Abstract:
According to the method suggested, the mast is submitted to an increasing force, and both this force and the deflection path are correlated to establish a characteristic load line. After it has been loaded, the mast is again relieved from the load, a characteristic load relief line is determined and the return force is correlated to the decreasing return path. The finds related to the mast solidity and anchorage are based on the tracing of the characteristic load relief line and the comparison with the characteristic load line.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a method for testing the solidity of vertically anchored masts. Furthermore the invention relates in particular to a device suitable for carrying out this method. 
     In the U.S. Pat. No. 5,212,654 methods for a destruction-free testing of masts with regard to their remaining solidity are described in order to still determine the loading still possible on the mast before this could break. If it is determined that the remaining solidity and thus the life-expectancy to be expected are too small, the mast concerned must be exchanged. 
     With these known methods for example it is proceeded such that the mast above it anchoring is loaded with a fixed predetermined force which corresponds to the previously calculated allowable residual solidity. If the lateral deflection of the mast after the force has reached the predetermined value is ascertained to be excessively high, this is a criterion for damage to the mast and the necessary exchange. 
     One also arrives at a suitable result when a previously calculated deflection corresponding to the theoretical residual solidity is predetermined and then the mast is loaded with a force from the side which increases until the deflection is achieved. If the force measured at the end of the testing procedure is ascertained to be excessively small then an exchange of the mast is to be carried out since with a damage-free and less elastic mast the force for reaching the fixed deflection would be comparatively larger. 
     Finally in the previously mentioned patent there is yet suggested a testing method with which the mast is loaded with a continuously measured force and simultaneously the lateral mast deflection is measured in order from these values at the end of the testing procedure to compute the residual solidity of the mast 
     With this method no provisions are made for the case that a damaged mast with increasing loading forces and bending moments makes a transition from the region of elastic deformation into a plastic deformation, thus could even buckle or break without this being able to be previously recognized and the test being stoped by releasing the mast loading. Inasmuch as this is concerned for this case it is only foreseen to support the mast with a frame or with cables, chains or likewise or to secure the mast loosely to a crane so that on buckling or breakage of the mast no damage may arise. 
     Furthermore the mast is still secured below, above its anchoring with a lock-nut so that the mast or its anchoring is fixed in tile ground against shifting. This however has the result that in the testing of the mast only the mast part which is located freely above the anchoring or the ground may be included and no details are possible as to the question whether or possibly the other part of the mast could be damaged or whether the mast at all is sufficiently stable. 
     In EP 0 638 794 A1 there is described a method for testing the solidity and bending resistance of a vertically anchored mast with which the mast likewise is subjected to a variable bending moment in that it is loaded with a force introduced above its anchoring and increasing in the course of the testing procedure, the measured value and the course of the force being used to determine the solidity of the mast. The mentioned force as well as also the distance about which the mast is laterally deflected at a selected location on account of the bending moment are measured simultaneously with sensors. 
     A linear dependency of the measured distance on the introduced force is evaluated as information of a mast deflection lying in the region of elastic deformation, whilst the determining of a non-linear dependency of the values measured by the sensors are evaluated as information of a plastic deformation and/or for a non-stable anchoring of the mast which is then recognized as not having bending resistance or is not stable and the testing procedure is stopped by unloading the mast. Thus with this method no safety precautions are to be made for the case that is not to be exected, specifically that the mast with this testing step may buckle or break. Moreover the testing procedure is only broken off by unloading the mast when a predetermined nominal value of the bending momemnt is achieved in the elastic region of deformation, which means that the mast is sufficiently stable and has bending resistance and does not need to be exchanged for another. 
     With all previously mentioned methods it is not possible to determine whether the mast tested in each case, in spite of deformation lying in the elastic region until reaching the testing load, is damaged by a fracture or by a corrosion region possibly going through the mast, so that in the case of such damage one may possibly arrive at an erroneous evaluation of the remaining stability of the mast, since for example with the application of the method according to EP 0 638 794 A1 a linear course of the function f=F(S), wherein F is the introduced force and S the lateral deflection of the mast, or a changing bending angle of the mast may give the delusion that the mast is not damaged. 
     This problem is solved by the method described in the Utility Model DE 296 07 045 U in which by way of a force unit the mast above its anchoring in the same plane of testing is loaded from the side, after one another with a compression force and with a tensile force, thus with oppositely directed bending moments so that for both cases of loading there results two functions f x  and f y  and these can be processed in an evaluation unit and compared. Furthermore these functions are usefully displayed on a monitor and/or graphically represented with a printer for the simultaneous assessment or subsequent evaluation. 
     These functions with an assumed straight course particularly give much information inasmuch as they give information whether there is damage caused for example by a fracture in the mast and where this damage is located. 
     If both functions f x , f y  have the same course and thus the same gradient, it may be concluded that in any case no damage of the mast in the vertical testing plane and in the mast region directly next to this plane will be present. If on the other hand the courses of the two functions f x , f y  related to the same zero point diverge and thus have differing gradients then a mast damage may be concluded even when the characteristic curves obtained from the two functions run linearly or straight, since a mast for example damaged with a fracture even after a further development of the fracture with an increasing loading of the mast will continue to behave elastically and a fracture formation at the most would result in a small kink in the otherwise continued linearly running characteristic curve. 
     As has already been mentioned, from the two functions obtained in the same testing plane and from their courses also the location of the damage may be concluded. If specifically e.g. the function f x  evaluated with the compression procedure has a larger gradient than the function f y  determined with the tensile procedure, this would mean that the fracture is located on the side of the mast on which the tensile force is indroduced, since it is to be expected that the mast on account of the smaller spreading of a transversly running fracture, without this at the same time having to become larger, will behave more elastically than with a compression force introduced in the opposite direction with which oppositely lying fracture surfaces are pressed together and the mast with this loading direction will behave less elastically as one without a fracture formation. In this context the same applies when the fracture would run vertically or with a vertical component, in the mast. On account of further criteria for assessing a mast to be tested the solutions specified in the Utility Model DE 296 07 045.9U are referred to, from which the invention also proceeds and of which the invention makes use. 
     All previously dealt with methods have the common disadvantage that with them the condition that the mast or its anchoring with the respective loading cases may change its position in or on the ground may not be exactly taken into account. In any case it may happen that with the testing procedures it may for example arise that movements and a tilting shifting of the mast or its anchoring may occur on or in the ground and at the same time ground material is permanently displaced by the tilting of the mast or its anchoring, which of course would have an such effect on the course of the functions f that these would no longer give clear information on the stability of the mast as such. 
     BRIEF SUMMARY OF THE INVENTION 
     In particular this disadvantage is to be alleviated by the invention in that a method and a testing device are put forward with which in a relatively simple and above all secure manner a sound decision and answer to the question can be achieved as to whether on the one hand a tested mast is adequately stable and whether oil the other hand the obtained measuring results may point to whether a shifting of the mast or its anchoring in the ground is present, wherein even on ascertaining such shifting, information is to be made possible whether the mast is damaged or not. 
     In one aspect this invention comprises a method for testing the stability of a vertically anchored mast with which the mast is loaded with an increasing force F 1  introduced above its anchoring, wherein this force and the measure S 1  about which the mast on account of the force effect is laterally deflected in one direction where appropriate are acquired and there results a function f 1 =F 1 (S 1 ), and with which the mast after completion of the loading procedure is again unloaded, wherein the restoring force F 2  of the mast, reducing with the unloading procedure is acquired in dependency on the reducing lateral deflection S 2  as a restoring movement, wherein there results a function f 2 =F 2 (S 2 ), and therein by way of the course of the function f 2  and of a further function (f 1 ;f 4 ) information on the stability of the mast and its anchoring is obtained. 
     In other aspect this invention comprises a method in which the mast after a first testing procedure in the same testing plane with a second testing procedure is loaded with a force F 3  directed oppositely to the force F 1  and this force as well as the lateral deflection S 3  of the mast resulting with the second testing procedure are acquired, wherein there results function f 3 =F 3 (S 3 ), wherein also in the second testing procedure an unloading of the mast is included in that the restoring force F 4  resulting with this unloading and the reducing deflection S 4  of the mast are acquired, wherein there results a function f 4 =F 4 (S 4 ), wherein with the first and second testing procedure in the case of not reaching the maximum test force (Fpmax) the course and the end values of loading characteristic curves ( 50 , 52 ) as well as the residual deflections (S 2 ,S 4 ) of evaluated unloading characteristic curves ( 51 , 53 ) are acquired and evaluated for determining the type of damage to the mast. 
     With the solution according to the method according to the invention it is even possible also to acquire the condition of the anchoring of the mast in the ground on testing the system mast/anchoring when the system has been subjected to the maximum test force. It becomes evidently recognisable whether the anchoring has behaved solidly or stably, i.e. whether the anchoring has resisted all forces acting on it and accordingly has not moved or whether on reaching the maximum testing force it has also given, thus has moved and as a rule has carried out a tilting movement. Indeed there are situations in practice where it is not neccesarily recognisable on the anchoring itself and/or on the ground surroundings of the anchoring whether a tilting movement and thus a tilting shifting of the anchoring has taken place during the testing procedure. Further it is recognisable whether with the tilting shifting of the mast and its anchoring, damage to the mast is present or not. Moreover it can also be recognized whether, with the anchoring which has remained solid, damage to the mast is present or not. 
     As essential reason for obtaining assessment characteristic curves giving information on testing the system mast/anchoring, apart from the recording of the respective loading characteristic curve, according to the invention also lies in the recording of the respective associated unloading characteristic curve. If with the test it is ascertained that the concerned evaluated unloading characteristic curve has a course deviating from its associated loading characteristic curve, thus for example has not returned to the zero point of the loading characteristic curve, then there is present at least one tilting shifting of the mast anchoring. If it is ascertained that the curve pair of the loading characteristic curve and unloading characteristic curve is identical up to the maximum test load, that therefore the unloading characteristics curve has the same steep course as the loading characteristic curve and returns to the zero point of the loading characteristic curve, then it is certain that the mast as well as its anchoring are in order. Furthermore it may also be ascertained that the mast is in order in spite of an ascertained tilting shifting of its anchoring. 
     Since it has been surprisingly ascertained that the unloading characteristic curve, which in the recorded force-deflection diagram runs back from its maximum test force applied in the region of elastic deformation until the test force is removed, represents a straight line, with a comparison of the unloading characteristic curve in each case with its associated loading characteristic curve or of the unloading characteristic curves amongst each other it can be recognized whether the mast alone and/or its anchoring is damaged or not, and specifically with the inclusion of the mast anchoring up to reaching the maximum test load. The mast anchoring is thus usually included with the testing method according to the invention and not isolated from the mast. The method according to the invention with respect to the previously known methods therefore permits in a simple manner increased information on the tested system of the mast and its anchoring. 
     For a further improvement of information capability on the damage to the mast and its anchoring the test loads applied directly to the mast for determining the loading characteristic curves and the unloading characteristic curves for each testing plane are applied in two opposite directions. This means for each testing plane a compression loading in the one direction and a tensile loading in the opposite direction. One thus obtains four characteristic curves, and from a comparison of these loading characteristic curves and unloading characteristic curves to one another there results even more exact information on tile damage or lack of damage to the mast and/or its anchoring. The information capability may be increased even further when a multitude of testing planes are applied, in particular when at the same time for each plane it is tested in two opposite directions. 
     A device for carrying out the method according to the invention comprises an evaluation unit which is equipped with means for determining an unloading curve belonging to the evaluated loading curve corresponding to the function f 1 , this unloading curve representing a function f 2  from the restoring values measured by the force and distance sensor. This means may consist of a computer which functions according to a suitable program 
     In a preferred formation the evaluation unit may be provided with means for comparing the courses of the functions f 1  and f 2  for the purpose of ascertaining a deviation of the two curves from one another as a criterion for damage to the mast and/or to its anchoring. These means may consist of electrical comparator circuits. 
     The measuring results of the testing procedure, i.e. the courses of the loading characteristic curves and the unloading characteristic curves according, to the functions f 1  and f 2  respectively may be displayed optically on a monitor and/or may be documented with a printer. Such a device is simple in its construction and is therefore inexpensive to manufacture as well as simple to handle. 
     Preferred formations of the invention are specified in the dependent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is hereinafter described in more detail with an embodiment example shown in the appended drawings. There are shown: 
     FIG. 1 a schematic and heavily simplified construction of a device in combination with a mast to be checked therewith and its anchoring, 
     FIG. 2 testing procedures on a mast and its anchoring with the device according to FIG. 1, 
     FIG. 3 the system of the mast and its anchoring in a perfect, and in a displaced condition, 
     FIGS. 4 to  13  diagrams which show loading and unloading characteristic curves with a mast including its anchoring, tested within one plane in two opposite directions. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to the FIGS. 1 and 2 a mast  1  is fastened vertically in the ground  3  by way of an anchoring  2 . The mast  1  is for example a light mast which where appropriate at its upper end comprises an arm  1   a  on whose end a street lamp  4  is mounted. 
     A device for testing the stability of the mast  1  including its anchoring  2  comprises a force unit  5  which for example can be attached to a mobile, schematically indicated vehicle  6 , a force sensor  7  which is located between the force unit  5  and the mast  1 , a distance sensor  8  preferably formed as a distance path sensor, which is arranged in the same vertical testing plane of the unit  5  and the force sensor  7 , for example on the other side of the mast, as well as an evaluation unit  9  circuited with the force sensor and the distance sensor. This evaluation unit comprises a computer  10 , e.g. a personal computer which is connected to a monitor  11  and/or to a printer  12 . Furthermore there is provided a transmitter  13  which leads the signals of the force sensor and of the distance sensor  8  in a processed form to the computer  10 . The more exact construction, which is not further decisive, of the above mentioned device, may be designed as is described in DE-U-94 04 664. 
     The evaluation unit  9  is formed in a manner such that the compressions force measuring results as well as the tensile force measuring results in the respective testing plane and in each case with respect to the associated mast deflection are displayed. The formation of the unit thus comprises means  20  for determining loading and unloading characteristic curves. For this correspondingly programmable computer components may be applied. In a further formation of the unit  9  this may also contain electrical comparator circuits  21  so that the obtained momentary curves or characteristic curves may be automatically compared to one another in the evaluation unit. If with a comparison of the characteristic curves a deviation from one another is determined, this results in that a damage to the mast and/or its anchoring is present. The evaluated characteristic curves may be optically (symbolically or alphabetically) preferably displayed on the monitor and/or represented with the printer. Additionally to the evaluated characteristic curves also an acoustic signal may be given. 
     The checking of the mast and its anchoring for stability is carried out as follows. 
     Firsty a first vertical testing plane is selected, in which the mast  1  is loaded by way of a force which engages the mast above the mast anchoring  2  at a predetermined location, i.e is loaded with bending. Preferably such a plane is selected in which the main loading of the mast lies. At the same time preferably the loading of the mast by way of wind forces is taken into account. 
     In FIG. 2 with the reference numeral  14  a first vertical testing plane is indicated in which also the main loading forces act on operation of the mast. It is assumed that firstly a compression force reaching up to a predetermined, maximum test value is exerted continuously increasingly onto the mast. The distance sensor  8  which is connected onto the mast at a predetermined location above the anchoring  2  comprises with this example the lateral, distance path deflections S belonging to the corresponding pressure force FD. With this both values are simultaneously and continuously inputted to the tranmitter  13  which in turn inputs them into the computer  10  suitably prepared. This computer processes the incoming readings, according to a program, i.e. it sets them into a relationship, and specifically as a function f of the force FD in dependency on the associated mast deflection. There thus arises a momentary loading characteristic curve  16  which is to be seen on the monitor  11 . Alternatively, or additionally this characteristic curve  16  may also be printed with the printer  12  connected to the computer  10  and thereby documented. 
     After reaching the maximum testing force in the elastic deformation region of the mast the test force further acting as a compression force is reduced il a continuously falling manner. Thereby again a characteristic curve is recorded in tile previously mentioned manner, this time however in the form of an unloading characteristic curve  17  and is displayed on the monitor  11  (indicated dashed) and/or is recorded with the printer  12 . In contrast to the evaluation of the loading characteristic curve  16  the evaluation of the unloading characteristic curve  17  is effected with the help of a suitably programmed computer program in the reverse direction, i.e. proceeding from the maximum test force until a test force with the value zero, wherein the reducing mast deflection S in each case is set into relation to the reducing test load FD. According to the condition of the tested system of the mast and its anchoring the unloading characteristic curve will have the same course as the loading characteristic curve or both characteristic curves will deviate from one another. On account of the course of the two evaluated characteristic curves the testing person may already carry out an assessment of the tested system. 
     The values of both characteristic curves  16  and  17  may however also be automatically compared by way of comparator circuits, and the result in each case may be displayed on the monitor  11  and/or documented with the printer  12 . 
     For the increased information ability on the stability or standing safety of the mast and/or its anchoring it is advantageous in the same vertical testing plane  14  to apply a second test force F in the opposite direction to the first test force. If the first test force is a compression force FD the second test force is a tensile force FZ which is exerted in a continuously increasing manner and subsequently in falling manner with a simultaneous measurement of the respective mast deflection. Corresponding to the above mentioned explanation again a momentary loading characteristic curve  16  and a momentary unloading characteristic curve  17  is obtained as the graphics on the monitor displays. These characteristic curves may likewise have the same gradient as the previously obtained characteristic curves, they may however also deviate from one another. Also these characteristic curves may be printed with the printer  12 . 
     For increasing even further the information capability on the stability o the mast  1  and its anchoring the mast many be tested in at least one further vertical testing plane  19  as explained previously. 
     This further testing plane runs preferably at right angles to the first vertical testing plane  14 . Again two momentary characteristic curves for the compression force and the tensile force application are obtained which are displayed on the monitor  11  and/or may be permanently documented with the printer  12 . If the mast has been examined in both testing planes  14  and  19 , then with this very good information is given with respect to the stability of the mast and its anchoring. 
     The characteristic curves of the diagrams in the subsequently described FIGS. 4 a  to  9   b  represent the measurement results evaluated by the evaluation unit. For the sake of simplicity the characteristic curves of these figures are to represent the results obtained in only one vertical testing plane. In this context they of course also apply to where appropriate several selected vertical testing planes. 
     It is to be assumed that the mast  1  and its anchoring  2  firstly is loaded on bending with a compression force. One obtains according to FIG. 4 a  for example a momentary loading characteristic curve  22  with the course as a straight line according to the function f with the unchanging gradient C 1 . This characteristic curve  22  runs from the zero point in the inclined and straight shape until reaching the maximum test load FPmax. Subsequently the mast is unloaded under a constant reduction of the compression force so that an unloading characteristic curve  23  is obtained. Also this characteristic curve shown dashed runs straight, and in the case shown according to the function f 2  with the unchanging gradient. This characteristic curve is evaluated as a retrograde characteristic curve, and specifically from the maximum test load FPmax back to the same zero point of the loading characteristic curve  22 , so that in the present case both characteristic curves  22 ,  23  overlap From this test result so far it results that the anchoring  2  of the mast has not changed, i.e. has behaved ideally and that also the mast itself has no damage. 
     In order to ensure the result of the first testing procedure in the same testing plane it is tested with an opposite force direction. For the purpose of avoiding a conversion of the testing device the mast is loaded in bending with a tensile force. The results of this second measuring procedure are represented in FIG. 4 b . One obtains firstly a loading characteristic curve  24  (solidly drawn), which has a straight course according to the function f 3  with an unchanging gradient C 3 . After reaching the maximum test load FPmax again a continuously reducing tensile force test loading of the mast is effected until the value zero. With this there arises a straight unloading characteristic curve  25 , shown dashed, according to the function f 4  with an unchanging gradient C 4 . On recognises from FIG. 4 b  that the courses of the two characteristic curves  24  and  25  are identical since also in this case the straight unloading characteristic curve  25  runs back into the zero point of the loading characteristic curve  24  and with its gradient C 4  corresponds to the gradient C 3 . The gradients C 1  to C 4  may be given to the monitor  11  and/or to the printer  12  in various angular degrees. 
     If then with the testing procedures according to the FIGS. 4 a  and  4   b  it is found out that the functions f 1 , f 2 , f 3  and f 4  so correspond to one another that also the respective gradients C 1 , C 2 , C 3  and C 4  are unchanged over the whole length of the straight characteristic curves, thus have the same value, then it follows that the whole system mast/anchoring is free of damage. 
     According to FIG. 5 a further mast in a vertical testing plane is tested up to a maximum testing force FPmax, and specifically it is loaded with bending firstly with a compression force, as is shown in FIG. 5 a  and subsequently with a tensile force, as FIG. 5 b  shows. One obtains also here a loading characteristic curve  26  beginning from the zero point and uniformly increasing as a function f 1  of the compression force F 1  in dependency on the deflection distance path S 1 . To this loading characteristic curve there belongs a gradient C 1 . After reaching the maximum test force an unloading characteristic curve  27  is recorded. Thereby the unloading function f 2  is obtained, and specifically as a function of the restoring force F 2  in dependency on the resulting deflection distance path S 2 . To this unloading characteristic curve there belongs a gradient C 2 . Since both characteristic curves overlap and return to the zero point, it may be concluded therefrom that the mast as well as its anchoring are in order. 
     There is then effected the second testing procedure in the same plane with a tensile loading. Tile result is represented in FIG. 5 b . Firstly the solidly represented loading characteristic curve  28  is evaluated and specifically as a function f 3  of the test force F 3  in dependency on the deflection distance path S 3 . To this characteristic curve there belongs a gradient C 3  which firstly has a step course and then a course becoming weaker. Subsequently the unloading characteristic curve  29  as a function f 4  of the restoring force F 4  in dependency on the reducing deflection S 4  is evaluated. To the straight unloading characteristic curve  29  running back there belongs the gradient C 4 . One ascertains that the unloading characteristic curve  29  does not return to the zero point, but there remains a residual distance path S 4 . 
     A comparison of the unloading characteristic curves  27  and  29  shows that they both have the same course and thus the same gradient over their whole course. From this it may be concluded that the mast itself is in order, thus for example has no fracture. Since however the unloading characteristic course  29  does not return to the zero point, but with a completely lifted restoring force there remains a residual distance path, it is therefore certain that the anchoring  2  of the mast  1  has been displaced in the sense of a tilting movement, as is shown dashed and exaggerated in FIG.  3 . The ground surrounding the anchoring has therefore given, which is to be recognized with the loading characteristic curve  28  according to FIG. 5 b  in that it blends into a very flat course, i.e. with a low gradient, in its upper section. On account of the fact that with the unloading of the mast the associated unloading characteristic curve  29  with respect to its restoring deflection does not return to the zero point, the upper, very flat section of the loading characteristic curve  28  is to be evaluated as a failure of the anchoring  2 . The functions f 3  and f 4  thus deviate from one another. 
     The representations according to the FIGS. 6 a  and  6   b  show the test results of a next mast and its anchoring. The courses of the testing procedures in the common testing plane are also described here as previously in combination with the FIGS. 4 and 5. One recognises in FIG. 6 a  that the loading characteristic curve  30  firstly takes an expected course, but then in its upper section blends into an increasingly reducing gradient. The returning unloading characteristic curve  31  is represented as a straight line, with the unchanging gradient C 2 . Also in this case there remains a residual deflection S 2 . Thus also here a tilting shifting of the mast anchoring  2  is given, somewhat comparable to the representation in FIG. 3, wherein the mast itself has no damage. 
     With the second testing procedure in which the mast is loaded on bending with a tensile loading, there results the diagram according to FIG. 6 b . The loading characteristic curve  32  deviates considerably from a straight line, and specifically firstly it has a flat course, which after a short deflection path then blends into a steeper course and in the upper section again returns into a flatter course, until the maximum test force has been reached. The subsequent unloading of the mast resulted again in a straight-lined, unloading characteristic curve  33  which again does not return to the zero point, but leaves behind a residual deflection S 4 . 
     One recognises that the courses of the unloading curves  31  and  33  overlap so that the gradient C 2  corresponds to the gradient C 4 . However the functions f 1  and f 3  deviate from the associated functions f 2  and f 4  from one another. From both pictures according to the FIGS. 6 a  and  6   b  it may again be concluded that with the first as well as with the second testing procedure the ground  3  has given with respect to the anchoring  2  of the mast  1 , and the mast anchoring is not perfect. 
     The representations according to the FIGS. 7 a  and  7   b  show the test results of a further mast and its anchoring. Also these representations are based on the previously described testing course. According to FIG. 7 a  there results a straight loading characteristic curve  34  running up to the maximum test load. The unloading characteristic curve  35  overlaps with the loading characteristic curve  34 , so that the functions f 3  and f 4  including their gradient are the same. Both characteristic curves have the same zero point. Thus the mast and the anchoring are without damage. 
     According to FIG. 7 b  the loading characteristic curve  36  likewise runs straight and the unloading characteristic curve  37  again overlaps with its associated loading characteristic curve  36 . Also in this case both lines over their whole length have the same gradient and additionally the same zero point. 
     Although in both cases no residual deflection has been ascertained, however the gradients of the first curve pair  34 ,  35  deviate from those of the second curve pair  36 ,  37 , wherein the second curve pair has a lower gradient than the first pair of curves. In total from the courses of the characteristic curves according to the FIGS. 7 a  and  7   b  it may be concluded that a shifting of the mast anchoring  2  has not taken place, however that the mast has damage. The damage, for example a fracture can be recognized at the lower gradient of the curve pair  36 ,  37 , since the mast behaves more elastically in the case of damage. 
     The next testing case is shown in the FIGS. 8 a  and  8   b . Also in this case the testing procedures are effected such as they were explained in combination with the FIGS. 4 and 5. FIG. 8 a  shows a loading characteristic curve  38  as a straight line and an unloading characteristic curve  39  likewise as a straight line. The courses of these two characteristic curves are identical, since in each case they have the same gradient over their whole length. 
     FIG. 8 b  shows that the loading characteristic curve  40  does not have a straight course but in its gradient becomes smaller with an increasing test force. The associated unloading characteristic course  41  runs again as a straight line with an unchanging gradient C 4 , the unloading characteristic curve  41  does not however return to the zero point but there remains a residual deflection S 4 . 
     A comparison of the curve pairs  38 ,  39  and  40 ,  41  shows that apart from an ascertained residual deflection S 4  also a different gradient of C 2  and C 4  thus a differing gradient of the unloading characteristic curves  39  and  41  is given. From this it is then to be concluded that the mast  1  is damaged and specifically on account of the differing gradients of C 2  and C 4 , as well as there being present a tilting shifting of the ground anchoring  2 . 
     Finally there is yet another testing case shown in the FIGS. 9 a  and  9   b . Also in this case the testing procedures are carried out as are described in combination with the FIGS. 4 and 5. 
     FIG. 9 a  shows that the loading characteristic curve  42  has a one-sided curved course, and specifically with a gradient C 1  becoming smaller. The associated unloading characteristic curve  43  again has a straight course also with an unchanging gradient C 2 . The unloading characteristic curve  43  does not however return to the zero point, but there remains a residual deflection S 2 . This means that the ground anchoring  2  of the mast has given way. 
     FIG. 9 b  shows that the loading characteristic curve  44  likewise has a curved course, and specifically firstly with a flat gradient C 3 , which then again becomes larger, and then becomes smaller. The associated unloading characteristic curve  45  again runs as a straight line and likewise does not return to the zero point. There remains a residual deflection S 4  of the mast which is larger that the firstly determined residual deflection S 2 . From the differing residual deflections S 2  and S 4  it follows that the gradient C 4  of the unloading characteristic curve  45  is steeper than the unloading characteristic curve  43 . 
     From the results of this testing case it results that the mast has a damage, for example in the form of a fracture, and that with both testing procedures there is given a tilting shifting of the mast anchoring  2 . 
     In particular from the testing cases according to FIGS. 7,  8  and  9  it results that the gradients C 2  and C 4  of the functions f 2  and f 4  are evaluated such that a damage-free mast is present when the gradients C 2  and C 4  are equal and that a mast is damaged when the gradients C 2  and C 4  deviate from one another. 
     Furthermore it can be determined on which side the mast is damaged when the gradients C 2  and C 4  of the respective unloading characteristic curves are not equal. If the gradient C 2  (compression force) is smaller than the gradient C 4  (tensile force), this gives the information that a damage is present on that side of the mast on which the force F 1  acted. If the gradient C 2  is greater than the gradient C 4 , then a damage is present on that side of the mast on which the force F 3  acted. 
     Furthermore it is possible that on testing the mast and its anchoring only the courses of the functions f 2  and f 4  thus the courses of the unloading characteristic curves are determined and evaluated with regard to any damage to the mast and/or tilting shifting of the system mast/anchoring. 
     Finally it is possible to determine the linear course of the functions f 2  and f 4 , thus the linear course of the unloading characteristic curves by measuring two values for F 2  and S 2  or F 4  and S 4  respectively. This manner of proceeding Simplifies the evaluation of the unloading characteristic curve. 
     With the previously described method the presence of reference characteristic curves may be done away with. The evaluation and assessment of the unloading characteristic curves gives sufficient information that the mast and/or its anchoring is damaged, wherein the damage of the anchoring is to be understood as a change of its position in the ground. 
     With the previously explained examples of the suggested method it is assumed that the maximum test load FPmax is always achieved. If this is not the case which means the momentary prevailing and loading test force leads already earlier to a gradient becoming more or less continuously flat, in particular of the upper course of the respective loading characteristic curve, then in many cases it is further possible also to conclude the one or the other type of damage to the mast itself. In such cases with the unloading characteristic curves as a rule there results permanent mast deflections which may be assessed together with the courses ol tile loading characteristic curves and their end force values. This is subsequently explained in more detail in combination with the FIGS. 10 to  13 . 
     According to FIG. 10 a  the mast to be checked is firstly again loaded on bending with a compression force, and specifically with a constantly increasing force, so that the solidly represented loading characteristic curve  50  according to the function f 1  arises. One recognises that the sought after maximum test force FPmax is not reached, but rather that the line  50  earlier in its gradient becomes more and more flat and at its upper end section blends into a curved shape. This first testing procedure is broken off at this position, and there arises on account of the still present elasticity of the mast the dashed unloading characteristic curve  51  according to the function f 2 . This line does not run back to the zero point, but there remains a permanent residual deflection of the mast S 2 , which is read off on the monitor with respect to the numbers or symbolically and/or documented with the printer. 
     According to FIG. 10 b  then the second testing procedure is carried out in which the mast is loaded on bending in the same plane with a tensile force. Also in this case there results a laoding characteristic curve  52  according to the function f 3 , shown solidly, wherein this line before reaching the maximum test force FPmax again in the upper section blends into a curvature becoming more flat. The unloading which is subsequent to this results in the unloading characteristic curve  53 , indicated dashed, according to the function f 4 . Also this line does not return to the zero point, but there results a permanent mast deflection S 4 . 
     A comparison of the two pairs of characteristic curves of these figures shows that the loading characteristic curves  50 ,  52  from their zero point increase constantly in a straight-lined manner, curve in their upper end section equally or roughly equally becoming more and more flat, and specifically with the same or roughly same end value below the maximum test force. The unloading characteristics curves  51  and  53  likewise have the same course, and there results mast deflections remaining the same or roughly the same which are both larger than zero. The result of these two testing procedures lies in the fact that a tilting shifting of the mast anchoring is not given, but that however tile mast itself is damaged. On account of the operation up to now the mast is damaged by a corrosion procedure which with the two testing procedures has expressed itself in that during the two testing procedures a plastification of the mast in the region of the corrosion location has taken place. Essential features for this are the fact that the mast damage with the two testing procedures with the same or roughly the same momentary test force below the maximum test force becomes recognisable in combination with the permanent residual deflection. 
     The two testing procedures in the FIGS. 11 a  and  11   b  disclose another type of damage to the tested mast. Also in this case the two testing procedures firstly compression force then tensile force are carried out as previously specified. There arises firstly a loading characteristic curve  54  according to the function f 1 , which in its upper end section ends with a gradient becoming flatter before reaching the maximum test force FPmax. The returning unloading characteristic curve  55  shown dashed, according to the function f 2 , again ends in a permanent residual deflection S 2 . 
     With the second testing procedure according to FIG. 11 b  there results another picture of the testing course. There firstly arises a loading characteristic curve  56  according to the function f 3 , which however as a whole runs straight and with which the maximum test force FPmax is reached. Since with this force the testing procedure is stopped as provided, there then arises the unloading characteristic curve  57  according to the function f 4  which in this case overlaps the loading characteristic curve  56  and thus returns to the zero point, which means that there is no sort of permanent residual deflection of the mast. 
     Although with the second testing procedure according to FIG. 11 b  no sort of damage could be discovered, thus neither to the mast itself nor to its anchoring, however FIG. 11 a  leaves no doubt as to a damage to the mast since also here no shifting of the mast anchoring is recognisable. The damage which can be deduced as a result of these two testing procedures is a fracture in the mast, which in the first testing procedure has enlarged, essentially increased in length, and specifically to the degree that a permanent residual defletion S 2  could be determined. The course of the two characteristic curves  54  and  55  as an identification as a fracture which is present in the mast and which has already weakened the mast to a high degree may be explained by FIG. 11 b . Since here the test has taken place in the opposite direction and with this the two fracture halves have been pressed onto one another, the mast with the second testing procedure has behaved practically like an undamaged mast. With the testing procedure according to FIG. 11 thus likewise no shifting of the mast anchoring is given, but the mast has fracture damage. 
     Yet a further type of damage can be deduced from the FIGS. 12 a  and  12   b  ). With the first testing procedure according to FIG. 12 a  (compression force) there results firstly a loading characteristic curve  59  according to the function f 1 , shown solidly. In its upper end region this line again blends into a curve becoming flatter with a momentary test force which likewise lies below the maximum test force FPmax. The testing procedure is again stopped, in order to avoid further damage to the mast. The then evaluated unloading characteristic curve  59  according to the function f 2  runs back in a straight manner, but does not end at the zero point of the force-distance system, but leaves behind a permanent residual deflection of the mast S 2 . The second testing procedure in the same testing plane with an opposite test force (tensile force) firstly results in a loading characteristic curve  60  according to the function f 3 , which firstly rises in a straight manner and in its upper end region again before reaching the maximum test force blends into a curve becoming flatter. The testing procedure is stopped and there results a returning unloading characteristic curve  61  according to the function f 4 , which likewise does not return to the zero point of the force-distance system, but results in a permanent residual deflection S 4  of the mast. 
     A comparison of the two pairs of characteristic curves of FIGS. 12 a  and  12   b ) firstly results in that the courses of the loading characteristic curves in their upper region as such are equal or essentially equal, that however in the second testing procedure a larger momentary test force was reached. Otherwise the pairs of characteristic curves  58  to  61  essentially have the same course. The further feature which has been ascertained is the fact that both unloading characteristic curves  59 ,  61  lead to permanent residual deflections of the mast with a stop of the testing. These results indicate a tension fracture corrosion or an intercrystaline corrosion of the mast. In the region of the fracture which with the first testing procedure has widened somewhat, during the operation of the mast a corrosion has taken place which with the second testing procedure is partly the cause of the plastification of the mast in the region of the corrosion, so that in the second testing procedure a higher momentary test force had to be applied. A shifting of the mast anchoring has not occured with these two test procedures. 
     A further test result is represented in the FIGS. 13 a  and  13   b . According to FIG. 13 a  there firstly results a solidly drawn loading characteristic curve  62  according to the function f 1 . This line  62  has for example a curved course from the beginning, which in its end region has already become relatively flat, so that the testing procedure (compression) is stopped at a momentary test force below the maximum test force FPmax. The connecting, returning unloading characteristic curve  63  shown dashed runs essentially straight and results at the end in a permanent residual deflection S 2 . The subsequent second testing procedure in the same testing plane, but however in the opposite direction (tensile force) results in a loading characteristic curve which firsly increases very gradually and then remains at an unchanging force value, wherein a deflection of the system mast/anchoring is to be ascertained over a certain distance. Accordingly there results a relatively steep rising of the loading characteristic curve  64 . 
     With the rising of the loading characteristic curve  64  then various variants of this line may occur. In a first variant this line runs with a constant gradient up to tie maximum test force FPmax. There then results a returning unloading characteristic curve  65  shown with a dash double-dot line which overlaps with the course of the second section of the line  64  and thus shows a residual deflection S 4 ′. A comparison of this result with the residual deflection S 2  according to FIG. 13 a  means that when the deflections as here in the case shown are equal or roughly equal no damage to the mast could be ascertained, but that a shifting of the mast anchoring is present. This result also indicates that the mast itself has not experienced a plastification. 
     In a second variant the loading characteristic curve  64  in the upper region of its second section before reaching a maximum test force, for example the momentary test force F 10 , may experience a curvature becoming flatter. If the testing procedure is immediately stopped, a returning unloading characteristic curve  66  shown dot-dashed may arise, this also resulting in the previously determined residual deflection value S 4 ′. In this case a shifting of the mast anchoring is present, wherein the mast has a fracture damage which has been ascertained in the second testing procedure but which has behaved completely elastically, because the unloading characteristic curve  66  returns to the lower end point from which the second, steeply rising section of the loading characteristic curve  64  is imagined to have began, as is deduced from FIG. 13 b.    
     A third variant in the testing procedure results when the loading characteristic curve  64  likewise in the second section at F 11  before reaching the maximum test force becomes considerably weaker. There then results a returning unloading characteristic curve  67  shown dashed, whose lower end likewise leads to a residual deflection S 4 . This residual deflection is however larger than the previously determined residual deflection S 4 ′. This indicates that apart from the shifting of the mast anchoring also a damage to the mast itself in the form of a fracture lengthening during the testing is present. In these cases there results a residual deflection S 4  which is larger than the residual deflection S 2  determined in the first testing procedure. 
     A fourth variant results with the fact that the testing loading of the mast according to the line  62  up to the test force F 11  has led to the fact that apart from a shifting of the mast anchoring also a damage to the mast itself has occured, which however cannot be more accurately recognized by the mast deflection S 2 . With the second testing procedure according to FIG. 13 b  there results a loading characteristic curve  64   a  which at its beginning runs roughly as the curve  64 , but already after the deflection S 3  rises steeply and then for example runs further as line  64 . As an unloading line there results line  67  with the residual deflection S 4 . Since in this case S 2 &gt;S 3  and the momentary test load F 11  in both testing procedures is equal or almost equal with as a whole an unequal course in particular of the loading characteristic curves, it results that S 3  is characteristic for the shifting of the mast anchoring in the first testing procedure, whilst the difference of the deflections ΔS=S 2 −S 3  is typical for the permanent mast deflection on account of a plastification of the mast caused by corrosion. 
     If it is desired to cut off the influence of the anchoring with the testing, then the mast at its lower end may be locked, which means the end region of the mast, which borders the anchoring, is connected to a mechanical means and by way of this is stabilized so that the anchoring is unmovable. Then only the bending deflection of the mast alone is acquired and evaluated with respect to the technical measurement. Also in this case the respective unloading characteristic curve is compared to the associated loading characteristic curve and the result evaluated as to the degree of damage to the mast. Finally it must be stressed that the arising deflections of the system mast/anchoring may also be determined by way of angular sensors and accordingly evaluated in the evaluation unit  9 .