
Fig. 2. Guy anchorage
American Journal of Environmental Engineering and Science 2014; 1(5): 104-
Table 2. Technical parameters of guy ropes
Guy ropes
φφφφ
[mm]
Am
[mm2]
Weight
[kg]
Rm
[MPa]
Inclination
[o]
5 6 7 8 9
37+A 28 294 2,78 1600 υ = 57,45
19+A 20 151 1,43 1800 υg =61,05
37+A 25 229 2,18 1600 υ = 54,46
S6×36+A 20 170 1,61 1600 υg =56,91
S6×36+A 20 170 1,61 1600 υg =66,31
S6×36+A 22 196 1,86 1600 υ = 45,74
S6×36+A 22 196 1,86 1600 υ = 77,20
19+A 14 72 0,69 1400 υ = 54,09
19+A 14 72 0,69 1400 υ = 55,69
S6×36+A 20 170 1,61 1600 υ = 46,42
Table 3. Values of introduced forces in guys
Tension force of rope [kN]
guy I guy II guy III average value
4 5 6 7
36,7 56,7 59,6 51,0 (50,34)
23,6
24,4
23,6
24,4
23,6
24,4
23,6
24,4
21,0 30,2 43,0 31,4
14,3
18,0
20,0
17,0
23,1
27,4
19,1
20,8
15,5
15,1
16,8
17,6
20,9
21,9
17,7
18,2
16,4 20,6 22,8 19,9
14,7 20,2 31,3 22,1
7,8 9,3 10,9 9,3
8,9 11,1 12,1 10,7
18,9 19,4 20,5 19,6 (19,47)
b)
anchorage systems: a) chimney „a”, b) chimney „b”, c) chimney „c”
-109 106
Inclination angle υυυυ
57,45
=61,05 υd =45,78
54,46
=56,91 ÷41,14 υd =47,85÷32,26
=66,31 ÷40,82 υd =58,71÷31,95
45,74÷41,74
77,20÷46,90
54,09÷35,38
55,69÷54,68
46,42
Stress
[MPa] average value
8
51,0 (50,34) 173,5
156,3
161,3
137,1
112,4
122,4
104,1
107,0
101,7
112,7
128,3
147,6
19,6 (19,47) 115,3
c)
107 Bernard Wichtowski and Janusz Hołowaty: Initial Tension Forces in Guys of Steel Industrial Chimneys at Adjustment Phase
a)
Fig. 3. Guy ropes of chimney „b”: a) before adjustment, b) after tension adjustment
3. Initial Tension Forces of
Guys in the place of connection with chimney
up elastic supports in the horizontal direction.
of such a support depends upon the
inclination angle of the guy, its modulus of
number of guys at a given level and, first of
tension. The forces of the initial tension of
correspondingly to the required horizontal
the elastic support whose calculation has been
6].
The range of initial stress in guy ropes
may be assumed in values recommended for
with a pipe shaft, i.e. ranging from 100
values in Table 3 relate to forces and initial
were introduced in the ropes during shaft
analysed chimneys.
In all 39 guys of ten chimneys, the introduced
tension of ropes of a given level, when
causes in them a stress of values larger than
value recommended in the literature
Corresponding values of forces in guys were
rope tension caused by the shortening of tensioning
the anchorage blocks. For example, in „c”
was shortened by a value of 50, 80 and a 100
very small range of bolts regulation in seven
same time, there was a necessity to shorten
shifting the foundation thimbles.
4. Analysis of Initial Tension
In seven chimneys, the value of initial tension
determined by the dynamic method by counting
vibration amplitudes in a defined time. By
the rope near its connection with anchoring,
was caused and the amplitude of vibrations
deflection) N in time t = 10 or 15 s. The rope
half of its spread is calculated according
obtained from the transformation of the formula,
circular frequency of vibrations [5, 7-9]:
Bernard Wichtowski and Janusz Hołowaty: Initial Tension Forces in Guys of Steel Industrial Chimneys at Adjustment Phase
b)
Guy ropes of chimney „b”: a) before adjustment, b) after tension adjustment
of Ropes
chimney shaft make
direction. The flexibility
diameter, length,
of elasticity, on the
of all, the initial rope
of guys are selected
rigidity (kN/m) of
been given in [1-3,
of steel chimneys
for ropes of masts
to 350 MPa. The
initial stresses which
adjustment of the
introduced average
they are attached,
than the minimum
σo = 100 MPa.
were introduced by
tensioning bolts with
„c” chimney, the bolt
100 mm. Following a
seven chimneys, at the
shorten the rope by
Tension Forces
tension forces was
counting the number of
a sharp jerking of
anchoring, a vertical wave
vibrations counted (full
rope initial tension at a
according to the Eq. (1)
formula, defining the
0.4077GF =
where
FG rope tension in kN,
G total rope weight in kN,
l rope length in m,
N number of amplitudes in time
t time of measuring N vibration
The initial tension force determined
is a force in the centre of guy spread
is determined according to the Eq.
sin cos
2 2A G
G GF F
υ υ = − +
where
υ is the declination angle from
chord.
The difference in the value of
and (2) is insignificant and depends
the rope. For example, for guys
difference amounts to 1,3 and 0,7%
3, col. 7).
The initial tension forces determined
guys of a cold chimney and
assembling temperature T0 = +10°C.
force in another temperature, its
which takes into account the current
following dependence:
G T mF T E Aα υ∆ = − ∆
where
αT coefficient of linear
12⋅10-6
/°C,
∆T difference between the
temperature, is equal Ta – T0,
E0 = 125 (145) elastic modulus
core (metal core) in GPa,
Am metallic area of guy wires
Bernard Wichtowski and Janusz Hołowaty: Initial Tension Forces in Guys of Steel Industrial Chimneys at Adjustment Phase
Guy ropes of chimney „b”: a) before adjustment, b) after tension adjustment
2
2
0.4077 G l N
t (1)
time t,
vibration amplitudes in s.
determined according to the Eq. (1)
spread and its value at FA anchor
Eq. (2):
2 2sin cos
2 2
G Gυ υ = − +
(2)
from the horizontal plane of guy
of forces according to the Eq. (1)
depends mainly on the weight of
guys of „a” and „h” chimney, this
0,7% (FG and FA forces in Table
determined in Table 3 relate to
are referred to the standard
+10°C. For the adjustment of the
its correction ∆FG is introduced,
current temperature Ta, from the
0
2cosG T m
F T E Aα υ∆ = − ∆ (3)
thermal expansion, is equal
the current and assembling
modulus for ropes with non-metal
wires in cm2.
American Journal of Environmental Engineering and Science 2014;
In three chimneys „d1”, „d2” and „e”, the
was adjusted by a direct method of measurement,
the value of forces with the use of the dynamometer
parallel into the rope. The measurement of
out with dynamometers of bow type of 30
dynamometers were assembled in special
member devices, specially prepared for
chimneys „d1” and „d2” these devices were
the ropes of a given fixing level only
measurement (Fig. 4a), and in „e” chimney they
permanently in guy ropes (Fig. 4b). The guy
level took place at the same time in a continued
permanent land survey control of chimney shaft
The permanent fixing of measuring
chimney rope allowed to conduct the measurement
forces occurring in various operating conditions.
analyses was conducted for a chimney out of
and in operation (warm) at external temperatures
and –4°C [8, 9]. The measured values of
ranged from 12 to 29% of the value of
average 22,5% at Text = +19°C and 23,5% at
Theoretically, the operating forces in gu
from the following dependence:
a)
Fig. 4. Guy sections close to the foundation with measuring
5. Conclusions
• All chimneys required an adjustment
simultaneous adjustment of rope initial
standard value because of significant deflection
vertical and a significant sag of ropes.
• As results from the analyses of the guys
section 4, it is not always necessary
tension, according to the Eq. (2). This
particular to guys of a small weight.
• A significant reduction in stresses found
guys causes an increase in the natural
American Journal of Environmental Engineering and Science 2014; 1(5): 104-
the guy initial tension
measurement, related to
dynamometer connected
forces was carried
30 kN range. The
special lock-tension
this purpose. In
were assembled into
only for the time of
they were installed
guy tension of a given
continued manner with a
shaft tilt.
devices into „e”
measurement of real
conditions. Such an
of operation (cold)
temperatures Text = +19
„operating forces”
initial tension (on
at Text = –4°C).
guys are determined
sina p init
e T m
T h T lF E A
l
υ∆ + ∆ =
where
Fe difference in the value
warm chimney,
∆Ta change in the temperature
(measured or calculated) in relation
initial tension, is equal Ta – Tinit
∆Tinit change in the temperature
initial tension temperature, is equal
hp length of a „working”
(distance between the top of inlet
fixed).
The equation (4) was used for
tension forces in „b” chimney guys.
in ropes was carried at Text =
temperatures of the shell for the
guys: h1 = 14,8 m – Tinit = 60°C
(compare Fig. 1).
b)
Guy sections close to the foundation with measuring device: a) chimney „d1” and „d2”, b) chimney „e”
of shafts with the
initial tension to the
deflection from the
ropes.
guys initial tension in
necessary to determine the
This note relates in
found out in chimney
natural period and in the
coefficient of wind operating
increase in the value of bending
• The assumption of the
stresses of a value σ >100
distribution of horizontal load,
side also take part.
References
[1] The CICIND Chimney Book.or Steel, CICIND, Zurich, 2005.
[2] Smith, BW, CommunicationLondon, 2007.
-109 108
0
sina p init
e T m
T h T lF E A
lα
∆ + ∆
(4)
of forces in guys at cold and
temperature of chimney shell
relation to the temperature at
init,
temperature of guys in relation to the
equal Ta – Text,
section of chimney shaft
inlet and the level where guys are
for the determination of initial
guys. The adjustment of forces
+3°C and measured average
the individual sections under the
60°C i h2 = 31,4 m – Tinit = 45°C
device: a) chimney „d1” and „d2”, b) chimney „e”
operating and in consequence an
bending moments [10].
guys initial tension causing
>100 MPa has it that in the
load, the guys from the leeward
Book. Industrial Chimneys of Concrete 2005.
Communication Structures, Thomas Telford,
109 Bernard Wichtowski and Janusz Hołowaty: Initial Tension Forces in Guys of Steel Industrial Chimneys at Adjustment Phase
[3] Rykaluk, K, Steel Structures. Chimneys, Towers and Masts, OWPW, Wrocław (in Polish), 2005.
[4] Włodarczyk, W, “On failures and desinging of steel chimneys”, Inżynieria i Budownictwo, No. 10, pp. 535-539 (in Polish), 1998.
[5] Wichtowski, B, “Adjustment of steel chimneys with be-level guyed”, Inżynieria i Budownictwo, No. 5, pp. 240-243 (in Polish), 2013.
[6] Pałkowski, Sz, Steel Structures, Selected Problems and Design, PWN, Warszawa (in Polish), 2001.
[7] Instruction ER-01, Operation of towers and masts, TP SA, Warszawa (in Polish), 1995.
[8] Wichtowski, B, “Forces in guys according thermal analysis of structural shell of a 40 m high steel chimney”, Przegląd Budowlany, No. 8-9, pp. 32-35 (in Polish), 1994.
[9] Wichtowski, B, Hołowaty, J, “Steel chimneys at adjustment phase. Initial tension forces in guys”, EUROSTEEL 2011, 6th European Conference on Steel and Composite Structures: Research – Design – Construction, Budapest 2011, pp. 2499-2504.
[10] Kozłowski, A, Baran R, “Variablility of loads on a guyed chimney in service”, Inżynieria i Budownictwo, No. 10, pp. 392-394 (in Polish), 1992.