【正文】 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 , the Table value should be multiplied by IStructE EC2 (Concrete) Design Manual 13 第一章 引言和適用 范圍 手冊的作用 這本手冊為設(shè)計鋼筋和預(yù)應(yīng)力混凝土建筑結(jié)構(gòu)提供了指導(dǎo)。 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 pleted structure. Standardized construction items will usually be cheaper and more readily available than purposemade items. Loads IStructE EC2 (Concrete) Design Manual 10 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) 2kN/mm ceiling and service load 2kN/mm Allowance for: demountable lightweight partitions* 2kN/mm blockwork partitions? 2kN/mm Weight of reinforced concrete should be taken as 24 3kN/m Design loads should be obtained using Table . Material properties For normal construction in the UK, a characteristic cylinder concrete strength ckf of 25 2N/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 ykf of 460 2N/mm should be used for hightensile reinforcement and 250 2N/mm for mild steel. 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 ) (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。 Part Liquid retaining and containment structures. All Eurocodes follow a mon editorial style. The codes contain ‘Principles’ and ‘Application rules’. Principles are general statements, definitions, requirements and sometimes analytical models. All designs must ply with the Principles, and no alternative is permitted. Application rules are rules monly adopted in design. They follow the Principles and satisfy their requirements. Alternative rules may be used provided that pliance with the Principles can be demonstrated. Some parameters in Eurocodes are designated by | _ | , monly 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 patibility 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. 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 nonsway. 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 ply with ENV 199211 together with the UK NAD ? Although British Standards have been referenced as loading codes in Sections 3 and 6, to ply with the UK NAD, the Manual can be used in conjunction with other loading codes ? The structures are braced and nonsway ? 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 monly used materials in construction。 IStructE EC2 (Concrete) Design Manual 2 Part Supplementary rules for the use of unbonded and external prestressing tendons。en de Normalisation (CEN) which is the European standards organization, its members being the national standards bodies of the EU and EFTA countries,. 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 ments 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 199111: Basis of design and actions on structures (EC1) DD ENV 199211: Design of concrete structures (EC2) DD ENV 199311: Design of steel structures