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BCAR and the Technical Guidance Documents Conference 2019

BCAR and the Technical Guidance Documents Conference 2019. Part A Structure Jim Mansfield Consulting Engineer Kavanagh Mansfield & Partners. TECHNICAL GUIDANCE DOCUMENT A. STRUCTURE INTRODUCTION AND GENERAL INFORMATION. Part A Structure. 3 Editions 1991 - 34 pages 1997 - 31 pages

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BCAR and the Technical Guidance Documents Conference 2019

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  1. BCAR and the Technical Guidance DocumentsConference 2019 Part A Structure Jim Mansfield Consulting Engineer Kavanagh Mansfield & Partners Jim Mansfield

  2. TECHNICAL GUIDANCE DOCUMENT A Jim Mansfield STRUCTURE INTRODUCTION AND GENERAL INFORMATION

  3. Part A Structure 3 Editions • 1991 - 34 pages • 1997 - 31 pages • 2012 - 45 pages All relate to; Part A of the second schedule of the Building Regulations relevant at the time of publication Jim Mansfield

  4. Part A The Requirements Section 1 Loading (A1) Ground Movement (A2) Definitions (A4) Section 2 Disproportionate Collapse (A3) Subsection 1 Sizes for certain structural elements for houses and other small buildings Subsection 2 Design and construction of all building types Subsection 3 Recovering of existing roof structures and structural safety of external wall cladding Jim Mansfield

  5. Text of Part A Second Schedule 2012 Loading A1 (1) A Building shall be designed and constructed, with due regard to the theory and practice of structural engineering, so as to endure that the combined actionsthat are liable to act on it are transmitted to the ground – (a) safely, and (b) Without causing such deflection or deformation of the any part of the building, or such movement of the ground, as will impair the stability of any part of another building. (2) In assessing whether a building complies with sub-paragraph (1) regard shall be had to the variable actions to which it is likely to be subjected in the ordinary course of its use for the purpose for which it is intended. Jim Mansfield

  6. Text of Part A Second Schedule 2012 Ground Movement 2012 A2 A Building shall be designed and constructed, with due regard to the theory and practice of structural engineering, so as to ensure that movements of the subsoil caused by subsidence, swelling, shrinkage or freezing will not impair the stability of any part of the building. Jim Mansfield

  7. Text of Part A Second Schedule 2012 Disproportionate Collapse 2012 A3 (1) A multi-storey building shall be (so)designed and constructed, with due regard to the theory and practice of structural engineering so as to ensurethat in the event of an accident the structure will not be damaged to an extent disproportionate to the cause of the damage. (2) For the purpose of sub-paragraph (1), where a building is rendered structurally discontinuous by a vertical joint, the building on each side of the joint may be treated as a separate building whether or not such joint passes through the substructure. Jim Mansfield

  8. Text of Part A Second Schedule 2012 Definitions Section A4 in all versions. The definitions vary 2012 Actions, Variable actions Actions means a set of forces (loads) applied to the structure (direct actions) or a set of imposed deformations or accelerations (indirect actions) Variableactions means actions for which the variation in magnitude is neither negligible nor monotonic such as imposed loads on building floors, wind actions or snow actions. Jim Mansfield

  9. Technical Specifications Building Regulations are for specific purposes e.g. to provide, in relation to buildings, for the health, safety and welfare of persons, the conservation of energy and access for people with disabilities. Technical specifications (including harmonised European Standards, European Technical approvals, National Standards and Agrement certificates) are relevant to the extent that they relate to those considerations. Refer to latest edition current at date of publication but, if revised newer version may be used as a source of guidance. Jim Mansfield

  10. Technical Guidance Document AStructure • Materials, methods of construction, standards and other specifications are those likely to be suitable for the purposes of the Regulations. • Works carried out in accordance with TGD A will, prima facie, indicate compliance with Part A. • Other approaches not precluded but may need justification. Building work must be carried out with proper materials and in a workmanlike manner. • Refer to Part D Materials and Workmanship. Other secondary structural references Part B Fire Safety Part C Site preparation and resistance to moisture Part K Stairways Ladders Ramps and Guards Jim Mansfield

  11. Construction Products Regulations 305/2011 These are European Regulations which supersede previous Construction Products Directive Basis of European Standards, Specifications, Eurocodes and Execution Standards Annex 1 7 Basic requirements for Construction works:- • Mechanical resistance and stability ~ Part A • Safety in case of fire ~ Part B • Hygiene, health and the environment ~Part C amongst others • Safety and accessibility in use • Protection against noise • Energy, economy and heat retention • Sustainable use of natural resources Close relationship to Building Regulation parts Jim Mansfield

  12. Construction Products Regulations 305/2011 European Regulations which supersede previous Construction Products Directive Basic requirements for Construction works:- Construction works as a whole and in their separate parts must be fit for their intended use, taking into account in particular the health and safety of persons involved throughout the life cycle of the works. Subject to normal maintenance, construction works must satisfy these basic requirements for construction works for an economically reasonable working life Jim Mansfield

  13. Construction Products Regulations 305/2011 Mechanical resistance and stability The construction works must be designed and built in such a way that the loadings that are liable to act on them during their constructions and use will not lead to any of the following:- • Collapse of the whole or part of the work • Major deformations to an inadmissible degree • Damage to other parts of the construction works or to fittings or installed equipment as a result of major deformations of the load bearing construction • Damage by an event to an extent disproportionate to the original cause Jim Mansfield

  14. Construction Products Regulations 305/2011 This document also sets out the requirements for Harmonized standards, for CE Marking, for Declaration of Performance etc. Material documentation Important part of BCAR process For Certification CE marking does not confirm suitability for use Jim Mansfield

  15. National Standards of Safety National standards of safety take precedence with National Authorities responsible for Safety levels in the member states. Irish Building Regulations take precedence with Irish National Annexes giving National Choice and allowing determination of Safety Levels. Irish National Annexes take account of Irish Climatic conditions and Iris Practice. Jim Mansfield

  16. Section 1 Structure Loading (A1) and Ground Movement (A2) 1.0.4 Definitions • 1.0.1 - Introduction • Safety depends on successful combination of design and execution • Refers to Eurocode • Refers to National Annexes • Refers to Actions • Design Assumption 1.0.2 Subsection 1 Small Buildings Walls Traditional Masonry Timber 1st Floors and Roofs No more than 2 storey houses, also garage and extension Not timber frame – 1.S.440 5 Parts 1.0.3 Other approaches Must have regard to 1.0.1 Jim Mansfield

  17. TGD A Structure 2012 CONTENTS Section 1 A1 Loading and A2 Ground movement Section 1 1.01 Introductionsee later slides 1.02 Subsectionsdescription of sub-sections 1.03 Other approaches Other design approached not precluded but essential to have regard to 1.0.1 1.04 Definitionsactions, types of walls, execution etc. Numbering system somewhat unclear Jim Mansfield

  18. TGD A Structure 2012 CONTENTS Section 1 A1 Loading and A2 Ground movement Sub-section 1 1.1.1 Basic requirements for stability 1.1.2 Timber sizes 1.1.3 Thickness of masonry walls 1.1.4 Chimney dimensions 1.1.5 Strip foundations of plain concrete Jim Mansfield

  19. TGD A Structure 2012 CONTENTS Section 1 A1 Loading and A2 Ground movement Sub-section 2 Design and construction of all building types - codes, standards and reference Primarily actions and materials but also Reference to Appraisal of existing structures Sub-section 3 Recovering of existing roof structures and structural safety of external wall cladding Jim Mansfield

  20. TGD A Structure 2012 CONTENTS Section 2 A3 Disproportionate collapse Unforeseen and Accidental actions Robustness of structures Consequences classes Measures to reduce effects of an accident Building type and use Horizontal and vertical ties, See Basis of Design, Actions and Material codes Jim Mansfield

  21. TGD A Structure 2012 Section 1 1.0.1 Introduction Safety depends on successful combination of design and execution Base design on identification of hazards and assessment of risks Consider conditions that can be foreseen Actions, materials, analysis, construction detailing, safety factors, workmanship and execution Jim Mansfield

  22. TGD A Structure 2012 Section 1 1.0.1 Introduction Introduces Eurocodes. These have been in place since 2012 (Many previously used Irish and British Standards now obsolete and withdrawn) 10 Eurocodes to date, 58 parts to date Some material independent:- Basis of design, Actions, geotechnical and seismic Some material dependant:- Concrete, Steel, Composite, Timber, Masonry and Aluminium Currently being updated. New versions available from 2020 References 2012 1997 Irish standards 3 15 European 26 0 British 11 22 Eurocodes 34 0 Others 8 5 Jim Mansfield

  23. TGD A Structure 2012 Section 1Eurocodes European documents applicable in around 30 European countries, mostly EU but also others Form basis of design standards in many other countries Each part has a National Annex for applicability in each country So each code such as I.S. EN 1990 has an Irish National Annex which must be used for structures in Ireland, irrespective of where the design originates. Similarly if designing in UK or elsewhere, one must use their National Annex (NA) National Annexes specify Nationally Determined Parameters (NDPs) May vary due to climate e.g. wind and snow, practice e.g. concrete specification etc. Can depend on historical practices, achieving same levels of safety as before Jim Mansfield

  24. TGD A Structure 2012 Section 1 Eurocodes Assumptions given in 1.0.1 • Design by appropriately qualified and experienced personnel • Execution by personnel with appropriate skill and experience • Adequate supervision and quality control during design and execution • Construction materials as per Eurocodes, execution standards and material or product specifications • Structure to be adequately maintained • Structure used as design assumptions • First Four covered by Regulations, • Final two -- Regulations not dependant but acknowledge their importance Jim Mansfield

  25. Contents Subsection 1 Size for certain structural elements for houses and other small buildings • 1.1.3 - Part 3 • The uses of masonry walls in house with not more than 2 floors, including the ground floor • Application • Use of this part • Wall types • Wall construction • External wall • Internal load bearing wall • Materials • Blocks • Bricks • Other units • Lintels • Mortar • Wall ties • Maximum loads • Maximum height • Retained earth • Building geometry • Lateral support and restraint • Buttressing • Openings and chases • Interaction of elements 1.1.1 - Part 1 Basic Requirements for Stability • 1.1.2 - Part 2 • Sizes of certain timber • floor, ceiling and roof members in houses • Application • Use of this part • 1.1.4 – Part 4 • Proportions for masonry chimneys above the roof surface • Height to width relationship • 1.1.5 – Part 5 • Strip foundations of plain concrete • Subsoil • Design • Minimum width Jim Mansfield

  26. Section 1.0.2 Subsection 1 Part 2 - Floors Applies only to houses with no more than two floors including the ground floor Timber floor etc Design Timber Members as I.S.EN1995.1.1 Height of building Guidance based onI.S. EN1991.1.4. Some exclusions for exposed terrain or funnelling Part 3 – Walls As Part 2, but Walls – traditional masonry Floors – timbers Roof – normal covering Timber frame I.S.440 Masonry as I.S.EN1996.2 4S S.R.325 Part 4 Chimneys Some limitations Houses no higher than 10m to top of roof Width greater than ½ height Span less than 5m floor Roofspan less than 12m Floor to ceiling less than 2.7m Many restrictions Very limited range of house types Part 5 Foundation Limitations on ground conditions Jim Mansfield

  27. TGD A Structure 2012 Sub section 1 Applicable to small buildings of traditional masonry with timber first floor and roofs, no more than two storeys and also for garages and annexes to houses. Sizes for certain structural elements for houses and other small buildings Not for Timber framed construction for which use I.S. 440 There are five parts Who would use this and when? Developers, Contractors, Architects, Engineers and Self Builders • This is a subset of • Consequence Class 1 in the Eurocodes which comprises:- • Single occupancy houses not exceeding 4 storeys • Agricultural buildings • Buildings into which people rarely go (with restrictions) Jim Mansfield

  28. TGD A Structure 2012 Sub section 1 Part 1 Brace roofs e.g. trussed rafters or some cut roofs If roof structure is braced and walls are designed and restrained to part 3 of this sub-section, no special provision need normally be made for wind pressure or suction Jim Mansfield

  29. TGD A Structure 2012 Sub section 1 Part 2 Sizes of timber floor, ceiling and roof elements Two-storey houses only Requirements as to loads and materials Rules for notches and holes Joist sizes not specified !!! Suggests use Eurocode for design SR 11:1988 was allowed in 1997 version but not referred to here Current use is SR 71 published in 2015, Jim Mansfield

  30. TGD A Structure 2012 Sub section 1 Part 3 Thickness of masonry walls in houses with not more than two floors Applicable for houses of traditional masonry construction with timber upper floors and normal lightweight roofs, Pantiles Timber framed construction to I.S. 440 Masonry walls to I.S. EN 1996 and SR 325. Cavity external walls using two 100mm leaves, blocks or bricks, or 215 hollow block walls Separating (party) walls 215 solid concrete blocks or two leaves of 100mm blocks, check TGD E for sound insulation requirements Concrete blocks to I.S. EN 771, mean strength 7.5N/mm2 for solid and lightweight blocks, 4.5N/mm2 for hollow Similar requirements for bricks and other units Jim Mansfield

  31. TGD A Structure 2012 Sub section 1 Part 3 Masonry Walls External and Internal walls in Solid, hollow or lightweight blocks Materials, including lintels, mortar and wall ties, should comply with standards Vertical design actions specified in Table 1 Height of buildings depend on wind loads, next slide Limitations on building geometry Lateral supports and bracing Openings and chases Wall tying and strapping Jim Mansfield

  32. TGD A Structure 2012 Sub section 1 Part 3 Maximum loads specified For roofs, floors and ceilings Maximum height of buildings Based on I.S. EN 1991-1-4 General actions wind actions Use procedure as in Diagram 1 of TGD A This allows for different wind speeds for buildings in town or country terrain, Determine wind speed for site based on location see map Correct for orography, i.e. hills, ridges, cliffs or escarpments Correct for altitude, for all sites above sea level Determine Site wind speed S based on above Jim Mansfield

  33. TGD A Structure 2012 Sub section 1 Part 3 Masonry Walls Wind loads Design wind speed varies across country 24.7m/s in Wexford to 27.0m/s in Achill Is house located on a hill or ridge, cliff or escarpment? Orography If so - wind speed to be factored depending on slope and distance from ridge Also correct for altitude above sea level Get Wind speed for site Is site in town or country and how far to sea Determine allowable height to ridge This can be quite onerous Jim Mansfield

  34. TGD A Structure 2012 Example site Cavan Country site, Altitude 90m above sea level Zone 2 moderately steep terrain V 25.5m/s O 1.13 A 1.09 S 31.4m/s Distance to sea greater than 20m Max height to ridge c 5.0m If in town 10m Jim Mansfield

  35. TGD A Structure 2012 Sub section 1 Part 3 Masonry Walls Lateral support and end restraint Buttressing Sizes of openings and chases Bearing lengths for lintels Maximum opening in walls no more than 3m Strapping of floors and ceilings Wall ties and their spacing especially at openings Joist hangers generally restraint type Reference to I.S. EN 1996 and SR 325 Jim Mansfield

  36. TGD A Structure 2012 Sub section 1 Part 4 Masonry Chimneys Height H defined from highest point of intersection to top of flue pot W lesser horizontal dimension of chimney at same point H/W no more than 4 - if site wind speed less than 26m/s H/W less than 3.5 - if site wind speed greater than 26m/s e.g. 450mm wide chimney, height is 1.8m in first case, 1.575m in second Ridge - no greater than height allowed in Part 3 Jim Mansfield

  37. TGD A Structure 2012 Sub section 1 Part 5 Strip Foundations of plain concrete No made ground or weaker soils Central foundations, Concrete C12/15 Assess ground conditions and loading Not suitable for weak soils Minimum widths specified – these can be quite narrow Thickness of foundation depends on width but 200mm minimum Details for steps and piers Jim Mansfield

  38. TGD A Structure 2012 Jim Mansfield

  39. Sub Section 2 All Building Types Codes Eurocodes for Design / Execution Standards Guidance on Appraisal of Existing Building Jim Mansfield

  40. TGD A Structure 2012 Sub section 2 Design and Construction of all building types – Codes , standards and references. List of standards and codes Execution standards for concrete, steel and foundations References to documents for appraisal of existing buildings Diagram 14 is snow map for Ireland with basic value to be modified for altitude Jim Mansfield

  41. TGD A Structure 2012 Sub section 3 Recovering of existing roof structures Assess weight of new materials Check structure for its adequacy Strengthen as appropriate Jim Mansfield

  42. TGD A Structure 2012 Sub section 3 Structural safety of external wall cladding Includes glazed curtain walling but not windows No guidance in respect of weather resistance Wall cladding to be safely fixed to resist applied actions Needs both vertical support and horizontal restraint Check loading Design Fixing types List of relevant design codes and standards Jim Mansfield

  43. Section 2 Disproportionate Collapse A3 References I.S.EN1991.1.7 and material codes including National Annex Determine Consequence Class Determine Measures Design and Construct • Consequence Class • Risk Group • Occupancy use • No. of storeys • Floor size Tying and Anchorage Measures Jim Mansfield

  44. TGD A Structure 2012 Section 2 Disproportionate Collapse Damage or failure of small part can lead to collapse of significant part of structure Provide robustness features Design to I.S. EN 1991-1-7 and other material specific codes Jim Mansfield

  45. TGD A Structure 2012 Section 2 Disproportionate Collapse Consequences Classes see table 6 Different requirements for horizontal and vertical ties or key element design Assess how procedure to be adopted Jim Mansfield

  46. Standards and Publications • Material Standards • Irish • European • British • Eurocodes • EN1990 – Basic Structural • EN 1991 – Actions • EN 1992 – 1999 Materials including Geotechnical and Seismic Other Publications Jim Mansfield

  47. Standards and publications Standards and publications List of standards and publications referenced Irish and British standards 59 standards Eurocodes 34 parts referenced - 58 in total Other Referred Publications 7 documents Other documents 3 documents Total 127 documents Jim Mansfield

  48. Execution Standards Execution Standards I.S. EN 13670 Execution of Concrete Structures I.S. EN 1090 Execution of steel and aluminium structures These specify execution classes, related but not similar to consequences classes Series of execution standards for Special Geotechnical works Jim Mansfield

  49. Certification Certification BCAR Assigned Certifier, Designer, Ancillary Certification For Engineers - forms ED, EI, EC Standard Industry forms Previously form BRSE 9101 When appointed under SE 9101 Jim Mansfield

  50. Certification Code of practice for inspecting and certifying buildings and works Roles for building owners, builders designers and Assigned certifiers Structure - Structural Engineers Design respective elements of work Mostly covered Part A 2nd Schedule and TGD A Jim Mansfield

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