Guards in Buildings - The Canadian Challenge. Greg Hildebrand, C.E.T., M.Sc.(Eng) Petr Vegh, Ph.D., P.Eng exp Services Inc.

Transcription

1 Guards in Buildings - The Canadian Challenge Greg Hildebrand, C.E.T., M.Sc.(Eng) Petr Vegh, Ph.D., P.Eng exp Services Inc.

2 The Problem An increased number of balcony guard rail failures over the past number of years. Failures are on-going. The majority involving glass infill panels failing catastrophically (and highly visibly) in a number of prominent buildings. Some failures related to system design and installation. 2

3 Failures resulted in heavy scrutiny of balcony guards from the media, regulatory authorities as well as the architectural and engineering communities. 3

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5 Heavier more robust guardrail systems used to be employed in high-rise residential buildings. Included materials such as: steel, cast in place or precast concrete, masonry, or combinations of these materials. 5

6 Metal Pickets 6

7 Metal Panel Guard 7

8 Precast Concrete Guard 8

9 The Problem Recent guards designs incorporate larger format glass infills which require a greater volume of glass than older infills. Many newer guards are cantilevered from the edge of the slab with minimally retained infills - By-Pass Guard configuration. Component Materials Procurement paths have changed. North American economy has impacted the quality of tempered glass employed. 9

10 By-Pass Glass Infill Guard. 10

11 By-Pass Glass Infill Guard. 11

12 By-Pass Glass Infill Guard. 12

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14 The Design Issues: There is no substantive guidance regarding the design and use of balcony guard rail systems other than the information given in the building code. (i.e., there is no applicable reference standard). Designers follow different protocols in the design of their guard rail systems. Some consider the guard loads independently, some consider guard and wind loads separately while some consider the combination of both. 14

15 The Design Issues: For wind, two methods are employed to establish load. The first method involves the calculation of the wind load according to the procedure given in Part 4 of the Code. (Procedure not specifically for guards). The second method, involves obtaining estimates using a wind tunnel study. The first method often result in overly conservative loads while the wind tunnel study results are varied (but still considered to be conservative). 15

16 The Design Issues: Data relating to actual wind loads acting on guard rail assemblies is not currently available. There are a number of lucid arguments from other jurisdictions that support the practice of employing guard and wind loads independently. There was no specific guidance given in existing Codes and Standards regarding the use of tempered and laminated safety glass for use in balcony guard rail systems. 16

17 The Design Issues: There was no mandated guidance regarding post-breakage retention for glass infill or balustrades. There are no mandated test procedures to evaluate a balcony guard system for guard load, wind load and impact testing. There is limited to no guidance regarding the materials and design of balcony guard rail assemblies. 17

18 The Temporary Fix for Glass Balustrades: Ontario Ministry of Municipal Affairs and Housing established an: Expert Advisory Panel to conduct a review and provide advice to the Ministry on Building Code standards for glass panels in balcony guards. The Panel s mandate was to make recommendations on whether and how the Building Code may be amended to address the problem of the breakage of balcony glass and its risk to persons nearby. 18

19 The Temporary Fix for Glass Balustrades: The expert committee developed seven recommendations. Which led to: 2006 Ontario Building Code requirement in the form of Supplemental Standard SB-13, Glass in Guards, which came into effect on July 1, 2012 (for reference in Sentence (1) of Division B of the Building Code). 19

20 The Temporary Fix for Glass Balustrades: 20

21 The Temporary Fix for Glass Balustrades: The last recommendation (No. 7) was that the Ontario Ministry of Municipal Affairs and Housing would: a)support the development of the proposed CSA Group Standard on Balcony Guard Rails; and b)will consider referencing the CSA Group Standard on Balcony Guard Rails, once it is published, in the Building Code. 21

22 CSA A500 22

23 CSA A500 Building Guards 0 Introduction 0.1 General 0.2 Expectations 0.3 Intent 1 Scope 1.1 General 1.2 Exceptions 1.3 Conflicting requirements 1.4 Terminology 2 Reference publications 3 Definitions 4 General Requirements 4.1 Responsibilities 4.2 Material and component requirements 23

24 CSA A500 Building Guards 5 Testing 5.1 General 5.2 Materials Testing 5.3 Structural Tests 5.4 Impact resistance testing 5.5 Post Breakage Retention Testing 5.6 Vibrational testing 5.7 In-situ (field) testing 6 Concrete used in guards 6.1 Materials 6.2 Design 6.3 Construction 7 Masonry used in guards 14 th Canadian 7.1 Materials Conference on Building Science and Technology 24

25 CSA A500 Building Guards 8 Glass used in guard panels 8.1 General 8.2 Materials 8.3 Design 8.4 Fabrication 8.5 Heating Soaking of Tempered Glass 8.6 Construction 9 Aluminium used in guards 9.1 General 9.2 Materials 9.3 Design 9.4 Fabrication 9.5 Assembly and fixing 14 th Canadian 10 Steel Conference on Building Science and Technology 25

26 CSA A500 Building Guards 11 Wood 11.1 General 11.2 Materials 11.3 Design 11.4 Fabrication 11.5 Preparation of wood 11.6 Durability 11.7 Preservative treatment 11.8 Protective finishes 11.9 Storage and handling Installation Protection of Fasteners Protection after installation 26

27 CSA A500 Building Guards Annex A (informative) Commentary A.X.X.X Title A.2 Title Annex B (informative) Bolt fixing of glass in barriers B.1 Bolt fixing of infill panels B.2 Base fixing of free-standing barriers Annex C (informative) Risk assessment for glass breakage Annex D (informative) Handling D.1 General D.2 Storage Annex E (informative) Test methods for guard re-evaluation Annex F (informative) Rigging Loads for Window Cleaning and Maintenance F.1 General F.2 Rigging loads 27

28 CSA A500 Building Guards Annex G (informative) Maintenance Plan for Aluminum and Glass Balcony Railing Systems 3. DOCUMENTATION AND RECORDS 4. MAINTENANCE GUIDELINES 5. ANNUAL INSPECTION AND REPAIR PLAN 6. GLASS BREAKAGE PROTOCOL 7. CLOSING ANNEX H (informative) Composites and other materials H.1 Plastics H.2 Infill panels H.3 Impact testing H.4 General inspection H.5 Assembly and installation Annex I: Combination Loads 28

29 CSA A500 Building Guards Includes: exterior and interior building guards. Excludes: (a) temporary guards regulated elsewhere by applicable health and safety requirements. ; (b) barriers for resisting impact from vehicles; (c) barriers used in Group A (Assembly Occupancy) and F (Industrial Occupancy) buildings as set out by the National Building Code of Canada.; or (d) walls acting as guards. 29

30 CSA A500 Building Guards Major Challenges Developing prescriptive requirements for guard types, materials, components and assemblies. Defining Loads and Application Parameters. Defining functional requirements (e.g., climbability, deflection criteria, etc.). Establishing test protocols (i.e., live / guard load load and impact testing. Defining failure criteria. 30

31 CSA A500 Building Guards Majorest Challenge Raising sufficient funds to publish the standard. Standard is now fully-funded and is reaching its final stages before final committee and public review. Still raising final funds for needed wind load research. 31

32 CSA A500 Building Guards The new Standard will try and improve on the overall design, installation, durability and performance of guards in buildings. Notwithstanding some of the previously illustrated issues associated with building guards, the standard will hopefully address some of the problems with the latest guard designs. 32

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