U.S. patent application number 15/117947 was filed with the patent office on 2017-01-19 for lattice mast having an open framework structure in particular an electricity pylon or telecommunication mast, and method for increasing the stability of lattice masts having an open framework structure.
The applicant listed for this patent is RWE INNOGY GMBH. Invention is credited to Daniel Bartminn.
Application Number | 20170016241 15/117947 |
Document ID | / |
Family ID | 52469827 |
Filed Date | 2017-01-19 |
United States Patent
Application |
20170016241 |
Kind Code |
A1 |
Bartminn; Daniel |
January 19, 2017 |
LATTICE MAST HAVING AN OPEN FRAMEWORK STRUCTURE IN PARTICULAR AN
ELECTRICITY PYLON OR TELECOMMUNICATION MAST, AND METHOD FOR
INCREASING THE STABILITY OF LATTICE MASTS HAVING AN OPEN FRAMEWORK
STRUCTURE
Abstract
The invention relates to a lattice mast (1) with an open
framework structure of angled profiles (3), in particular an
electricity pylon or telecommunications mast, comprising at least
one or more cladding profiles (9a, 9b) which extend over at least
part of the length of at least one angled profile (3), wherein at
least one cladding profile has a curved incident-flow surface and
forms a flow shielding of a wind-exposed edge of the angled profile
(3), wherein the incident-flow surface is at least approximately
spherically curved and has a flow resistance coefficient which is
less than that of the unshielded angled profile (3).
Inventors: |
Bartminn; Daniel; (Elmshorn,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RWE INNOGY GMBH |
Essen |
|
DE |
|
|
Family ID: |
52469827 |
Appl. No.: |
15/117947 |
Filed: |
February 5, 2015 |
PCT Filed: |
February 5, 2015 |
PCT NO: |
PCT/EP2015/052379 |
371 Date: |
October 3, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E04H 9/14 20130101; E04B
1/19 20130101; E04H 12/10 20130101; E04B 1/92 20130101; E04B
2001/0053 20130101; E04H 9/16 20130101 |
International
Class: |
E04H 9/14 20060101
E04H009/14; E04B 1/19 20060101 E04B001/19; E04B 1/92 20060101
E04B001/92; E04H 12/10 20060101 E04H012/10; E04H 9/16 20060101
E04H009/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2014 |
DE |
10 2014 001 893.8 |
Claims
1. A lattice mast with an open framework structure of angled
profiles, comprising at least one cladding profile that extends
over at least part of the length of at least one angled profile,
wherein said at least one cladding profile has an incident-flow
surface that forms a flow shielding of a wind-exposed edge of the
angled profile, wherein the incident-flow surface has a flow
resistance coefficient that is less than that of an unshielded
angled profile, and wherein said at least one cladding profile
comprises a back-foamed shell-like profile segment.
2. The lattice mast of claim 1, wherein the incident-flow surface
is at least approximately spherically curved or has a polygonal
contour which is at least similar to a spherical or elliptical arc
contour.
3. The lattice mast of claim 1, wherein the curved incident-flow
surface of the at least one cladding profile is expediently
symmetrically with respect to said exposed edge.
4. The lattice mast of claim 1, wherein said at least one cladding
profile has a maximum projection area selected from the group
consisting of no more than 60% greater, no more than 40% greater,
and no more than 20% greater, than the maximum projection area of
the unclad angled profile.
5. The lattice mast of claim 1, wherein said at least one cladding
profile forms a structural unit with at least one angled
profile.
6. The lattice mast of claim 1, wherein said at least one cladding
profile is connected to at least one angled profile by at least one
fastening selected from a group consisting of adhesive bonding,
riveting, clamping, fastening with Velcro, binding, screwing,
stapling, and foaming.
7. The lattice mast claim 1, wherein multiple cladding profiles are
connected to one another and/or to at least one angled profile of
the framework via nodes of a framework structure, forming a
structural unit.
8. The lattice mast claim 1, wherein at least one cladding profile
complements the angled profile to form a closed profile
cross-section.
9. The lattice mast of claim 1, wherein multiple cladding profiles
form a closed or approximately closed profile cross-section at
least partially enclosing the angled profile.
10. The lattice mast of claim 1, wherein multiple cladding profiles
are complemented to form a closed or approximately closed spherical
or elliptical cross-section.
11. The lattice mast of claim 1, wherein at least one shell-like
profile segment comprises profile legs, wherein at least one free
end of at least one profile leg is frayed or has strips or holes or
at least one additional perforated profile that reduces flow
resistance and/or increases aerodynamic damping.
12. A method for increasing the stability of lattice masts
comprising an open framework structure comprising angled profiles,
using at least one cladding profile, comprising cladding at least
one angled profile with a cladding profile that has at least one at
least approximately spherically curved incident-flow surface
wherein at least one wind-exposed edge of said angled profiles is
thereby shielded by the cladding profile, and wherein the angled
profile is complemented or clad at least partially to form an
essentially closed or approximately closed, at least partially
round or facetted profile cross-section, and further comprising
upgrading said lattice mast to form a lattice mast in which the at
least one cladding profile is configured as a shell-like profile
segment that is back-foamed.
13. The method of claim 12, further comprising the step of a
subsequent upgrading of a lattice mast to form an aerodynamically
clad lattice mast as claimed in claim 1.
14. The method of claim 12, wherein said lattice mast is an
electricity pylon or telecommunications mast.
15. The lattice mast of claim 1, wherein said lattice mast is an
electricity pylon or telecommunications mast.
Description
FIELD
[0001] The invention relates to a lattice mast with an open
framework structure of angled profiles, in particular an
electricity pylon or telecommunications mast.
[0002] The invention moreover relates to a method for increasing
the stability of a lattice mast with an open framework structure of
angled profiles, in particular of electricity pylons or
telecommunications masts.
[0003] A lattice mast within the sense of the present invention is
understood to include, for example, a mast for receiving overhead
electricity transmission lines. A radio mast or antenna mast, or a
telecommunications mast, is likewise understood as a lattice mast
within the sense of the present invention. Lattice masts with open
framework structures can, however, also be lattice masts on bridges
or pylons. Lastly, a lattice mast within the sense of the present
invention can also be a mast for mounting a wind power
generator.
[0004] An open framework structure within the sense of the present
invention is understood to include a framework structure with
struts which are not provided with infilling and which is not
permanently inhabited and is not used for residential purposes.
[0005] The aerodynamic cladding according to the present invention
is provided with angled profiles for open framework structures.
BACKGROUND
[0006] Framework structures comprising angled profiles have the
advantage that they are particularly light and the individual
profile struts can be connected to each other relatively easily,
for example by rivets, welds or bolts.
[0007] Such lattice masts are usually constructed from a row of
structural elements arranged one above the other, wherein each
stage forms a framework structure which has three or more
trapezoidal framework panels which each consist of corner supports
braced to one another. The corner supports are designed as angled
profiles, and the struts connecting the latter can likewise be
designed partly as angled profiles, and partly also as plate
profiles.
[0008] The design of such framework structures is generally
subordinated to the requirements for the bearing load and for the
wind load acting on the construction.
[0009] The measurement or dimensioning of the structural elements
forming the framework structure is, on the one hand, dependent on
the free buckling length of the individual elements and on the
tensile or compressive stress prevailing in the latter, and, on the
other hand, on the interaction of longitudinal forces and lateral
forces which are introduced into the construction, for example, by
wind loads.
[0010] In order to stabilize lattice constructions or framework
structures of this type, numerous bracing systems are known which
are optimized with respect to the arrangement of the framework
struts and with regard to the total weight of the lattice
structure. Such a system is described, for example, in GB 675,859
A.
[0011] The optimal design of framework structures for the expected
wind load and bearing load relative to the optimal weight generally
presents relatively few problems. In the case of existing framework
structures, for example in the case of existing lattice masts for
overhead electricity transmission lines, it may be necessary from
time to time to repair and/or replace parts of the structure. In
some circumstances, this requires new stability checks. Existing
installations do not meet increased stability requirements in some
circumstances, in particular also owing to increased load
requirements or owing to a structural weakness which is to be
expected after standing for a relatively long period of time.
[0012] In such cases, there may be a need for time-consuming
tensioning. A crane construction is known from DE 1 509 022 US
which is characterized in that it is clad at least in part by
flow-promoting rotatably mounted hollow profiles which adjust
themselves to the respective direction of the oncoming wind.
[0013] The support for an overhead transmission line mast, which
has a protective concrete cover in the base region, is know from G
87 00 379.1.
[0014] Further prior art is known from the documents JP 2002 276
200 A and CN102155106 A.
SUMMARY
[0015] The object of the invention is to provide a lattice mast
which has a design which can be produced relatively simply in the
course of subsequent upgrading.
[0016] The object of the invention is moreover to provide a
suitable method for increasing the stability of lattice masts as
part of subsequent upgrading.
[0017] This object is achieved in particular by the features of
claim 1 and by the features of claim 11.
[0018] Preferred alternative embodiments of the lattice masts and
of the method according to the invention for increasing the
stability of lattice masts are apparent from the dependent
claims.
[0019] According to one aspect of the invention, a lattice mast
with an open framework structure of angled profiles is provided, in
particular an electricity pylon or telecommunications mast,
comprising at least one or more cladding profiles which extend over
at least part of the length of at least one angled profile, wherein
at least one cladding profile has an incident-flow surface and
forms a flow shielding of a wind-exposed edge of the angled
profile, wherein the incident-flow surface has a flow resistance
coefficient which is less than that of the unshielded angled
profile.
[0020] The incident-flow surface is preferably at least
approximately spherically curved or has a polygonal or facetted
contour which is similar to a spherical or elliptical arc contour.
"Facetted" within the sense of the invention is understood to mean
a polygonal surface which is similar to an arc contour.
[0021] An angled profile within the sense of the invention is
understood to mean, for example, a T-profile, L-profile, I-profile,
Z-profile, U-profile, C-profile or the like.
[0022] The invention makes use of the fact that the wind load on a
construction is determined from the product of a reference pressure
with a flow resistance coefficient and of the exposed surface of
the construction. The reference pressure is dependent on the air
density and the wind speed. The flow resistance coefficient here
describes the characteristic of the wind flow about a structural
element of the relevant framework structure, for example about an
angled profile. Sharp edges of a profile tend to generate
turbulence and are therefore more prone to wind loads than facetted
or rounded edges or round or tubular profiles. An octagon has, for
example, a flow resistance coefficient of Cw=1.3, compared with a
flow resistance coefficient of Cw=2.0 for sharp-edged angled
profiles.
[0023] If the flow rate of a fluid which initially flows laminarly
is increased, the characteristic of the flow changes from laminar
to neutral and then to unstable so that the initially orderly flow
becomes undulating. As a result, the flow resistance coefficient
increases significantly. At sharp profile edges, the flow
resistance coefficient Cw (dimensionless) can assume a magnitude of
approximately 2.0, whilst for round elements or for example also
for spherical elements it is approximately between 0.176 and 0.48,
depending on the Reynolds number. In the case of very high Reynolds
numbers, the resistance coefficient of a sphere increases, whereas
it can assume low values in the case of relatively low Reynolds
numbers.
[0024] The invention makes use of these fluid mechanical
circumstances which are known per se. By providing a
correspondingly clad lattice mast, the flow resistance coefficient
of at least some of the exposed angled profiles can be reduced
significantly, as a result of which the wind load on the
construction is likewise significantly reduced. In the most simple
case, this can be achieved for example by at least one exposed
critical edge of an angled profile being shielded with a cladding
profile, wherein the cladding profile has a rounded or curved
incident-flow surface. In the case of a lattice mast, it can for
example be provided to shield all or some of the corner supports or
corner profiles by means of corresponding cladding profiles. These
cladding profiles can be fastened, for example only over part of
the length of the relevant angled profiles, to the latter, and
shield the angled profiles in each case only over part of their
length. It is likewise possible within the scope of the invention
to correspondingly clad only the node points of the framework.
[0025] According to another aspect of the present invention, the
cladding profiles can be designed with variable cross-sections
along the angled profile to be clad in order thus to prevent the
possibility of vortices being induced, or to optimize the
aerodynamic damping.
[0026] In the case of a lattice mast structure, the relevant
cladding profile can be arranged, for example, such that it shields
the apex of an angled profile, which forms for example an isosceles
triangle in cross-section.
[0027] In the case of a lattice mast structure having three or four
corner supports, the construction is generally selected such that
the corner supports are designed as angled profiles with an
essentially isosceles-triangle cross-section, wherein the apexes of
the relevant angled profiles point outward. A significant reduction
in the wind load is obtained by cladding these apexes.
[0028] The curved incident-flow surface of at least one cladding
profile is expediently arranged symmetrically with respect to the
relevant profile edge.
[0029] In particular lightweight plastic, aluminum, or steel
profiles come into consideration as cladding profiles and these can
be designed as shell-like elements but also as solid profiles.
[0030] In a preferred alternative embodiment of the lattice mast
according to the invention, it is provided that the at least one
cladding profile has a maximum projection area which is no more
than 60%, preferably no more than 40%, and more preferably no more
than 20% greater than the maximum projection area of the unclad
angled profile. It is ensured as a result that the incident-flow
surface, which is included in the calculation of the wind load,
with respect to the unclad profile is not so great that the
advantage of the reduced flow resistance coefficient is completely
eradicated as a result.
[0031] In, for example, the case of a cladding profile with an
approximately arc-shaped incident-flow surface, the diameter of the
relevant cladding profile can be at most 20% greater than the
diagonal of an angled profile designed as a corner profile.
[0032] An approximately spherically curved incident-flow surface
within the sense of the present invention is also understood to be
an elliptical or parabolic or asymmetrically curved incident-flow
surface.
[0033] An alternative embodiment of the lattice mast according to
the invention is characterized in that the at least one cladding
profile forms a structural unit with at least one angled
profile.
[0034] A structural unit within the sense of the present invention
is understood to mean that the cladding profile and the relevant
angled profile complement each other to form a load-bearing
supporting component.
[0035] The at least one cladding profile can, for example, be
connected to at least one angled profile by means of one or more
types of fastening selected from a group comprising adhesive
bonding, riveting, welding, clamping, fastening with Velcro,
binding, screwing, stapling, or foaming. Combinations of these
types of fastening are also possible. For example, a cladding
profile can be adhesively bonded to the relevant angled profile,
but at the same time the latter can also additionally be fastened
by means of straps, bands or the like which are tensioned around
the angled profile and the cladding profile.
[0036] In an advantageous embodiment of the invention, it is
provided that the at least one cladding profile complements the
angled profile to form a closed profile cross-section. It can, for
example, be understood that the cladding profile closes or covers
only one open side of an angled profile.
[0037] Instead of the angled profile being complemented to form a
closed profile cross-section, it can also be provided that at least
one cladding profile partially or also completely encloses the
angled profile and forms a closed or approximately closed profile
cross-section. For this purpose, it can for example be provided
that the cladding profile comprises multiple elements which are
connected to one another via a hinge, for example a film hinge.
[0038] It can alternatively be provided that multiple cladding
profiles form a closed or approximately closed profile
cross-section which at least partially encloses the angled profile.
These cladding profiles can, for example, be detachably connected
to one another, but alternatively they can be fastened to the
angled profile, for example in a partially overlapping manner, by
means of clamping elements which grip around the angled profile. In
a preferred and advantageous alternative embodiment of the
cladding, it is provided that multiple cladding profiles complement
one another to form a closed or approximately closed spherical or
ellipsoidal cross-section. The profile cross-section formed by one
or more cladding profiles can completely enclose the angled
profile. This profile cross-section does not have to have a
symmetrical design and instead the cladding profiles can also form
an asymmetrically ellipsoidal cross-section.
[0039] This can be achieved for example by two cladding profiles,
which are designed as shell-like profile segments, being provided
with different radii of curvature, wherein one cladding profile
with a first radius of curvature and a second cladding profile with
a second radius of curvature complement each other to form a closed
profile cross-section and enclose the angled profile, wherein the
first radius of curvature is preferably smaller than the second
radius of curvature, and the first radius of curvature surrounds
the exposed edge to be shielded of the angled profile.
[0040] If the angled profile to be clad is, for example, an angled
profile with two profile legs and a vertex, the vertex can be
shielded by a first cladding profile with a first small radius of
curvature, whereas the open side of the angled profile is shielded
by a second cladding profile with a second larger radius. In this
way, an incident-flow side is defined by the first angled profile,
via which incident-flow side an air flow is led out over the free
ends of the legs of the angled profile.
[0041] The at least one or more cladding profiles are, as
mentioned, designed as shell-like profile segments, or
alternatively, in particular when it is intended for the cladding
profile or profiles in each case to form a complement to the
profile cross-section of the angled profile, they can be also
designed as solid profiles.
[0042] The shell-like profile segments can be arranged spaced apart
from the relevant angled profile; for example, the shell-like
profile segments can be mounted via webs at a distance from the
angled profile.
[0043] In the invention, it is provided that at least one or more
cladding profiles are back-foamed, wherein the foam simultaneously
provides a means of adhesion with respect to the relevant angled
profile.
[0044] The at least one or more cladding profiles can also be
designed as shell-like profile segments, the free edges of which
are extended by fringes, fibers, or perforated profiles. In
particular as a result of such a design of profile legs, it is
possible to prevent the formation of turbulence at the free ends of
the profile legs, as a result of which a relatively favorable
aerodynamic effect is also obtained.
[0045] According to a further aspect of the invention, a method for
increasing the stability of lattice masts with an open framework
structure of angled profiles, in particular of electricity pylons
or telecommunications masts, using at least one cladding profile is
provided, wherein the method comprises the cladding of at least one
angled profile with at least one cladding profile which has at
least one at least approximately spherically curved or facetted
incident-flow surface in such a way that at least one wind-exposed
edge of the angled profiles is shielded by the relevant cladding
profile, wherein the angled profile is complemented or clad to form
an essentially closed or approximately closed, at least partially
and at least approximately round or facetted profile
cross-section.
[0046] The method is preferably characterized by a subsequent
upgrading of a lattice mast to form an aerodynamically clad lattice
mast with one of the abovedescribed features.
[0047] In an advantageous alternative embodiment of the method
according to the invention, the cladding profiles, in particular
those which are designed as a structural unit with an angled
profile, are connected at node points of the framework structure so
that they overlap the angled profiles and/or to one another in a
force-fitting, interlocking, or bonded manner, for example by
adhesive bonding, plugging together, clamping, bolting, or
screwing. In this way, the entire supporting function of the
original framework structure can be replaced by an exoskeleton made
from the cladding profiles.
[0048] In such an alternative embodiment of the method, the
cladding profiles are preferably connected to one another and/or to
the angled profiles only at the node points of the framework
structure.
[0049] Different alternative embodiments of the aerodynamic
cladding of lattice masts were described above, wherein the
abovedescribed alternative embodiments of the cladding can be
applied in combination on a single lattice mast.
[0050] Within the scope of the invention, the aerodynamic cladding
of all the profiles and profile struts of the framework structure
is possible, wherein, as also indicated above, also only parts of
this lattice mast or also only nodes of the framework can be clad
correspondingly.
[0051] The cladding profiles can be formed both as individual
profile shell segments and as individual solid profile elements or
from multiple profile segments which are connected inseparably to
one another.
[0052] The method preferably comprises the fastening of the
cladding profiles to the lattice mast with a framework structure
with the aid of at least one climbing robot.
DESCRIPTION OF THE DRAWINGS
[0053] The invention is explained below with the aid of an
exemplary embodiment shown in the drawings, in which:
[0054] FIG. 1 shows a schematic view of a lattice mast as an
overhead transmission mast for holding overhead electricity
transmission lines,
[0055] FIG. 2 shows a cross-section through a corner support of the
lattice mast shown in FIG. 1, with an aerodynamic cladding
according to the invention according to a first alternative
embodiment, and
[0056] FIG. 3 shows a section through a corner support of the
lattice mast shown in FIG. 1, with an aerodynamic cladding
according to a second alternative embodiment according to the
invention in an exploded view.
DETAILED DESCRIPTION
[0057] The lattice mast 1 in FIG. 1 is designed as a conventional
open steel framework construction with four corner supports 2 which
in the present case are designed as open angled profiles 3 with two
legs 4 of equal length and a vertex 10.
[0058] As can be seen in FIG. 1, in the region where it is erected
the lattice mast occupies a relatively large footprint, and the
four corner supports 2 of the lattice mast 1 converge in the
direction of the mast tip 5. In each case, two corner supports 2
form, together with cross-struts 6, trapezoidal panels of a mast
stage. Each mast stage is overall described by four trapezoidal
panels, and multiple mast stages extend vertically from the base of
the lattice mast 1 to its mast tip 5. The individual panels of the
stages of the lattice mast 1 are designed as framework structures
with diagonally extending struts which act as pressure rods or
tension rods depending on the magnitude of the transverse loading
of the lattice mast 1. The lattice mast 1 owes its shape, which
tapers toward the mast tip 5, to the expected bending stress on the
lattice mast 1 due to wind load and due to the bearing load of the
lines. The lines 7 are suspended from mast cross-arms 8 in a known
fashion. The geometry of the mast cross-arms 8 is adapted to the
expected bending moment distribution resulting from the weight of
the lines 7.
[0059] A view in section of a corner support 2 of the lattice mast
1 as an angled profile 3 within the sense of the present
application is shown in FIG. 2, which illustrates a first exemplary
embodiment according to the invention.
[0060] The cross-struts 6 provided on the lattice mast 1, the
diagonal struts provided on said cross-struts, and other structural
elements can likewise be clad in a corresponding aerodynamic
fashion as angled profiles within the sense of the invention.
[0061] Two cladding profiles, a first cladding profile 9a of which
is designed as a profile shell segment with a first radius of
curvature and a second cladding profile 9b of which is designed as
a second profile shell segment with a second radius of curvature,
are fastened at the corner support 2 as aerodynamic cladding.
[0062] Both the first cladding profile 9a and the second cladding
profile 9b can be designed, for example, in the form of plastic
shells which can be adhesively bonded, screwed, riveted, stapled,
or otherwise connected to the angled profile 3. The first cladding
profile 9a is designed as a curved profile shell with a first
smaller radius of curvature, whereas the second cladding profile 9b
is likewise designed as a curved profile shell with a second larger
radius of curvature. Both cladding profiles 9a and 9b completely
enclose the angled profile and form a closed, asymmetrically
ellipsoidal cross-section.
[0063] The first cladding profile 9a forms an incident-flow surface
which shields and surrounds the vertex 10 of the symmetrically
designed angled profile 3. The first cladding profile 9a is
connected to the symmetrical angled profile 3, or fastened to the
latter, in the region of the ends of the legs 4 of said symmetrical
angled profile 3. The second cladding profile 9b, which clads and
shields that open side of the angled profile 3 which is opposite
the vertex 10, has a relatively larger radius of curvature and is
likewise fastened to the angled profile 3 in the region of the ends
of the legs 4 of the angled profile 3.
[0064] In the exemplary embodiment shown in FIG. 2, flow shielding
of the vertex 10 is primarily provided, and the first cladding
profile 9a is accordingly arranged symmetrically with respect to
the vertex 10 and forms the windward side of the flow profile,
whereas the second cladding profile 9b forms the lee side.
[0065] In the drawings, the cladding enclosing as a whole the
angled profile 3 is designed as closed, but the invention is to be
understood such that the profile surface does not need to be
completely closed and instead it can also be designed to be only
partially closed on the lee side (second cladding profile 9b).
[0066] As can also be seen in particular in the drawing in FIG. 2,
the maximum diameter of the first cladding profile 9a and hence of
the whole clad profile cross-section is greater by a factor of 1.2
than a diagonal which connects the ends of the legs 4 of the angled
profile 3. In other words, the projected area of the completely
clad angled profile 3 is greater by a factor of 1.2 than the
projected area of the unclad angled profile 3.
[0067] In the alternative embodiment of the aerodynamic cladding
shown in FIG. 3, a first cladding profile 9a and a second cladding
profile 9b are likewise provided which are each designed as solid
profiles which are likewise connected to the legs 4 of the angled
profile 3 in a form-fitting or bonded manner. The cladding profiles
9a, 9b according to the second exemplary embodiment complement the
symmetrical angled profile 3 to form an asymmetrically elliptical
profile which is similar to a round cross-section.
LIST OF REFERENCE NUMERALS
[0068] 1 lattice mast
[0069] 2 corner supports
[0070] 3 angled profiles
[0071] 4 legs
[0072] 5 mast tip
[0073] 6 cross-struts
[0074] 7 lines
[0075] 8 mast cross-arms
[0076] 9a first cladding profile
[0077] 9b second cladding profile
[0078] 10 vertex
* * * * *