A cement and concrete industry publication
User Guide to RC Spreadsheets: v4 (Addendum to v3) User Guide to Excel Spreadsheets for reinforced concrete design to BS EN 1992:2004 Part 1-1 and its UK National Annex (incl AMD 1) and BS 8110: Part 1, 1997 (incl Amd 4)
C H Goodchild BSc CEng MCIOB MIStructE R M Webster CEng FIStructE
Foreword This 4th edition or version 4 of the User Guide to the RC Spreadsheets is intended to be read as an addendum to the version 3 publication[1] published in July 2006. This 4th edition covers revisions to the Eurocode series of spreadsheets (produced by The Concrete Centre) that have proved necessary following publication of amendment AMD 1 to the UK National Annex to Eurocode 2 in December 2009 and subsequent withdrawal of BS 8110 in March 2010. It also formally introduces five new spreadsheets in the Eurocode series and gives additional commentary on others. RC-spreadsheets:v4 is intended to help with the rapid production of clear and accurate design calculations for reinforced concrete elements to both Eurocode 2 and BS 8110-1:1997. The first version of this publication and the spreadsheets were produced by the Reinforced Concrete Council (RCC). Since its release in 2000 the spreadsheets have proved enormously popular and have been maintained by the RCC and its successor, The Concrete Centre.
Acknowledgements The ideas and illustrations come from many sources. The help and guidance received from many individuals are gratefully acknowledged. Thanks are due to members of the original project’s Advisory Group for their time and effort in helping to make the project feasible and in bringing it to fruition. The members of the Advisory Group are listed on the inside back cover. TCC55X Axial Column Shortening (24 storeys) was sponsored by Adams Kara Taylor.
Published by MPA - The Concrete Centre Riverside House, 4 Meadows Business Park, Station Approach, Blackwater, Camberley, Surrey GU17 9AB Tel: +44 (0)1276 606800 Fax: +44 (0)1276 606801 CCIP-053. Published August 2010. © MPA - The Concrete Centre User Guide v1 published by the British Cement Association on behalf of the Reinforced Concrete Council. User Guide v2 published electronically by The Concrete Centre. User Guide v3 published by The Concrete Centre. CCIP-008 - July 2006 CCIP publications are produced on behalf of the Cement and Concrete Industry Publications Forum – an industry initiative to publish technical guidance in support of concrete design and construction. CCIP publications are available from the Concrete Bookshop at www.concretebookshop.com Tel: +44 (0)7004 607777 All advice or information from MPA - The Concrete Centre is intended for those who will evaluate the significance and limitations of its contents and take responsibility for its use and application. No liability (including that for negligence) for any loss resulting from such advice or information is accepted by MPA - The Concrete Centre or their subcontractors, suppliers or advisors. Readers should note that MPA - The Concrete Centre publications are subject to revision from time to time and should therefore ensure that they are in possession of the latest version.
Contents
User Guide to RC Spreadsheets: v4 (Addendum to v3) Contents CONTENTS IN FULL AND LOCATION OF GUIDANCE
2
INTRODUCTION
4
GENERAL NOTES
6
USING THE SPREADSHEETS
8
AMENDMENTS TO V3 SPREADSHEET DESCRIPTIONS
9
ADDITIONAL SPREADSHEETS TO EUROCODE 2
11
TCC15 Axially Loaded Walls and Columns
11
TCC22 FE Assistant
12
TCC55X Axial Column Shortening
14
TCC62 Retaining Wall Design
16
TCC63 Core Wall Design
21
TCC94 Two Way Slab
24
REFERENCES
27
1
Contents in full and location of guidance Contents in full and location of guidance in User Guides to RC Spreadsheets: v3 and v4 User Guide v3
v4
INTRODUCTION
1
4
GENERAL NOTES
3
6
Using the spreadsheets
10
8
Amendments to V3 spreadsheet descriptions
9
Menu.xls
179
General notes to Eurocode 2 versions
181
Elements
TCC11 Element Design.xls
185
TCC12 Bending and Axial Force.xls
194
TCC13 Slab Punching.xls
196
TCC14 Crack Width.xls
201
TCC15 Resistance of Axially Loaded Walls/Slabs
Analysis
TCC21 Subframe Analysis.xls
TCC22 FE Assistant
Slabs
TCC31 One-way Slabs.xls
208
TCC31R Rigorous One-way Slabs.xls
214
TCC32 Ribbed Slabs (A&D).xls
221
TCC33 Flat Slabs (A&D).xls
228
TCC33X Flat Slabs (A&D).xls
237
Beams
TCC41 Continuous Beams.xls
243
TCC41R Rigorous Continuous Beams.xls
249
TCC42 Post-tensioned Analysis & Design.xls (Beta)
256
TCC43 Wide Beams (A & D).xls
264
Columns
TCC51 Column Load Take-down Design.xls
270
TCC52 Column Chart generation.xls
276
TCC53 Column Design.xls
278
TCC54 Circular Column Design.xls
280
TCC55 Axial Column Shortening.xls
282
10*
TCC55X Axial Column Shortening (24 storeys)
14
Walls
TCC62 Retaining Wall Design.xls
16
TCC63 Core Wall Design
21
Stairs
TCC71 Stair Flight & Landing - Single.xls
284
Foundations
TCC81 Foundation Pads.xls
287
TCC82 Pilecap Design.xls
291
Tabular versions
TCC94 Two Way Slab
* Amendment 2
16
SPREADSHEETS TO EUROCODE 2
11
9* 11
205 12
9*
24
Contents in full and location of guidance
User Guide v3 SPREADSHEETS TO BS 8110
v4
17
Elements
RCC11 Element Design.xls
19
RCC12 Bending and Axial Force.xls
26
RCC13 Punching Shear.xls
28
RCC14 Crack Width.xls
33
Analysis
RCC21 Subframe Analysis.xls
35
Slabs
RCC31 One-way Solid Slabs (A & D).xls
38
RCC31R Rigorous One-way Slabs.xls
43
RCC32 Ribbed Slabs (A & D).xls
50
RCC32R Rigorous Ribbed Slabs.xls
56
RCC33 Flat Slabs (A & D).xls
64
Beams
RCC41 Continuous Beams (A & D).xls
72
RCC41R Rigorous Continuous Beams (A & D).xls
78
RCC42 Post-tensioned Slabs & Beams (A & D).xls
85
RCC43 Wide Beams (A & D).xls
107
Columns
RCC51 Column Load Take-down & Design.xls
113
RCC52 Column Chart generation.xls
118
RCC53 Column Design.xls
120
RCC54 Circular column charting.xls
123
Walls
RCC61 Basement Wall.xls
125
RCC62 Retaining Wall.xls
132
Stairs
RCC71 Stair Flight & Landing - Single.xls
139
RCC72 Stairs & Landings - Multiple.xls
142
Foundations
RCC81 Foundation Pads.xls
146
RCC82 Pilecap Design.xls
149
Tabular versions
RCC91 One-way Solid Slabs (Tables).xls
158
RCC92 Ribbed Slabs (Tables).xls
161
RCC93 Flat Slabs (Tables).xls
166
RCC94 Two-way Slabs (Tables).xls
173
RCC95 Continuous Beams (Tables).xls
175
ADMIN FOLDER
298
REFERENCES AND FURTHER READING
299
27
3
Introduction The RC spreadsheets were originally produced under the Reinforced Concrete Council’s project, ‘Spreadsheets for concrete design to BS 8110 and EC2’. They were released in January 2000 and have been maintained and extended by the RCC and its successor The Concrete Centre. They continue to be supported by The Concrete Centre. Version 4 of the User Guide covers version 4 of the spreadsheets. The Concrete Centre series of spreadsheets have been updated in line with amendment 1 of the UK National Annex to Eurocode 2 in December 2009. Whilst BS 8110 was ‘withdrawn’ by BSI early in 2010, it was recognised that some projects and indeed some practitioners may wish to continue using this standard in the short to medium term. Thus the RCC series of spreadsheets have been updated and are reissued. In 2006, the introduction of Eurocode 2[2], its National Annex and Amendment of BS 8110:1997[3] necessitated the revision of all the spreadsheets produced to that date and the publication of version 3 of the User Guide. The third edition of the User Guide provided guidance on the use of all spreadsheets produced to July 2006. The vast majority of version 3 of the User Guide remains valid and the decision was made that version 4 should take the form of an addendum to version 3. Therefore only those areas that are significantly different or new are contained in version 4. For instance, version 4 formally introduces five new spreadsheets to the Eurocodes. Detailed descriptions of the majority of spreadsheets will be found in version 3 of the User Guide. For the experienced engineer, the spreadsheets allow the rapid production of clear and accurate design calculations. The spreadsheets allow younger users to understand concrete design and help them to gain experience by studying their own ‘what if’ scenarios. The individual user should be able to answer his/ her own questions by chasing through the cells to understand the logic used. Cells within each spreadsheet can be interrogated and can have their formulae checked and values traced. The original spreadsheets reflected a consensus of opinion on several design issues. The version 3 Eurocode 2 spreadsheets reflected a consensus of opinion of a limited number of engineers. Version 4 Eurocode spreadsheets benefit from a few years use - students and young engineers may follow the ‘model’ calculations presented in the spreadsheets to form an understanding of current reinforced concrete design.
The spreadsheets are intended to follow normal design practice and cater for the design of low- to mediumrise multi-storey concrete framed buildings. They are offered as shareware. However, users are required to register when using them in any commercial capacity*. The original project was jointly funded by the RCC and the Department of the Environment Transport and the Regions (DETR) under its Partners in Technology scheme. It was made possible by the support and contributions of time given by individual members of industry. The project was managed by the RCC and guided by an 80-strong Advisory Group of interested parties, including consulting engineers and software houses. In producing the original spreadsheets several issues had to be addressed. Firstly, which spreadsheet package should be used? Excel (© Microsoft Corporation) appeared to hold about 70% of the market amongst structural engineers and was thus adopted. More specifically, Excel ’97© was originally adopted as being de facto the most widely available spreadsheet in the field. To avoid complications, it was decided not to produce corresponding versions using other spreadsheet packages. The spreadsheets are compatible with later versions of Excel. Whilst the spreadsheets to BS 8110 provide a consensus of current commercial reinforced concrete design practice, the spreadsheets to Eurocode 2, provide a consensus of design procedures to this new design code. The introduction of Eurocode 2 will provide commercial opportunities for those who are prepared to use it. The spreadsheets should help with the transition between Eurocode 2 and BS 8110. It is believed that both novices and experienced users of spreadsheets will be convinced that spreadsheets have a great potential for teaching BS 8110 and Eurocode 2, improving concrete design and, above all, improving the concrete design and construction process.
Version 2.x The version 2.x released in 2003[4] introduced new spreadsheets to BS 8110, to the more finalised EN 1992-1-1 (Eurocode 2) and an overarching menu spreadsheet. Previously issued spreadsheets to BS 8110 were updated.
* Registration is through The Concrete Bookshop www.concretebookshop.com 4
Introduction The new spreadsheets introduced were:
TCC71 Stair Flight and Landing - single
Menu
TCC81 Foundation Pads
BS 8110 RCC31R Rigorous One-way Slabs RCC32R Rigorous Ribbed Slabs RCC41R Rigorous Continuous Beams RCC43 Wide Beams (A&D) RCC54 Circular Column Design RCC82 Pilecap Design
Eurocode 2 RCCen11 Element Design RCCen12 Bending and Axial Force RCCen13 Punching Shear RCCen14 Crack Width RCCen21 Subframe analysis RCCen31 One-way Solid Slabs (A & D) RCCen31R Rigorous* One-way Solid Slabs
TCC82 Pilecap Design Spreadsheets numbered RCCen11, RCCen12 etc released as Beta versions were released for use as TCC11, TCC12 etc.
Version 4 The release of version 4 of the spreadsheets follows the publication of amendment AMD 1 of the UK National Annex to Eurocode 2 to BS EN 1992-1-1 (Eurocode 2)[2] Whilst BS 8110 was ‘withdrawn’ by BSI early in 2010, it was recognised that some projects and indeed some practitioners may wish to continue using this standard in the short to medium term. Thus the RCC series of spreadsheets have been updated and are reissued. The opportunity has been taken to formally introduce new spreadsheets as follows:
Eurocode 2 TCC15 Resistance of Axially Loaded Walls/slabs
RCCen32 Ribbed Slabs (A & D)
TCC22 FE Assistant
RCCen33 Flat Slabs (A & D)
TCC62 Retaining Wall Design
RCCen41 Continuous beams (A & D)
TCC63 Core Wall Design
RCCen41R Rigorous* Continuous Beams
TCC94 Two Way Slab
RCCen43 Wide Beams (A&D)
Using and improving the spreadsheets
RCCen52 Column Chart generation RCCen53 Column Design RCCen55 Axial Column Shortening RCCen81 Foundation Pads RCCen82 Pilecap Design
Version 3 The release of version 3 of the spreadsheets followed the publication of BS EN 1992-1-1 (Eurocode 2)[2] and the UK National Annex and the publication of Amendment 3 to BS 8110 Part 1: 1987. The requirements within these documents necessitated the revision of all previously published spreadsheets. The opportunity was taken to introduce new spreadsheets as follows:
Since their release in 2000 the spreadsheets have proved to be enormously popular. They may now be regarded as having now been thoroughly tested by engineers in practice but this does not mean that they are infallible! The user is referred to Managing the spreadsheets and other General Notes that follow. The usefulness and robustness of previous spreadsheets have been enhanced by user feedback. Please email
[email protected] with any suggestions or comments. Comments or suggestions for improvement are welcomed. Contact The Concrete Centre’s Helpdesk at
[email protected].
BS 8110 RCC82 Pilecap Design
Eurocode 2 TCC33X Flat Slabs (Whole floor) TCC41R Rigorous Continuous Beams TCC42 Post-tensioned Slabs and Beams (A&D) (b version) TCC43 Wide Beams (A&D) TCC54 Circular Column Charting 5
General notes Managing the spreadsheets Use Spreadsheets can be a very powerful tool. Their use has become increasingly common in the preparation of design calculations. They save time, money and effort. They provide the facility to optimise designs and they can help instill experience. However, these benefits have to be weighed against the risks associated with any endeavour. These risks must be recognised and managed. In other words appropriate levels of supervision and checking, including self-checking, must, as always, be exercised when using these spreadsheets.
Advantages For the experienced engineer, the spreadsheets help in the rapid production of clear and accurate design calculations for reinforced concrete elements. The contents are intended to be sufficient to allow the design of low to medium-rise multi-storey concrete framed buildings. Spreadsheets allow users to gain experience by studying their own ‘what if’ scenarios. Should they have queries, individual users should be able to answer their own questions by chasing through the cells to understand the logic used. Cells within each spreadsheet can be interrogated, formulae checked and values traced. Macleod[8] suggested that, in understanding structural behaviour, doing calculations is probably not a great advantage; being close to the results probably is. Other benefits include quicker and more accurate reinforcement estimates, and the possibilities for electronic data interchange (EDI). Standardised, or at least rationalised, designs make the checking process easier and quicker.
Appropriate use In its deliberations[9] the Standing Committee on Structural Safety (SCOSS) noted the increasingly wide-spread availability of computer programs and circumstances in which their misuse could lead to unsafe structures.
These circumstances include: People without adequate structural engineering knowledge or training may carry out the structural analysis. There may be communication gaps between the design initiator, the computer program developer and the user. A program may be used out of context. The checking process may not be sufficiently fundamental. The limitations of the program may not be sufficiently apparent to the user. For unusual structures, even experienced engineers may not have the ability to spot weaknesses in programs for analysis and detailing. The committee’s report continued: “Spreadsheets are, in principle, no different from other software…” With regard to these spreadsheets and this publication, The Concrete Centre hopes to have addressed more specific concerns by demonstrating “clear evidence of adequate verification” by documenting the principles, theory and algorithms used in the spreadsheets. The spreadsheets have also had the benefit of the Advisory Group’s overview and inputs. Many, especially the spreadsheets to BS 8110, have had several years use and maintenance. Inevitably, some unconscious assumptions, inconsistencies, etc. will remain.
Liability A fundamental condition of use is that the user accepts responsibility for the input and output of the computer and how it is used. As with all software, users must be satisfied with the answers these spreadsheets give and be confident in their use. These spreadsheets can never be fully validated but have been through Beta testing, both formally and informally. However, users must satisfy themselves that the uses to which the spreadsheets are put are appropriate.
Control Users and managers should be aware that spreadsheets can be changed and must address change control and versions for use. The flexibility and ease of use of spreadsheets, which account for their widespread popularity, also facilitate ad hoc and unstructured approaches to their subsequent development. Quality Assurance procedures may dictate that spreadsheets are treated as controlled documents and subject to comparison and checks with previous methods prior to adoption. Users’ Quality Assurance schemes should address the issue of changes. The possibilities of introducing a company’s own password
6
General Notes to the spreadsheets and/ or extending the revision history contained within the sheet entitled Notes! might be considered.
Application The spreadsheets have been developed with the goal of producing calculations to show compliance with codes. Whilst this is the primary goal, there is a school of thought[9] that designers are primarily paid for producing specifications and drawings that work on site and are approved by clients and/ or checking authorities. Producing calculations happens to be a secondary exercise, regarded by many experienced engineers as a hurdle on the way to getting the project approved and completed. From a business process point of view, the emphasis of the spreadsheets might, in future, change to establishing compliance once members, loads and details are known. Certainly this may be the preferred method of use by experienced engineers. The spreadsheets have been developed with the ability for users to input and use their own preferred material properties, bar sizes and spacings, etc. However, user preferences should recognise moves for efficiency through standardisation. Another long-term objective is automation. To this end, spreadsheet contents might in future be arranged so that input and output can be copied and pasted easily by macros and/ or linked by the end-user. There are counter arguments about users needing to be closer to the calculations and results in order to ensure they are properly considered – see Appropriate use on the previous page. We emphasise that it is up to the user how he/ she uses the output. The spreadsheets have been produced to cater for both first-time users and the very experienced without putting the first-time user off. Nonetheless, their potential applications are innumerable.
Summary With spreadsheets, long-term advantages and savings come from repeated use but there are risks that need to be managed. Spreadsheets demand an initial investment in time and effort, but the rewards are there for those who make the investment. Good design requires sound judgement based on competence derived from adequate training and experience, not just computer programs. For further general notes on use, familiarisation and layout of the spreadsheets the user is urged to consult the handbook to version 3, to which this booklet is an addendum.
7
Using the spreadsheets Frequently Asked Questions Macros When loading the individual spreadsheets, Excel may warn about the presence of macros. All the macros provided in the files are either to allow automated printing of the ‘calculations’ or to provide choices by way of combo-boxes. The printing macros have been assigned to buttons. Turning the macros off may affect the actual function of the spreadsheets but will certainly make printing of the sheets as configured more difficult and make the choice of options very much more difficult.
Fonts Unless the appropriate fonts Tekton and Marker (supplied in the CD-ROM) have been installed by the user, the appearance on screen will be different from that intended. These upright fonts have been used to emulate a designer’s handwriting and to allow adequate information to be shown across the page and in each cell. If problems are experienced it is most likely that the fonts on your computer screen will have defaulted to the closest approximation of the fonts intended (e.g. the toolbar may say Tekton but a default font such as Arial will have been used). The spreadsheets will work but not as intended – ends of words may be missing, numbers may not fit cells resulting in a series of hashes, #####. Column width and cell overlap problems only occur when the correct fonts are not loaded. It is strongly recommended that the Tekton and Marker fonts are copied into your computer’s font library. The Freeware fonts may be found in the Fonts folder on the CD-ROM. They may be copied in the following manner, either: Start/Settings/Control Panel/Fonts/ File/ Add Fonts and when asked ‘copy fonts to system directory?’ answer ‘yes’. or Through Microsoft Explorer and copying (or dragging) the font files into your font library, usually contained in Windows/ Set-up/ Fonts
Help A printed copy of this User Guide is available from The Concrete Bookshop www.concretebookshop.com. The User Guide is also available as an Adobe Acrobat file User Guide pdf (on the CD-ROM). A copy of Adobe Acrobat Reader will be required to read this file.
8
Help is also available at the following places: Within Excel under Help to the right hand side of the spreadsheets, cells under Operating Instructions contain help and error messages. Queries may be emailed to
[email protected]. Preference will be given to those who have registered.
Support Any questions, comments, developments and suggestions are welcomed. Please email them to
[email protected]. Preference will be given to those who are registered, as detailed above.
Availability/registration The spreadsheets may not be used for commercial purposes until the user has purchased and validated a licence. Licences may be purchased from The Concrete Bookshop www.concretebookshop.com or via The Concrete Centre website. Licences may be validated via www.concretecentre.com/rcspreadsheets. The purchase price includes: Permission to use the spreadsheets for commercial purposes for at least one year A hard copy of this publication and User Guide to RC Spreadsheets: v3 CD-ROM containing RC Spreadsheets: v4, together with Admin files, which themselves contain fonts, issue sheets, user guide files etc. Occasional e-mails to inform registrants of any revisions or changes to the spreadsheets or other relevant information Details of how to download updates of the spreadsheets Preferential treatment with regard to support Further information, updates, FAQs, free trial download versions of some spreadsheets, latest news and other information on the RC-Spreadsheet suite is available on www.concretecentre.com/rcspreadsheets
Overseas use The spreadsheets have been developed and maintained for use within the UK. The Concrete Centre reserves the right to pass details of non-UK registrants to any future owner of the non-UK copyright or overseas distributor of the spreadsheets.
Updates Registrants will be provided with information on how to download updates.
Amendments to v3 spreadsheet descriptions
Amendments to v3 spreadsheet descriptions Users should be aware of the following changes to the descriptions given in version 3 of the User Guide.
All TCC spreadsheets
TCC13 Slab Punching.xls Version 4 has been updated to revised UK National Annex.
All of the TCC series of spreadsheets to Eurocode 2 have been revised in line with amendment AMD 1 of the UK National Annex to Eurocode 2 published in December 2009. They have also been rebranded to reflect The Concrete Centre becoming part of The Mineral Products Association.
In version 4, the options for determining the shear enhancement factor b have been changed. Instead of a choice between the using the default factors to Clause 6.4.3(6) of EC2 and a manual input of bVEd, one can now choose either the default factors or to calculate b by inputting additional data.
Changes to the National Annex included:
The methods used for determining b are described in Clauses 6.4.3(3) for internal columns, 6.4.3(4) for edge columns and 6.4.3(5) for corner columns. However at the time of writing [July 2010], there is a gap in the perimeter column clauses in that no method is given for calculating U1* when the slab edge does not align with the outside face of the column. This omission has been queried with BSI committee B525/2, but in the meantime, the following assumptions have been made:
Use of BS 8500 for recommendations for concrete quality for a particular exposure class and reinforcement cover. Values of k1 and k2 in Cl 4.4.1.3(4) (cover to foundations rationalised) Limiting value of cot y where shear coexists with applied tension Strength reduction factor for concrete cracked in shear (v1 in Cl 6.2.3(3)) Limit of vED < 2 vRdc at the first punching shear perimeter (Cl 6.4.5(4)) Spacing of links in columns using concrete stronger than C50/60 Clarification of crack width calculation (Table NA.4) Revisions to span : depth verification of deflection (Table NA.5, Notes 5 and 6) Details of changes to individual spreadsheets may be found in the Notes! sheet of each spreadsheet or within the latest version of Spreadsheet Issue sheet .xls within the ADMIN folder. Changes to span : depth and punching shear calculations caused the more major amendments to the spreadsheets. Amendments that warrant further discussion are outlined below.
Slab edge outside column - U1* unchanged but U1 increases. Slab edge inside column - U1* unchanged but MIN[1.5d, 0.5C1] replaced by MIN[1.5d, 0.5(C1 –inset)]. If the Eurocode 2 committee decide that a differing method is more appropriate in these situations, the spreadsheet will of course be updated. In the meantime, we are confident that the methods currently used are safe to use. Other recent changes to this spreadsheet include: vEd,max corrected to 0.5vfcd Correction to edge column face shear when hole on North face of column. New routine for hole reductions at column faces.
It should be noted that the encastré option available in many spreadsheets is intended to enable modelling of continuity of more than 6 spans.
In the determination of punching shear stresses, Version 4 deducts loads within the loaded area.
All RCC spreadsheets
TCC41 Continuous Beam (A & D).xls
All RCC spreadsheets have been subject to minor revisions and have been rebranded to reflect The Concrete Centre becoming part of The Mineral Products Association. These spreadsheets are suitable for design calculations to the now withdrawn BS 8110 (up to and including Amendment 4).
TCC41 now uses a tension flange width for span top steel if a span hogs between 0.4L and 0.6L; otherwise bw is selected. The mid span tension flange width has been set to the average bt of the supports at either end. This seems to give the best detailing arrangement both for cantilevers and normal spans. An extra line has been added for each span on the SPANS page, so the user knows what width to place the top steel within.
9
TCC55 Axial Column Shortening Following the release of TCC55 a number of enquiries were received which resulted in the following FAQ being released giving additional guidance for the axial column shortening spreadsheet. Q1: If I have a building less than 11 storeys how is the information input? Is the load just input as zero on the upper floors? A1: No – start at the top, and leave the bottom line blank. Q2: If I have a building of 10 storeys, taking 14 days construction per floor, giving 140 days to occupancy. How could I look at the effects say, mid way through construction? A2:The plot of vertical displacement on the RESULTS page is the amount of displacement occurring after the floor at the indicated level is cast. Ie. it may be that the slab should be constructed this amount “high”. You should not need any other value. It is the differential between adjacent columns/walls that can be critical, but remember that moments induced by differential shortening will redistribute column reactions, so this effect should not be neglected. Q3: Would I adjust the “days to occupancy” figure to reflect the moment in time I want the results for? A3: No – this will not work. This input only fixes when the permanent portion of the imposed loading is applied. Q4: Finally (and most importantly..), is the spreadsheet available for an increased number of floors? We are currently about to start construction on a 35 storey building where creep may be an issue with respect to the cladding package. Would it be possible to obtain a spreadsheet of this size? A4: TCC55X which has input for 24 storeys is included in the spreadsheet package. To go higher than this, storeys can be grouped together if care is taken with the input.(See TCC55X)
10
TCC15 Resistance of Retaining Members.xls
TCC15 Resistance of Retaining Members.xls TCC15.xls determines the flexural and shear resistances of slab or wall sections at both ULS and SLS for given values of axial stress and permissible maximum crack width. It also generates a plot of axial stress against moment for the section and a design table for varying levels of primary reinforcement.
MAIN! This single sheet contains of all of the main input for materials and section data. Environmental details and age at loading are also input as these are required to calculate the creep factors that determine SLS behaviour. For the given parameters, moment and shear resistances are given together with a value of the SLS neutral axis depth, as this may affect the permissible maximum crack with to BS EN 1992-3. The chart at the bottom of this page shows resistance curves for both the ultimate and service conditions.
TABLE! On this sheet a table of resistances for varying amounts of primary reinforcement can be generated by clicking the macro button. A warning message appears if the data displayed do not match those on the MAIN! page.
Calcs! This page contains the calculations required to generate the results. These are quite complex at SLS where there are a variety of limiting conditions.
Ref! Ref! Defines the values of various parameters used in the spreadsheet.
Notes! This sheet gives disclaimers and revision history.
TCC15 Resistance of Axially Loaded Walls / Slabs / MAIN!
11
TCC22 FE Assistant.xls This spreadsheet provides values of creep factors, concrete tensile strengths and free shrinkage strains for use with finite element slab design programs that take account of concrete cracking (non-linear analysis). The methods used are those recommended in Concrete Society Technical Report No TR58, “Deflections in concrete slabs and beams”. With programs that do not account for cracking, creep factors substantially HIGHER than those calculated by this spreadsheet should be employed, to allow for the increased displacements caused by cracking and shrinkage. Both creep factors and concrete tensile strength are related to the loading history of a member, and are also dependent upon relative humidity, ambient temperature, cement type and member geometry (equivalent thickness). The characteristic cylinder strength of the concrete (fck) is also required. The user should note that this should be the actual characteristic strength, which may well be higher than that specified from minimum strength specifications.
h, fct, e! This single sheet consists of all of the main input and output. Most inputs, which are in blue and underlined, should be self-explanatory. In addition to the loading history and the inputs mentioned above, there is a switch which allows for construction loading from a slab above to be taken into account. In many instances, this temporary construction loading will determine the critical values required for FE design. In the results section values are given for both the direct concrete tensile strength fctm, and the flexural tensile strength fctm,fl. The user should make a judgement between these two values, depending upon the degree of restraint that may be present. There are several explanatory notes and hints at the right hand side of this page.
Calculations! Calculations! provides the detailed derivations for the combined creep factor h, autogenous and free shrinkage strains eca and eed, and critical concrete tensile strength fctm(t).
Notes! This sheet gives disclaimers and revision history.
12
TCC22 FE Assistant /h, fct, e! TCC22 FE Assistant /h, fct, e!
TCC22 FE Assistant/Calculations!
13
TCC55X Axial Column Shortening.xls This spreadsheet works out axial column shortenings exactly as TCC55, except that it will cater for up to 24 storeys. As it is a larger file, it has been included as a separate spreadsheet. The pages in this spreadsheet are as TCC55, except that results are now located on a new RESULTS! page in order to gain space.
TCC55X Axial Column Shortening / MAIN!
14
Operation is identical to spreadsheet TCC55, except that at the top of the MAIN! page, it is now possible to enter three different phases for the application of the permanent portion of the imposed loading.
TCC55X Axial Column Shortening.xls TCC55X Axial Column Shortening / RESULTS!
15
TCC62 Retaining Wall.xls TCC62.xls designs simple retaining walls with stems up to 3.0 m high. While section design is to Eurocode 2, this spreadsheet has been developed using the geotechnical rules and methods contained in Eurocode 7[5]. In particular, reference has been made to TCC “How to” leaflets number 8 “Foundations” and number 9 “Retaining Walls”[6]. The approach is very different from that of the earlier BS8110 spreadsheet (RCC62). Instead of comparing characteristic pressures with a “permissible” maximum value, two ultimate combinations of actions are employed together with two sets of factored resistances. The spreadsheet is intended to cover only short walls and to help ‘general’ engineers who, from time to time, design retaining walls as part of a wider interest in structures rather than the specialists. The 3.0 m wall height is an arbitrary limit set for short wall which is intended to cover over 90% of the cases encountered in general structural designs. Although many of the design principles still apply to higher walls, criteria such as wall movements and the validity of the assumptions made (e.g. no wall friction or inadequate drainage behind the wall) require further consideration and investigation. The spreadsheet does not cover embedded (e.g. contiguous bored pile) retaining walls. The effects of compaction pressures are considered for the wall stem design, but because of their short-term and localised nature, they are not considered to be critical in terms of bearing or sliding. Stability analysis is done about the toe of the base. (Stability analysis taken about toe of nib is ignored; the nib is a section sticking down from general level of the base, and stability analysis about its toe can give strange answers). Global slope stability checks are not undertaken in the spreadsheet and should be addressed using other means. Input is required only on the first sheet.
DATA! This single sheet consists of all of the main inputs. Most inputs, which are in blue and underlined, should be self-explanatory. The key diagram at the top of the sheet defines most input parameters. The active diagram below serves as a visual check on geometric data. Operating instructions and error messages are shown in column L: hints on sizing are given at L26:L39. The lower ground level must be at least level with the top of the base. Covers required are nominal covers to bending reinforcement.
16
The designer should determine the characteristic soil parameters’ from the Site Investigation Report, local knowledge or for estimation purposes from appropriate text or guidance*. Related design properties are then automatically derived using the two sets of partial load and material factors according to the UK National Annex to BS EN 1997. Thus, Combination 1 and Combination 2 values of earth pressure coefficients and factored loads are calculated. Formulae for each property and action are shown at the right hand side of the sheet. In determining earth pressures, the simplified Rankine’s formula for smooth vertical walls has been employed (calculation model A in ‘How To’ leaflet 9). However when the heel projection, bh is too small to strictly meet Rankine criteria, reduced values of c (angles of active thrust to horizontal) are used. For the calculation of ultimate bearing pressures, rectangular stress blocks are used. The spreadsheet is based on a number of assumptions which should be assessed as being true or erring on the safe side in each case. These are: Wall friction is zero
Granular backfill is used. Even a small value of effective cohesion, c´, can significantly reduce active pressures. However, to acknowledge the fact that many retaining walls are built with granular backfill for drainage and to err on the side of caution, the spreadsheet assumes only cohesionless materials.
The spreadsheet does not include checks on rotational slide/ slope failure. The location of any nib influences potential slip planes. The spreadsheet check on deflection of the wall does not include that due to base rotation. The spreadsheet is not intended for walls over 3.0 m high. The spreadsheet includes for concrete self weight. Adequate drainage system is provided behind the wall. Checks for temperature/shrinkage effects are not included. The spreadsheet does not include checks on the effects of seepage of ground water beneath the wall. Many engineers have reservations about including the effect of passive pressure in front of the wall so a combo box is provided at cell L16, where the inclusion of passive pressure can be switched on or off. Where passive pressure is allowed, an allowance for unplanned excavation in front of the base is made in
TCC62 Retaining Wall.xls determining the height of the passive pressure, hp. In accordance with BS EN 1997-1-1[5] Cl 9.3.2.2, this allowance is the lesser of 500 mm or hb/10. In the usage chart, design checks show how efficiently the selected data are working. Design status is shown at cell I36.
GEODesign! GEODesign! considers sliding, overturning about the toe (toppling) and bearing pressures for Combination 1 and Combination 2. Again formulae for each action, moment and parameter are shown at the right hand side of the sheet. The relevant partial factors are not shown in these formulae but are used in the appropriate cells. In terms of sliding, the undrained resistance is ignored if cohesion for the foundation material specified at DATA!H36 is less than 10 kN/m2. In this case it is recommended that the allowance of passive pressure at DATA!L16 is switched off.
RCDesign! The wall stem, base, heel and shear key are in turn designed and checked for flexure, shear, and bar spacing. For the concrete section Combination 1 is critical. In addition a span/depth deflection check is made on the stem.
Weight! Weight gives the approximate weight of reinforcement required per metre length of wall. Simplified curtailment rules are used. The figures should be regarded as estimates as the spreadsheet cannot deal with designers’ and detailers’ preferences, rationalisation, steps, changes in levels or direction etc.
Ref! Ref! Defines the values of various parameters used in the spreadsheet. These include NPDs according to Eurocode 2 and the partial factors for Combination 1 and Combination 2 according to the UK National Annex to Eurocode 7. Details of compaction plant loads and basic formulae are given.
Notes! This sheet gives disclaimers and revision history.
* Guidance on typical soil densities, angles of shearing resistance and surcharge loadings is given Guide to the Design and Construction of Concrete Basements[7]
17
TCC62 Retaining Wall / DATA!
18
TCC62 Retaining Wall.xls TCC62 Retaining Wall / GEODesign!
19
TCC62 Retaining Wall / RCDesign!
20
TCC63 Core Wall Design.xls
TCC63 Core Wall Design.xls TCC63.xls determines the distribution of lateral moments between simple core walls and then finds the amount of reinforcement required. The program will accept a maximum of four cores. Input is required over two pages.
GEOMETRY! This single sheet contains of all of the inputs for basic building plan geometry and core dimensions. Most inputs, which are in blue and underlined, should be self-explanatory. The legend diagram at the top of the sheet defines the geometry input parameters, and the active diagram below serves as a visual check on the input of core dimension data. After determining the section data for each core, percentages of lateral moment to each core and in each orthogonal direction are displayed. These include the effects of in-plane torsion due to the eccentricities of the cores from the centre of the structure.
CORE! On this sheet the total characteristic lateral moments in each direction are input, then after selecting one of the cores, the local coordinates and characteristic values of up to eight vertical loads are entered. After selecting the type of building usage, six ULS combinations are calculated and stresses (both compressive and tensile) and required reinforcement are produced for up to eight locations within the core. Again, there is an active diagram as a visual check on the input of vertical loads.
Gra! This page contains only data used in generating the various charts.
Ref! Ref! Defines the values of various parameters used in the spreadsheet. These include NPDs according to Eurocode 2 and the c values from Table A 1.1 of BSEN 1990.
Notes! This sheet gives disclaimers and revision history.
21
TCC63 Core Wall Design / GEOMETRY!
22
TCC63 Core Wall Design.xls TCC63 Core Wall Design / CORE!
23
TCC94 Two-way slabs (Tables).xls This spreadsheet designs restrained two-way solid slabs in accordance with Eurocode 2. Moment and shear factors have been taken from Tables 3.14 and 3.15 of BS 8110: Part 1 (these yield-line factors are equally valid for use with EC2). Input is required on the first two sheets.
MAIN! This single sheet consists of the input and main output. In itself it should prove adequate for the design of restrained two-way slabs. Inputs are underlined and most should be self-explanatory. Self-weight, moment and shear factors are calculated automatically. The use of these factors is limited by the conditions for which they were produced, i.e. similar loads on adjacent spans and similar spans adjacent. Where these relevant conditions are not met, users should consider alternative methods of analysis. Whilst ultimate reactions to beams are given, shear per se is not checked as it is very rarely critical. The dimension ly must be greater than lx : bays where lx ¢ ly are invalid. It is recognised that B1 can be parallel to ly and the user should specify in which layers the top and bottom reinforcement are located (see cells D33 and H33). In line 32 the user is asked to specify the diameters of reinforcement to be used. This reinforcement should be provided at the required centres in accordance with BS 8110 Clause 3.5.3.5 (1) to (7) (middle strips and column strips, torsion reinforcement at corners where an edge or edges is/are discontinuous). The spreadsheet highlights whether additional reinforcement for torsion is required or not. As noted under Deflection, the area of steel required, Asreq, may be automatically increased in order to reduce service stress, ss, and increase modification factors to satisfy deflection criteria. An approximate reinforcement density is given. This is approximate only and excludes supporting beams, trimming to holes, etc.
24
WEIGHT! Weight! gives an estimate of the amount of reinforcement required in a slab. Simplified curtailment rules are used to determine lengths of bars. The figures should be treated as approximate estimates only as they cannot deal with the effects of designers’ and detailers’ preferences, rationalisation, the effects of holes, etc. To the right of the sheet are calculations of bar length, etc. Support widths are required as input as they affect curtailments and lengths.
Refs! This sheet comprises the values for nationally determined parameters that have been used in the spreadsheet. These data reflect the values given in the UK National Annexes for EN 1990 and EN 1992.
Notes! This sheet gives disclaimers and revision history.
TCC94 Two-way Slabs (Tables).xls TCC94 Two-way slabs (Tables).xls / MAIN!
25
TCC94 Two-way slabs (Tables).xls / Weight!
26
TCC94 Two-way Slabs (Tables).xls
References 1 GOODCHILD C H & WEBSTER R M User Guide to RC Spreadsheets: v3, CCIP-008. The Concrete Centre, 2006. 2
BRITISH STANDARDS INSTITUTION. BS EN 1992 1-1, Eurocode 2 – Part 1-1: Design of concrete structures – General rules and rules for buildings. BSI, 2004. Including National Annex to BS EN 1992-1-1, Eurocode 2 – Part 1-1: Design of concrete structures – General rules and rules for buildings 2005 incorporating National Amendment No 1, BSI, 2009.
3
BRITISH STANDARDS INSTITUTION. BS 8110: 1997 Structural use of concrete. Part 1. Code of practice for design and construction. British Standards Institution, London, 1997 up to and including Amendment 4.
4
GOODCHILD C H & WEBSTER R M User Guide to RC Spreadsheets: v2, The Concrete Centre, Published electronically based on GOODCHILD C H & WEBSTER R M User Guide to RC Spreadsheets. British Cement Association on behalf of the Reinforced Concrete Council
5
BRITISH STANDARDS INSTITUTION. BS EN 1997-1, Eurocode 7 – Geotechnical design Part 1: General rules. BSI, 2004 Including National Annex to BS EN 1997-1, Eurocode 7 – Geotechnical design
6 BROOKER, O. et al. How to design concrete structures using Eurocode 2 (compendium), CCIP 006. The Concrete Centre, 2006. 7 NARAYANAN, R S & GOODCHILD, C H, Guide to the Design and Construction of Concrete Basements, TCC CCIP-044, Due 2010 8 MACLEOD, I.A. ET AL. Information technology for the structural engineer. The Structural Engineer, Vol. 77, No. 3, 2 February 1999. pp. 23 - 25. 9
STANDING COMMITTEE ON STRUCTURAL SAFETY, Standing Committee on Structural Safety, 10th Report, July 1992-June 1994, SETO Ltd, London, 1994 pp. 32
27
28
The Advisory Group Members S Alexander S Alhayderi Dr H Al-Quarra I Baldwin C Barker M Beamish A Beasley T Bedford G Belton R Bhatt R Bickerton P Blackmore D Blackwood M Brady C Buczkowski A Campbell Dr P Chana G Charlesworth L Cheng Mr Chichger R Collison A Craddock M Morton J Curry J Dale
H Dikme C P Edmondson J Elliot I Feltham G Fernando M Fernando I Francis A Fung P Gardner J Gay P Green A Hall N Harris G Hill D W Hobbs R Hulse M Hutcheson A Idrus N Imms P Jennings D Kennedy G Kennedy R Jothiraj Dr S Khan A King
G King S King K Kus I Lockhart M Lord B Lorimer M Lovell Dr Luker J Lupton M Lytrides Prof I Macleod F Malekpour A McAtear A McFarlane F Mohammad A Mole M Morton R Moss B Munton C O’Boyle Dr A Okorie T O’Neill B Osafa-Kwaako D Patel D Penman
M Perera B Quick Y Raqif A Rathbone M Rawlinson P Reynolds H Riley N Russell U P Sarki T Schollar A Stalker A Starr M Stevenson B Stoker B Treadwell A Truby R Turner T Viney Dr P Walker B Watson J Whitworth C Wilby S Wilde A Wong E Yarimer
User Guide to RC Spreadsheets: v4 (Addendum to v3)
This update to the user guide provides guidance on the use of RC Spreadsheets v4 for the design of reinforced concrete elements. The release of version 4 of the spreadsheets and user guide follows revision of The Concrete Centre series in line with amendment AMD 1 of the UK National Annex to Eurocode 2 . The RCC series of spreadsheets remain suitable for design calculations to the BS 8110 (up to and including Amendment 4), which was ‘withdrawn’ in early 2010.
Charles Goodchild is Principal Structural Engineer for The Concrete Centre where he promotes efficient concrete design and construction. He was responsible for the concept, content and management of this publication and of the RC Spreadsheets. Rod Webster of Concrete Innovation & Design is principal author of the spreadsheets. He has been writing spreadsheets since 1984 and is expert in the design of tall concrete buildings and in advanced analytical methods.
For more information on the spreadsheets visit www.concretecentre.com/rcspreadsheets
CCIP 053 Published August 2010 © MPA - The Concrete Centre Riverside House, 4 Meadows Business Park, Station Approach, Blackwater, Camberley, Surrey, GU17 9AB Tel: +44 (0)1276 606800 Fax: +44 (0)1276 606801
www.concretecentre.com
