AU629841B2

AU629841B2 - Testing of poles

Info

Publication number: AU629841B2
Application number: AU39091/89A
Authority: AU
Inventors: Krzysztof Jan Deuar
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-08-03
Filing date: 1989-07-31
Publication date: 1992-10-15
Anticipated expiration: 2009-07-31
Also published as: AU3909189A

Description

s by his Patent Attorneys, GRANT ADAMS COMPANY, 11~- ~1111 1 i r- i i. i I-I r r.I; 4I .i -i ;I -r ;^lr 629841 COMMONWEALTH OF AUSTRALIA Patents Act 1990 Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: KRZYSZTOF JAN DEUAR 17 Henderson Road, Burpengary, Queensland, 4505, Australia.

KRZYSZTOF JAN DEUAR GRANT ADAMS COMPANY Patent Trade. Mark Attorneys Level 9 National Mutual Centre 144 Edward Street BRISBANE QUEENSLAND 4000

AUSITRALIA.

0 0 0 *0 0 COMPLETE. SPECIFICATION FOR THE INVENTION ENTITLED "TESTING OF POLES" The following statement is a full description of the invention including the best method of performing it known to the applicant.

Brisb ane secona da Declared at this .s day of u.U. u

TO:

THE COMMISSIONER OF PATENTS.

(IMPORTANT Cross out inapplicable words in the above Form.) 2 THIS INVENTION relates to a method of and apparatus for the testing of poles. (Throughout the specification, the term "poles" shall be used to include electricity, telephone and telegraph poles; fence and retaining wall posts and the like.) Wood rot, bores, termites and other factors operate to reduce the strength, and therefore, the service life of poles. For safety reasons, the strength of the poles must be periodically checked and. the future life of the pole established. As wood rot generally occurs below ground level, a simple visual inspection is not sufficient and mechanical strength tests must be carried out.

Prior to the testing methods and apparatus disclosed in parent Patent Application No 589766, no simple, efficient and reliable test method had been available and so poles. were often replaced well before the end of their effective life. This naturally increases the operating expenses of the electricity authority.

It is- an object of the present invention to provide alternative miethods and apparatus for applying the load to the poles being tested.

It is a preferred object to provide a method 25 for calculating the residual strength of the poles.

Other preferred objects, will become apparent from the following description.

In one embodiment, the present invention *resides in a method for testing a pole including the 30 steps of: applying a preset load to the pole above ground level; measuring the displacement of the pole under the load; and from the applied load and the displacement, Rs )1 3 calculating the residual strength of the pole from predetermined formula(e), tabulated scales, or by a programmed, calculator or computer; wherein: the load is applied by pushing or pulling the load above ground level by a mechanical jack or turnbuckle, pneumatic or hydraulic ram(s) or a winch, being portable, mounted on wheels or vehicles, and the applied load is measured by a load cell or gauge.

In a second embodiment, the preselt invention relates to a method for testing a pole including the steps of: applying a load to the pole above ground level to cause the pole to undergo a preset displacement; measuring the load applied to the pole; and from the applied load and the displacement, Xcalculating the residual strength of the pole from predetermined formula(e), tabulated scales, or by a programmed calculator or computer; wherein: the load is applied by pushing or pulling the load above ground level by a mechanical jack or turnbuckle, pneumatic or hydraulic ram(s) or a winch, being portable, mounted on wheels or vehicles, and the applied load is measured by a load cell or gauge.

In a third embodiment, the present invention resides in a method for testing a pole including the steps of: tcalculating the minimum required strength of the pole including any required safety factors; 30 applying a preset load to the pole above S ground level equivalent to the calculated minimum strength; and observing if the pole withstands the applied load without exceeding a displacement indicating a failure. and so meet the minimum required strength; prdtrie omua() auaedsaeo Ta 4 wherein: the load is applied by pushing or pulling the load above ground level by a mechanical jack or turnbuckle, pneumatic or hydraulic ram(s) or a winch, being portable, mounted on wheela or vehicles, and the applied load is measured by a load cell or gauge.

In a fourth, embodiment, the present invention.

resides in an apparatus for testing a pole including: means to apply a load to the pole above ground level; load cell means to measure the load applied.

to the pole; means to measure the displacement of the pole under the applied load; and means to calculate the residual strength of the pole from the applied load and. the displacement; wherein: the load is applied by pushing or pulling the load above ground level by a mechanical jack or turnbuckle, pneumatic or hydraulic ram(s) or a winch, being portable, mounted. on wheels or vehicles, and the applied load is measured by a load cell or gauge.

The applied load is, preferably measured by a load cell or other suitable equivalent means.

25 The displacement of the pole in both deflection and rotation as well as deformation of the pole is preferably measured and this. may be effected by displacement gauges mounted on a reference frame, strain *gauges or the like.

30 The applied loads, displacements and deformations of the pole may be recorded manually or automatically by the use of any suitable computer system.

Stability of the pole in case of its failure can be provided by a safety frame, safety rope or safety at~ *A-i clamps mounted to the boom of the crane, of the pole testing vehicle or other heavy equipment.

The excessive movement of the pole at ground level is limited by a chain, rope, frame, bar or clamps.

connected to the pole testing equipment or other heavy -and stable machinery and objects such as concrete blocks, adjacent trees or the like.

The residual strength and other test parameters may be calculated from predetermined formula(e) or tabulated scales or be fed into a programmed, calculator or computer.

To enable the invention to be fully understood, preferred embodiments will now be described with reference to the accompanying drawings, in which: FIG 1 is a schematic view showing a pole being tested under a preset applied load; FIG 2 is a diagram showing an invented arrangement of dial gauges to predict accurately the residual strength of substantially decayed poles; and FIG 3 is a view of the apparatus for proof loading of standing poles.

Referring to FIG 1, the residual strength of the pole 10 is measured by the displacement of the pole under a preset applied load of, eg. 100 N.

25 A specially designed boom 11 is a part of a crane 12 powered by a hydraulic unit 13 mounted on a test vehicle 14. A load cell 15 electrically connected to the computer processing unit 16 measures the load :.'iapplied to the pole 10 or otherwise the load is 30 calculated directly from the pressure exerted in the hydraulic power unit 13. If necessary, the. load is further resolved by a computer 16 into its horizontal and vertical components.

Safety clamps 17 are mounted at the end of the boom 11 to support the pole both in horizontal and 6 vertical direction should the pole fall under the applied, load.

An adjustable length chain 19 is connected to a lowered frame 18 mounted to the test vehicle 14 to prevent the. pole. 10 from excessive horizontal movement at ground level.

A reference frame 20 provides a base for a plurality of, spaced displacement gauges 21 which are.

releasably attached to the pole The displacement of the pole 10 is recorded manually or electronically from the displacement gauges 21 mounted on the reference frame 20 or directly from the hydraulic power unit if the pole deflection is measured at the, boom .11 level.

The residual strength of the pole 10 is calculated by feeding the applied load and displacement data into a programmed- computer or preferably it can be computed and displayed automatically by the computer processing unit 16. The computer 16 also calculates the minimum required strength for the pole 10 based on the maximum loads. applicable to the pole multiplied by a required safety factor allowing for any additional decay before the next periodic test. In this case, additional data is fed through, the computer 16 including the size 25 of the pole 10, maximum wind forces, the direction., size, number and tension of the. wires attached to the S" pole and other relevant factors. Preferably, the minimum required strength of the pole is determined in the office before the test.

30 Referring now to FIG 2, the pole is pulled with a preset load P using the winch rope 11 and displacements of the pole are measured, using the dial gauges 1 to 7 in order to determine the ultimate bending i strength of the pole. The new method of determinatior i of the residual. strength of decayed poles is explained.

7 in detail in Appendix 1.

With reference to FIG 3, the pole 10 is tested under a Go/No Go situation. The minimum required strength for the pole is calculated based on the maximum wind velocity and any safety factors whi.ch must be allowed for. A load (pushing or pulling) equivalent to the minimum required strength is applied to the pole using hydraulic rams 11, 12 and 13, and hand. held. or built in computer indicating the applicable oil pressure, and the pole and oil pressure is observed. If the pole fails (oil pressure drops), it must be reinforced or replaced. If the pole remains intact, it satisfies the minimum required strength and replacement is not required. This method can be used where the ultimate strength of the pole is not required.

It will be readily apparent to the skilled addressee that the present invention provides simple, efficient and reliable means. for determining the residual strength of poles in a non-destructive manner (unless the pole's strength, is below a preset safety level).

Various changes and modifications may be made to the embodiments described without departing from the scope of the present invention defined in the appended 25 claims.

0.:.8 oo r t nd aGomr strengt o t ii: 8 APPENDIX 1 FIG 2 shows a detailed example of the invented method of testing poles and calculating the residual strength of substantially decayed poles at ground line zone.

The horizontal load P is applied by an electric winch 11 fitted on the truck or other. suitable means.

Specially designed arms 12 and 13 are used for the attachment of dial gauges 1, 2, 3, and 4 to measure the rotation of the solid wood sections at the level of the application of load P (gauges 1 and 2) and decayed sections of the pole at ground line (gauges 3 and 4).

The tripod 14 serves as the reference base for the measurement of three horizontal pole deflections using dial gauges 5, 6, and 7.

The following formulas are used for the determination of the residual pole strength.

(Pa-RH,)dmeL,- M (ewx+esf)r where: M the residual strength of partially decayed pole at ground line in kNm.

P the preset horizontal load applied 25 to the pole in kN.

a the distance from load P to the critical cross-section of the pole 'at ground line in m.

R the resultant reaction of conductors 30 at the top of the pole in kN.

He the distance from the conductors to the critical cross-section of the pole at ground line in m.

35 dm the horizontal distance between dial gauges 3 and 4 in m.

*i e.it the ultimate strain of the solid timber fibre.

9 e the strain obtained from dial gauge 1.

e the strain obtained from dial gauge r the maximum distance from the neutral axis of the decayed crosssection of the pole at ground line to the outer solid timber fibre in m Reaction R, is calculated from the following formula: 3 0. 098dae.E R= H,-a where: d, the. diameter of solid cross-section of the pole at the level of horizontal load P in m.

the solid fibre strain obtained from dial gauges 1 and 2.

the actual. modulus of elasticity of solid wood at the level of load P in kN/m'.

o: *0t o.

le 0 Strains and e. are obtained from the following formulas: I R31 IR41 hV IRi JR21 d., 2 1,h 'where: RI-R4 the readings from dial gauges 1-4 corresponding to applied load P in Mm.

the measuring span (vertical) of dial gauges 3 and 4 in mm.

I the horizontal distance between dial gauges 1 and 2 in m.

h the measuring span (vertical) of dial gauges 1 and 2 in mm.

Distance r can be calculated. as: d57 r= 2 d, e +e^ where: the diameter of residual solid wood of the critical cross-section of the pole at ground line in m.

the measured distance from the outer fibre of solid wood of the critical cross-section to dial guage 4 in m.

Actual modulus of elasticity Ea and its reciprocal f.

are calculated from the following formulas.

1 Ea fa 0 40*

S

I..

*0 9 4t 4 50 40 0 0.0.

4 00

S

4 0.

0 1* 0 and a2H 3 daea H 2 -0.84aH,+O.133a 2 f. c a- c 2(H,-a)d a (H&-0.34a) 2 (H,-0.17a)2 Va 2 va/2+v,] d-da(das+d.) (2d5V+d.)3.4a 3

P

where: dgs the original diameter of solid wood of the critical cross-section at ground line when the pole was new in m.

v, the horizontal deflection of the pole at the level of load P in m.

v~/ 2 the horizontal deflection of the pole at the middle of the distance 9 A 3 5 0 j *1 11 a between the load. P and ground line in m.

v .the horizontal deflection of the pole at ground line in m.

Deflections va, va/2, and v, are calculated from the readings of dial gauges 5, 6 and 7.

v. JR5)/1000 va/ 2 IR6l/1000 v, IR71/1000 Where R5, R6 and R7 are the readings in mm, corresponding to the applied load P, taken from dial gauges 5, 6, and 7.

The above formulas represent a sophisticated structural analysis and therefore a portable hand held computer is required to make the new technique practical for everyday use.

The new method. explained by the above example is a first known approach to accurately predict- the ultimate Sstrength of standing poles which may have a substantial external and internal decay at their critical zone at the ground level.

S. *o

Claims

2. A method for testing the residual strength of a pole anchored in the ground including the steps of: applying a load to the pole above ground level to cause the pole to undergo a preset displacement; measuring the load applied t pole;. and from the applied load and the displacement, calculating the residual strength of the pole from predetermined formula.(e), tabulated scales, or by a programmed calculator or computer; wherein: the load is applied by pushing or pulling the load above ground level by a mechanical jack or turnbuckle, pneumatic or hydraulic ram(s) or a winch, being portable, mounted on wheels or vehicles, and the applied load is measured by a load cell or gauge-
3. A method according to Claim 1 or Claim 2 wherein: the displacement of the pole is measured in both deflection and rotation. by displacement gauges B i^j*r I:; L-3 A? w 1 nl ii i 13 mounted on a ref erence frame.
4. A method according to any one of Claims 1 to 3 whereinz the residual strength of the pole is dependent or. factors including the height and diameter of the pole, the type and number of conductors, the spacing between the pole and adjacent poles and/or the estimated maximum wind forces on the pole. A method according to Claim 4 wherein: the residual strength of the pole is calculated by the method. hereinbefore described in Appendix 1.
6. A method for testing the residual strength of a pole anchored in the ground. including the steps of: cali.ulating the minimum required strength. of the pole including any required safety factors; applying a preset load to the pole above ground level equivalent to the calculated minimum strength; and observing if the pole withstands the applied load without exceeding a displacement indicating a failure and so meet the miinimum required. strength; :wherein: the load is applied. by pushing or pulling 25 the load above ground. level by a mechanical jack or turnbuckle, pneumatic or hydraulic ram(s) or a winch, *being portable, mounted on wheels or vehicles, and the applied load is measured by a load. cell or gauge.
7. An apparatus for the residual strength of a pole anchored in the ground according to the method of any one of Claims 1 to 5, the apparatus including:. means to apply a load to the pole above ground level; load cell means to measure the load applied to the pole; The following statement is a full description of the S• invention including the best method of performing it known to the applicant. Of' 14, means to measure the displacement of the pole under the applied load.; and means to calculate the residual strength of the pole from the applied load and the displacement; wherein: the load is applied by pushing or pulling the load above ground level by a mechanical jack or turnbuckle, pneumatic or hydraulic ram(s) or a winch, being portable, mounted on wheels or vehicles, and the applied load is measured by a load cell oy gauge.
8. Apparatus according to Claim 7 wherein: the hydraulic rams are fitted to the crane or lifter-borer truck.
9. Apparatus according to Claim. 7 or Claim 8 wherein: the displacement of the pole in both deflection and rotation is measured by displacement gauges or strain gauges mounted. on a reference frame. Apparatus according to any one of Claims 7 to II. Apparatus according to Claim 10 wherein: the residual strength is calculated by the 25 method hereibefore described in Appendix 1.
12. A method for testing poles substantially as hereinbefore described with reference to FIGS 1 and 2; or FIGS 2 and 3; of the accompanying drawings.
13. Apparatus for testing poles substantially as 30 hereinbefore described with reference to FIGS 1 and 2; or FIGS 2 and 3; of the. accompanying drawings... DATED this sixteenth day of July 1992. KRZYSZTOF JAN DEUAR, By his Patent Attorneys, S3 GRANT ADAMS COMPANY. E