Manual for the design of reinforced concrete building ...

1 The Institution of Structural EngineersThe Institution of Civil EngineersMARCH2000 Manual for the design of reinforced concrete building structures to EC2 Published for the Institution of Structural EngineersConstitutionD J LeeCBE BScTech DIC FEng FIStructE FICE Chairman, (until April 1995)(previously G Maunsell & Partners)R S Narayanan BE(Hons) MSc DIC FEng FIStructE Chairman,(from May 1995)(S B Tietz & Partners)Professor A W BeebyBSc(Eng) PhD CEng MIStructE MICE(University of Leeds)P G CobbCEng MICE(Sir Robert McAlpine & Sons Ltd)R F D PoveyCEng FIStructE(Mitchell McFarlane & Partners)S S RayBSc CEng FICE(Robert Benaim & Associates)R T WhittleMACEng MICE(Ove Arup & Partners)K R WilsonMACEng MICE(G Maunsell & Partners)R J W MilneBSc, Secretary to the Task Group(The Institution of Structural Engineers)Editorial PanelThe final version was prepared by an Editorial Panel consisting of:R S Narayanan,ChairmanK R WilsonR J W Milne,Secretarybe contacted at 11 Upper Belgrave Street, London SW1X Introduction.

2 Aims of the Manual .. Eurocode system .. Scope of the Manual .. Contents of the Manual ..122 General principles .. General .. Stability .. Robustness .. Movement joints .. Fire resistance and durability ..143 design principles reinforced concrete .. Loading .. Limit states .. Ultimate limit state .. Serviceability limit states .. Material and design stresses ..174 Initial design reinforced concrete .. Introduction .. Loads .. Material properties .. Structural form and framing .. Fire resistance and durability .. Stiffness .. Sizing .. Introduction .. Loading .. Width of beams and ribs .. Sizes and reinforcement of columns .. Walls .. Shear in flat slabs at columns .. Adequacy of chosen sections to accommodate the reinforcement .. Bending moments and shear forces .. Provision of reinforcement .. The next steps .. Reinforcement estimates ..255 Final design .. Introduction .. Checking of all information .. Preparation of a list of design data.

3 Amendment of drawings as a basis for final calculations .. Final design calculations ..28 IStructE EC2 ( concrete ) design Slabs .. Introduction .. Fire resistance and durability .. Fire resistance .. Durability .. Bending moments and shear forces .. General .. One-way spanning slabs .. Two-way spanning slabs on linear supports .. Flat slabs .. Section design solid slabs .. Bending .. Shear .. Openings .. Span/effective depth ratios .. Section design ribbed and coffered slabs .. Bending .. Span/effective depth ratios .. Shear .. Beam strips in ribbed and coffered slabs .. Notes on the use of precast floors .. Structural frames .. Division into subframes .. Elastic analysis .. Redistribution of moments .. design shear forces .. Beams .. Introduction .. Fire resistance and durability .. Fire resistance .. Durability .. Bending moments and shear forces .. Section design .. Bending .. Minimum and maximum amounts of reinforcement.

4 Shear .. Span/effective depth ratios .. Columns .. Introduction .. Slenderness, fire resistance and durability .. Slenderness .. Fire resistance .. Durability .. Axial loads and moments non-slender columns .. Axial loads and moments slender columns .. General .. Calculation of first-order moments .. Calculation of the ultimate deflection .. Section design .. Reinforcement ..644 IStructE EC2 ( concrete ) design Walls .. Introduction .. Slenderness, fire resistance and durability .. Slenderness .. Fire resistance .. Durability .. Axial load and moments .. In-plane bending .. Bending at right-angles to the walls .. Slender walls .. Section design .. Walls not subject to significant bending at right-angles to the wall .. Intersecting walls .. Reinforcement .. Openings in shear and core walls .. Staircases .. Introduction .. Fire resistance, durability and concrete grades .. Bending moments and shear forces .. Effective spans.

5 Stairs spanning between beams or walls .. Stairs spanning between landing slabs .. Stair with open wells .. Span/effective depth ratios .. Section design .. design of non-suspended ground floor slabs .. Guidance for the design of basement walls .. General .. Bending moments and shear forces .. Section design .. Foundation .. Reinforcement .. Foundations .. Introduction .. Durability and cover .. Types of foundation .. Plan area of foundations .. design of spread footings .. Axially loaded unreinforced pad footings .. Axially loaded reinforced pad footings .. Eccentrically loaded footings .. design of other footings .. Strip footings .. Combined footings and balanced footings .. Reinforcement .. design of rafts .. design of pile caps .. Reinforcement in pile caps .. Robustness ..78 IStructE EC2 ( concrete ) design General .. Tie forces and arrangements .. Detailing .. General .. Bond conditions .. Anchorage and lap lengths.

6 Transverse reinforcement .. Additional rules for high-bond bars exceeding 32mm in diameter .. Curtailment of bars in flexural members .. Corbels and nibs ..876 design principles prestressed concrete .. Introduction .. Loading .. Limit states .. Ultimate limit state .. Serviceability limit states .. Materials, prestressing components and design stresses ..927 Initial design prestressed concrete .. Introduction .. Loads .. Material properties .. Structural form and framing .. Fire resistance and durability .. Stiffness .. Slabs .. Beams .. Sizing .. Introduction .. Loading .. Width of beams and ribs .. Punching shear in flat slabs at columns .. Adequacy of chosen sections to accommodate the tendons and reinforcement .. Bending moments and shear forces .. Provision of tendons and reinforcement .. The next step .. Reinforcement estimates ..1048 Final design prestressed concrete .. Introduction .. Fire resistance and durability.

7 Fire resistance .. Durability .. Flexural design .. Tendon profile .. Tendon force profile .. Initial force (Pn,o) .. Final force (Pn,oo) ..1126 IStructE EC2 ( concrete ) design Analysis of the structure .. General .. Beams and one-way solid slabs .. Two-way solid slabs on linear supports .. Flat slabs .. Ribbed slabs .. Serviceability limit state .. concrete stresses .. Crack control .. Transfer .. Ultimate limit state .. Bonded tendons .. Unbonded tendons .. Minimum reinforcement .. Tendon spacing .. Shear design .. General .. Standard method .. Variable-strut inclination method .. Shear in flat slabs .. Detailing of shear reinforcement .. Minimum reinforcement .. Maximum spacing .. Arrangement of links .. Openings .. Anchorage zones .. General .. Pretensioned members .. Post-tensioned members .. General .. Bursting .. Overall equilibrium .. Spalling .. Couplers .. Tendon extensions .. Robustness and detailing.

8 140 References ..141 Appendix A Reinforcement quantities ..142 Appendix B design data ..146 Appendix C Exposure classes related to environmental conditions ..147 Appendix D Column design charts ..148 Appendix E Foundations ..152 IStructE EC2 ( concrete ) design Manual78 IStructE EC2 ( concrete ) design ManualIStructE EC2 ( concrete ) design Manual9 ForewordThe Eurocode for the design of concrete Structures(EC2) is likely to be published as aEuronorm (EN) in the next few years. The prestandard (ENV) for EC2 has now been avail-able since 1992. To facilitate its familiarisation the Institution of Structural Engineers andthe Institution of Civil Engineers decided to prepare a Manualfollows in the footsteps of influential guides published by the Institution ofStructural Engineers and uses the format of the green book (Manualfor BS 8110). As withthe green book the scope of the Manualcovers the majority of concrete building structuresand has now been extended to cover slender columns and prestressed concrete .

9 An appen-dix for the structural design of foundations using limit state philosophy (as foreseen byENVEC7), has also been included. It is hoped that this extended scope will be welcomedby practitioners. It is a helping hand not a substitute for the greater range in mandate to our Task Group was to produce a Manual , the results of which wouldcomply with ENV EC2 and the UK National Application Document (NAD) these areexplained in Section 1 of the Manual . This latter requirement imposed certain we had to use the UK boxed values (see section 1), refer to BS loading codes and useBS 8110 for fire design . During the drafting period, further ENVstandards have been pub-lished, in particular for loading (EC1) and for fire design (EC2, Part ). The designer canuse this Manualin conjunction with these standards, but it should be noted that these ENVprestandards have their own NADs, which should be should find this Manualconcise and useful in practical design . This Manualis laid out for hand calculations, but the procedures are equally suitable for computer thanks are due to all the members of the drafting Task Group (and their organi-sations) who have given their valuable time voluntarily, in particularly difficult economiccircumstances in the industry.

10 I am also grateful to Bob Milne of the Institution, for actingas my secretary with characteristic enthusiasm. Many members had commented on an ear-lier draft and these have contributed to its improvement. Users of this Manualshould for-ward their comments to the Institution so that they can be taken into account in the 1992 the Committee started work under the chairmanship of David Lee who joins mein commending this Manualto the J. LeeChairman (until April 1995)R. S. NarayananChairman(since May 1995)10 IStructE EC2 ( concrete ) design Aims of the ManualThis Manualprovides guidance on the design of reinforced and prestressed concrete build-ing structures. Structures designed in accordance with this Manual will normally complywith DD ENV 1992-1-1: 19921(hereinafter referred to as EC2). Eurocode systemThe structural Eurocodes were initiated by the European Commission but are now pro-duced by the Comit Europ en de Normalisation (CEN) which is the European standardsorganization, its members being the national standards bodies of the EU and EFTA coun-tries, will eventually publish these design standards as full European Standards EN(Euronorms), but initially they are being issued as Prestandards ENV.