SANS 10120-3 A-1986 Code of practice for use with standardized specifications for civil engineering construction and contract documents Part 3 Guidance for design Section A General.pdf

1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. LAIIT 3 : GUIDANCE FOf? 1111s 1 t ;l1 SECTION A CONTENTS Clause PRF+TF;tJL)LiH CONS IUI?.I?AIIONS . 1 1nvest.iq;lt.ions 1 . Protect:ion of structures J E

4、xisting underground services . 1 . Mministratiori l . Housirw for Blacks 3 Tendezs l Documentation 1 Essential PSA clauses when GCC not applicable l . Contract agreement % Contractors camp ? Existirg underyrourld services 2 . Combined fixed and time-related activities 2 . Prime costs. provisional su

5、ms. daywork and temporary works 3 Tests and samples 3 . Plant itcms to be designated 3 Fixed charye for all other obliyations 3 Provisional. sums and prime cost items 3 Temporary works 3 DESIGN REQUIREMENTS . 4 Tolerances . 4 General . . 4 Degrees of accuracy 4 . Considerations 4 Design to uvercome

6、practical problems 4 . APPLICARILlTY OF OTHER CODFS 4 TEST IHOCEIXRES 4 Control Tests . 4 QUNATY CCNTROL AND OTHEII CONSIDEIWTIONS . 5 Second Revision March 1W6 This section of the code supersedes Approved by the COIINCIL OF TliE SOUTfl AFIIICXN DUHEALI 01. STANUARUS SAHS 0120 : Part 3 section A- 98

7、6 Gfmeral SABS 1200 A : GEEIEMI. NOTE: The clause number(s) given at the beyinning or aftel the heading of a clause is/are, ulllcss otherwise stated, the numher(s) of the relevant clause(s) of SABS 1200 A. 1. PRr-TLNDER CONSIDERATIOPIS 3 .l INVESTIGATIONS 1.1.1 Protection of Structures (Subclause 5.

8、3). Where existinq structures, site boundaries, etc., arr endangered by the removal of lateral support, design protective measures to rcpJace natural lateral suppart and arrange for them to be executed and paid Tor under the contrat-1 3 .l .? -tiny Underground Services (Subc:lause 5.4) 1.1.2.1 Iacat

9、ing. Pay part-icular attention to investiqating t-he positions of exist.ing services wllero it- is import-ant that their exact location be known for the purpose of the construction of the works or the relocation of other services. Excavate sufficient trial holes, or use other means for locating sf!r

10、vices, in order to verify the correctness of the information supplied in the project specification reyarding thc position of important services or t.0 cst.ablish the position of existing important. services to ensure that the drawingsand the items scheduled are accurate. (See also 1.3.4 below.) 1.1.

11、2.2 Ownership and rlecisions cm prot.ection. Establish ownership atid ascertain f rom the authority owniny each service the importance of the various cables, pipes, etc., that have to be protected or relocated and at t.he same t.ime obtain a decision on whet.her they should he encased in concrete or

12、 placed in duc:ts, etc. 1.1.2.3 Effect of cnnstruction plant and conr1itions. In the case of contracts involving construction or reconstruction ot roacls, specify the niiriimum protection for important services within the road prism where the final or existing level of the services does not provide

13、sufficient cover to protect these services when construction plant is working over the top of them at subgrade level. 1.2 ADMINISTRATION 1.2.1 tlousing for Blacks a) Restrict.ions on housing for Blacks exist over a major portion of the Northcrn and Western Cape Province. Public tenders are open to a

14、ll contractors and contractors from other areas may underestjmaLe the delays. onstruction work in areas lying to the south of the Orange River and west of a line (the Eiselen Lint!) runninq east of Prieska, Britstowtl, Victoria West, Beaufort West, Prince Alhcrt, George and KnySna, is likely to be a

15、ffected. b) Ensure (see (6) below) that each contractor tendering for work in such areas is made avare of thesc. problems and is advised to provide in the appendix to his tender, under the heading “TIME FUR CO#FLETION“, adequate time to allow for delays in obtaining the necessary authority t.o emplo

16、y the type of labour he requires and to obtain or construct acceptable accomnmdation for the labourers. C) The start of the works will probably be delayed unless the requirements of the officials of the Department of Co-operation and Development responsible for the area in whlc11 the project is to b

17、e constructed are ascertainecl. d) Set the requirements out in the project specification, preferably i.n the form of a copy of a letter from the official concerned. (See also Subclause 3.2.1 (PSA 1) of Section A of Fart 2 of the codc.) 1.2.2 Tenders. Ensure that, before the start of construction, ac

18、tion has been taken on the matters set out in (a) and (b) of Subclause 3.1.2 of the Introduction. 1.3 DOCIIMENTATJON 1.3.1 Essential PSA Clauses when Gaction A-1986 General Prime Costs, Provisional Sums, Daywork and Temporary Works (Subclause 0.1.2.1). Subclause 8.1.2.1 of SABS l200 A makes provisio

19、n for the inclusion in the Prelimjnary and General Section oL the schedule of items to cover prime costs, provisional sums, daywork and temporary works because it is often convenient to group such isolated activit.ies in one portion of the document. Although this qroupiny may increase clerical work

20、sliqhtly whre the employer wishes to know the cost of each section of the work, and it removes some iiems from the sections of the schedule to which they are related, the grouping has been adopted in the British civil engineering standard method of measurement2) (CESMM) . The grouping has the merit

21、of minimiziny the risk of prime cost and provisional items bcing overlookcdby both the engineer ancl the contractor during the course of the contrart, resulting in specialized materials being ordered too late, or tenders from nominated subcontractors being called too late. Either of these oversights

22、 may lead to disruption of the contractors program. The inclusion of daywork items with estimated quantities has the advantage of ensuring that the employer budgets for the cost of expected daywork and that the contractor prices it realistically (his rates affect his tender sum). The execution of te

23、mporary works frequently necessitates considerable installation expenditure followed by continuing maintenance expenditure and finally t.he removal expenditure. These are typically preliminary and general cost structure activities. The grouping may be cumbersome when there are many prime cost or pro

24、visional sum items or when the forecasting of daywork is imyracticable or when temporary works are associated with one particular activity only or are so extensive as to warrant a separate sectior of the schedule. Tests and Samples (Subclauses 8.3.2, 8.4.2 and 8.4.5). The contractors rates cover the

25、 cost of all normal control testing and the provision of samples of aggregates and samples such as those for tests on compaction or earthworks, slump tests, and crushing tests on concrete cubes, but they do not cover additional or special tests. A general rate to cover such unforeseeable costs would

26、 be uneconomical. Where such tests are or may be required, provide particular items it1 either the Preliminary and Genelal Section of the schedule ox in the section applicable to the tests. Fur instance, incorporate the testing of a reservoir for watertightness in the Preliminary and General Section

27、 and the testing of welds in a steel pipeline in the Pipeluie Section. Plant Items to Le Designated (Item (3) of both Subclause 8.3.2.2 and Subclause 8.4.2.2). The costs of earthmoving and concreting plant such as bulldozers and concrete mixers are generally included in the rates for such act.ivitie

28、s. Examples of the types of plant and circumstances that warrant the provision of particular items in the schedule are: a) Where the capital cost of the plant is high and recovery through rates would not be achieved for approximately a year or more, such as 1) in the provision and operation of a dre

29、dger: i) Provide dredger . Sum ii) Operate dredger (for designated operations for stated periods) SLUII or /day or 2) in the provision and operation of a crushing, pumpirg or Latching plant: i) Establish crushing plant (or pumpiny plant or batching plant for concrete dam). Sum ii) Operate plant (des

30、ignated items for designated operations for stated periods) . Sum or /day or /m3 b) Wliere plant may have to stand pendirg the outcome of tests, standing time . /working week or ddy C) Where the number of units of measurable work can vary over a wide range such as in exploratory drilling, drilling a

31、nd grouting, etc.: 1) Provide drill rig . Sum 2) Move drill rig /mve 3) Operate drill rig . /m Fixed Charye for All other Obligations (Subclauses 8.3.3 and 8.4.5). This item is provided An the schedule to enable the contractor to cover the cost of any activity that he expects to undertake to ensure

32、compliance with the requirements of the conditions of contract and of SABS 1200 A, and for which, in the contractors opinion, the engineer has not made provision in his schedule. The item need not be priced but if it is not priced Subclause 1.1.6 of the preamble to the schedule will be applicable. (

33、See Section A of Part 4 of the code.) Provisional Sums and Pri.me Cost ltems (Clause R) Stated sums for trigonometrical survey (Subclause 8.8.5). Where provision is made in the schedule for t.rigonometrica1 survey as specified in Subclause 8.8.5 of SADS 1200 A, ensure that the sums stated ace adequa

34、te to cover the cost of a) searching for and recording of all trigonornet.rica1 survey beacons and bertch marks, as ordered, and plotting of boundary pegs in the vicinity of the works. b) the protection by the contractor in the manner ordered, of beacons, marks and pegs located in terms of (a) above

35、 and the repositioning or re-establishing of trigonometrical survey beacons, bench marks and plot houndary pegs that must. be removed or buried in accordance with the finished dimensions of the works. Temporary Works (Subclause 8.8) _Special water control (Subclause 8.8.6). In terms of Subclause 5.

36、5 of SARS 1200 A the Contractor is expected to keep the works dry by divertiny and controlling stormwater and subsurface water (see Subclause 3.2.4 of Section A of Part 5 of the code). Provision is made for items to be scheduled in terms of Subclauses 8.3.2.2(h) or 8.3.3, and R.4.2.2(h) or 8.4.5 of

37、SARS 1200 A to cover the cost of such work. Alternatively, the Contractor may cover such costs by including them in the rates for scheduled items of work. Ensure that all such rates are not inflated, where a special water risk is known to exist or likely to occur in an identifiable part of the works

38、 by settinq out the details in a suitable project specification clause, and scheduling an item Eor the special water risk in terms of Subclause 8.8.6 of SRRS 1200 A. The following is an examle of a special water risk that warranted a scheduled item: In a pipeline G km long, a length of 0,5 km was t

39、o be laid across a beach and the engineer required that, where the highwater mark was mare than 1 m above the bottom nf the trench, the contractor should a) excavatc further and place an extra 700 mm thick bedding layrr of 13 mm crushed stone: arrd b) so grade the trritch that any water was led to s

40、umps from which it could be pumped. The schedule inc1udc.d a suitable item. 2) Published by the Tnstjtution of Civil Cnqineers, ,ondon, in 1976. SABS 0120 : Part 3 Section A-1906 General DESIGN REQUIREMENTS TOLERANCES (Clause 6) General. Clause 6 of ShsS 1200 A is intended to help designers and cone

41、truct.ors to avoid the problems that can arise if the effects of inaccuracy are not anticipated. Its purpose is to give guidance on how problems of fit can be overcome, largely by design, and how inaccuracies can be corrtxolled during the construction process. Degrees of Accuracr. Ahsolute accuracy

42、exists only in theory. Tolerable degrees of inaccuracy have to be accepted in practice and the standardized specifications lay down degrees of inaccuracy that are acceptable for all practical purposes. Ensure that the tolerance specified is as large as possible, without rendering the finished constr

43、uction unacceptable for the purpose for which it is intended. Xf the permissible deviations opecified are finer tlmn can be achieved by normal t.enhniques, special action may be required, such as a) revised methods of manufacture and construction; b) increased supervision and control; and C) special

44、 t.raining of workmen. Such measures may increase the cost of individual processes or even the whole project. Decide whether any increased cost incurred by such measures is justified by the results obtained or can be offset in part by savings in other directions. Indicate in the detail drawinqs perm

45、issible deviations appropriate to the works being designed. (Refer to SMS 0155) for further guidance.) Considerations. Crien specifying the standard of accuracy, take into account the following cansidera- tions: a) Aesthetic. The deviation permissible depends on the function of the structure and t.h

46、e standard of finish appropriate to it. b) Structural. The design of structural components and their erection should avoid eccentricities of loading or inadequate areas for load bearing that would result in design stresses being exceeded. c) LBgJ1. The finished structure should be located correctly

47、in relation to the boundaries of the site. The location could be affected by the accuracy of the survey or the setting out. d) Economic. To avoid excessive production costs or the costs of adjustments such as cutting to fit, regard should be paid to the combined cost of both when tolerances are spec

48、ified, and the tolerances should be consistent with the expected method of manufacture or construction. Design to Overcome Practical Problems. Greater accuracy may be achieved during construction if, during the design stage, consideration is given to the practical problems that may arise during cons

49、truction, and measures are taken in the design to overcome the problems. Typical examples of such measures are: a) Components should be of such a size, shape and mass that i hey can be handled and placed in positron easily, with or without the use of mechanical aids. b) The design should be such as to minimize (not emphasize) possible visual defects or inaccura C-11 the degree of control cxpectcd on ?he job, as shown in l?j.q, l. Tt also depends on tlc pfrmissille percentage of failures. lrmal“ control 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Strength ( MPa) Figure