GB2462719A

GB2462719A - Improvements in or relating to analysing structural members

Info

Publication number: GB2462719A
Application number: GB0914254A
Authority: GB
Inventors: Peter Seaman
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-08-18
Filing date: 2009-08-14
Publication date: 2010-02-24
Anticipated expiration: 2029-08-14
Also published as: GB2462719B; GB0821983D0; DE112009001972T5; GB0914254D0; GB0815038D0; WO2010020760A1

Abstract

Analysing a structural member 10 in a tensioned condition, where at least one calibrating measurement of a predetermined dimension LXof said structural member 10 has been taken from a predetermined first position on the structural member 10 to a second position 19 on structural member, and the, or each, calibrating measurement has been recorded. A further measurement of the predetermined dimension LXof the structural member 10 in the tensioned condition is taken from the predetermined first position to the second position 19, and comparing the, or at least one of the, calibrating measurements with the further measurement to provide an indication of the tension in the structural member 10. The calibration measurements may be taken when the structure is in an untensioned condition. The further measurement may be compared to the calibrating measurement by calculating the difference between the two measurements to determine an indication of the tension in the structure member. The measurement data may be recorded on a database which may also record one of, the location at which the structure is installed, the length of the dimension of the installed structure from one or more positions, the date of installation and the temperature of the surroundings during installation.

Description

Improvements In or Relating to Analysing Structural Members This invention relates to methods of analyzing structural members.

Embodiments of the invention relate to methods of measuring tension in structural members. More particularly, but not exclusively, this invention relates to methods of determining changes in length of structural members.

It is well known to use elongate structural members in the construction of bridges and other structures. The elongate structural members may be in the form of tendons, turnbuckles, forks and the like. Such structural members are manufactured to be able to perform at predetermined tensions. However, during the life of the structure, the tension within the structural member can change.

Methods have been provided which attempt to determine the tension in such structural members in order to find out whether the predetermined tension at which structural member can operate has been exceeded.

According to one aspect of this invention, and there is provided a method of analysing a structural member, comprising taking a calibrating measurement of a predetermined dimension of the structural member from a predetermined first position on the structural member to a second position on the structural member, and recording the calibrating measurement.

Advantageously, the predetermined dimension is a dimension along which tension is to be applied to the structural member. The method may comprise marking said predetermined first position.

In a first embodiment, the step of taking the calibrating measurement may comprise taking the calibrating measurement of the predetermined dimension when the structural member is in an untensioned condition.

The step of taking the calibrating measurement may comprise taking the calibrating measurement of the predetermined dimension when a predetermined tension is applied to the structural member. Advantageously, the predetermined dimension is a dimension along which the predetermined tension is applied.

In a second embodiment, the method may comprise taking a plurality of calibrating measurements of the predetermined dimension at a plurality of respective predetermined tensions on the structural member, and recording each of said calibrating measurements and each of said predetermined tensions.

In the second embodiment, the method may comprise taking a first calibrating measurement at a first predetermined tension, recording said first calibrating measurement and said first predetermined tension, taking a second calibrating measurement at a second predetermined tension, recording said second calibrating measurement and said second predetermined tension.

Advantageously, the predetermined dimension is a dimension along which the, or each, predetermined tension is applied.

The first and second positions may comprise first and second points or may comprise first and second regions.

The second position may be an end of the structural member. Alternatively, the second position may be a discontinuity in the structural member, such as a groove, slit or shoulder.

The predetermined first position is desirably on a face extending substantially at right angles to the predetermined dimension to be measured. The second position is desirably on a face extending substantially at right angles to the dimension to be measured.

The step of marking the predetermined first position may be before or after the predetermined dimension has been measured. The step of marking the predetermined first position desirably comprises deforming the structural member at the aforesaid predetermined first position.

The predetermined first position may be marked by stamping, engraving, embossing, or by chemical marking.

The recording of the, or each, calibrating measurement may comprise recording the calibrating measurement on a database on a data-processing arrangement.

The database may include further details of the structural member. Alternatively, if desired, the step of recording the calibrating measurement may comprise writing the calibrating measurement onto a suitable record sheet.

Where the method comprises taking a plurality of calibrating measurements at a plurality of respective predetermined tensions, the recording of the calibrating measurements may comprise recording each of the calibrating measurements and each of the respective predetermined tensions in correspondence with each other on the database, or on the record sheet.

The step of taking the calibrating measurement may comprise emitting from a signal emission device a signal to be transmitted along the structural member.

The signal may be a sonic signal, and may be transmitted along the structural member from the predetermined first position. The step of taking the calibrating measurement may comprise measuring the period of time for the signal to return to the predetermined first position. The emitted signal may be an ultrasonic signal.

Thus, in one embodiment, the calibrating measurement of the dimension is effected by measuring the aforesaid period of time and, thereafter calculating the dimension from said period of time and from properties of the structural member.

The aforesaid properties of the structural member may comprise the density of the structural member. The method of calculating the length would be immediately apparent those skilled in the relevant art. Moreover, devices for emitting signals and carrying out such calculations are available. A suitable such device is sold by the company Norbar Torque Tools Ltd under the names USM-I and USM-Il.

The recording of the calibrating measurement may further include recording one or more items of information selected from the following: the length of the dimension; the identity of the material of the structural member; the density of the material of the structural member; the cross-sectional area of the structural member; the maximum tension the structural member is designed to accommodate.

The recording of the information may comprise recording one or more further items of information selected from the following: the date of manufacture of the structural member; the type of structural member; the type or designation of equipment used to measure the dimension.

The method may include taking a further measurement of the predetermined dimension from the aforesaid predetermined first position to the aforesaid second position. The method may comprise comparing the further measurement with the first measurement. In the first embodiment, the method may comprise calculating the difference between the further measurement and the first measurement to provide an indication of the tension in the structural member. In the second embodiment, the method may comprise comparing the further measurement with at least one of the plurality of calibrating measurements to provide an indication of the tension in the structural member.

According to another aspect of this invention, there is provided a method of analysing a structural member in a tensioned condition, where at least one calibrating measurement of a predetermined dimension of said structural member has been taken from a predetermined first position on the structural member to a second position on structural member, and the, or each, calibrating measurement has been recorded, said method comprising taking a further measurement of the predetermined dimension of the structural member in the tensioned condition from the predetermined first position to the second position, and comparing the, or at least one of the, calibrating measurements with the furtehr measurement to provide an indication of the tension in the structural member.

In a first embodiment, the calibrating measurement may have been taken when the structural member is in an untensioned condition. In a second embodiment, a plurality of calibrating measurements may have been taken at a plurality of respective predetermined tensions.

In the first embodiment, the method may comprise comparing the calibrating measurement with the further measurement, and calculating the difference between the further measurement and the first measurement to provide an indication of the tension in the structural member. In a second embodiment, the method may comprise comparing the further measurement with at least one of the plurality of calibrating measurements to provide an indication of the tension in the structural member.

The method may comprise recording the further measurement. The recording of the further measurement may comprise entering the further measurement onto the database to allow the data-processing arrangement to compare the further measurement with the first measurement and provide an indication of the tension in the structural member.

The recording of the further measurement may include recording one or more items of further information selected from the following: the location at which structural member is installed; the length of the dimension of the installed structural member from one or more positions; the date of installation of the structural member; the temperature of the surroundings during installation of the structural member.

Thus, in one embodiment, the step of taking the further measurement, when the structural member has been installed in a structure, allows the tension in the installed structural member to be determined.

The step of taking the aforesaid further measurement may occur just after the structural member has been installed. In one embodiment, this allows the installer to check that the structural member is in good structural health.

Alternatively, the further measurement can be taken after a substantial period of time has elapsed, for example several months or years, so that the tension in the structural member can be determined. In one embodiment, this allows the structural member to be checked to find out whether it is in good structural health. The aforesaid length of time elapsed may be recorded.

The method may further include taking a third measurement of the predetermined dimension from the aforesaid predetermined first position to the aforesaid second position, comparing the third measurement with said further measurement and/or with the first measurement, and calculating the difference between the third measurement and the first measurement and/or with the aforesaid further measurement to provide an indication of the tension and/or a change of the tension in the structural member.

The third measurement may be taken after a substantial period of time has elapsed, for example several months or years, so that the tension in the structural member can be determined. In one embodiment, this allows the tension in the structural member to be checked to find out whether it is in good structural health.

The method may comprise recording the third measurement. The recording of the third measurement may comprise entering the third measurement onto the database to allow a data-processing arrangement to compare the third measurement with the first measurement and/or the further measurement and/or the third measurement and provide an indication of the tension, or a change of and the tension, in the structural member.

The recording of the third measurement may include recording one or more items of information selected from the following: the location in which structural member is installed; the length of the dimension of the installed structural member from one or more positions; the date of installation of the structural member; the temperature of the surroundings during installation of the structural member.

Thus, in one embodiment, the step of taking the third measurement, after the structural member has been installed in a structure, allows the tension in the installed structural member to be determined.

The method may comprise taking additional measurements of the predetermined dimension measurement of the dimension from the aforesaid predetermined first position to the aforesaid second position, comparing said additional measurement with said further measurement and/or with the first measurement, and calculating the difference between the additional measurement and the aforesaid further measurement and/or with the first measurement to provide an indication of the tension, and/or a change of the tension, in the structural member.

The method may comprise recording the additional measurement. The recording of the additional measurement may comprise entering the additional measurement onto the database to allow a data-processing arrangement to compare the additional measurement with the first measurement and provide the indication of the tension, or change in tension, in the structural member.

The recording of the additional measurement may include recording one or more items of information selected from the following: the location in which structural member is installed; the length of the dimension of the installed structural member from one or more positions; the date of installation of the structural member; the temperature of the surroundings during installation of the structural member.

The method may comprise taking one or more additional measurements of the predetermined dimension to determine the tension in the structural member periodically.

According to another aspect of this invention, there is provided a load calibrating apparatus comprising a component holding arrangement, a load applying arrangement for applying a load to the component, a load measuring arrangement for measuring the load applied to the component, and a length measuring arrangement for measuring the length of a predetermined dimension of the component.

The load applying arrangement may comprise a jack and a drive assembly for driving the jack. The drive assembly may comprise a hydraulic system. The hydraulic system may comprise a hydraulic pump.

The load measuring arrangement may comprise a load cell and a display arrangement.

The length measuring arrangement may comprise a signal emitting device, which may be an ultrasonic emitting device. The length measuring arrangement may further comprise a display arrangement for displaying the length measured.

The holding arrangement may comprise a jig, and may include a component securing member, which may be elongate. The holding arrangement may include first and second component securing members. The, or each, component securing member may comprise opposite end regions. A first end region of each component securing member may be secured to the jig, and a second opposite end region of each component securing member may be secured to the component.

An end region of one of the component securing members may be secured to the load applying arrangement. An end region of one of the component securing members may be secured to the load measuring arrangement. In one embodiment, a first end region of the first component securing member may be secured to the load applying arrangement, and a first end region of the second component securing member may be secured to the load measuring arrangement.

At least one embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of a step of measuring a predetermined dimension in a structural member in an untensioned condition; Figure 2 is a diagrammatic view of a step of measuring the predetermined dimension in structural member shown in Figure 1 in a tensioned condition installed in a structure; Figure 3 is a diagrammatic view of a step of measuring another predetermined dimension in a structural member in a tensioned condition installed in a structure; Figure 4 is an example of a screen view of a database showing the measurements of the predetermined dimensions; Figures 5A to 5C show a sequence of events of the method according to an embodiment of the invention; and Figure 6 is a diagrammatic side view of an apparatus for use with a second embodiment.

Referring to Figure 1, there is shown a structural member, comprising a component 10, of a building structure. The component 10 is in the form of a turnbuckle suitable for use in a structure, such as a bridge or other building structure. It will be appreciated by the skilled person that the component 10 could be any other structural member, such as a tendon, bolt, fork or the like.

The component 10 comprises a main part 11, which has a length L1. The component 10 shown in Figure 1 has not yet been installed in the structure, and therefore is not under tension. It is desired to take an accurate measurement of a predetermined dimension, such as the length L1, on the component 10, and this is carried out by the use of an ultrasonic emission device 12, which comprises a handset 12A, including an internal data-processing arrangement, and a probe in the form of a transducer 12B connected to the handset by a cable 12C, having a connector 12D to connect the cable 12C to the transducer 12B. The handset 12A can cause the transducer 12B to emit an ultrasonic pulse along the component 10, and to detect the ultrasonic pulse after the ultrasonic pulse is reflected (see below).

A predetermined first position in the form of a predetermined first region 14 is provided on a first end face 16 of the component 10. The first region 14 is marked, for example by stamping a circle onto the first face 16. The transducer 12B is disposed on the first region 14.

In addition to the predetermined first region 14, each of the components 10 is provided with a plurality of further first regions 14A, 14B and 14C, spaced around the first face 16. This allows the operator to decide which of the first regions 14, 14A, 14B or 14C would be the most suitable for the measurement to be taken from. Alternatively, the operator can take a measurement at each of the positions 14, 14A, 14B and 14C, to provide an average of the length L1.

A second position in the form of a second region 19 is provided on a second end face 22 opposite the first end face 16. Although the second region 19 is designated by a broken line in Figure 1, it will be appreciated that the second position 14 does not need to be marked in order to carry out the steps described herein, or for the method to function correctly.

The first and second end faces 16, 22 are substantially parallel to each other, and substantially perpendicular to the length L1.

The ultrasonic emission device 12 emits an ultrasonic pulse from the transducer 12B, which is transmitted along the component 10, as shown by the arrow A to the second region 19 on the second end face 22.

The ultrasonic pulse is reflected from the second end face 22 back to the transducer 12B. The detection of the ultrasonic pulse after it has been reflected from the second region 19 at the second end face 22 is registered by the ultrasonic emission device 12. The time taken for the ultrasonic pulse to be emitted and detected by the transducer 12B after the ultrasonic pulse has been reflected from the second position 19 is recorded..

Suitable calculations can then be performed, to work out the distance travelled by the ultrasonic pulse, and hence the length L1 of the predetermined first dimension. These calculations can be carried out by the ultrasonic emission device 12. A suitable such ultrasonic emission device which can carry out the necessary calculation is sold by the company Norbar Torque Tools Ltd under the names USM-I and USM-Il The length L1 of the component 10 can then be recorded on a database for future reference, as described below. An example of a screen view of a page of the database is shown in Figure 4.

The page of the database shown in Figure 4 comprises the first section A, in which the date of the recording is entered in box Al, as well as information relating to the component itself. As can be seen from Figure 4, the information that can be entered is as follows: the job number is recorded in box A2; the component I.D. is recorded in box A3,; the type of component is recorded in box A4; the material from which component is manufactured is recorded in box A5; the density of the material is recorded in box A6; the date of manufacture of the component is recorded in box A7; the cross-sectional area of the component is recorded in box A8; the maximum tension that the component was designed to accommodate is recorded in box A9, and other manufactured parameters are recorded in boxes AlO, All, A12, A13.

The page of the database shown in Figure 4 also includes a second section B, in which information relating to the measurement of a predetermined dimension is recalled. In the version show in Figure 4, information recorded in section B is as follows: the length of the dimension from one end of the component to the opposite end is recorded in box BI, or the length of the dimension from one end of the component to a discontinuity in the component is recorded in box B2; the temperature of the surroundings when the measurement is taken is recorded in box B3; the type of transducer used, or the I.D. of the component is recorded in box B4.

The above recording of information takes place in a workshop by the manufacturer of the component 10 before the component 10 is dispatched to the customer for installation in the structure.

An internally threaded aperture 17 extends inwardly from the first end face 16 of the component 10, and is used to attach the component 10 to a further structural member (see Figure 2). A further internally threaded aperture 23 extends inwardly from the end face 22 to attach another structural member to the component 10 (also see Figure 2). The thread on the first mentioned internally threaded aperture 17 is a right-hand thread, and the thread on the further internally threaded aperture 23 is a left-hand thread.

Referring to Figure 2, there is shown the installation of the component 10, which is used to connect together two further structural members in the form of elongate tendons 26, 28. The elongate tendons 26, 28 are threaded at their ends to co-operate threadably with the internal threads in the apertures 17 in the end faces 16, 22.

In order to ensure that the tendons 26, 28 are safely secured together, the component 10 is tightened onto the threaded ends of the tendons 26, 28. This places the component 10 and the elongate tendons 26, 28 in a tensioned condition.

The component 10 and the elongate tendons 26, 28 are manufactured to be able to operate at predetermined tensions. If these predetermined tensions are exceeded, there is a danger that either the tendons 26, 28, and/or the component 10, will fail. In view of this, it is important to ensure that the tension in the elongate tendons 26, 28 and in the component 10 is at, or below, the predetermined tension.

In order to check the tension in the component 10, a further measurement of the predetermined dimension is performed, since the component 10 is under tension, it will have been stretched by the tension therein, and now has a length Lx, extending from the first face 16 to the second region 19 on the second face 22.

The length Lx is measured in the same way as described above with reference to Figure 1, in that the transducer 12B is disposed on the first face 16 and the ultrasonic emission device 12 causes an ultrasonic pulse to be emitted from the transducer 12B. The ultrasonic pulse is transmitted along the component 10, as shown by the arrow A. The reflection of the ultrasonic pulse from the second region 19 at the second end face 22 is detected by the transducer 12B.

The time taken for the ultrasonic pulse to be emitted and the reflection detected is used to calculate the length Lx, in the same way as described above with reference to Figure 1. Since tension forces are applied to the component 10 in its condition as shown in Figure 2, the length Lx is greater than the length L1.

As shown in Figure 4, each page of the database comprises a third section C, in which it is possible to record information obtained after the component 10 is installed in a building structure. In section C, the information recorded includes the location at which the component is installed in box Co. The section C also includes three subsections designated Cl, C2, and C3. Each of the subsections Cl, C2, and C3 includes the following: a box C4 for recording the location at which the component is installed; three boxes designated C5, C6 and C7 for recording the length of the predetermined dimension taken from various positions, if appropriate on the component; a box C8 for recording the dates on which the component was tensioned; and a box C9 for recording the temperature of the surroundings at the times the measurements are taken. The second and third subsections C2, C3 also include a further box ClO for recording the length of time elapsed from the measurements taken in subsection Cl to the present measurement.

The third section C also includes a fourth subsection Cli for indicating the tension in the component calculated by the software for the first, second and third measurements. The subsection CII includes a first box C12, labelled "FIRST" in Figure 4, in which is shown the tension in the component calculated by the software from the information provided in the first subsection Cl. The subsection CII includes a second box C13, labelled "SECOND" in Figure 4, in which is shown the tension in the component calculated by the software from information provided in the second subsection C2. The subsection Cli includes a third box C14, labelled "THIRD " in Figure 4, in which is shown the tension in the component calculated by the software from information provided in the third subsection C3.

Immediately after installation of the component 10, the length Lx, the date and the temperature of the surroundings is taken and entered onto the subsection Cl of the database, in the appropriate boxes as described above. The calculation can then be performed comparing the length Lx with the length L1 to work out the tension in the component 10. This calculation is can be performed by suitable software on the data-processing arrangement on which the database is stored, and the value of the tension is shown in box C12 Thus, by determining the tension in the component 10, the operator can determine whether the tension in the component 10 has reached, or exceeded, a predetermined value.

It is also desirable to be able to determine the tension in the component 10 after a substantial passage of time. For example, there may be concerns about the danger of failure in the structural members of the structure, and it can be desirable to determine the structural health of the component 10.

In view of this, a further measurement of the length Lx, and the temperature can then be carried out, and this information can be recorded in subsection C2, along with the date the measurements are taken, and the time elapsed from the measurements recorded in subsection Cl. The software can be used to calculate the tension in the component 10 after the aforesaid passage of time.

This allows the operator to determine the structural health of the component 10.

If desired, yet another measurement of above parameters can be taken after a further period of time, and the measured length L, as well as the date, temperature and time elapsed from the measurements recorded in subsection Cl can then be recorded in the appropriate boxes in subsection C3. The tension in the component 10 can then be determined.

It is possible for the length L1 to be measured for a plurality of structural members, and the length L1 so measured can be recorded on the database for comparison with measured length Lx taken at a later time to determine the tensions in the structural members.

There is thus provided a simple and effective method of determining the tension in structural members in the building so that the danger of one or more of the structural members failing can be determined.

Various modifications can be made without departing from the scope of the invention. For example, the component 10 could be any other suitable structural member, such as a tendon, or a fork. Also, the predetermined first region may be marked by stamping, engraving, embossing, or by chemical marking.

If desired, the second region 19 need not be provided on the second end face 22. Instead, as shown in Figure 3, the second region 19 could be provided at a discontinuity on the main part 11 of the component 10. The embodiment shown in Figure 3 comprises many the same features as the embodiment shown in Figures 1 and 2, and these features have been designated with the same reference numerals in Figure 3 as in Figures 1 and 2.

In Figure 3, the discontinuity is a recess 30 defined in the main part 11, and extending inwardly from a slot defined in the surface of the main part 11. As can be seen from Figure 3, there are a plurality of slots and associated recesses spaced around the circumference of the main part 11. The recess 30 is aligned with the predetermined first region 14 and constitutes a second region 32. In Figure 3, the second region 19 is a wall 31 of the recess 30, the wall 31 being closest to the first face 16.

The predetermined dimension to be measured is from the first face 16 of the predetermined first region 14 to the wall 31 of the recess 30. The length of this dimension is designated by the letters LD, and is initially measured by the ultrasonic emission device 12 when the component 10 is in an untensioned condition. The pulse emitted by the transducer 12B of the ultrasonic emission device 12 travels along the main part 11 in the direction of the arrow A, and is reflected back when the ultrasonic pulse strikes the wall 31 recess 30. The time taken from the emission of the ultrasonic pulse to its detection by the transducer 12B after reflection of the pulse from the wall 31 allows the length LD to be determined accurately. The length LD is then recorded on the database the same way as described above.

In the same way as with the above described embodiment shown in Figures 1 and 2, the length LD can be measured after the component 10 has been installed and placed under tension. This measurement after installation can be compared with the original measurement of the length LD to calculate the amount by which the structural under 10 has stretched, and thereby calculate the tension in the component 10.

It will be appreciated that the dimensions measured, as described above can vary from component to component in a structure. Figures 5A to 5C show a further embodiment in which measurement is made of dimensions in different components.

In Figure 5A, the length LA of a first structural member in the form of a turnbuckle 110, and the length LB of a second structural member in the form of a tendon 210 are measured by the use of an ultrasonic emission device 12, in the manner as described above. The relevant information relating to the measurement and of the structural members is then recorded onto sections A and B of the database, as shown in Figure 4, and described above.

The turnbuckle 110 is provided with internal threads 112, and the tendon 210 is provided with external threads 212 at opposite ends regions 214, 216. The turnbuckle 110 is then threadably secured to the tendon 210 at the end region 214 of the tendon 210. The tendon 210 is then threadably secured to a connecting fork 118 at the end region 216 of the tendon 210.

A further tendon 310 is connected to the turnbuckle 110 at its opposite end region, and shown to provide an elongate structural arrangement, generally designated 150.

Referring to Figure 5B, the elongate structural arrangement is then installed in a building structure, the securing fork 118 being secured to the support arrangement 120 of the building structure. The elongate structural arrangement is then tensioned by rotating the turnbuckle 110 about its longitudinal axis, as would be understood by those skilled in the art. This tightens on the turnbuckle onto the tendons 210, 310, thereby increasing the tension along the structural arrangement 150. As a result of this increase in tension, the lengths of the turnbuckle 110 and the tendon 210 increases.

The tension in the turnbuckle 110 and the tendon 210 can be determined by the use of the ultrasonic emission device 12 which is used to measure the lengths LA and LB of the turnbuckle 110 and the tendon 210 in Figure 5B, i.e. just after installation of the elongate structural arrangement 150.

When the necessary information has been recorded on the subsection Cl of respective pages of the database, the tension in the turnbuckle 110 and in the tendon 210 can be calculated and shown in the respective boxes C12.

Figure 5C shows the measurement of the same dimensions in the elongate structural arrangement 150 after the passage of a substantial period of time, for example several months or years.

The lengths LA and LB of the turnbuckle 110 and the tendon 210 are measured again by the ultrasonic emission device 12, and the relevant information recorded in the respective second subsection C2 of the relevant pages of the database.

The tensions in the turnbuckle 110 and the tendon 210 are then calculated by the software and shown in the respective boxes C13. These figures of the respective tensions indicate the structural health of the elongate structural arrangement 150.

If desired, a further measurement of the lengths LA and LB can be made after the passage of a further period of time, and misinformation also recorded on the database in the respective third subsection C3,and the calculated tension indicated in the box C14.

Figure 6 shows a load calibrating apparatus 200 for use with a second embodiment. The apparatus 100 comprises a jig 202 for holding a component 10, the component 10 being a structural member of a building structure.

The jig 202 comprises a frame 204, having a first end portion 206, and a second opposite end portion 208. A plurality of frame members 210 extend between the first and second end portions 206, 208.

A first component securing member 212 extends from the first end portion 206 towards the second end portion 208, and a second component securing member 214 extends from the second end portion 208 towards the first end portion 206.

In the embodiment shown in Figure 6, the first component securing members 212 is elongate and has opposite threaded ends 212A and 212B, and the second component securing member is also elongate and has opposite threaded ends 214A and 214B.

The end 212A of the first component securing member 212 extends through a load applying means 216. The end 212A is secured to the load applying means 216 by a first nut 218. The opposite end 212B of the first component securing member 212 is threadably secured to the component 10.

The end 214A of the second component securing member 214 extends through a load measuring means 220. The end 214A is secured to the load measuring means 220 by a second nut 222. The end 214B of the second component securing member 214 is threadably secured to the component 10.

In the embodiment shown, the load applying means 216 comprises a jack 224, which may be a hydraulically operated jack, and a hydraulic system 226. The first component securing member 212 is secured to the jack 224.

The hydraulic system 226 comprises a hydraulic pump 228 and a hose 230 to provide fluid communication between the hydraulic pump 228 and the jack 224.

In the embodiment shown, the load measuring means 220 comprises a load cell 232 for measuring loads applied by the load applying means 216. the load measuring means 220 further includes a display device 234 for displaying the load measured by the load cell 232.

The load calibrating apparatus 200 further includes an ultrasonic emission device 12 comprising a handset 12A, including an internal data-processing arrangement, and a probe in the form of a transducer 12B connected to the handset by a cable 120, having a connector 12D to connect the cable 12C to the transducer 12B.

The handset 12A can cause the transducer 12B to emit an ultrasonic pulse along the component 10, and to detect the ultrasonic pulse after the ultrasonic pulse is reflected (see below), thereby measuring the length of the component 10.

In operation, a point or region 236 is marked on the component 10 in the manner described above. The length of the component 10 in an untensioned condition is then measured using the ultrasonic emission device 12, and this measurement recorded on a suitable database.

A first load is then applied to the component 10 through the component securing members 212, 214 by the load applying means 216, thereby tensioning the component 10. The first load so applied is measured using the load measuring means 220 and recorded on the database.

The length of the component 10 with the first load applied is measured by the ultrasonic device 12, and recorded on the database. This measurement of the length is also recorded on the database in a manner that relates it to the first load recorded on the database. For example, the first load applied to the component by the load applying means 216 could be lOKn.

A second load is then applied to the component 10 by the load applying means 216. The second load can be, for example 20k N, which is recorded on the database.

The second load so applied is measured using the load measuring means 220.

When the load measured by the load measuring means 220 reaches the desired level, for example 2OKn, the length of the component 10 is measured using the ultrasonic emission device 12, and the measured length is recorded on the database in a manner that relates it to the second load so recorded.

The above process can be repeated for a plurality of further loads applied to the component 10, for example 3OKn, 4OkN, 5OKn, 6OkN, 7OkN, 8OkN, 9OkN, and lOOkN. Each load is recorded on the database, and the respective lengths of the component 10 at each of the above loads are measured using the ultrasonic device 12. Each length so measured is recorded on the database so that it corresponds to the corresponding load.

Thus, a database is compiled which comprises the respective lengths of the component 10 at a plurality of different measured loads applied thereto.

When the component is installed in a building structure, it may be desired to test the structural health of the component in situ. In order to do this, the operator can measure the length of the installed component from the position or region 236 using the ultrasonic emission device 12. The length of the component 10 50 measured can then be compared to the measurements of the lengths of the component 10 at different loads taken during calibration in the load calibrating apparatus 200, as described. This comparison will provide the operator with an indication of the load on the component lOin situ.

Claims

Claims 1. A method of analysing a structural member in a tensioned condition, where at least one calibrating measurement of a predetermined dimension of said structural member has been taken from a predetermined first position on the structural member to a second position on structural member, and the, or each, calibrating measurement has been recorded, said method comprising taking a further measurement of the predetermined dimension of the structural member in the tensioned condition from the predetermined first position to the second position, and comparing the, or at least one of the, calibrating measurements with the further measurement to provide an indication of the tension in the structural member.
2. A method according to Claim 1, wherein the calibrating measurement has been taken when the structural member is in an untensioned condition.
3. A method according to Claim 1, wherein a plurality of calibrating measurements have been taken at a plurality of respective predetermined tensions.
4. A method according to Claim 1, 2 or 3 comprising comparing the, or at least one, calibrating measurement with the further measurement, and determining therefrom an indication of the tension in the structural member.
5. A method according to Claim 1, 2 or 4 comprising comparing the calibrating measurement with the further measurement, and calculating the difference between the further measurement and the first measurement to provide an indication of the tension in the structural member.
6. A method according to Claim 1, 3 or 4 comprising comparing the further measurement with at least one of the plurality of calibrating measurements to provide an indication of the tension in the structural member.
7. A method according to any preceding Claim comprising recording the further measurement, by entering the further measurement onto a database to allow the data-processing arrangement to compare the further measurement with the calibrating measurement and provide an indication of the tension in the structural member.
8. A method according to Claim 7, wherein the recording of the further measurement includes recording one or more items of further information selected from the following: the location at which structural member is installed; the length of the dimension of the installed structural member from one or more positions; the date of installation of the structural member; the temperature of the surroundings during installation of the structural member.
9. A method according to any preceding Claim, wherein the step of taking the aforesaid further measurement occurs just after the structural member has been installed, thereby allowing the installer to check that the structural member is in good structural health.
10. A method according to any preceding Claim, including taking a third measurement of the predetermined dimension from the aforesaid predetermined first position to the aforesaid second position, comparing the third measurement with said further measurement and/or with the, or at least one, calibrating measurement, and determining therefrom indication of the tension, and/or a change of the tension, in the structural member.
11. A method according to Claim 10 comprising comparing the calibrating measurement with the third measurement, and calculating the difference between the third measurement and the first measurement to provide indication of the tension, and/or a change of the tension, in the structural member.
12. A method according to Claim 10 comprising comparing the third measurement with at least one of the plurality of calibrating measurements to provide indication of the tension, and/or a change of the tension, in the structural member.14. A method according to Claim 10, 11 or 12 including recording the third measurement onto a database to allow a data-processing arrangement to compare the third measurement with the first measurement and/or the further measurement and provide an indication of the tension, or a change of and the tension, in the structural member.15. A method according to Claim 14, wherein the recording of the third measurement includes recording one or more items of information selected from the following: the location in which structural member is installed; the length of the dimension of the installed structural member from one or more positions; the date of installation of the structural member; the temperature of the surroundings during installation of the structural member.16. A method according to any of Claims 10 to 15 comprising taking additional measurements of the predetermined dimension from the aforesaid predetermined first position to the aforesaid second position, comparing said additional measurement with said further measurement and/or with the first measurement, and determining therefrom indication of the tension, and/or a change of the tension, in the structural member.17. A method according to Claim 16 comprising comparing the calibrating measurement with the additional measurement, and calculating the difference between the additional measurement and the first measurement to provide indication of the tension, and/or a change of the tension, in the structural member.18 A method according to Claim 16 comprising comparing the additional measurement with at least one of the plurality of calibrating measurements to provide an indication of the tension, and/or a change of the tension, in the structural member.19. A method according to Claim 16 comprising recording the additional measurement onto a database to allow a data-processing arrangement to compare the additional measurement with the first measurement and provide the indication of the tension, or change in tension, in the structural member.A method according to Claim 19, wherein the recording of the additional measurement includes recording one or more items of information selected from the following: the location in which structural member is installed; the length of the dimension of the installed structural member from one or more positions; the date of installation of the structural member; the temperature of the surroundings during installation of the structural member.21. A method according to any of Claims 16 to 20 comprising taking one or more additional measurements of the predetermined dimension to determine the tension in the structural member periodically.22. A method according to any preceding Claim comprising taking the calibrating measurement of a predetermined dimension of the structural member from a predetermined first position on the structural member to a second position on the structural member, and recording the calibrating measurement.23. A method according to Claim 22, wherein the predetermined dimension is a dimension along which tension is to be applied to the structural member, and the method includes marking said predetermined first position.24. A method according to Claim 22 or 23, wherein the step of taking the calibrating measurement comprises taking the calibrating measurement of the predetermined dimension when the structural member is in an untensioned condition.25. A method according to Claim 22 or 23, wherein the step of taking the calibrating measurement comprises taking the calibrating measurement of the predetermined dimension when a predetermined tension is applied to the structural member. the predetermined dimension being a dimension along which the predetermined tension is applied.26. A method according to Claim 22 or 23 comprising taking a plurality of calibrating measurements of the predetermined dimension at a plurality of respective predetermined tensions on the structural member, and recording each of said calibrating measurements and each of said predetermined tensions.27. A method according to Claim 26 comprising taking a first calibrating measurement at a first predetermined tension, recording said first calibrating measurement and said first predetermined tension, taking a second calibrating measurement at a second predetermined tension, recording said second calibrating measurement and said second predetermined tension, each predetermined dimension being a dimension along which each predetermined tension is applied.28. A method according to any of Claims 22 to 27, wherein the second position is an end of the structural member, or is a discontinuity in the structural member, such as a groove, slit or shoulder.29. A method according to any of Claims 22 to 28, wherein the predetermined first position is on a face extending substantially at right angles to the predetermined dimension to be measured, and the second position is on a face extending substantially at right angles to the dimension to be measured.30. A method according to any of Claims 22 to 29, wherein the step of marking the predetermined first position comprises deforming the structural member at the aforesaid predetermined first position.31. A method according to any of Claims 22 to 30, wherein the recording of the, or each, calibrating measurement comprises recording the calibrating measurement on a database on a data-processing arrangement.32. A method according to Claim 31 when dependent upon Claim 26 or 27, wherein the recording of the plurality of calibrating measurements comprises recording each of the calibrating measurements and each of the respective predetermined tensions in correspondence with each other on the database.33. A method according to Claim 31 or 32, wherein the recording of the calibrating measurement further includes recording one or more items of information selected from the following: the length of the dimension; the identity of the material of the structural member; the density of the material of the structural member; the cross-sectional area of the structural member; the maximum tension the structural member is designed to accommodate.34. A method of analysing a structural member, comprising taking a calibrating measurement of a predetermined dimension of the structural member from a predetermined first position on the structural member to a second position on the structural member, and recording the calibrating measurement.35. A method according to Claim 34, wherein the predetermined dimension is a dimension along which tension is to be applied to the structural member, and the method includes marking said predetermined first position.36. A method according to Claim 34 or 35, wherein the step of taking the calibrating measurement comprises taking the calibrating measurement of the predetermined dimension when the structural member is in an untensioned condition.37. A method according to Claim 34 or 35, wherein the step of taking the calibrating measurement comprises taking the calibrating measurement of the predetermined dimension when a predetermined tension is applied to the structural member. the predetermined dimension being a dimension along which the predetermined tension is applied.38. A method according to Claim 34 or 35 comprising taking a plurality of calibrating measurements of the predetermined dimension at a plurality of respective predetermined tensions on the structural member, and recording each of said calibrating measurements and each of said predetermined tensions.39. A method according to Claim 38 comprising taking a first calibrating measurement at a first predetermined tension, recording said first calibrating measurement and said first predetermined tension, taking a second calibrating measurement at a second predetermined tension, recording said second calibrating measurement and said second predetermined tension, each predetermined dimension being a dimension along which each predetermined tension is applied.40. A method according to any of Claims 34 to 39, wherein the second position is an end of the structural member, or is a discontinuity in the structural member, such as a groove, slit or shoulder.41. A method according to any of Claims 34 to 40, wherein the predetermined first position is on a face extending substantially at right angles to the predetermined dimension to be measured, and the second position is on a face extending substantially at right angles to the dimension to be measured.42. A method according to any of Claims 34 to 41, wherein the step of marking the predetermined first position comprises deforming the structural member at the aforesaid predetermined first position.43. A method according to any of Claims 34 to 42, wherein the recording of the, or each, calibrating measurement comprises recording the calibrating measurement on a database on a data-processing arrangement.44. A method according to Claim 43 when dependent upon Claim 38 or 39, wherein the recording of the plurality of calibrating measurements comprises recording each of the calibrating measurements and each of the respective predetermined tensions in correspondence with each other on the database.45. A method according to Claim 43 or 44, wherein the recording of the calibrating measurement further includes recording one or more items of information selected from the following: the length of the dimension; the identity of the material of the structural member; the density of the material of the structural member; the cross-sectional area of the structural member; the maximum tension the structural member is designed to accommodate.46. A load calibrating apparatus comprising a component holding arrangement, a load applying arrangement for applying a load to the component, a load measuring arrangement for measuring the load applied to the component, and a length measuring arrangement for measuring the length of a predetermined dimension of the component.47. A load calibrating apparatus according to Claim 46, wherein the load applying arrangement comprises a jack and a drive assembly for driving the jack.48. A load calibrating apparatus according to Claim 47, wherein the drive assembly comprises a hydraulic system, having a hydraulic pump.49. A load calibrating apparatus according to Claim 46, 47 or 48, wherein the load measuring arrangement comprises a load cell and a display arrangement.50. A load calibrating apparatus according to any of Claims 46 to 49, wherein the length measuring arrangement comprises a signal emitting device and a display arrangement for displaying the length measured.51. A load calibrating apparatus according to Claim 50, wherein the signal emitting device comprises an ultrasonic emitting device.52. A load calibrating apparatus according to any of Claims 46 to 51, wherein the holding arrangement comprises a jig and a component securing member, 53. A load calibrating apparatus according to Claim 52, wherein the holding arrangement includes first and second component securing members, each component securing member having opposite end regions, a first end region of each component securing member being secured to the jig, and a second opposite end region of each component securing member being secured to the component.54. A load calibrating apparatus according to Claim 53, wherein an end region of one of the component securing members is secured to the load applying arrangement, and an end region of one of the component securing members secured to the load measuring arrangement.55. A load calibrating apparatus according to Claim 54, wherein a first end region of the first component securing member is secured to the load applying arrangement, and a first end region of the second component securing member is secured to the load measuring arrangement.56. A method substantially as herein described with reference to Figures 1 and 2.57. A method substantially as herein described with reference to Figures 3 and 5Ato 5C.58. A load calibrating apparatus substantially as herein described with reference to Figure 6.