Abstract:
A method for testing the stability of vertically braced masts wherein the relevant mast is subjected to the load of a bending force starting from a defined initial value, and increasing to a maximum pre-set testing force above its bracing, the mast thereby being laterally displaced. The load is then removed from the mast and is subjected to a restoring force which reduces to zero. The mast is evaluated in conjunction with the load removal procedure to determine damage to the mast and/or its bracing. The mast is subjected to an additional bending force in the opposite direction of the first bending force, and the load is once again removed from the mast in a second test procedure. A possible remaining displacement of the mast/bracing system is evaluated in conjunction with the highest mast loads to determine the type of possible damage to the mast.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a method for testing the stability of vertically anchored masts in which the mast above its anchoring is loaded with an increasing bending force proceeding from a defined initial value until at the most a maximum, predetermined test force and at the same time is laterally deflected and in which the mast after completion of the loading procedure is again unloaded and with this is subjected to a restoring force reducing to zero. 
     In EP0 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 moment 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. 
     In accordance with one embodiment, the following results and information were achieved: 
     
       
         
               
               
             
           
               
                   
               
               
                 RESULT: 
                 INFORMATION: 
               
               
                   
               
             
             
               
                 A) S2 &gt; 0, S4 &gt; 0 
                 no tilting shifting, but a 
               
               
                 loading characteristic curve course equal, 
                 plastification of the mast in 
               
               
                 whose end force values are approximately 
                 both testing procedures. 
               
               
                 equal; 
               
               
                 b) S2 &gt; 0, S4 = 0; S2 = 0, S4 &gt; 0 
                 no tilting shifting but a 
               
               
                 loading characteristic curve course 
                 fracture lengthened on 
               
               
                 unequal, essentially a straight lined 
                 testing. 
               
               
                 reaching of FPmax in a testing procedure; 
               
               
                 c) S2 &gt; 0, S4 &gt; 0 
                 no tilting shifting, but 
               
               
                 loading characteristic curve course 
                 tension fracture corrosion 
               
               
                 essentially equal, however, end force 
                 or intercrystalline corrosion 
               
               
                 values in the second testing procedure 
                 in the mast. 
               
               
                 higher; 
               
               
                 d) S2 = S4 
                 only tilting shifting in first 
               
               
                 as a whole an unequal loading 
                 testing procedure. 
               
               
                 characteristic curve course second loading 
               
               
                 characteristic curve beginning very flat and 
               
               
                 steeply rising at 54 until Fpmax; 
               
               
                 e) S2 &lt; S4 
                 tilting shifting in the first 
               
               
                 as a whole an unequal loading 
                 testing procedure, fracture 
               
               
                 characteristic curve course, second loading 
                 recognition with the second 
               
               
                 characteristic curve beginning very flat and 
                 testing procedure. 
               
               
                 steeply rising at S4; 
               
               
                 f) S2 &gt; S3 
                 tilting shifting and 
               
               
                 as a whole an unequal loading 
                 plastification of the mast 
               
               
                 characteristic curve course, second loading 
                 with the first testing 
               
               
                 characteristic curve beginning very flatly 
                 procedure. 
               
               
                 and at S3 increasing heavily, testing forces 
               
               
                 equal with both testing procedures; 
               
               
                   
               
             
          
         
       
     
     With this method 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 this method a linear course of the function S=f(F), 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. 
     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 on 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. 
     From one aspect, the invention relates to a method for testing the stability of vertically anchored masts in which the mast above its anchoring is loaded with an increasing bending force F 1  proceeding from a defined initial value until at the most a maximum, predetermined test force FPmax and at the same time is laterally deflected and in which the mast after completion of the loading procedure is again unloaded and with this is subjected to a restoring Force F 2  reducing to zero, wherein in combination with the unloading procedure exclusively a lateral defection S 2  of the mast remaining at F 2 =zero is ascertained and is evaluated as damage to the mast and/or its anchoring. 
     From another aspect, the invention relates to a method for testing the stability of vertically anchored masts in which the mast above its anchoring in a first resting procedure is loaded with an increasing bending force F 1  measured from a defined initial value until at the most a maximum predetermined test force FPmax and at the same time is laterally deflected and in which the mast after completion of the loading procedure is again unloaded and with this is subjected to a restoring force F 2  reducing to zero, and in which the master after the first testing procedure in the same testing plane in a second testing procedure is loaded with a second test force F 3  directed oppositely to the first test force F 1  and with this is laterally deflected, whereupon the mast is again unloaded and with this is subjected to a reducing restoring force F 4  reducing to zero, wherein in combination with the loading procedures at least the highest reached test force FP in each case or at least a part course of the loading characteristic curve at least of the second testing procedure is determined, wherein in combination with the unloading procedures exclusively a possible lateral deflection S 2 , S 4  of the mast remaining at F 2 =0 and/or F 4 =0 is ascertained and wherein the results of both ascertainings are evaluated as damage to the mast and/or as a damage to its anchoring. 
     With the solution according to the method according to the invention in a surprising and very simple manner it is possible to acquire the condition of the system mast/anchoring and also the condition of the anchoring of the mast in the ground as well as of the mast even on testing, and specifically even then when with the testing of the system the maximum testing force has not been reached. It becomes evidently recognisable whether the anchoring and/or the mast has behaved solidly or stably. With respect to the anchoring it is thus recognisable 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. 
     An essential reason for obtaining informative results on the testing of the system mast/anchoring in the simplest case of testing according to the invention lies exclusively in the drawing up and evaluation of the remaining lateral deflection, where appropriate present, of an unloading following a loading of the mast. If it is to be found that the restoring force reduced to zero after the complete unloading of the mast leads to a permanent residual deflection, then a damage to the mast and/or a tilting shifting of the mast anchoring is present. 
     The method according to the invention thus with respect to the methods known up to now in a very simple and quick manner permits an increased information capability of the tested system the mast and its anchoring. 
     For the further increase of the information cabability with respect to the damage to the mast and its anchoring, for each testing plane two testing forces acting in opposite directions are exerted on the mast in order to determine possible remaining residual deflections after the unloading. This means that for each testing plane, e.g. a compression loading in the one direction and a tensile loading in the opposite direction is applied. With this one obtains where appropriate two permanent residual deflections. Further as an alternative at least with the second testing procedure at least partly a loading characteristic curve is determined and drawn up, and specifically its course at the beginning and end. As a further alternative also the highest testing force values are measured and used for evaluation. From a comparison of these residual deflections with the part loading characteristic curve or with the highest testing force values there results even more exact information on the damage or lack of damage to the mast and/or its anchoring, in particular on the type of damage to the mast. 
     The information capability of the whole test may be even further increased in that a multitude of testing planes are used, in particular when with this for each plane one tests in opposite directions. 
    
    
     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, 
     FIG. 4 the diagram of the testing procedure, in which the mast in a vertical plane is only loaded once and subsequently unloaded again, 
     FIGS. 5 to  9  diagrams which show loading and unloading procedures with a mast including its anchoring, tested within a vertical plane plane in two opposite directions. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to FIGS. 1-3 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  whose on end a street lamp  4  is mounted. 
     For the improved understanding of the invention first of all a device for testing the stability of the mast  1  including its anchoring  2  is described. It comprises a force unit  5  which for example is attachable on 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  connected to 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 compression 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  9  thus comprises means  20  for determining loading characteristic curves and possible permanent residual deflections after unloading. For this correspondingly programmable computer components may be applied. The unit  9  may also contain further electrical processing circuits  21  in order to automatically evaluate the obtained curves or characteristic curves and residual deflections in a relationship to one another in the evaluation unit. The evaluated readings and computed values as well as damage determination may be optically (symbolically or alphabetically) displayed on the monitor and/or represented with the printer. 
     The testing of the mast and its anchoring for stability is carried out as follows. 
     First, a 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. Such a vertical testing plane is indicated in FIG. 2 with reference numeral  14 . 
     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 deflections S belonging to the corresponding pressure force FD. With this both values are simultaneously and continuously inputted to the transmitter  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 from which the associated mast deflection S is dependent. 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. The evaluation of a complete loading characteristic curve is not absolutely necessary, also a part course is sufficient. Alternatively the evaluation of the highest force readings is sufficient. 
     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 in a continuously falling manner until it has reached the value zero. With this a possible permanent residual deflection is indicated at  17  and is displayed on the monitor  11  and/or drawn with the printer  12 . By way of a possible, any occuring residual deflection already an evaluation of the standing safety of the mast and its anchoring may be effected. 
     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 preferably a tensile force FZ which is exerted in a continuously increasing manner and subsequently in falling manner, wherein with a reducing testing force any occuring permanent residual deflection S is measured and evaluated. At least with the second testing procedure a loading characteristic curve is at least partly evaluated and drawn up for evaluation. 
     For increasing even further the information capability on the stability of the mast  1  and its anchoring the mast may be tested in at least one further vertical testing plane  19  as explained previously, and specifically either in a single test procedure or in two oppositely directed test procedures. These further testing planes run preferably at right angles to the first testing plane  14 . 
     The diagrams of the subsequently described FIGS. 4 to  9   b  represent the measuring and computing results as well as the determination of damage resulting from these, in only a single vertical testing plane. In the same sense they also apply to several selected vertical testing planes. 
     The diagram according to FIG. 4 relates to a single testing procedure. It is assumed that the mast  1  is subjected at a selected height above its anchoring  2  to a horizontally acting bending force F 1  which via the mast also acts on its anchoring. The bending force is exerted onto the mast up to a predetermined maximum test force FP max, wherein the mast laterally deflects. For the respective momentary bending force there results an associated lateral deflection in particular of the mast, so that according to the function S=f(F) a course of force which loads the mast according to the unbroken line  25  in FIG. 4 is computed. This loading line  25  firstly increases uniformly and in its upper region, as is shown here, e.g. assumes a gradient which becomes flatter. With this the maximum test may be reached. Advantageously the loading line  25  is displayed on the monitor. After reaching the maximum test force the mast  1  by way of a reduction of the bending force is unloaded, wherein also the lateral deflection again becomes smaller. The unloading of the mast is indicated with arrow  26 . With this the unloading force F 2  which becomes smaller and the associated correspondingly reduced lateral deflection during the unloading are essentially not measured. However at the end of the unloading procedure it is measured whether with the mast unloading returned back to the force value zero there remains a lateral deflection as is indicated in FIG. 4 at S. On unloading the mast thus exclusively as an important criterion it is recorded and evaluated whether possibly a lateral deflection of the system of the mast and its anchoring has remained. In the present case according to FIG. 4 a permanent lateral deflection S has been ascertained. From this with the help of the automatic evaluation unit  9  it results that the mast and/or its anchoring is/are suffer damage. This result may also occur when the maximum test force is not reached and the testing procedure must be terminated before, as is indicated in a dot-dashed manner at  25   b  in FIG.  4 . 
     If with the loading it results that the loading line does not change in its upper course, but continues to run in a straight manner, as is indicated dashed in FIG. 4 at  25   a , then it results in the usual case that also with an unloading of the mast, a permanent lateral deflection cannot be ascertained. In this case no damage to the mast and/or its anchoring is given. 
     In FIG. 4 for example there is shown the loading characteristic curve  25  over its full length, thus beginning with a defined initial force with a value equal to zero. One may however also proceed in that only a part course of the loading characteristic curve  25  is evaluated, for example the upper half or an upper end course of the loading curve  25 . In this case the evaluation of the loading characteristic curve  25  begins e.g. defined at the force F 1 ′ and the associated lateral mast deflection for this. Such a manner of proceeding may also be applied to all subsequently described embodiment examples. 
     If with the determining of damage according to the previously described example it is desired to know whether the damage concerns only the mast or only its anchoring or both, then in the same vertical testing plane there is carried out a further testing procedure in which the second bending force is directed oppositely to the preceeding bending force. If the first bending force was a compression force then the second bending force will be a tensile force, in order to prevent a repositioning of the device used for the testing. Such a device is shown in FIGS. 5 to  9 . 
     According to FIG. 5 a  the mast to be tested in a first testing procedure is for example loaded with a continuously increasing bending force F 1  so that in combination with the associated mast deflection S, according to the first function S=f(F 1 ) there results a loading characteristic curve  27 . One recognises that the sought after maximum test force FPmax is not reached, but that the curve  25  previously in its gradient becomes flatter and flatter and at its upper end section blends into an arcuate shape. This first testing procedure is terminated at this location and on account of the still present elasticity of the mast there is effected a springing back of the system mast/anchoring. The unloading of the mentioned system is effected by the reduction of the first bending force as now being a decreasing bending force F 2  to the value zero according to the arrow  28 , wherein exclusively a possible remaining residual deflection of the system is measured and evaluated. One recognises in the present case that after the bending force F 2  returned back to zero there is given a permanent residual deflection S 2  which is given in numbers on the monitor or is symbolically read off and/or documented with the printer. 
     According to FIG. 5 b  in the same vertical testing plane there is carried out second testing procedure, and specifically in the same manner as was described in combination with FIG. 5 a . The second increasing bending force F 3  leads to a loading characteristic curve  29 , wherein this curve before reaching the maximum test force FPmax again blends into an upper section with a curvature becoming flatter. The subsequent unloading (decreasing bending force F 4 ) is indicated with arrow  30 , wherein again after completion of the unloading one merely takes account of the remaining lateral deflection. In the present case there resulted with the unloading a permanent residual deflection S 4  of the system which is measure and evaluated. 
     With this complete checking with both testing procedures the maximum test force FPmax was not reached, as is indicated at E in the Figures. However there may also be cases where the maximum test force is reached. This is indicated dashed in the FIGS. 5 a  and  5   b . Furthermore as already indicated previously, with this whole testing procedure it may likewise be proceeded such that the loading characteristic curves  27  and  29  are only evaluated and drawn up when only their upper course is to be kept. In this case the computation of the desired course of curve only begins when the test bending forces have reached the value F 1 ′ and F 3 ′. 
     A comparison of the two diagrams according to the FIGS. 5 a  and  5   b  shows that the loading characteristic curves  27  and  29  in their upper end section curve becoming flatter, and specifically with the same or roughly the same end value E of the test force applied in each case. Furthermore it is evident that in both cases the same or roughly the same residual deflections S 2  and S 4  were ascertained, which are both larger than zero. The damage result of the two testing procedures determined in the evaluation unit  9   c  lies in that a tilting shifting of the mast anchoring is not present but that there is damage to the mast itself. The mast has been damaged by a corrosion procedure which in the two testing procedures has shown itself in that on testing a plastification of the mast in the region of the corrosion location has taken place. Essential features for this are that the mast damage with the two testing procedues with the same or roughly the same momentary test force are recognizable in combination with a permanent residual deflection. 
     The two testing procedures in the FIGS. 6 a  and  6   b  disclose a different type of damage to the tested mast. Also in this case the two testing procedures were in each case carried out with a bending force as previously explained. In the first testing procedure a loading characteristic curve  31  was obtained, which in its upper end section has a curvature becoming flatter and finally reaches the maximum test force FPmax. It may however also end at E below the maximum test force, wherein the corresponding curvature is indicated at  31   a . The unloading of the mast according to the arrow  32  effected after the loading resulted in a permanent residual deflection. 
     With the second testing procedure according to FIG. 6 b  there resulted a different picture of the course of testing. There fistly resulted a loading characteristic curve  33  which however as a whole runs straight and with which the maximum test force FPmax has been reached. The subsequent unloading of the mast resulted in no permanent residual deflection as is indicated in FIG. 6 b  with the numeral  0 . Although with the second testing procedure no type of damage could be discovered, thus neither to the mast itself or to the anchoring, however from FIG. 6 a  without doubt it is concluded that there is damage to the mast. The permanent residual deflection S 2  determined in the first testing procedure indicates a fracture in the mast, which with the first testing procedure has enlarged such that a permanent residual deflection could be ascertained. The fracture damage to the mast may be explained by FIG. 6 b  since here the testing has taken place in the opposite direction and with this the fracture halves were pressed onto one another so that the mast with the second testing procedure has practically behaved like an undamaged mast. With the whole testing according to FIG. 6 thus likewise no shifting of the mast anchoring has been ascertained. 
     Yet a further type of damage can be deduced from the FIGS. 7 a  and  7   b . With the first testing procedure according to FIG. 7 a  (compression force) there firstly resulted a loading characteristic curve  34  according to the first function S=f (F 1 ). At its upper end region again this line blends into a curvature becoming flatter, and specifically at a momentary test force which lies below the maximum test force. The testing procedure was terminated, and after the completed unloading of the mast according to the arrow  35 , that is with the test force returned back to zero, a permanent residual deflection S 2  was ascertained. The second testing procedure in the same testing plane with an opposite test force (tensile force) resulted in a loading characteristic curve  36  according to the third function S=f(F 3 ) which at its upper region on reaching the maximum test force blends into a curvature becoming flatter. The subsequent unloading according to arrow  37  resulted in a permanent residual deflection S 4 . In both cases the respective loading characteristic curve may also end at a correspondingly lower value E which is indicated in each case at  34   a  and  36   a.    
     A comparison of the diagrams according to the FIGS. 7 a  and  7   b  results in that the courses of the loading characteristic curves  34 ;  36  at their upper region as such are equal or are essentially equal, but that in the second testing procedure a larger momentary test force was reached. Furthermore in each case permanent residual deflections S 2  and S 4  were ascertained. These results indicate a tension fracture corrosion or an intercrystalline 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 on testing the mast is the cause for its plastification in the region of the corrosion so that with this second testing procedure a higher test force had to be applied. The two remaining residual deflections S 2  and S 4  are equal or roughly equal so that a shifting of the mast anchoring with these two testing procedures can be ruled out. 
     A further test result is shown in the FIGS. 8 a  and  8   b . According to FIG. 8 a  there resulted a loading characteristic curve  38  according to the first function S=f (F 1 ). This line has for example an arcuate course from the very beginning, and the testing procedure (compression force) was terminated below the maximum test force FPmax at E. The subsequent unloading of the mast  1  and its anchoring  2 , effected according to the arrow  39 , but not drawn up, leads to a remaining and measured residual deflection S 2 . The subsequent second testing procedure in the same testing plane, but in the opposite direction (tensile force) resulted in a loading characteristic curve  40  which in its lower course  40  a firstly increases gradually and then sets into a constant value, wherein a deflection of the system mast/anchoring is to be ascertained over a certain stretch S. Thereafter there is effected a relatively steep increase in the loading characteristic curve, wherein the maximum test force FPmax can be reached, as is indicated at  40   c . The upper course of the line  40  may however at E before reaching the maximum test force blend into a curvature which is indicated at  40   d . The respective unloading, thus reduction in test force until the value zero, according to the arrows  41  and  42  leads to permanent residual deflections S 4  and S 4 ′ respectively. 
     On account of the measuring and computation results according to the diagram according to FIG. 8 a  it is recommended with the second testing procedure to evaluate and draw up at least a part course of the loading characteristic curve  40  in order to be able to better evaluate the remaining residual deflections with the respective unloading. As FIG. 8 b  shows also the lower part course  40   a  of the loading characteristic curve  40  may be an important criterion. Alternatively or additionally however also the upper part course  40   d  of the line  40  may represent a criterion. The middle part course shown in dashed lines of the loading characteristic curve  40  as well as of also all other loading characteristic curves is relatively unimportant so that its evaluation may be omitted. Whilst with the first testing procedure one may omit the evaluation and drawing up of the loading characteristic curve  38 , wherein however the value of the highest reached test force is to be taken account of and where appropriate kept, it is important that at least in the second testing procedure at least a part course of the loading characteristic curve  40  is to be drawn up and evaluated. 
     In a first variant of the test according to FIG. 8 it results that the ascertained and measured residual deflection S 4  is equal to or is essentially equal to the residual deflection S 2 , wherein the loading characteristic curve  40  after an initially flat course  40   a  blends into a steep and roughly unchanging course until the maximum test force. This means that the mast itself does not have any damage, but that there is present a shifting of the mast anchoring. 
     With the second variant of the testing procedure according to FIG. 8, in which the highest value E of the reached test force in the second testing procedure corresponds to or roughly corresponds to the highest value E of the test force in the first testing procedure, and in which a larger residual deflection S 4 ′ has been ascertained, it results that not only a shifting of the mast anchoring is present, but that also the mast itself has damage in the form e.g. of a fracture. 
     The FIGS. 9 a  and  9   b  show a further variant which is similar to the last mentioned of the FIGS. 8 a  and  8   b . After the loading characteristic curve  43  according to FIG. 9 a  has advantageously been evaluated and drawn up in its upper part course or alternatively the highest value of the reached test force E has been retained, there is only effected an unloading of the system mast/anchoring until the value zero as shown by the arrow  44 . At this unloading a permanent residual deflection S 2  was ascertained. According to FIG. 9 b  there resulted in the second testing procedure a loading characteristic curve  45  which initially at  45   a  runs flat and then blends into a steeper course and finally has an arcuate end course  45   b  becoming flatter and reaching test force E. It is shown that the lower part course of the line  45  only runs relatively flat in the initial region  45   a , and specifically over a deflection path S 3 , and then becomes considerably steeper. After the completed unloading of the mentioned system according to the arrow  46 , thus with the restoring force with the value equal to zero, there results a permanent residual deflection S 4 . The highest reached test force E according to FIG. 9 b  corresponds in its value to the value of the test force in the first testing procedure according to FIG. 9 or is roughly equal to this. 
     The test result according to FIG. 9 lies in the fact that a shifting of the mast anchoring and a damage to the mast is present. The tilting shifting of the mast anchoring is already clear from the fact that the residual deflection S 3  is smaller than the residual deflection S 2 . S 2  is thus composed together from S 3  which indicated a mast shifting, and of ΔS, which indicates a damage to the mast itself. The sum of S 3  and ΔS may with this correspond to the remaining residual deflection S 4 . 
     While the method herein described, and the form of apparatus for carrying this method into effect, constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, and that changes may be made in either without departing from the scope of the invention, which is defined in the appended claims.