Rethinking CTBUH Height Criteria in the Context of Tall Timber

Transcription

1 Rethinking CTBUH Height Criteria in the Context of Tall Timber Rob Foster, Senior Lecturer, University of Queensland 0

2 Perkins + Will 1

3 PLP Architecture 2

4 PLP Architecture Forte 2013 Emma Cross 3

5 PLP Architecture Treet

6 PLP Architecture TallWood House at Brock Commons

7 Mjøstårnet

8 What is the world s tallest timber building 7

9 Outline Discuss the role of the CTBUH Criteria in classifying tall buildings Highlight the challenges to the existing classifications raised by the emergence of engineered timber as a contemporary structural material Explain a recent proposal for updating the existing classifications and terminology, to accommodate timber and other new materials Pre-Conference Workshop on Tall Timber 8

10 CTBUH Criteria Criteria available at 9

11 CTBUH Criteria Tallness Height Material Function Status 10

12 Tallness Height relative to context Proportion Tall building technologies 11

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15 Tallness Foster, R.M., Reynolds, T.P.S. and Ramage, M.H. (2017). Rethinking CTBUH Height Criteria in the Context of Tall Timber, CTBUH Journal, (4),

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17 Tallness Tall for a. building 16

18 Tallness Taller than local building regulations allow 17

19 Tallness Taller than the firefighters ladder 18

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21 Structural material 20

22 Structural material Steel Both the main vertical/lateral structural elements and the floor systems are constructed from steel. Note that a building of steel construction with a floor system of concrete planks or concrete slab on top of steel beams is still considered a steel structure. 21

23 Structural material Concrete Both the main vertical/lateral structural elements and the floor systems are constructed from concrete. 22

24 Structural material - Mixed-Structure Utilizes distinct steel and concrete systems, one on top of the other. Steel/concrete indicates a steel structural system located on top of a concrete structural system, with the opposite true of concrete/steel. 23

25 Structural material Composite A combination of both steel and concrete components are used together in the main structural elements. 24

26 Structural material Composite Examples include buildings which utilize: steel columns with a floor system of concrete beams; a steel structure with a concrete core; concrete-encased steel columns; concrete-filled steel tubes; etc. 25

27 So where does this leave us? A tall building can be: Steel Concrete Mixed (steel over concrete, or concrete over steel) Composite (steel and concrete) is that really all a tall building can be? 26

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29 Proposal Initiated as a forum discussion in the ASCE Journal of Structural Engineering Foster, R.M., Reynolds, T.P.S. and Ramage, M.H. (2016). Proposal for defining a tall, timber building, Journal of Structural Engineering, 142(12), , /(ASCE)ST X

30 Proposal Continued as a proposal in the CTBUH Journal for possible consideration by the CTBUH Height and Data Committee Foster, R.M., Reynolds, T.P.S. and Ramage, M.H. (2017). Rethinking CTBUH Height Criteria in the Context of Tall Timber, CTBUH Journal, (4),

31 Hard cases make bad law Oliver Wendell Holmes 30

32 Proposal A single-material tall building is defined as one where the main vertical and lateral structural elements and floor systems are constructed from a single material. As such, a steel, concrete or timber tall building is defined as one where the main vertical and lateral structural elements and floor systems are constructed from steel, concrete or timber respectively. 31

33 Hard cases Treet Bergen, Norway Concrete slabs every fourth storey? Provide additional mass to the building The concrete does not act as a primary load path Is this a timber building? 32

34 Proposal A composite tall building utilizes a combination of materials acting compositely in the main structural elements, thus including an otherwise steel or timber building with a concrete core. Materials may be listed in order of prevalence by mass in the building structure. 33

35 Hard cases Limnologen Vaxjo, Sweden Full height vertical steel ties for stability So steel forms the tension load path for the lateral load resisting system Is this a timber building? Arkitektbolaget Kronoberg AB 34

36 Proposal A mixed-structure tall building is any building that uses distinct single-material systems above or below each other. There are three main types of mixed structural systems: a steel / concrete or timber / concrete tall building indicates a steel or timber structural system located above a concrete structural system, with the opposite true of a concrete / steel building. 35

37 Proposal Additionally: If a tall building is of steel or timber construction with a floor system of concrete planks or slab supported on steel or timber beams, it is considered a steel or timber building. 36

38 Proposal Additionally: If a tall building has columns or walls of one material and a floor system supported on beams of a different material, it is considered a composite tall building. 37

39 Hard cases What about connections? 38

40 Proposal Additionally: If a tall building is of timber construction with local connections between timber elements formed using steel or another material, it is considered a timber building. 39

41 Proposal Foster, R.M., Reynolds, T.P.S. and Ramage, M.H., (2017) Rethinking CTBUH Height Criteria in the Context of Tall Timber, CTBUH Journal, (4),

42 Proposal Foster, R.M., Reynolds, T.P.S. and Ramage, M.H., (2017) Rethinking CTBUH Height Criteria in the Context of Tall Timber, CTBUH Journal, (4),

43 Proposal Foster, R.M., Reynolds, T.P.S. and Ramage, M.H., (2017) Rethinking CTBUH Height Criteria in the Context of Tall Timber, CTBUH Journal, (4),

44 Proposal It is further suggested that a building in which a single-material structure occupies 85% or more of the building height or floor area be considered as a single-material building. Single material >85% 43

45 Proposal In the conference themed issue of the CTBUH Journal Foster, R.M., Reynolds, T.P.S. and Ramage, M.H. (2017). Rethinking CTBUH Height Criteria in the Context of Tall Timber, CTBUH Journal, (4),

46 Pre-Conference Workshop Workshop held 29 October 2017 Presentations and discussion on a range of topics including tall timber building case studies, advances in structural technologies, sustainability and fire Moving towards producing a state-of-the-art guide for tall timber On the topic of this presentation, a range of views were presented: There is a need for agreement on definitions / criteria To be considered tall, it should be impressive If it hasn t been built, it doesn t count The main vertical and lateral load resisting systems should be made of timber 45

47 Acknowledgements My co-authors and collaborators on this research and the resulting proposal: Thomas Reynolds, University of Edinburgh Michael Ramage, University of Cambridge The EPSRC and the Leverhulme Trust The CTBUH, Carsten Hein and ARUP for hosting the Pre-Conference Workshop on Tall Timber 46

48 Thank you. 47