1、BRITISH STANDARD BS7334-4: 1992 ISO 8322-4: 1991 Measuring instruments for building construction Part 4: Methods for determining accuracy in use of theodolitesBS7334-4:1992 This British Standard, having been prepared under the directionof the Basic Data andPerformance Criteria for CivilEngineering a
2、nd Building Structures Standards Policy Committee, was published underthe authority of the Standards Board and comesintoeffect on 31March1992 BSI08-1999 The following BSI references relate to the work on this standard: Committee referenceBDB/4 Draft for comment88/10402DC ISBN 0 580 20620 3 Committee
3、s responsible for this British Standard The preparation of this British Standard was entrusted by the Basic Data and Performance Criteria for Civil Engineering and Building Structures Standards Policy Committee (BDB/-) to Technical Committee BDB/4, upon which the following bodies were represented: A
4、ssociation of County Councils Brick Development Association British Standards Society Building Employers Confederation Chartered Institution of Building Services Engineers Concrete Society Department of Education and Science Department of the Environment (Building Research Establishment) Incorporate
5、d Association of Architects and Surveyors Institute of Clerks of Works of Great Britain Inc. Institution of Civil Engineers Institution of Structural Engineers Institution of Water and Environmental Management Royal Institute of British Architects Royal Institution of Chartered Surveyors Society of
6、Chief Architects of Local Authorities The following body was also represented in the drafting of the standard, through subcommittees and panels: Chartered Institute of Building Amendments issued since publication Amd. No. Date CommentsBS7334-4:1992 BSI 08-1999 i Contents Page Committees responsible
7、Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 General 1 4 Procedures for theodolites 3 Figure 1 Flow diagram for accuracy-in-use tests 2 Figure 2 Layout of four targets 3 Table 1-A Measurement of horizontal angles, gon-system Exampleoffieldobservations and calculation
8、6 Table 1-B Measurement of horizontal angles, gon-system Fieldobservations and calculation 7 Table 2-A Measurement of horizontal angles with sexagesimaltheodolite Example of field observations and calculation 8 Table 2-B Measurement of horizontal angles with sexagesimal theodolite Field observations
9、 and calculation 9 Table 3-A Measurement of vertical angles, gon-system Exampleoffieldobservations and calculation 10 Table 3-B Measurement of vertical angles, gon-system Fieldobservationsand calculation 11 Table 4-A Measurement of vertical angles with sexagesimal theodolite Example of field observa
10、tions and calculation 12 Table 4-B Measurement of vertical angles with sexagesimal theodolite Field observations and calculation 13 Publication(s) referred to Inside back coverBS7334-4:1992 ii BSI 08-1999 National foreword This Part of BS7334 has been prepared under the direction of the Basic Data a
11、nd Performance Criteria for Civil Engineering and Building Structures Standards Policy Committee. It is identical with ISO8322-4:1991 “Building construction Measuring instruments Procedures for determining accuracy in use Part4:Theodolites” published by the International Organization for Standardiza
12、tion (ISO), and gives the testing procedures to be adopted for theodolites. The series of Parts comprising BS7334 will assist in ascertaining whether particular measuring equipment is appropriate to intended measuring tasks; they are also intended for assessing the accuracy in use of measuring instr
13、uments in general use on construction sites. The Parts are referred to in BS5606:1990 “Guide to accuracy in building”. ISO8322 consists of the following parts, under the general title “Building construction Measuring instruments Procedures for determining accuracy in use”: Part 1: Theory; Part 2: Me
14、asuring tapes; Part 3: Optical levelling instruments; Part 4: Theodolites; Part 5: Optical plumbing instruments; Part 6: Laser instruments; Part 7: Instruments when used for setting out; Part 8: Electronic distance-measuring instruments up to150m; Part 9: Electronic distance-measuring instruments up
15、 to500m; Part 10: Testing short-range reflectors. The Technical Committee has reviewed the provisions of ISO7077, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. Cross-references International standard Corresponding British
16、Standard ISO3534:1977 a BS5532 Statistical terminology Part 1:1978 Glossary of terms relating to probability and general terms relating to statistics (Identical) ISO4463-1:1989 BS5964 Building setting out and measurement Part 1:1990 Methods of measuring, planning and organization and acceptance crit
17、eria (Identical) ISO7078:1985 BS6953:1988 Glossary of terms for procedures for setting out, measurement and surveying in building construction (including guidance notes) (Identical) a ISO3534 is also related to BS4778 “Quality vocabulary” Part2:1979 “National terms”.BS7334-4:1992 BSI 08-1999 iii A B
18、ritish Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a f
19、ront cover, an inside front cover, pagesi toiv, pages1to14, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS7334-4:1992 BSI 08-1999 1
20、 1 Scope This part of ISO8322 specifies test procedures to be adopted when determining and assessing the accuracy in use of theodolites for measurement of horizontal and vertical angles in the gon and degree system. The procedures given in this part of ISO8322 apply when these theodolites are used i
21、n building construction for surveying, check and compliance measurements and also when obtaining accuracy data. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO8322. At the time of publication, the edit
22、ions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO8322 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid
23、International Standards. ISO3534:1977, Statistics Vocabulary and symbols. ISO4463-1:1989, Measurement methods for building Setting-out and measurement Part1:Planning and organization, measuring procedures, acceptance criteria. ISO7077:1981, Measuring methods for building General principles and proce
24、dures for the verification of dimensional compliance. ISO7078:1985, Building construction Procedures for setting out, measurement and surveying Vocabulary and guidance notes. 3 General 3.1 Before commencing surveying, check and compliance measurements, when obtaining accuracy data or setting out, it
25、 is important that the operator investigate whether the accuracy in use of the measuring equipment is appropriate to the intended measuring task. This International Standard recommends that the operator carry out test measurements under field conditions to establish the accuracy achieved when he use
26、s a particular measuring instrument and its ancillary equipment. To ensure that the assessment takes account of various environmental influences, two series of measurements need to be carried out under different conditions. The particular conditions to be taken into account may vary depending on whe
27、re the tasks are to be undertaken. These conditions will include variations in air temperature, wind speed, cloud cover and visibility. Note should also be made of the actual weather conditions at the time of measurement and the type of surface over which the measurements are made. The sets of condi
28、tions chosen for the tests should match those expected when the intended measuring task is actually carried out. See ISO7077 and ISO7078. The procedures are designed so that the systematic errors are largely eliminated and assume that the particular instruments are in known and acceptable states of
29、user adjustment according to methods detailed in the manufacturers handbooks. Accuracy-in-use procedures require repeat tests to be made with the same instrumentation and the same observer, within a short interval of time. These are “repeatability conditions” as defined in ISO3534. The accuracy in u
30、se is expressed in terms of the standard deviation. 3.2 Figure 1 indicates schematically the decisions to be made when establishing that the accuracy associated with a given surveying method and particular measuring equipment is appropriate to the intended measuring task. In particular, the decision
31、s apply when adopted by a particular operator under a range of environmental conditions which are likely to occur when the task is actually carried out. Where the contract documentation specifies the required tolerance for the intended measuring task, it is recommended that this tolerance, which is
32、normally given in terms of the permitted deviation P (P =2,5B) of the measuring task, be compared with the accuracy-in-use data obtained either from previous accuracy-in-use tests or from general data A which indicate the expected accuracy in use of given measuring equipment. On those occasions that
33、 the previously obtained data indicate that the accuracy in use associated with the given measuring equipment does not meet the specified permitted deviation of the measuring task, consideration should be given to either selecting a different method and/or a more precise instrument or discussing wit
34、h the designer the need for such a small permitted deviation. See ISO4463-1.BS7334-4:1992 2 BSI 08-1999 Assumptions: P is the permitted deviation of the measuring task A is the accuracy in use, generally expressed as deviation A; (both P and A are considered to include the dimensional variability as
35、sociated with 2,5 times the standard deviationB) s are the standard deviations obtained in field tests Figure 1 Flow diagram for accuracy-in-use testsBS7334-4:1992 BSI 08-1999 3 Before obtaining an overall estimate of the accuracy in use, it is recommended that each standard deviation for a given se
36、ries of measurements under-taken under particular environmental conditions be compared, as indicated in Figure 1, to the specified permitted deviation. Where the comparison shows that the specified permitted deviation has not been achieved for one series of measurements, an additional series of meas
37、urements should be carried out under environmental conditions as near as possible similar to those which applied in that original series of measurements. 4 Procedures for theodolites 4.1 Accuracy test procedure The following test procedure shall be adopted for determining the accuracy in use, by a p
38、articular survey team with a particular instrument and its ancillary equipment. When setting up the theodolite for different series of observations, take special care when centring over the station. Achievable accuracies of centring expressed in terms of standard deviations are the following: a) Plu
39、mb bob: 1mm to2mm (worse in windy weather). b) Optical plummet: 0,5mm (to be checked for its own adjustment). c) Centring rod: 1mm. With targets at100m distances a mis-centring of2mm could affect the observed angle by up to1,2mgon(4 ). The shorter the distance the greater the effect. If the targets
40、have to be re-set for each series, similar care shall be taken with their centring. 4.2 Measurement of horizontal directions The measurement results for horizontal directions should be given in a table (see Table 1-B). An example of a completed table, with the results in gon, is given in Table 1-A.
41、The results with a sexagesimal theodolite are shown in Table 2-A. 4.2.1 Observations 4.2.1.1 Establish four targets A, B, C and D spread over as large an angle as possible, but at least100gon or 90 , at distances from a fixed theodolite station O, and of a form commensurate with that expected on the
42、 particular construction site. (See Figure 2.) The positions of the targets and theodolite shall be precisely defined in stable locations for the duration of the test measurements and be such that the targets are readily visible from the theodolite station. 4.2.1.2 Each series of measurements shall
43、consist offour separate sets of readings of directions OA, OB, OC and OD (see column2 of Table 1-B). The four points are observed with the telescope in the face-left position (see column3) in the sequence ABCD and in the face-right position (seecolumn4) in the sequence DCBA. After each set move the
44、horizontal circle through about50gon or45 and observe the same sequence for that set. Observe a second series on a different day. 4.2.1.3 Record the environmental conditions. Changes in environmental conditions during the construction period may render the test result inapplicable. In such a case re
45、peat the test under the new conditions. 4.2.2 Calculation procedure A complete example of the analysis is given in Table 1-A for a universal theodolite using the measurements given in columns3 and4. 4.2.2.1 Reduce the directions of each set to direction OA as0,0000 in the face-left position (see col
46、umn5) and in the face-right position (see column6). EXAMPLE For set1, target B, face left: 70,79588,9813=61,8145gon Figure 2 Layout of four targetsBS7334-4:1992 4 BSI 08-1999 4.2.2.2 Calculate the means m (column7) of the values in column5 and the corresponding values of column6. This gives four val
47、ues to each target of which all those towards target A are0,0000. EXAMPLE For set1, target C: 1/2 (126,165 2+126,163 6)=126,164 4 gon 4.2.2.3 Calculate the averaged values M (column8) of the groups of four values in column7 to each target. These need not be repeated against each set. EXAMPLE For tar
48、get B in all four sets: 1/4 (61,814 6+61,8151+61,816 5+61,8152) =61,815 4 gon 4.2.2.4 Calculate the differences d (column9) between the values of column8 and the corresponding values in column7. EXAMPLE For set 1, target B: 61,815 461,814 6=+0,8mgon 4.2.2.5 Calculate the arithmetic meansof the diffe
49、rences d (column9) in each set. EXAMPLE For set 1: 1/4 (0,0+0,8+0,70,5)=+ 0,2mgon 4.2.2.6 Calculate the deviations v (column10) for each target direction as the differences d minus the relevant for each set. EXAMPLE For set1, target B: 0,8(+0,2)=+0,6mgon The sum of the deviations for each set shall be approximately zero. In this caseis not taken as the true value or as the value accepted as true, but as the value by which the calculated mean of each direction in a set misfit
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