Standard Method of Detailing Structural Concrete

✍ Scribed by Baldwin L.

• Publisher: The Institution of Structural Engineers I Standard method of detailing structural concrete
• Year: 2024
• Tongue: English
• Leaves: 228
• Edition: 4
• Category: Library

✦ Synopsis

This Manual is a working document for concrete reinforcement that can be used to interpret the designer’s instructions in the form of drawings and schedules for communication to the construction site.
The information given is essential for both the designer and detailer — and both parties are responsible for ensuring that they are working with correct information, particularly as the designer is likely to be just one component of a wider project team.
The information and guidance is based on Eurocodes and UK practice but considered relevant for use in most parts of the world with only minor adjustment.
The purpose of this Manual is to provide a standard reference that can be used by practising designers and detailers, as well as being a valuable teaching aid for more junior engineers. It uses 'Model Details’ (MDs) to illustrate the preferred method of detailing for each type of structural element (Chapter 6).
It is assumed that it is the designer’s responsibility to specify design requirements clearly to the detailer — and the detailer’s responsibility to implement these requirements in a consistent, unambiguous and complete way, for the end user. Certain details have design implications, and this guidance does not attribute a lesser degree of responsibility to the designer. In detailing reinforcement for structural concrete, the impact on the entire project team should be borne in mind; poor detailing can lead to other issues/additional costs at a later stage.
The term ’standard method’ should also be clarified. It is not intended that any one detail should be copied verbatim for all situations, but all the principles should be followed. Details can be prepared with different objectives in mind, e.g. to reduce labour on site by allowing off-site prefabrication of reinforcement into cages, or to utilise the materials most readily available in a particular location — the principles covered in this Manual apply to almost any objective.
The details have been prepared with the following priorities in mind:
•
technical correctness and safety
•
buildability and speed of construction
•
labour and material costs
The previous (third) edition of this Manual (2006-20) introduced detailing rules that conformed to the current version of principal standards at that time, which remains the case for this edition:
BS EN1992-1 -1. Eurocode 2. Design of concrete structures. General rules and rules for buildings^
BSEN 1992-1-2. Eurocode 2. Design of concrete structures. General rules. Structural fire design2
BSEN 1992-2. Eurocode 2. Design of concrete structures. Concrete bridges. Design and detailing rules3
BS EN 1992-3. Eurocode 2. Design of concrete structures. Liquid retaining and containing structures4
It should be noted that UK National Annex values are embedded in the equations and tables.
In general, the conventional use of materials covered by European Standards or British Standards is assumed. Where other authoritative documents exist, this Manual refers to them rather than repeating them in full. It refers to generic rather than particular proprietary systems — and any proprietary systems shown are for general illustrative purposes only and are not specifically endorsed.

✦ Table of Contents

Task Group
Publishing
Acknowledgements
Contents
Foreword
Owen Brooker
1 Introduction and scope
Communication of information
2.1 General
2.2 The reinforcement process
Box 1: Checklist of information to be provided by designer
Box 2: Construction information to be coordinated between designer, contractor and detailer
2.3 Designer detailing
2.4 Contractor detailing
2.5 BIM and 3D detailing
2.6 Electronic data interchange (EDI)
2.7 Typical methods of providing required information for detailing
2.7.1 Flat slabs
2.7.3 Pile caps
Figure 2.5: Calculation sheet sketch (pile cap)
3 Drawings
3.1 General
3.2 Types of drawings
3.2.1 Structural drawings
3.22 Reinforcement drawings
3.2.3 Standard details
3.2.4 Diagrams
3.2.5 Record drawings
3.3 Photocopying and reduction
3.4 Abbreviations
3.5 Dimensions of drawing sheets
Table 3.1: Size of drawing sheets
3.6 Borders
3.7 Title and information panels
Figure 3.2: Layout of key information
3.8 Key
3.9 Orientation
3.9.1 Site plans
3.9.2 All other drawings
3.10 Thickness of lines
3.11 Lettering
3.12 Spelling
3.13 Dimensions
Figure 3.3 : Dimension lines
3.14 Levels
3.14.1 Datum
3.14.2 Levels on plan
3.14.3 Levels on section and elevation
Figure 3.4 : Levels on sections
3.15 Scales
3.16 Plans
3.17 Elevations
3.18 Sections
3.19 Gridlines and a recommended reference system
Figure 3.5 : Framing plan
3.20 Layout of slabs
3.20.1 Methods of preparing GA drawings for concrete structures
Table 3.2: GA drawings: information shown on plan
On section
3.20.3 Fixing in concrete
3.20.4 GA drawing for concrete structures
3.21 Layout of foundations
3.22 Layout of stairs
4 Detailing and scheduling
4.1 Detailing techniques
4.1.1 Tabular method of detailing
Table 4.1: Tabular method of detailing — examples
4.1.2 Template drawings/typical details
4.1.3 Overlay drawings
4.2 Detailing reinforcement
4.2.1 General
4.2.2 Intersection and layering of reinforcement
Figure 4.3: Detail of beam comer
Figure 4.4: Plan of reinforcement at beam/column intersection
4.2.3 Preformed cages
Flexible detailing
Internal beam/column intersection
External beam/column intersection
4.2.4 Straight bars
4.2.5 Welded fabric
4.2.6 Chairs
4.3 Precast concrete
4.4 Checklist for detai ler
4.5 Schedules and scheduling
4.5.1 General
Figure 4.7 : Typical bar schedule
Figure 4.8 : Typical fabric schedule
4.5.2 Allowances for tolerances/deviations
4.5.3 Out-of-plane deviations
4.6 Procedure for checking reinforcement drawings and schedules
Box 3: Checking of reinforcement drawings
5 Technical information and requirements
5.1 Reinforcement
5.1.1 General
5.1.2 Strength/ductility properties
5.1.3 Bar identification
5.1.4 Notation
5.1.5 Specifying stainless steel
5.1.6 Sizes of reinforcing bars
5.1.7 Length and overall dimensions of reinforcing bars
5.1.8 Rebending bars
5.1.9 Large diameter bends
5.1.10 Structural tying reinforcement to ensure robustness
Peripheral ties
Internal ties
Horizontal ties to columns and/or walls
Vertical ties
Continuity and anchorage of ties
5.1.11 Fabric reinforcement
Standard fabric
Purpose-made fabric
Bending of fabric
Laps in fabric
5.2 Cover to reinforcement
5.2.1 General
Nominal cover
Deviation, Ac^
Limit to positive tolerance, Ac(pluS)
Overall section depth h (mm)
5.2.2 Cover for durability
5.2.3 Cover for fire resistance
5.2.4 Fixing reinforcement to obtain correct cover
5.2.5 Minimum spacing of reinforcement
5.3 Cutting and bending tolerances
Bending dimension
‘Closed’ detailing tolerances
Table 5.8: Standard deductions between two concrete faces
Distance between concrete faces (mm) Deduction {mm)
5.4 Anchorage and lap lengths
5.4.1 General
5.4.2 Laps in reinforcement
Transverse reinforcement for bars in tension
Transverse reinforcement for bars permanently in compression
5.4.3 Additional rules for large bars
5.4.4 Bundled bars
General
Anchorage of bundles of bars
Figure 5.10 : Anchorage of widely staggered bars in bundle
Lapping bundles of bars
Figure 5.11 : Lap joint in tension, including a fourth bar
5.4.5 Laps in welded fabric
Laps of the main reinforcement
Figure 5.12 : Lapping of welded fabric
Table 5.9 : Values of the coefficient a6
Percentage of lapped bars relative to the total cross-section area
Table 5.10 : Required lap lengths for secondary wires of fabrics
Size of secondary wires (mm)
5.5 Welding of reinforcement
5.5.1 General
5.5.2 Semi-structural welding
5.5.3 Tack welding
6 Common structural elements
6.1 Introduction
6.2 Slabs
6.2.1 Scope
6.2.2 Design and detailing notes
6.2.2.1 Minimum area of reinforcement
6.2.2.2 Bar spacing
6.2.2.3 Anchorage and lapping of bars
Figure 6.1: Anchorage of bottom reinforcement at end supports
6.2.2.4 Simplified rules for the curtailment of reinforcement
6.2.2.5 Notation for the locating layers of reinforcement
6.2.2.6 Typical bar and indicator lines
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6.2.2.7 Two-way slabs
Figure 6.3: Arrangement for reinforcement strips for two-way slabs
6.2.2.8 Hat slabs
6.2.2.9 Internal panels
6.2.2.10 Slab at edge and comer columns
6.2.2.11 Edge reinforcement
6.2.2.12 Trimming holes in a slab
6.2.2.13 Secondary reinforcement
6.2.2.14 Fabric reinforcement
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6.2.2.15 Carpet reinforcement
6.2.2.16 Shear reinforcement in flat slabs
Figure 6.8: Recommendations for placing orthogonal links adjacent to edge column with hole
6.2.2.17 Connection to walls
6.2.2.18 Movementfconstruction joints
Figure 6.11: Dowel systems
6.23 Detailing information
6.2.4 Presentation of working drawings
Figure 6.15: Flat slab (shear reinforcement)
ONE- AND TWO-WAY SLABS:
SPAN AND INTERNAL SUPPORT
Simplified rules for slab — continuous slab curtailment
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ONE- AND TWO-WAY SLABS: EXTERNAL AND RESTRAINED SUPPORTS
ONE- AND TWO-WAY SLABS;
EXTERNAL UNRESTRAINED SUPPORTS
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CANTILEVER SLABS
FLAT SLABS: SPAN AND INTERNAL SUPPORT
Section of column strip j
Section of middle strip
FLAT SLABS: SHEAR REINFORCEMENT
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FLAT SLABS: COLUMN DROPS
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Pull-out bars or similar approved
COUPLER/THREADED BAR
6.3 Beams
6.3.1 Introduction
6.3.2 Design and detailing notes
6.3.2.1 Minimum area of reinforcement
6.3.2.2 Bar spacing
6.3.2.3 Bars along the side faces of beams
6.3.2.4 Link spacing
6.3.2.5 Maximum pitch
6.3.2.6 Maximum lateral pitch of legs
6.3.2.7 Anchorage and lapping of bars
6.3.2.8 Simplified curtailment rules (longitudinal reinforcement in beams)
Figure 6.17: Layout of reinforcement for flexible detailing of beams
6.3.2.9 Hanger bars
6.3.2.10 Top bars at internal support (simplified rules)
6.3.2.11 Bottom splice bars at internal support
6.3.2.12 Bottom bars in span (simplified rules)
6.3.2.13 U-bars at end of beam
6.3.2.14 Lacer bars at sides of beam
6.3.2.15 Anchorage of bottom reinforcement at end supports
6.3.2.16 Partial fixity with monolithic construction
6.3.2.17 Flanged beams at intermediate supports of continuous beams
6.3.2.18 Curtailment of longitudinal reinforcement in cantilevers
6.3.2.19 Arrangement of links
Figure 6.22 : Required shape of torsion links
6.3.2.20 Connection to edge supports
Figure 6.23 : Beam-to-wall connection
6.3.2.21 Deep beams
6.3.3 Detailing information
6.3.4 Presentation of working drawings
Figure 6.24: Working drawing (beams): Traditional method
Figure 6.25: Working drawing (beams): Representational method
BEAM ON GRIDLINE 6/E-F
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SPAN AND SUPPORT DETAILS
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BROAD SHALLOW SECTIONS
CANTILEVER BEAMS
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6.4 Columns
6.4.1 Introduction
6.4.2 Design and detailing notes
Figure 6.27: Requirement of links in columns
6.4.3 Detailing information
6.4.4 Presentation of working drawings
Figure 6.31 : Working drawing (columns): Traditional method
BOTTOM DETAIL
INTERMEDIATE DETAIL: NOMINAL LINKS FOR NORMAL STRENGTH CONCRETE
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C| INTERMEDIATE DETAIL: NOMINAL LINKS FOR
O HIGH STRENGTH CONCRETE
INTERMEDIATE DETAIL: OFFSET COLUMNS
TOP DETAIL
TOP DETAIL (INCL, SPLICE BARS)
CIRCULAR COLUMNS: HELICAL LINKS
CIRCULAR COLUMNS: CIRCULAR LINKS
6.5 Walls
6.5.1 Introduction
6.5.2 Design and detailing notes
Maximum spacing
6.5.3 Detailing information
6.5.4 Presentation of working drawing
GENERAL DETAILS
CORNER DETAILS
HALF-LANDING DETAIL
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HOLE DETAILS
6.6 Retaining walls
6.6.1 Introduction
6.6.2 Design and detailing notes
Simple earth-retaining walls
Water-resisting retaining walls or retaining walls which are required to prevent water seepage, e.g. basements
6.6.3 Detailing information
6.6.4 Presentation of working drawings
EXTERNAL CANTILEVER WALL
BASEMENT RETAINING WALL
VERTICAL CONSTRUCTION JOINTS
6.7 Foundations
6.7.1 Introduction
6.7.2 Design and detailing notes
^s,dbmin = 0.001 Ac > 150mm2/m
6.7.3 Detailing information
6.7.4 Presentation of working drawings
MULTI-COLUMN BASE
GROUND SLAB AND BEAM
TRENCHES
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6.8 Staircases
6.8.1 Introduction
6.8.2 Design and detailing notes
Figure 6.42: Details for stair flight landing
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6.8.3 Detailing information
6.8.4 Presentation of working drawings
Figure 6.44: Working drawing: Cantilever stair flights
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6.9 Corbels, half-joints and nibs
6.9.1 Introduction
6.9.2 Design and detailing notes
Minimum vertical pitch
6.9.3 Detailing information
WITHOUT WELDS
WITH WELDS
6.10 Composite slabs
6.10.1 Introduction
6.10.2 Design and detailing notes
6.10.3 Detailing information
Prestressed concrete
7.1 General
7.2 Prestressing strand
7.3 Post-tensioning
7.3.1 Anchorage and tendons
7.3.2 Anchor cover and spacing
7.3.3 Anchor pockets and stressing access
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7.3.4 Tendon ducts
7.3.5 Anti-bursting reinforcement
Figure 7.12b: Example multistrand bonded post-tensioning primary anti-burst reinforcement
7.3.6 Tendon profile detailing
Figure 7.14: Legend for post-tensioned strand (alternative systems also used)
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7.4 Pre-tensioning
7.4.1 Anchorage and debonding
7.4.2 Transmission zones
7.4.3 Strand cover and spacing
7.4.4 Supports and bearings
7.4.5 Tendon profiles
7.5 Exchange of information
Box 4: Checklist of information to be provided by the designer, post-tensioning
Box 5: Checklist of information to be provided by the designer pre-tensioning
8 Precast concrete
8.1 Introduction
Length
Height
Width
Weight
8.2 Particular durability problems
Appendix A: Changes to reinforcement since 1948
Symbol used on drawings lb/in2 (MPa)
CP 114:1957
London by-laws: 1952
BS 4466:1981
Table A6: Circa 1983-1984
I Symbol used on drawings I MPa
CP 110: amendment (1983) (characteristic strength)
Table A7: Circa 1985-2004
Material properties [ Symbol used on drawings | MPa
BS 8110:1985
BS 4466:1989
BS 8110:1997
Symbol used on drawings MPa
Either:
Or
Table AB: Continued
Table A8: Continued
Appendix B: Bar shapes (BS 8666:2020)
Table B1: Bar shapes (BS 8666:2020)
Shape Code | Shape | Total length of bar L measured along centreline
Total length of bar L measured along centreline
Total length of bar L measured along centreline
Shape Code I Shape
Total length of bar L measured along centreline
Table B1: Continued
I Total length of bar L measured along centreline
Total length of bar L measured along centreline
Appendix C: Scheduling radii
Table C1: Minimum scheduling radii, madrel diameters and end projections
Nominal size of bar d | Minimum value between two bends X
Table C3: Limit for which a preformed radius is required
Appendix D:
Mechanical couplers for bars
Type 1: Couplers with parallel threads
Type 2: Couplers with taper-cut threads
Type 3: Couplers with integral threads over full length bar
Type 4: Metal sleeves swaged onto bars
Type 5: Threaded couplers swaged onto ends of reinforcing bars
Type 6: Wedge locking sleeves
Type 7: Couplers with shear bolts and serrated saddles
Appendix E:
Lap and anchorage lengths
Table E1: Lap and anchorage lengths
Appendix F: Effective anchorage length
Table Fl: L-bars
Table F2: U-bars
Appendix G: Minimum overall depth of various U-bars
Appendix H: Large diameter bends
Appendix I: Abbreviations
Appendix J: Fabric types
References
Appendix K: Bar areas/weights