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建筑 材料 土木工程 外文翻译 外文文献 英文文献

建筑 材料 土木工程 外文翻译 外文文献 英文文献
建筑 材料 土木工程 外文翻译 外文文献 英文文献

1 Introduction and scope

1.1 Aims of the Manual

This Manual provides guidance on the design of reinforced and prestressed concrete building structures. Structures designed in accordance with this Manual will normally comply with DD ENV 1992-1-1: 19921 (hereinafter referred to as EC2).

1.2 Eurocode system

The structural Eurocodes were initiated 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 EFTA countries,e.g. BSI.

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 life 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 document. At present the following Eurocode parts have been published as ENVs but as yet none has been converted to an EN:

DD ENV 1991-1-1: Basis of design and actions on structures (EC1)

DD ENV 1992-1-1: Design of concrete structures (EC2)

DD ENV 1993-1-1: Design of steel structures (EC3)

DD ENV 1994-1-1: Design of composite steel and concrete structures (EC4)

DD ENV 1995-1-1: Design of timber structures (EC5)

DD ENV 1996-1-1: Design of masonry structures (EC6)

DD ENV 1997-1-1: Geotechnical design (EC7)

DD ENV 1998-1-1: Earthquake resistant design of structures (EC8)

DD ENV 1999-1-1: Design of aluminium alloy structures (EC9)

Each Eurocode is published in a number of parts, usually with ‘General rules’ and ‘Rules for buildings’ in Part 1. The various parts of EC2 are:

Part 1.1 General rules and rules for buildings;

Part 1.2 Supplementary rules for structural fire design;

Part 1.3 Supplementary rules for precast concrete elements and structures;

Part 1.4 Supplementary rules for the use of lightweight aggregate concrete;

Part 1.5 Supplementary rules for the use of unbonded and external prestressing tendons;

Part 1.6 Supplementary rules for plain or lightly reinforced concrete structures;

Part 2.0 Reinforced and prestressed concrete bridges;

Part 3.0 Concrete foundations;

Part 4.0 Liquid retaining and containment structures.

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 comply with the Principles, and no alternative is permitted. Application rules are rules commonly adopted in design. They follow the Principles and satisfy their requirements. Alternative rules may be used provided that compliance with the Principles can be demonstrated.

Some parameters in Eurocodes are designated by | _ | , commonly referred to as boxed values. The boxed values in the Codes 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 part of each ENV.

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 national 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 might rewrite particular clauses of the code in the interest of safety or economy. This is however rare.

1.3 Scope of the Manual

The range of structures and structural elements covered 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 and prestressed concrete building structures. In using the Manual the following should be noted:

? The Manual has been drafted to comply with ENV 1992-1-1 together with the UK NAD

? 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 ? The structures are braced and non-sway

? The concrete is of normal weight

? The structure is predominantly in situ

? Prestressed concrete members have bonded or unbonded internal tendons

? The Manual can be used in conjunction with all commonly used materials in construction; however the data given are limited to the following:

– concrete up to characteristic cylinder strength of 50N/mm2 (cube strength 602

N/mm)

– high-tensile reinforcement with characteristic strength of 4602

N/mm

– mild-steel reinforcement with characteristic strength of 2502

N/mm

– prestressing tendons with 7-wire low-relaxation (Class 2) strands

? High ductility (Class H) has been assumed for:

– all ribbed bars and grade 250 bars, and

– ribbed wire welded fabric in wire sizes of 6mm or over

? Normal ductility (Class N) has been assumed for plain or indented wire welded fabric.For structures or elements outside this scope EC2 should be used.

1.4 Contents of the Manual

The Manual covers the following design stages:

? gene ral principles that govern the design of the layout of the structure

? initial sizing of members

? estimating of quantities of reinforcement and prestressing tendons

? final design of members.

2 General principles

This section outlines the general principles that apply to both initial and final design of both reinforced and prestressed concrete building structures, and states the design parameters that govern all design stages.

2.1 General

One engineer should be responsible for the overall design, including stability, 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.

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 progressively under the effects of misuse or accidental damage to any one element.

The engineer should consider engineer site constraints, buildability2, maintainability and decommissioning.

The engineer should take account of his responsibilities as a ‘Designer’ under the Construction (Design & Management) Regulations.3

2.2 Stability

Lateral stability 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. 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 subdividing wall. The core and shear walls should preferably be distributed throughout the structure and so arranged that their combined shear centre is located approximately on the line of the resultant in plan of the applied overturning forces. Where this is not possible, the resulting twisting moments must be considered when calculating the load carried by each strongpoint. These walls should generally be of reinforced concrete not less than 180mm thick to facilitate concreting, but they may be of 215mm brickwork or 190mm solid blockwork properly tied and pinned up to the framing for low- to medium-rise buildings.

Strongpoints should be effective throughout the full height of the building. If it is essential for strongpoints to be discontinuous at one level, provision must be made to transfer the forces to

other vertical components.

It is essential that floors be designed to act as horizontal diaphragms, particularly if precast units are used.

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.

2.3 Robustness

All members of the structure should be effectively tied together in the longitudinal, transverse and vertical directions.

A well-designed and well-detailed cast-in situ structure will normally satisfy the detailed tying requirements set out in subsection 5.11.

Elements whose failure would cause collapse of more than a limited part of the structure adjacent to them should be avoided. Where this is not possible, alternative load paths should be identified or the element in question strengthened.

2.4 Movement joints

Movement joints may need to be provided to minimize the effects of movements caused by, for example, shrinkage, temperature variations, creep and settlement.

The effectiveness of movement joints depends on their location. 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 joint. Some examples of positioning movement joints in plan are given in Fig. 2.1.

Movement joints may also be required where there is a significant change in the type of foundation or the height of 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 storey and for open buildings and exposed slabs additional joints should normally be provided to give approximately 25m spacing. Joint spacing in exposed parapets should be approximately 12m.

Joints should be incorporated in the finishes and in the cladding at the movement joint locations.

2.5 Fire resistance and durability

For the required period of fire resistance (prescribed in the Building Regulations), the structure should:

? have adequate loadbearing capacity

? limit the temperature rise on the far face by sufficient insulation, and

? have sufficient integrity to prevent the formation of crack s that will allow the passage of fire and gases.

Fig. 2.1 Location of movement joints

The design should take into account the 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:

? the required performance criteria

? the expected environmental conditions

? the composition, properties and performance of materials

? the shape of members and detailing

? the quality of workmanship

? any protective measure

? the likely maintenance during the intended life.

Concrete of appropriate quality with adequate cover to the reinforcement should be specified. The above requirements for durability and fire resistance may dictate sizes for members greater than those required for structural strength alone.

3 Design principles – reinforced concrete

3.1 Loading

The loads to be used in calculations are:

(a) Characteristic dead load,k G : the weight of the structure complete with finishes, fixtures and

fixed partitions (BS 4648)

(b) Characteristic imposed load,k Q (BS6399,Parts1and 53)

(c) Characteristic wind load, W k (90% of the load derived from CP3, Chapter V, Part 62)* (d) Nominal earth load,n E (BS 78004)

(e) At the ultimate limit state the horizontal forces to be resisted at any level should be the greater

of:

(i) 1.5% of the characteristic dead load above that level, or

(ii) 90% of the wind load derived from CP3, Chapter V, Part 62, multiplied by the appropriate

partial safety factor.

The horizontal forces should be distributed between the strongpoints according to their stiffness.

In using the above documents the following modifications should be noted:

(f) The imposed floor loads of a building should be treated as one load to which the reduction

factors given in BS 6399: Part 1:51996are applicable.

(g) Snow drift loads obtained from BS 6399: Part 3:51998 should be multiplied by 0.7 and treated

in a similar way to an imposed load and not as an accidental load.

3.2 Limit states

This Manual adopts the limit-state principle and the partial factor format of EC2.

3.2.1 Ultimate limit state

The design loads are obtained by multiplying the characteristic loads by the appropriate

partial factor f from Table 3.1.

The ‘adverse’ and ‘beneficial’ factors should be used so as to produce the most onerous

condition.

3.2.2 Serviceability limit states

Provided that span/effective depth ratios and bar diameter and spacing rules are observed

it will not be necessary to check for serviceability limit states.

f

The Table uses the simplified combination permitted in EC2.

?For pressures arising from an accidental head of water at ground level a partial factor of 1.15 may be used.

3.3 Material and design stresses

Design stresses are given 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

N/mm at 28 days). C25/30 is a concrete with cylinder strength of 25 and cube strength of 302

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 cylinder strength,

f.

ck

Partial factors for concrete are 1.5 for ultimate limit state and 1.0 for serviceability limit state. The strength properties of reinforcement are expressed in terms of the characteristic yield

f.

strength,

yk

Partial factors for reinforcement steel are 1.15 for ultimate limit state and 1.0 for serviceability limit state.

4 Initial design – reinforced concrete

4.1 Introduction

In the initial stages of the design of building structures it is necessary, often at short notice,to produce alternative schemes that 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 nature of finishes, let alone firm dimensions, but it is nevertheless expected that viable schemes be produced on which reliable cost estimates can be based.

It follows that initial design methods should be simple, quick, conservative and reliable. Lengthy analytical methods should be avoided.

This section offers some advice on the general principles to be applied when preparing a scheme for a structure, followed by methods for sizing members of superstructures. Foundation design is best deferred to later stages when site investigation results can be evaluated.

The aim should be to establish a structural 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.

Sizing of structural 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 cases – 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.

Simple structural schemes are quick 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.

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 structurally sensitive details and straightforward temporary works with minimal requirements for unorthodox sequencing to achieve the intended behaviour of the completed structure.

Standardized construction items will usually be cheaper and more readily available than purpose-made items.

4.2 Loads

Loads should be based on BS 4648,BS6399:Parts1 and 53 andCP3:ChapterV :Part 62

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 advantage of in the initial design stage except when assessing the load on the foundations.

Loading should be generous and not less than the following in the initial stages:

floor finish (screed) 1.82kN/mm

ceiling and service load 0.52kN/mm

Allowance for:

demountable lightweight partitions* 1.02kN/mm

blockwork partitions? 2.52kN/mm

Weight of reinforced concrete should be taken as 243kN/m

Design loads should be obtained using Table 3.1.

4.3 Material properties

For normal construction in the UK, a characteristic cylinder concrete strength ck f of 252N/mm should be assumed for the initial design. In areas with poor aggregates this may have to be reduced.

For UK steels a characteristic strength yk f of 4602N/mm should be used for high-tensile reinforcement and 2502N/mm for mild steel.

4.4 Structural form and framing

The following measures should be adopted:

(a) provide stability against lateral forces and ensure braced construction by arranging suitable

shear walls deployed symmetrically wherever possible

(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

(c) allow for movement joints (see subsection 2.4)

(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

(e) adopt a minimum column size of 300mm × 300mm or equivalent area

(f) provide a robust structure.

The arrangement should take account of possible large openings for services and problems with foundations, e.g. columns immediately adjacent to site boundaries may require balanced or other special foundations.

4.5 Fire resistance and durability

The 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 periods 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 members, sizes and cover should be increased (see Section 5 and Appendix C).

4.6 Stiffness

To provide adequate stiffness, the effective depths of beams, slabs and the waist of stairs should not be less than those derived from Table 4.2.

Beams should be of sufficient depth to avoid the necessity for excessive compression reinforcement and to ensure that economical amounts of tension and shear reinforcement are provided. This will also facilitate the placing of concrete.

*To be treated as imposed loads.

?To be treated as dead load s when the layout is fixed.

Table 4.1 Minimum member sizes and cover? for initial design of continuous members

?C over is to main reinforcement.

Table 4.2 Basic ratios of span/effective depth for initial design (yk f = 4602N/mm )

1. For two-way spanning slabs (supported on beams), the check on the ratio of span/effective depth should be carried out on the shorter span. For flat slabs, the longer span should be taken.

2. For flanged sections with the ratio of the flange to the rib width greater than 3, the Table value should be multiplied by 0.8.

3. For members, other than flat slab panels, which support partitions liable to be damaged by excessive deflection of the member, and where the span exceeds 7m, the Table value should be multiplied by 7/span.

4. For flat slabs where the greater span exceeds 8.5m, the Table value should be multiplied by 8.5/span.

土木工程类专业英文文献及翻译

PA VEMENT PROBLEMS CAUSED BY COLLAPSIBLE SUBGRADES By Sandra L. Houston,1 Associate Member, ASCE (Reviewed by the Highway Division) ABSTRACT: Problem subgrade materials consisting of collapsible soils are com- mon in arid environments, which have climatic conditions and depositional and weathering processes favorable to their formation. Included herein is a discussion of predictive techniques that use commonly available laboratory equipment and testing methods for obtaining reliable estimates of the volume change for these problem soils. A method for predicting relevant stresses and corresponding collapse strains for typical pavement subgrades is presented. Relatively simple methods of evaluating potential volume change, based on results of familiar laboratory tests, are used. INTRODUCTION When a soil is given free access to water, it may decrease in volume, increase in volume, or do nothing. A soil that increases in volume is called a swelling or expansive soil, and a soil that decreases in volume is called a collapsible soil. The amount of volume change that occurs depends on the soil type and structure, the initial soil density, the imposed stress state, and the degree and extent of wetting. Subgrade materials comprised of soils that change volume upon wetting have caused distress to highways since the be- ginning of the professional practice and have cost many millions of dollars in roadway repairs. The prediction of the volume changes that may occur in the field is the first step in making an economic decision for dealing with these problem subgrade materials. Each project will have different design considerations, economic con- straints, and risk factors that will have to be taken into account. However, with a reliable method for making volume change predictions, the best design relative to the subgrade soils becomes a matter of economic comparison, and a much more rational design approach may be made. For example, typical techniques for dealing with expansive clays include: (1) In situ treatments with substances such as lime, cement, or fly-ash; (2) seepage barriers and/ or drainage systems; or (3) a computing of the serviceability loss and a mod- ification of the design to "accept" the anticipated expansion. In order to make the most economical decision, the amount of volume change (especially non- uniform volume change) must be accurately estimated, and the degree of road roughness evaluated from these data. Similarly, alternative design techniques are available for any roadway problem. The emphasis here will be placed on presenting economical and simple methods for: (1) Determining whether the subgrade materials are collapsible; and (2) estimating the amount of volume change that is likely to occur in the 'Asst. Prof., Ctr. for Advanced Res. in Transp., Arizona State Univ., Tempe, AZ 85287. Note. Discussion open until April 1, 1989. To extend the closing date one month,

英文文献翻译

中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离,该技术需使用长柱色谱法。尽管这种技术得到的效果非常好,但是其需要消耗大量的时间,并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时,这些问题显得更加突出。近年来,几种制备系统已经进行了改进,能将分离时间减少到1-3h,并允许各成分的分辨率ΔR f≥(使用薄层色谱分析进行分析)。在这些方法中,在我们的实验室中,媒介压力色谱法1和短柱色谱法2是最成功的。最近,我们发现一种可以将分离速度大幅度提升的技术,可用于反应产物的常规提纯,我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等(ΔR f≥),而且构建这个系统花费非常低,并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础,专门针对快速分离,介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的,优化实验使用苯甲醇作为样本,放在一个20mm*5in.的硅胶柱60内,使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间(r)和峰宽(w,w/2)的比率进行测定的(Figure 1),结果如图2-4所示,图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。

外文翻译 - 英文

The smart grid Smart grid is the grid intelligent (electric power), also known as the "grid" 2.0, it is based on the integration, high-speed bidirectional communication network, on the basis of through the use of advanced sensor and measuring technology, advanced equipme nt technology, the advanced control method, and the application of advanced technology of decision support system, realize the power grid reliability, security, economic, efficient, environmental friendly and use the security target, its main features include self-healing, incentives and include user, against attacks, provide meet user requirements of power quality in the 21st century, allow all sorts of different power generation in the form of access, start the electric power market and asset optimizatio n run efficiently. The U.S. department of energy (doe) "the Grid of 2030" : a fully automated power transmission network, able to monitor and control each user and power Grid nodes, guarantee from power plants to end users among all the nodes in the whole process of transmission and distribution of information and energy bi-directional flow. China iot alliance between colleges: smart grid is made up of many parts, can be divided into:intelligent substation, intelligent power distribution network, intelli gent watt-hourmeter,intelligent interactive terminals, intelligent scheduling, smart appliances, intelligent building electricity, smart city power grid, smart power generation system, the new type of energy storage system.Now a part of it to do a simple i ntroduction. European technology BBS: an integration of all users connected to the power grid all the behavior of the power transmission network, to provide sustained and effective economic and security of power. Chinese academy of sciences, institute of electrical: smart grid is including all kinds of power generation equipment, power transmission and distribution network, power equipment and storage equipment, on the basis of the physical power grid will be modern advanced sensor measurement technology, network technology, communication

土木工程外文翻译

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