DE102014001893A1 - Aerodynamic cladding on truss structures as well as methods for increasing the stability of truss structures - Google Patents

Abstract

The invention relates to an aerodynamic cladding on truss structures with angle profiles, comprising at least one or more cladding profiles (9a, 9b) extending over at least a partial length of at least one angle profile (3), wherein at least one cladding profile has a curved inflow surface and a flow shading of a wind exposed Edge of the angle profile (3) forms, wherein the inflow surface is at least approximately spherically curved and has a Strömungswiderstandsbeiwert smaller than that of the unshaded angle profile (3).

Description

The invention relates to an aerodynamic cladding on truss structures with angle profiles, in particular on steel truss structures.

The invention further relates to a method for increasing the stability of framework structures, in particular on open steel truss structures with angle profiles, such as lattice masts or bridges, pylons or the like.

An open truss structure in the sense of the present invention is to be understood as a truss structure whose struts are not provided with infills.

The aerodynamic fairing according to the present invention is intended for open truss structures with angle profiles.

Angle profiles comprehensive framework structures have the advantage that they are particularly lightweight and the individual profile struts are relatively easy to connect to each other, for example, by riveting, welding or screwing.

Truss structures of the type mentioned above are used, for example, as lattice masts for receiving electrical transmission lines. Such lattice towers are usually constructed from a series of superimposed structural elements, each step forming a truss structure having three or more trapezoidal truss panels, each consisting of mutually braced corner posts. The corner supports are designed as angle profiles, these connecting struts can also be partially formed as angle profiles, in part also as tab profiles.

The design of such framework structures is usually subordinated to the requirements of the load and the wind load acting on the structure.

The design or dimensioning of the truss structure forming components on the one hand depends on the free buckling length of the individual elements in this prevailing tensile stress or compressive stress and on the other hand by the interaction of longitudinal forces and lateral forces, which are registered for example by wind loads in the building.

For the stabilization of lattice structures or truss structures of this type, numerous strut systems are known which are optimized with regard to the arrangement of the truss struts and with regard to the total weight of the lattice structure. Such a system is for example in the GB 675,859 A described.

When constructing new truss structures, the optimal design of truss structures for expected wind load and payload is usually relatively unproblematic in terms of weight optimization. In existing truss structures, such as existing lattice towers for electrical power lines, it may be necessary from time to time to repair and / or renew parts of the construction. This may require new proof of strength. Existing systems may not meet increased stability requirements, in particular because of increased load requirements or because of expected over a longer life structural weakening.

In such cases, an elaborate upgrade of existing framework structures may be required.

The invention has for its object to provide appropriate means and a suitable method for upgrading existing framework structures.

This object is achieved in particular by the features of claim 1 and by the features of claim 11. Preferred variants of the aerodynamic fairing provided according to the invention on a truss structure and of the method according to the invention for increasing the stability of truss structures result from the subclaims.

An aerodynamic cladding on a truss structure in the sense of the invention is to be understood in particular as the truss structure with an aerodynamic cladding.

According to one aspect of the invention, an aerodynamic fairing is provided on truss structures having angle profiles, particularly steel truss structures comprising at least one or more fairing profiles extending over at least a partial length of at least one angle profile, at least one fairing profile having an inflow area and a flow shutoff of a wind exposed edge forms the angle profile, wherein the inflow surface has a Strömungswiderstandsbeiwert which is smaller than that of the unshaded angle profile.

Preferably, the inflow surface is at least approximately spherically curved or has a polygonal or faceted contour, which is approximated to a spherical or elliptical arc contour. "Faceted" in the sense of the invention is to be understood as meaning a polygonal surface which approximates to an arc contour.

For the purposes of the present invention, an angle profile means, for example, a T-profile, L-profile, I-profile, Z-profile, U-profile, C-profile or the like.

The invention makes use of the fact that the wind load on a building is determined from the product of a reference pressure with a drag coefficient and the exposed surface of the building. The reference pressure depends on the air density and the wind speed. The flow resistance coefficient describes the characteristic of the wind flow around a structural element of the relevant truss structure, for example, an angle profile. Sharp edges of a profile tend to create turbulence and are therefore more susceptible to wind loads than faceted or rounded edges or round or tubular profiles. For example, an octagon has a drag coefficient of Cw = 1.3 versus a drag coefficient of Cw = 2.0 for sharp-edged angle profiles. When the flow rate of an initially laminar flowing fluid is increased, the characteristic of the flow changes from laminar to indifferent and then too unstable, so that the initially ordered flow changes to a wavy state. This significantly increases the drag coefficient. At sharp profile edges, the drag coefficient Cw (dimensionless) may be on the order of about 2.0, while for round members or, for example, spherical members as well, it may be between about 0.176 and 0.48, depending on the Reynolds number. With very large Reynolds numbers, the resistance coefficient of a sphere increases, whereas it can assume low values at relatively low Reynolds numbers.

The invention makes use of these and per se known fluidic relationships. By providing a corresponding fairing to truss structures with angle profiles, the drag coefficient of at least some of the exposed angle profiles can be significantly reduced, thereby also significantly reducing the wind load on the structure. In the simplest case, this can be achieved, for example, by shading at least one exposed critical edge of an angle profile with a lining profile, wherein the lining profile has a rounded or curved inflow surface. In a tower construction or a lattice mast, for example, it may be provided to shade all or some corner supports or corner profiles by means of corresponding covering profiles. This fairing profiles, for example, be attached only over part lengths of the respective angle profiles with this and shade the angle profiles each only over a partial length. It is also possible within the scope of the invention to clad only the nodes of the framework accordingly.

According to a further aspect of the present invention, the cladding profiles along the cladded angle profile with variable cross-sections can be designed so as to prevent possible vortex excitations, or to optimize the aerodynamic damping.

In a lattice mast structure, for example, the relevant trim profile can be arranged so that it shadows the vertex of an angle profile, which forms an isosceles triangle, for example, in cross section.

In a lattice mast structure with three or four corner columns, the construction is usually chosen so that the corner posts are formed as angle sections with substantially isosceles cross-section, with the vertices of the respective angle profiles facing outward. Cladding these vertexes results in a significant reduction in wind load.

Conveniently, the curved inflow surface of at least one trim profile is arranged symmetrically to the relevant profile edge.

Lightweight plastic, aluminum or steel profiles come into consideration as the trim profile, these can be designed as shell-shaped elements or as solid profiles.

In a preferred variant of the aerodynamic cladding according to the invention, it is provided that the at least one cladding profile has a maximum projection area which is at most 60%, preferably at most 40%, further preferably at most 20% greater than the maximum projection area of the non-clad angle profile. This ensures that the inflow area, which is included in the calculation of the wind load, is not increased compared to the unclad profile so that the advantage of the reduced drag coefficient is thereby completely consumed.

For example, in a cladding profile with an approximately circular arc inflow, the diameter of the relevant cladding profile may be a maximum of 20% greater than the diagonal of an angle profile formed as a corner profile.

Under an approximately spherically curved inflow in the context of the present invention, an elliptical or parabolic or asymmetrically curved inflow is to be understood.

A variant of the aerodynamic fairing according to the invention is characterized in that the at least one fairing profile with at least one angle profile forms a structural composite.

Under a structural composite in the context of the present invention is to be understood that the cladding profile and the respective angle profile complement each other to a load-bearing, supporting component.

The at least one trim profile can be connected, for example, by means of one or more types of fastening selected from a group comprising gluing, riveting, welding, clamping, burying, binding, screwing, stapling or foaming with at least one angle profile. Combinations of these types of attachment are also possible. For example, a trim profile can be glued to the relevant angle profile, but at the same time this can also be secured by means of clamps, bandages or the like, which span the angle profile and the trim profile, in addition.

In an advantageous embodiment of the invention, it is provided that the at least one trim profile supplements the angle profile to form a closed profile cross-section. By this may be understood, for example, that the trim profile closes or covers only an open side of an angle profile.

Instead of supplementing the angle profile to a closed profile cross-section, provision may also be made for at least one trim profile to partially or completely surround the angle profile and form a closed or approximately closed profile cross-section. For this purpose, it may be provided, for example, that the cladding profile comprises a plurality of elements connected to one another via a hinge, for example a film hinge.

Alternatively it can be provided that a plurality of cladding profiles form a closed or approximately closed, the angle profile at least partially enclosing profile cross-section. These cladding profiles can for example be releasably connected to each other, alternatively they can be secured in this example, partially overlapping manner by means of clamping elements, the angle profile encompassing this. In a preferred and advantageous variant of the cladding is provided that a plurality of cladding profiles complement each other to a closed or approximately closed spherical or ellipsoidal cross-section. The profile cross-section formed by one or more trim profiles can completely enclose the angle profile. This profile cross-section does not have to be symmetrical, but the cladding profiles can also form an asymmetrical ellipsoidal cross-section.

This can be achieved, for example, by providing two cladding profiles, which are designed as shell-shaped profile segments, with different radii of curvature, one cladding profile having a first radius of curvature and a second cladding profile having a second radius of curvature complementing one another to form a closed profile cross section and enclosing the angle profile, wherein the first radius of curvature is preferably smaller than the second radius of curvature and the first radius of curvature encloses the exposed and shaded edge of the angle profile.

For example, if the angle profile to be covered is an angle profile with two profile legs and an angle peak, the angle peak may be shadowed by a first trim profile having a first small radius of curvature, whereas the open side of the angle profile is shadowed by a second fairing profile having a second larger radius. In this way, an inflow side is defined by the first angle profile, over which an air flow is carried over the free ends of the legs of the angle profile.

The at least one or the cladding profiles may, as mentioned, be designed as shell-shaped profile segments, alternatively, in particular if the cladding profiles or the cladding profiles are each intended to complement the profile cross-section of the angle profile, these may also be formed as solid profiles.

In a preferred variant of the invention it is provided that at least one or the cladding profiles are foam-backed with rigid foam, wherein the hard foam simultaneously provides an adhesion to the respective angle profile.

The at least one or the cladding profiles can also be designed as shell-shaped profile segments whose free edges are extended by fringes, fibers or hole profiles. In particular, by such a design of profile legs, it is possible to prevent vortex formation at the free ends of the profile legs, whereby also a relatively favorable aerodynamic effect is achieved.

According to another aspect of the invention, there is provided a method for increasing the stability of truss structures on open steel trusses having angled profiles, such as lattice masts or bridges, the method comprising lining at least some of the angle profiles with trim profiles having at least one at least approximately spherically curved or faceted inflow surface such that at least one wind-exposed edge of the angle profiles is shaded by the respective trim profile, wherein the angle profile is at least partially supplemented or cladded to a substantially closed or approximately closed at least partially and at least approximately round or faceted profile cross-section.

The method is preferably characterized by a subsequent upgrading of a truss structure to an aerodynamically clad framework structure with one of the features described above.

In an advantageous variant of the method according to the invention, the cladding profiles, in particular those which are designed as a structural composite with an angle profile, at nodes of a truss structure or nodes of the truss structure across the angle profiles and, or with each other positively, positively or materially connected, for example by gluing, Insert, clamp, bolt or bolt. In this way can be replaced by an exoskeleton of the cladding profiles, the entire support function of the original framework structure.

In such a variant of the method, the trim profiles are preferably connected to each other and / or with the angle profiles only at the nodes of the truss structure.

In the foregoing, various variants of the aerodynamic cladding on truss structures have been described, with the previously described cladding variants being applicable to a single structure in combination.

In the context of the invention, the aerodynamic cladding of all profiles and profile struts on a truss or lattice structure is possible, wherein, as also indicated above, only parts of this lattice structure or even nodes of the framework can be clad accordingly.

The cladding profiles can be formed both as individual profile shell segments as well as individual solid profile elements or from several inseparably interconnected profile segments.

The method preferably comprises the attachment of the trim profiles to a structure with a truss structure using at least one climbing robot.

The invention will be explained below with reference to an embodiment shown in the drawings.

Show it:

1 a schematic representation of a lattice mast as a transmission line mast for receiving electrical transmission lines,

2 a cross section through a corner support of in 1 illustrated lattice mast with an aerodynamic fairing according to the invention according to a first variant and

3 a section through a corner support of in 1 illustrated lattice mast with an aerodynamic fairing according to a second variant according to the invention as an exploded view.

The lattice mast 1 in 1 is as a conventional open steel framework construction with four corner columns 2 formed in the present case as open angle profiles 3 with two legs of equal length 4 and an angle vertex 10 are formed.

The lattice mast is described here, for example, as a truss structure with angle profiles, in particular for an open steel truss structure, as already mentioned, the invention is to be understood that as truss structures and bridge structures, pylons or similar structures may be provided.

Again 1 can be seen, takes the lattice mast in the field of its establishment a relatively large footprint to complete, the four corner supports 2 of the lattice mast 1 converge towards the mast top 5 , Two corner supports each 2 make up together with cross struts 6 trapezoidal fields of a mast step. Each mast level is described in total by four trapezoidal fields, several mast steps extend in height from the base of the lattice mast 1 to the mast top 5 , The individual fields of the steps of the lattice mast 1 are designed as truss structures with diagonal struts, depending on the height of the transverse load of the lattice mast 1 act as pressure rods or as tension rods. Towards the direction on the mast top 5 slimming form of the lattice mast 1 is the expected bending stress of the grid mast 1 due to wind load and due to the load of the lines owed. The wires 7 are in a known manner to mast boom 8th suspended. The geometry of the mast boom 8th is in a known manner the expected bending moment course due to the weight of the lines 7 customized.

In 2 , which illustrates a first embodiment according to the invention, is a sectional view of a corner support 2 of the lattice mast 1 as an angle profile 3 shown in the context of the present application.

The on the lattice mast 1 provided cross struts 6 , the diagonal struts provided on this and other construction elements can also be aerodynamically clad according to the invention as angle profiles.

At the corner support 2 are attached as aerodynamic cladding two cladding profiles, of which a first cladding profile 9a as a profile shell segment with a first radius of curvature and a second trim profile 9b is formed as a second profile shell segment with a second radius of curvature.

The first cladding profile 9a such as the second panel profile 9b may be formed, for example, in the form of plastic shells, with the angle profile 3 glued, screwed, riveted, stapled or connected in any other way. The first cladding profile 9a is formed as a curved profile shell with a first smaller radius of curvature, whereas the second panel profile 9b is also formed as a curved profile shell with a second larger radius of curvature. Both cladding profiles 9a and 9b completely enclose the angle profile and form a closed, asymmetrical ellipsoidal cross-section.

The first cladding profile 9a forms an inflow surface, which is the angle vertex 10 the symmetrically formed angle profile 3 shadows and surrounds. The first cladding profile 9a is in the area of the ends of the thighs 4 the symmetrical angle profile 3 connected to the latter, or attached to the latter. The second panel profile 9b that's the angle crest 10 opposite open side of the angle profile 3 clad and shaded, has a relatively larger radius of curvature and is also in the region of the ends of the legs 4 the angle profile 3 attached to this.

At the in 2 illustrated embodiment is primarily a Strömungsabschattung the angle vertex 10 provided, the first cladding profile 9a is accordingly with respect to the angle vertex 10 symmetrically arranged and forms the windward side of the airfoil, whereas the second fairing profile 9b forming the lee side.

In the drawing, the total is the angle profile 3 However, the invention is understood to mean that the profile surface does not have to be completely closed, but rather, this can also on the leeward (second fairing profile 9b ) may be formed only partially closed.

As in particular the picture in 2 it can be seen, is the maximum diameter of the first trim profile 9a and thus the entire clad profile cross-section by a factor of 1.2 greater than a diagonal, the ends of the legs 4 the angle profile 3 combines. In other words, the projecting area of the fully clad angle profile 3 is 1.2 times larger than the projected area of the non-clad angle profile 3 ,

At the in 3 illustrated variant of the aerodynamic fairing are also a first trim profile 9a and a second panel profile 9b provided, which are each formed as solid profiles, which also with the legs 4 the angle profile 3 are positively connected or materially connected. The panel profiles 9a . 9b according to the second embodiment supplement the symmetrical angle profile 3 to an asymmetrical elliptical, approximate to a round cross-section profile.

LIST OF REFERENCE NUMBERS

1

lattice boom

2

corner posts

3

angle sections

4

leg

5

mast top

6

crossbars

7

cables

8th

Mastausleger

9a

first panel profile

9b

second panel profile

10

angle point

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• GB 675859A [0009]

Claims (14)

Aerodynamic cladding on truss structures with angle profiles, in particular on steel truss structures, comprising at least one or more cladding profiles 9a . 9b which extends over at least a partial length of at least one angle profile ( 3 ), wherein at least one trim profile ( 9a . 9b ) has an inflow surface and a Strömungsabschattung a wind-exposed edge of the angle profile ( 3 ), wherein the inflow surface has a flow resistance coefficient which is smaller than that of the unshaded angle profile (FIG. 3 ). Aerodynamic fairing according to claim 1, characterized in that the inflow surface is at least approximately spherically curved or has a polygonal contour, which is at least approximated to a spherical or elliptical arc contour. Asymmetrical cladding according to claim 1 or 2, characterized in that the curved inflow surface of the at least one cladding profile ( 9a . 9b ) is arranged symmetrically to the edge. Aerodynamic fairing according to one of claims 1 to 3, characterized in that the at least one fairing profile ( 9a . 9b ) has a maximum projection area which is at most 60%, preferably at most 40%, more preferably at most 20% greater than the maximum projection area of the non-clad angle profile (FIG. 3 ). Aerodynamic fairing according to one of claims 1 to 4, characterized in that the at least one fairing profile ( 9a . 9b ) with at least one angle profile ( 3 ) forms a structural composite. Aerodynamic fairing according to one of claims 1 to 5, characterized in that the at least one fairing profile ( 9a . 9b ) by means of one or more types of fastening selected from a group comprising gluing, riveting, welding, clamping, burying, binding, screwing, stapling or foaming on at least one angle profile ( 3 ) is attached. Aerodynamic fairing according to one of claims 1 to 6, characterized in that several cladding profiles ( 9a . 9b ) over nodes of a truss structure with each other and / or with at least one angle profile ( 3 ) of the framework are connected forming a structural composite. Aerodynamic fairing according to one of claims 1 to 7, characterized in that the at least one fairing profile ( 9a . 9b ) the angle profile ( 3 ) to a closed profile cross-section. Aerodynamic fairing according to one of claims 1 to 7, characterized in that several cladding profiles ( 9a . 9b ) form a closed or approximately closed, the angle profile at least partially enclosing profile cross-section. Aerodynamic fairing according to one of claims 1 to 9, characterized in that a plurality of fairing profiles ( 9a . 9b ) are complementary to a closed or approximately closed spherical or elliptical cross-section. Aerodynamic fairing according to one of claims 1 to 10, characterized in that the at least one or the fairing profiles ( 9a . 9b ) are formed as cup-shaped profile segments and that preferably the at least one or the trim profiles ( 9a . 9b ) is backfoamed with hard foam. Aerodynamic profile according to claim 11, characterized in that at least one shell-shaped profile segment comprises profile legs, wherein at least one free end of at least one profile limb is frayed or has bands or holes or at least one additional hole profile, which reduce the flow resistance and / or increase the aerodynamic damping. A method for increasing the stability of truss structures, in particular on open steel truss structures with angle profiles, in particular lattice masts or bridges, comprising the cladding at least some of the angle profiles with cladding profiles having at least one at least approximately spherically curved inflow surface, such that at least one wind exposed edge of the angle profiles of the Shade profile is shaded, and that the angle profile is at least partially supplemented or cladded to a substantially closed or approximately closed, at least partially round or faceted profile cross-section. A method according to claim 13, characterized by a subsequent upgrading of a truss structure to an aerodynamically clad framework structure according to one of claims 1 to 12.

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