土木工程畢業(yè)設(shè)計(jì)--外文翻譯

1、<p>　　1 Introduction and scope</p><p>　　1.1 Aims of the Manual</p><p>　　This Manual provides guidance on the design of reinforced and prestressed concrete building structures. Structures de

2、signed in accordance with this Manual will normally comply with DD ENV 1992-1-1: 19921 (hereinafter referred to as EC2).</p><p>　　1.2 Eurocode system</p><p>　　The structural Eurocodes were initi

3、ated by the European Commission but are now produced by the Comité Européen de Normalisation (CEN) which is the European standards organization, its members being the national standards bodies of the EU and EFT

4、A countries,e.g. BSI.</p><p>　　CEN will eventually publish these design standards as full European Standards EN (Euronorms), but initially they are being issued as Prestandards ENV. Normally an ENV has a lif

5、e of about 3 years to permit familiarization and trial use of the standard by member states. After formal voting by the member bodies, ENVs are converted into ENs taking into account the national comments on the ENV docu

6、ment. At present the following Eurocode parts have been published as ENVs but as yet none has been conve</p><p>　　DD ENV 1991-1-1: Basis of design and actions on structures (EC1)</p><p>　　DD ENV

7、 1992-1-1: Design of concrete structures (EC2)</p><p>　　DD ENV 1993-1-1: Design of steel structures (EC3)</p><p>　　DD ENV 1994-1-1: Design of composite steel and concrete structures (EC4)</p&

8、gt;<p>　　DD ENV 1995-1-1: Design of timber structures (EC5)</p><p>　　DD ENV 1996-1-1: Design of masonry structures (EC6)</p><p>　　DD ENV 1997-1-1: Geotechnical design (EC7)</p><

9、;p>　　DD ENV 1998-1-1: Earthquake resistant design of structures (EC8)</p><p>　　DD ENV 1999-1-1: Design of aluminium alloy structures (EC9)</p><p>　　Each Eurocode is published in a number of p

10、arts, usually with ‘General rules’ and ‘Rules for buildings’ in Part 1. The various parts of EC2 are:</p><p>　　Part 1.1 General rules and rules for buildings;</p><p>　　Part 1.2 Supplementary rul

11、es for structural fire design;</p><p>　　Part 1.3 Supplementary rules for precast concrete elements and structures;</p><p>　　Part 1.4 Supplementary rules for the use of lightweight aggregate conc

12、rete;</p><p>　　Part 1.5 Supplementary rules for the use of unbonded and external prestressing tendons;</p><p>　　Part 1.6 Supplementary rules for plain or lightly reinforced concrete structures;&

13、lt;/p><p>　　Part 2.0 Reinforced and prestressed concrete bridges;</p><p>　　Part 3.0 Concrete foundations;</p><p>　　Part 4.0 Liquid retaining and containment structures.</p><

14、p>　　All Eurocodes follow a common editorial style. The codes contain ‘Principles’ and ‘Application rules’. Principles are general statements, definitions, requirements and sometimes analytical models. All designs must

15、 comply with the Principles, and no alternative is permitted.</p><p>　　Application rules are rules commonly adopted in design. They follow the Principles and satisfy their requirements. Alternative rules may

16、 be used provided that compliance with the Principles can be demonstrated. </p><p>　　Some parameters in Eurocodes are designated by | _ | , commonly referred to as boxed values. The boxed values in the Codes

17、 are indicative guidance values. Each member state is required to fix the boxed value applicable within its jurisdiction. Such information would be found in the National Application Document (NAD) which is published as p

18、art of each ENV.</p><p>　　There are also other purposes for NADs. NAD is meant to provide operational information to enable the ENV to be used. For certain aspects of the design, the ENV may refer to nationa

19、l standards or to CEN standard in preparation or ISO standards. The NAD is meant to provide appropriate guidance including modifications required to maintain compatibility between the documents. Very occasionally the NAD

20、 might rewrite particular clauses of the code in the interest of safety or economy. This is however</p><p>　　1.3 Scope of the Manual</p><p>　　The range of structures and structural elements cove

21、red by the Manual is limited to building structures that do not rely on bending in columns for their resistance to horizontal forces and are also non-sway. This will be found to cover the vast majority of all reinforced

22、and prestressed concrete building structures. In using the Manual the following should be noted:</p><p>　　? The Manual has been drafted to comply with ENV 1992-1-1 together with the UK NAD</p><p&g

23、t;　　? Although British Standards have been referenced as loading codes in Sections 3 and 6, to comply with the UK NAD, the Manual can be used in conjunction with other loading codes</p><p>　　? The structures

24、 are braced and non-sway</p><p>　　? The concrete is of normal weight</p><p>　　? The structure is predominantly in situ</p><p>　　? Prestressed concrete members have bonded or unbonde

25、d internal tendons</p><p>　　? The Manual can be used in conjunction with all commonly used materials in construction; however the data given are limited to the following:</p><p>　　– concrete up

26、to characteristic cylinder strength of 50N/mm2 (cube strength 60)</p><p>　　– high-tensile reinforcement with characteristic strength of 460</p><p>　　– mild-steel reinforcement with characteristi

27、c strength of 250</p><p>　　– prestressing tendons with 7-wire low-relaxation (Class 2) strands</p><p>　　? High ductility (Class H) has been assumed for:</p><p>　　– all ribbed bars a

28、nd grade 250 bars, and</p><p>　　– ribbed wire welded fabric in wire sizes of 6mm or over</p><p>　　? Normal ductility (Class N) has been assumed for plain or indented wire welded fabric. For stru

29、ctures or elements outside this scope EC2 should be used.</p><p>　　1.4 Contents of the Manual</p><p>　　The Manual covers the following design stages:</p><p>　　? general principles t

30、hat govern the design of the layout of the structure</p><p>　　? initial sizing of members</p><p>　　? estimating of quantities of reinforcement and prestressing tendons</p><p>　　? fi

31、nal design of members.</p><p>　　2 General principles</p><p>　　This section outlines the general principles that apply to both initial and final design of both reinforced and prestressed concrete

32、 building structures, and states the design parameters that govern all design stages.</p><p>　　2.1 General</p><p>　　One engineer should be responsible for the overall design, including stability

33、, and should ensure the compatibility of the design and details of parts and components even where some or all of the design and details of those parts and components are not made by the same engineer.</p><p&g

34、t;　　The structure should be so arranged that it can transmit dead, wind and imposed loads in a direct manner to the foundations. The general arrangement should ensure a robust and stable structure that will not collapse

35、progressively under the effects of misuse or accidental damage to any one element.</p><p>　　The engineer should consider engineer site constraints, buildability2, maintainability and decommissioning.</p&g

36、t;<p>　　The engineer should take account of his responsibilities as a ‘Designer’ under the Construction (Design & Management) Regulations.3</p><p>　　2.2 Stability</p><p>　　Lateral sta

37、bility in two orthogonal directions should be provided by a system of strongpoints within the structure so as to produce a braced non-sway structure, in which the columns will not be subject to significant sway moments.

38、Strongpoints can generally be provided by the core walls enclosing the stairs, lifts and service ducts. Additional stiffness can be provided by shear walls formed from a gable end or from some other external or internal

39、subdividing wall. The core and shear walls should</p><p>　　Strongpoints should be effective throughout the full height of the building. If it is essential for strongpoints to be discontinuous at one level, p

40、rovision must be made to transfer the forces to other vertical components.</p><p>　　It is essential that floors be designed to act as horizontal diaphragms, particularly if precast units are used.</p>

41、<p>　　Where a structure is divided by expansion joints each part should be structurally independent and designed to be stable and robust without relying on the stability of adjacent sections.</p><p>　　

42、2.3 Robustness</p><p>　　All members of the structure should be effectively tied together in the longitudinal, transverse and vertical directions.</p><p>　　A well-designed and well-detailed cast-

43、in situ structure will normally satisfy the detailed tying requirements set out in subsection 5.11.</p><p>　　Elements whose failure would cause collapse of more than a limited part of the structure adjacent

44、to them should be avoided. Where this is not possible, alternative load paths should be identified or the element in question strengthened.</p><p>　　2.4 Movement joints</p><p>　　Movement joints

45、may need to be provided to minimize the effects of movements caused by, for example, shrinkage, temperature variations, creep and settlement.</p><p>　　The effectiveness of movement joints depends on their lo

46、cation. Movement joints should divide the structure into a number of individual sections, and should pass through the whole structure above ground level in one plane. The structure should be framed on both sides of the j

47、oint. Some examples of positioning movement joints in plan are given in Fig. 2.1.</p><p>　　Movement joints may also be required where there is a significant change in the type of foundation or the height of

48、the structure. For reinforced concrete frame structures in UK conditions, movement joints at least 25mm wide should normally be provided at approximately 50m centres both longitudinally and transversely. In the top store

49、y and for open buildings and exposed slabs additional joints should normally be provided to give approximately 25m spacing. Joint spacing in exposed parapets should</p><p>　　Joints should be incorporated in

50、the finishes and in the cladding at the movement joint locations.</p><p>　　2.5 Fire resistance and durability</p><p>　　For the required period of fire resistance (prescribed in the Building Regu

51、lations), the structure should:</p><p>　　? have adequate loadbearing capacity</p><p>　　? limit the temperature rise on the far face by sufficient insulation, and</p><p>　　? have suf

52、ficient integrity to prevent the formation of cracks that will allow the passage of fire and gases.</p><p>　　Fig. 2.1 Location of movement joints</p><p>　　The design should take into account the

53、 likely deterioration of the structure and its components in their environment having due regard to the anticipated level of maintenance. The following inter-related factors should be considered:</p><p>　　?

54、the required performance criteria</p><p>　　? the expected environmental conditions</p><p>　　? the composition, properties and performance of materials</p><p>　　? the shape of member

55、s and detailing</p><p>　　? the quality of workmanship</p><p>　　? any protective measure</p><p>　　? the likely maintenance during the intended life.</p><p>　　Concrete of

56、 appropriate quality with adequate cover to the reinforcement should be specified.</p><p>　　The above requirements for durability and fire resistance may dictate sizes for members greater than those required

57、 for structural strength alone.</p><p>　　3 Design principles – reinforced concrete</p><p>　　3.1 Loading</p><p>　　The loads to be used in calculations are:</p><p>　　(a)

58、Characteristic dead load,: the weight of the structure complete with finishes, fixtures and fixed partitions (BS)</p><p>　　(b) Characteristic imposed load, (BS6399，Parts1and)</p><p>　　(c) Charac

59、teristic wind load, Wk (90% of the load derived from CP3, Chapter V, Part)*</p><p>　　(d) Nominal earth load,(BS)</p><p>　　(e) At the ultimate limit state the horizontal forces to be resisted at

60、any level should be the greater of:</p><p>　　(i) 1.5% of the characteristic dead load above that level, or</p><p>　　(ii) 90% of the wind load derived from CP3, Chapter V, Part, multiplied by the

61、 appropriate partial safety factor.</p><p>　　The horizontal forces should be distributed between the strongpoints according to their stiffness.</p><p>　　In using the above documents the followin

62、g modifications should be noted:</p><p>　　(f) The imposed floor loads of a building should be treated as one load to which the reduction factors given in BS 6399: Part 1:are applicable.</p><p>　

63、　(g) Snow drift loads obtained from BS 6399: Part 3: should be multiplied by 0.7 and treated in a similar way to an imposed load and not as an accidental load.</p><p>　　3.2 Limit states</p><p>　

64、　This Manual adopts the limit-state principle and the partial factor format of EC2.</p><p>　　3.2.1 Ultimate limit state</p><p>　　The design loads are obtained by multiplying the characteristic l

65、oads by the appropriate</p><p>　　partial factor from Table 3.1.</p><p>　　The ‘a(chǎn)dverse’ and ‘beneficial’ factors should be used so as to produce the most onerous</p><p>　　condition.&

66、lt;/p><p>　　3.2.2 Serviceability limit states</p><p>　　Provided that span/effective depth ratios and bar diameter and spacing rules are observed</p><p>　　it will not be necessary to ch

67、eck for serviceability limit states.</p><p>　　Table 3.1 Partial factors for loads γf at the ultimate limit state</p><p>　　The Table uses the simplified combination permitted in EC2.</p>&

68、lt;p>　　?For pressures arising from an accidental head of water at ground level a partial factor of 1.15 may be used.</p><p>　　3.3 Material and design stresses</p><p>　　Design stresses are giv

69、en in the appropriate sections of the Manual. It should be noted that EC2 specifies concrete strength class by both the cylinder strength and cube strength (for example C25/30 is a concrete with cylinder strength of 25 a

70、nd cube strength of 30 at 28 days). Standard strength classes are C20/25, C25/30, C30/37, C35/45, C40/50, C45/55 and C50/60. All design equations which include concrete compressive strength use the characteristic 28 day

71、cylinder strength,.</p><p>　　Partial factors for concrete are 1.5 for ultimate limit state and 1.0 for serviceability limit state.</p><p>　　The strength properties of reinforcement are expressed

72、 in terms of the characteristic yield strength,.</p><p>　　Partial factors for reinforcement steel are 1.15 for ultimate limit state and 1.0 for serviceability limit state.</p><p>　　4 Initial des

73、ign – reinforced concrete</p><p>　　4.1 Introduction</p><p>　　In the initial stages of the design of building structures it is necessary, often at short notice,to produce alternative schemes that

74、 can be assessed for architectural and functional suitability and which can be compared for cost. They will usually be based on vague and limited information on matters affecting the structure such as imposed loads and n

75、ature of finishes, let alone firm dimensions, but it is nevertheless expected that viable schemes be produced on which reliable cost estimates can </p><p>　　It follows that initial design methods should be s

76、imple, quick, conservative and reliable. Lengthy analytical methods should be avoided.</p><p>　　This section offers some advice on the general principles to be applied when preparing a scheme for a structure

77、, followed by methods for sizing members of superstructures. Foundation design is best deferred to later stages when site investigation results can be evaluated.</p><p>　　The aim should be to establish a str

78、uctural scheme that is suitable for its purpose, sensibly economical, and not unduly sensitive to the various changes that are likely to be imposed as the overall design develops.</p><p>　　Sizing of structur

79、al members should be based on the longest spans (slabs and beams) and largest areas of roof and/or floors carried (beams, columns, walls and foundations). The same sizes should be assumed for similar but less onerous cas

80、es – this saves design and costing time at this stage and is of actual benefit in producing visual and constructional repetition and hence, ultimately, cost benefits.</p><p>　　Simple structural schemes are q

81、uick to design and easy to build. They may be complicated later by other members of the design team trying to achieve their optimum conditions, but a simple scheme provides a good ‘benchmark’ at the initial stage.</p&

82、gt;<p>　　Loads should be carried to the foundation by the shortest and most direct routes. In constructional terms, simplicity implies (among other matters) repetition; avoidance of congested, awkward or structura

83、lly sensitive details and straightforward temporary works with minimal requirements for unorthodox sequencing to achieve the intended behaviour of the completed structure.</p><p>　　Standardized construction

84、items will usually be cheaper and more readily available than</p><p>　　purpose-made items.</p><p><b>　　4.2 Loads</b></p><p>　　Loads should be based on BS，BS6399：Parts1 a

85、nd andCP3：ChapterV：Part</p><p>　　Imposed loading should initially be taken as the highest statutory figures where options exist. The imposed load reduction allowed in the loading code should not be taken adv

86、antage of in the initial design stage except when assessing the load on the foundations. </p><p>　　Loading should be generous and not less than the following in the initial stages: </p><p>　　flo

87、or finish (screed) 1.8</p><p>　　ceiling and service load 0.5</p><p>　　Allowance for:</p><p>　　demountable lightweight partitions* 1.0</p><p&g

88、t;　　blockwork partitions? 2.5</p><p>　　Weight of reinforced concrete should be taken as 24</p><p>　　Design loads should be obtained using Table 3.1.</p><p>　　4.3 Materi

89、al properties</p><p>　　For normal construction in the UK, a characteristic cylinder concrete strength of 25 should be assumed for the initial design. In areas with poor aggregates this may have to be reduced

90、.</p><p>　　For UK steels a characteristic strength of 460 should be used for high-tensile reinforcement and 250 for mild steel.</p><p>　　4.4 Structural form and framing</p><p>　　Th

91、e following measures should be adopted:</p><p>　　(a) provide stability against lateral forces and ensure braced construction by arranging suitable shear walls deployed symmetrically wherever possible</p&g

92、t;<p>　　(b) adopt a simple arrangement of slabs, beams and columns so that loads are carried to the foundations by the shortest and most direct routes</p><p>　　(c) allow for movement joints (see subse

93、ction 2.4)</p><p>　　(d) choose an arrangement that will limit the span of slabs to 5m to 6m and beam spans to 8m to l0m on a regular grid; for flat slabs restrict column spacings to 8m</p><p>　　

94、(e) adopt a minimum column size of 300mm × 300mm or equivalent area</p><p>　　(f) provide a robust structure.</p><p>　　The arrangement should take account of possible large openings for serv

95、ices and problems with foundations, e.g. columns immediately adjacent to site boundaries may require balanced or other special foundations.</p><p>　　4.5 Fire resistance and durability</p><p>　　T

96、he size of structural members may be governed by the requirement of fire resistance and may also be affected by the cover necessary to ensure durability. Table 4.1 shows the minimum practical member sizes for different p

97、eriods of fire resistance and the cover to the main reinforcement required for continuous members in dry and humid environments without frost. For other exposure classes, cover should be increased. For simply supported m

98、embers, sizes and cover should be increased (see Section 5 </p><p>　　4.6 Stiffness</p><p>　　To provide adequate stiffness, the effective depths of beams, slabs and the waist of stairs should not

99、 be less than those derived from Table 4.2.</p><p>　　Beams should be of sufficient depth to avoid the necessity for excessive compression reinforcement and to ensure that economical amounts of tension and sh

100、ear reinforcement are provided. This will also facilitate the placing of concrete.</p><p>　　*To be treated as imposed loads.</p><p>　　?To be treated as dead loads when the layout is fixed.</p

101、><p>　　Table 4.1 Minimum member sizes and cover? for initial design of continuous members</p><p>　　*Thickness of structural topping plus any non-combustible screed.</p><p>　　?Cover is

102、to main reinforcement.</p><p>　　Table 4.2 Basic ratios of span/effective depth for initial design ( = 460)</p><p>　　Notes to Table 4.2</p><p>　　1. For two-way spanning slabs (suppor