CN103790427A - Steel tube component connecting structure capable of restraining vortex-induced vibration - Google Patents

Abstract

The invention relates to a steel tube component connecting structure capable of restraining vortex-induced vibration. The connecting structure is applicable to the connecting node of the connecting rod of a power transmission tower in a normal-wind-speed environment. An inserting board is disposed at the end of the connecting rod. The connecting rod is connected to the connecting node of the power transmission tower through the inserting board. The inserting board is asymmetrical in section bending rigidity. The major axis of the section of the inserting board is parallel with the wind blowing direction. Compared with the prior art, the steel tube component connecting structure has the advantages that by the asymmetrical section bending rigidity of the inserting board, maximum bending rigidity in the transverse wind direction is guaranteed, stable vortex-induced vibration of steel tube components can be avoided, fatigue damage caused by repeated vibration is reduced, and the steel tube component connecting structure is feasible in engineering, economical and energy saving.

Description

A kind of steel tube component syndeton that suppresses vortex-induced vibration

Technical field

The present invention relates to power transmission steel pipe tower structure, especially relate to the steel tube component syndeton that can suppress vortex-induced vibration in a kind of Transmission Tower.

Background technology

Under normal wind speed, power transmission tower steel tube component beam wind is subject to Karman vortex street control to vibration, beam wind easily occurs to vibration repeatedly, be vortex-induced vibration, when stable vortex-induced vibration occurs repeatedly steel tube component, easily there is fatigue failure in the weld seam of Nodes, the easy loose or dislocation of bolt, causes structural failure.In Transmission Tower work progress, conventionally adopt the mode joint steel pipe members such as single plate, U-shaped plate, cross plug board and flange.For single plate, U-shaped plate, generally by plate horizontal positioned to facilitate installation, but show through case history and correlative study, there is larger defect in this kind of node, very easily causes steel tube component generation vortex-induced vibration phenomenon.

In power industry standard, the regulation that suppresses vortex-induced vibration is limited, and lacks practicality.China's industry standard " delivery designing technique regulation " regulation " the starting of oscillation critical wind velocity of steel tube component; can be tried to achieve by equal diameter steel pipe starting of oscillation critical wind velocity curve (first vibration mode) according to the slenderness ratio of steel tube component and two ends connection, generally be not less than 15m/s ".According to the method for designing of power transmission tower, structure adopts truss model, and rod member two ends are hinged joint, and according to afore mentioned rules, steel tube component slenderness ratio can not exceed 87, and the design length that to a certain degree limits steel tube component prevents vortex-induced vibration.This restriction is too harsh, and steel tube component can not be brought into play own performance advantage, and increases tower weight, the economy requirement of having run counter to line construction.External standard there is no the concrete clause that calculates steel tube tower vortex-induced vibration, and Britain's specifications recommend should be carried out pre-anti-resonance with the measure of aerodynamics component structure to the structure that may exceed critical wind velocity.Standard clause is not for referencial use clearly, and in engineering design, vortex-induced vibration problem cannot accurately be considered.

The Yang Jing of China Electric Power Research Institute ripple etc. (Yang Jingbo, Dai Zebing, Li Qinghua. the rod end constraint of typical node construction steel pipe component and determining of starting of oscillation critical wind velocity. power construction, 2006,27 (4): 37-40; Yang Jingbo, Lee just, Wang Jingchao. UHV transmission line steel tube tower aeolian vibration control. power construction, 2008,29 (9): 10-13) some research work have also been carried out, propose that spirality cringle, short rib etc. are set on steel pipe and reduce member vortex-induced vibration, and carried out wind tunnel test.But these classical oscillation damping methods cannot be used in engineering design, can only serve as the vortex-induced vibration control of means to save the situation for existing structure.

Summary of the invention

Object of the present invention is exactly to provide a kind of steel tube component syndeton that suppresses vortex-induced vibration in order to overcome the defect that above-mentioned prior art exists, this syndeton is utilized plate cross section bending rigidity asymmetry, guarantee beam wind to bending rigidity maximum, can make steel tube component that stable vortex-induced vibration does not occur, reduce repeatedly to vibrate the fatigue damage causing, there is engineering feasibility and economical and energy saving.

Object of the present invention can be achieved through the following technical solutions:

A kind of steel tube component syndeton that suppresses vortex-induced vibration, this syndeton is applied to the connected node of power transmission tower connecting rod under normal wind speed environment, the end of connecting rod is plate, be connected to by plate on the connected node of power transmission tower tower body, plate is the asymmetric plate of cross section bending rigidity, and what the strong axle in plate cross section was parallel to wind carrys out flow path direction setting.

Described plate is single plate or U-shaped plate, on the plate cross section of this form, and down wind bending rigidity minimum, beam wind is to bending rigidity maximum, and therefore the inhibition of vortex-induced vibration is the most obvious.

Compared with prior art, the present invention utilizes plate cross section bending rigidity asymmetry, guarantee beam wind to bending rigidity maximum, can make steel tube component that stable vortex-induced vibration does not occur, reduce repeatedly to vibrate the fatigue damage causing, compared with reducing the slenderness ratio of steel tube component in traditional design thinking, there is higher engineering feasibility and economical and energy saving.

Accompanying drawing explanation

Fig. 1 is the syndeton schematic diagram that the present invention is applied to power transmission tower cross-arm Nodes;

Fig. 2 is the schematic diagram of power transmission tower;

Fig. 3 is the strong axle in plate cross section and the schematic diagram of weak axle, and wherein (a) is single plate, (b) is U-shaped plate;

Fig. 4 is the arrangement diagram of steel tube component vortex-induced vibration wind tunnel test;

Fig. 5 be in Fig. 4 A-A to view;

Fig. 6 be in Fig. 5 B-B to view.

The specific embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.

Embodiment

A kind of steel tube component syndeton that suppresses vortex-induced vibration, this syndeton is applied to the connected node of power transmission tower connecting rod under normal wind speed environment, the end of connecting rod 2 is the asymmetric plate 1 of cross section bending rigidity, be connected to by plate 1 on the connected node 3 of power transmission tower tower body, build power transmission tower as shown in Figure 2.

By wind tunnel test, the vortex-induced vibration inhibition ability of plate pattern is compared.Test adopts the test specimen of seven kinds of different sizes, as shown in table 1 respectively:

Table 1

Wherein S, U, C, F represent that respectively single plate, U-shaped plate, cross plug board are connected with flange, and three bit digital after letter represent test specimen slenderness ratio, the digitized representation connecting bolt number after "-".

As shown in Figure 4, Figure 5 and Figure 6, in test, install by plate 1 on the bearing 8 of rotating disk 5 at steel pipe connecting rod 2, connecting rod 2 cross section midpoint are laid laser displacement gauge 6, be used for measuring connecting rod 2 beam wind to (vertically) displacement response and down wind (level to) displacement response, and acceleration transducer 7 is for measuring down wind acceleration responsive and beam wind to acceleration responsive.

According to vortex-induced vibration theory, due to the asymmetry of eddy current, on steel tube component, produce the lift component of alternation, wind changes within the specific limits to the frequency of steel tube component impact force, the corresponding frequency of impact force amplitude is wind and acts on the frequency of alternating force on cylinder, this frequency is relevant with wind speed and cylinder diameter, and available formula (1) calculates:

$f_s=\mathrm{St}\frac{v}{D}---\left(1\right)$

In formula: f _s-wind acts on the frequency (Hz) of cylinder alternating force

V-wind speed (m/s)

D-cylinder diameter (mm)

St-Si Tuoluoha number (Strouhal number).

Si Tuoluoha number depends on the cylinder body shape being surrounded by fluid, and different bluff sections has different Si Tuoluoha numerical value.Due to object to stream character, flow separation, Vortex Shedding etc. relevant with Reynolds number, therefore Si Tuoluoha number is except relevant with the shape of object, also relevant with Reynolds number.Si Tuoluoha number can obtain by wind tunnel test, and then calculates the Vortex Shedding frequency under its different wind speed according to formula (1).

For peripheral flow, in sub-critical Reynolds number district, it is a metastable numerical value that beam wind is put corresponding reduction speed to peak response.Reduction wind speed is defined as:

v _r＝v/f _nD(2)

The scope of this value is generally 5.5 < v _r< 6.5.Cylinder beam wind is relevant with Skop-Griffin number to vortex-induced vibration peak value, and this parameter-definition is:

S _G＝8π ²St ²ζM ^*(3)

Wherein, ζ is cylinder damping ratio, M ^*for mass ratio,

Cylinder peak swing A _maxratio and S with body diameter D _gpass be:

$\frac{A_{\max }}{D}=\frac{0.385}{{(0.12+S_G^2)}^{1/2}}---\left(4\right)$

Formula (4) can be estimated the maximum amplitude of steel tube component generation vortex-induced vibration thus, and makes comparisons with experimental data, the results are shown in Table 2.

Table 2

Operating mode number	Test specimen numbering	Damping ratio %	SG	Theoretical value Amax/D	Experiment value Amax/D
						1	S140-2	0.55	16.61	2.3173E-02	1.9959E-02
2	S160-2	0.62	18.72	2.0557E-02	2.3951E-02
						3	S180-2	0.40	12.08	3.1856E-02	3.0420E-02
4	S200-2	0.97	29.30	1.3141E-02	3.7270E-02
						5	C200-8	1.27	38.36	1.0037E-02	1.4670E-02
6	F200-4	0.57	17.21	2.2360E-02	2.7029E-02

The hinged member bending in two ends vibrates 1 rank self-vibration circular frequency:

${\mathrm{\&omega;}}_1=\frac{{\mathrm{\&pi;}}^2}{{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00002339866600011.png,HDA00002339866600032.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}\sqrt{\frac{\mathrm{EI}}{m}}---\left(5\right)$

In formula, l is rod member length; E is steel modulus of elasticity, gets 2.06 × 10 ¹¹/ m ²i is second moment of area; M=ρ .A is the quality of rod member unit length, and wherein A is steel tube section area, and ρ is steel density, gets 7850kg/m ³; The radius of gyration in cross section

for steel pipe

d is outer diameter of steel pipes, and d is pipe diameter; Slenderness ratio λ=l/i; Rod member 1 rank natural frequency f ₁=ω ₁/ 2 π.1 rank natural frequency when steel tube member bar two ends are hinged can be expressed as:

${\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HDA00002339866600011.png,HDA00002339866600032.png"\; state="\{\{state\}\}">f</figure-callout>}}_1=\frac{32187}{{\mathrm{\&lambda;}}^2\sqrt{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00002339866600011.png,HDA00002339866600032.png"\; state="\{\{state\}\}">D</figure-callout>}}^2+d^2}}---\left(6\right)$

In formula, D, d, l unit are m.

On formula (6) basis, introduce the adjustment coefficient k of steel tube member bar 1 rank natural frequency with respect to the hinged result in two ends, 1 rank natural frequency of steel tube member bar is got:

${\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HDA00002339866600011.png,HDA00002339866600032.png"\; state="\{\{state\}\}">f</figure-callout>}}_1=\frac{32187}{{\mathrm{\&lambda;}}^2\sqrt{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00002339866600011.png,HDA00002339866600032.png"\; state="\{\{state\}\}">D</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA00002339866600011.png,HDA00002339866600032.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}}\&CenterDot;k---\left(7\right)$

Drawn by formula (7), the steel tube component that single plate is connected with U-shaped plate, 1 rank natural frequency of weak axle approaches the hinged result in two ends, and 1 rank natural frequency of strong axle approaches the affixed result in two ends; 1 rank natural frequency of strong axle is approximately 2 times of weak axle.

The conclusion of above-mentioned wind tunnel test is:

1, connect for asymmetric plate cross section, as single plate and U plate, the strong axle in its cross section and weak axle are as shown in Fig. 3 (a) and Fig. 3 (b).A little less than connecting cross section, axle is parallel to the flow path direction that comes of wind, be that down wind cross section bending rigidity is larger, beam wind to bending rigidity hour, all there is stable beam wind to vibration in the steel tube component of different slenderness ratio, amplitude is larger, beam wind is evenly full to displacement time-history curves, is stable vortex-induced vibration phenomenon; Now down wind response is very little.When the strong axle in cross section is parallel to the flow path direction that comes of wind, beam wind is unstable to vibration amplitude, changes greatlyr, and beam wind is all less to displacement and down wind displacement numerical value, and both approach, and stable vortex-induced vibration does not occur.This be due to down wind bending rigidity hour, rod member is larger in the flexural vibrations of down wind, beam wind to exciting force acting in conjunction under, rod member torsions that bend, is difficult to the stable Across-wind Resonance of Tall effect of generation, i.e. vortex-induced vibration.

2, connecting (as cross plug board, flange connects) for symmetrical section, can there is stable vortex-induced vibration in steel tube member bar.When rod member slenderness ratio is identical, flange type of attachment is simple, and damping ratio is little, and its stable vortex-induced vibration amplitude is slightly larger than cross plug board and connects.

3, the steel tube component being connected with U plate for single plate, 1 rank natural frequency of weak axle approaches the hinged result in two ends, and 1 rank natural frequency of strong axle approaches the affixed result in two ends; 1 rank natural frequency of strong axle is approximately 2 times of weak axle.

Therefore, the present invention adopts single plate or U-shaped plate, what the strong axle in plate cross section was parallel to wind carrys out flow path direction setting, and weak axle carrys out flow path direction setting perpendicular to wind, the syndeton of the power transmission tower cross-arm Nodes of building as shown in Figure 1, down wind cross section bending rigidity minimum, beam wind, to bending rigidity maximum, is now difficult for occurring stable vortex-induced vibration.

Claims (2)

1. one kind can be suppressed the steel tube component syndeton of vortex-induced vibration, this syndeton is applied to the connected node of power transmission tower connecting rod under normal wind speed environment, the end of connecting rod is plate, be connected to by plate on the connected node of power transmission tower tower body, it is characterized in that, described plate is the asymmetric plate of cross section bending rigidity, and what the strong axle in plate cross section was parallel to wind carrys out flow path direction setting.

2. a kind of steel tube component syndeton that suppresses vortex-induced vibration according to claim 1, is characterized in that, described plate is single plate or U-shaped plate.

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