Seismic Design of Timber Buildings Dr. Tobias Smith University of Canterbury, Christchurch, New Zealand

Transcription

1 Testing conducted by: AureconGroup, BRANZ Pull-over test of timber framed school building Seismic Design of Timber Buildings Dr. Tobias Smith University of Canterbury, Christchurch, New Zealand T. Smith, 29 th October

2 Copyright Materials This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is prohibited. University of Canterbury/PreStressed Timber Ltd T. Smith, 29 th October 2014 Program Education Credit Information Canadian Wood Council, Wood WORKS!and the Wood Solutions Fair is a Registered Provider with The American Institute of Architects Continuing Education System; the Architectural Institute of British Columbia and the Engineering Institute of Canada. Credit earned on completion of this program will be reported on behalf of members of each CES provider for those who complete a participation form at the registration counter. Certificates of Completion for non-aia, AIBC or EIC members are available on request. This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. T. Smith, 29 th October

3 Outline Introduction What happened in Christchurch? How do we design against earthquakes? Innovative solutions and Pres-Lam technology Examples Opportunities for Tall Buildings Where I come from Vancouver, Canada Courtesy of D. Moroder Christchurch New Zealand 3

4 Where I come from Where I come from 4

5 Countries strong in Timber Engineering Courtesy of D. Moroder Countries with Timber Framed Houses Courtesy of D. Moroder 5

6 Countries strong in Seismic Design Courtesy of D. Moroder Seismic Timber Design Courtesy of D. Moroder 6

7 And why is that? Japan Vancouver Chile New Zealand Seismicity of The Shakey Isles Movement of fault = 40mm per year Geoffrey Cox The Restless Country 7

8 Seismicity of The Shakey Isles M M M M M M M The Christchurch Earthquake Main quake: 4 September 2010, 4.30am. M7.1. No deaths 8

9 The Christchurch Earthquake Ground accelerations, 2010 The Christchurch Earthquake Main quake: 4 September 2010, 4.30am. M7.1. No deaths Aftershock: 22 February 2011, 1 pm. M deaths 9

10 The Christchurch Earthquake Ground accelerations, 2011 The Christchurch Earthquake 1.5 Spectral acceleration (g) Design spectrum Building period (s) 10

11 The Christchurch Earthquake Damage to the city Unreinforced Masonary The Christchurch Earthquake Damage to the city Concrete Structures Two reinforced concrete structures in the collapsed, one of these accounted for over half of the total casualties. Collapse of these structures was created by poor seismic detailing 11

12 The Christchurch Earthquake Damage to the city Liquefaction Significant damage to both buildings and infrastructure was created by liquefaction Sections of the city have now been abandoned due to the ground conditions Liquefaction also created significant damage to commercial buildings Timber Structures in the CHCH EQ Timber Housing Solid Wood Housing (NOT CLT) Solid wood housing performed very well however serviceability following the event was an issue Although Cross-Lam has become part of the rebuild process, there were no examples in CHCH at the time of the earthquake 12

13 Timber Structures in the CHCH EQ Timber Housing Drywall lining Most of the residential building stock, performed very well but costly to repair Timber Structures in the CHCH EQ Timber Housing External Veneer Heavy external veneers performed poorly in many cases, especially near epicenter 13

14 Timber Structures in the CHCH EQ Timber Housing Falling Chimneys Chimneys also presented a significant hazard, falling and outside of houses. This also created hazard to adjoining properties Timber Structures in the CHCH EQ Timber Housing Rockfall and Liquefaction Blah Blah Blah Blah 14

15 Timber Structures in the CHCH EQ Timber Housing Rockfall and Liquefaction Liquefaction damage due to use of shallow, occasionally unreinforced, foundation slabs Timber Structures in the CHCH EQ Timber Housing Soft Storey Soft story collapse was an issue for a small amount of modern timber framed apartments In some cases this collapse was progressive over a series of events 15

16 Timber Structures in the CHCH EQ Timber Housing Soft Storey Timber Structures in the CHCH EQ Engineered Timber Buildings Their was not a significant stock of engineered timber buildings in CHCH, however, all performed very well 16

17 Timber Structures in the CHCH EQ Engineered Timber Buildings Shear Damage Courtesy of W. Y. Kam Timber Structures in the CHCH EQ What does Christchurch look like now? 17

18 Courtesy of W. Y. Kam Timber Structures in the CHCH EQ What does Christchurch look like now? Courtesy of M. Taylor 18

19 Timber Structures in the CHCH EQ What does Christchurch look like now? Courtesy of M. Taylor Current seismic design practice Our current design choices Minor earthquake Earthquake engineering philosophy Moderate earthquake Big earthquake No damage Repairable damage No deaths, Damage is ok Not good enough Society wants more 19

20 Current seismic design practice Our current design choices Bad Behavior Good Behavior This saves lives, but it is not good enough Current seismic design practice Our current design choices Courtesy of S. Pampanin This building displayed almost prefect good seismic behavior Courtesy of S. Pampanin 20

21 Current seismic design practice This was our choice for Christchurch following a major earthquake Repair is just too expensive, and people are nervous about the results Current seismic design practice Damage to timber connections Bad Behavior Seim and Vogt 2013 Seim and Vogt 2013 Lauriola

22 Current seismic design practice Damage to timber connections Good Behavior But how do we repair it and what would it cost? Lauriola 2006 Lauriola 2006 Versuche zur DIN 1052 We need to shift the goal posts Updating our thinking to performance based design Higher expectations of modern society ( the three Ds ): No victims nor collapse (Deaths) Minimum level of damage or direct costs (Damage = Dollars) Minimum business interruption and recovering (indirect) costs (Downtime) Courtesy of S. Pampanin 22

23 Ways to do this in timber Base Isolation Courtesy of F.C. Ponzo, M. Simonetti, A Di Cesare, D. Nigro Ways to do this in timber Base Isolation Courtesy of F.C. Ponzo, M. Simonetti, A Di Cesare, D. Nigro 23

24 Smith et al. GLUe LAMinated: GLULAM CROSS-LAMinated: CROSS-LAM PREStressed LAMinated Timber: Pres-Lam Damage Limiting System (c/o Miss S. Nakaki) (Palermo et al. 2005) Originally conceived for reinforced concrete (PRESSS) Combination of post-tensioning cable and (in high siesmic areas) internal or external reinforcing Separates ductility from material damage 24

25 Bill and Ben at 10 TVNZondemand Pres-Lam Damage Limiting System Repair Courtesy of S. Pampanin Demolish Pres-Lam changes the way in which a system remains following earthquake loading, replacing damaged reinforcing following a major event 25

26 Pres-Lam for frames Damage Limiting System Post-tensioning provides moment connections Pres-Lam for walls Damage Limiting System U U U 26

27 Pres-Lam System Performance Top-lateral Force [kn] Hybrid specimen 3 HY f p0 = 0.6f py -0,05-0,04-0,03-0,02-0,01 0 0,01 0,02 0,03 0,04 0,05 Drift Smith et al. Pres-Lam separates good seismic performance from system damage The Flag-shaped hysteresis loop Ductility without Damage Self-centering Energy Dissipation A Hybrid System F D F + D = F D Unbonded Posttensioned (PT) tendons Internal or External reinforcing Combination of PT Tendons and Reinforcing 27

28 Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti 28

29 Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti 29

30 Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti 30

31 Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti 31

32 Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti Pres-Lam Timber Wall Under Lateral Loading Courtesy of F. Sarti 32

33 Testing of Pres-Lam Systems Gravity Frames Van Beerschoten et al. Pres-Lam not only provides excellent seismic performance but it can also reduc beam heights and achieve longer bay lengths Testing of Pres-Lam Systems Wall systems Sarti et al. Moroder et al. Pres-Lam walls with internal and external reinforcing. Testing has also been performed on the transfer of forces within a Pres-Lam frame, Economics of connections. 33

34 Testing of Pres-Lam Systems Moment Frames in LVL and Glulam Armstrong et al. Smith et al. Frame testing has been performed in both LVL and Glulam. Numerous connection details and reinforcing methods have been investigated as well as reinforcing techniques Testing of Pres-Lam Systems Complete Building System Post-tensioning Tendons Newcombe et al. 34

35 Testing of Pres-Lam Systems Complete Building System Shaking Table Testing Smith et al. Frame subjected to 200% of design earthquake loading with no damage Testing of Pres-Lam Systems Moment Cross-Lam Stairwell Dunbar et al. 35

36 Pres-Lam in Practice Relocation of the STIC Test building to become offices The test building, following being subjected to several massive earthquake events was moved and converted into an office structure As an office structure, it went through the Christchurch seismic sequence It has recently been dismantled and moved to begin its third life as a law office Pres-Lam in Practice The first Pres-Lam Building in the World Architect: Irving Smith Jack, Engineer: Aurecon 36

37 Pres-Lam in Practice The first Pres-Lam Building in the World Architect: Irving Smith Jack, Engineer: Aurecon Photo: Irving Smith Jack Architects Pres-Lam in Practice The first Pres-Lam Building in the World Architect: Irving Smith Jack, Engineer: Aurecon 37

38 Pres-Lam in Practice The first Pres-Lam Auditorium in the World Architect and Engineer: Opus International Pres-Lam in Practice The first Pres-Lam Auditorium in the World Architect and Engineer: Opus International Photo: Opus International 38

39 Pres-Lam in Practice The first Pres-Lam Auditorium in the World Architect and Engineer: Opus International Photo: Opus International Pres-Lam in Practice The first Pres-Lam Auditorium in the World Architect and Engineer: Opus International Photo: CartertonDistrict Council 39

40 Pres-Lam in Practice A gravity dominated Pres-Lam Frame Architect: Athfeild Architects, Engineer: Dunning Thornton Consultants Pres-Lam in Practice A gravity dominated Pres-Lam Frame Architect: Athfeild Architects, Engineer: Dunning Thornton Consultants 40

41 Pres-Lam in Practice A gravity dominated Pres-Lam Frame Photo: Trends Magazine NZ Architect: Athfeild Architects, Engineer: Dunning Thornton Consultants Photo: Trends Magazine NZ Pres-Lam in Practice The Largest Pres-Lam Building Architect and Engineer: Opus International Photo: Opus International The largest building built with Pres-Lam is the new office structure for Trimble Navigation Ltd. It has been equipped with smart building technology as a full future proof solution. 41

42 Pres-Lam in Practice The Largest Pres-Lam Building Architect and Engineer: Opus International Photo: Conorboyd Photography Pres-Lam in Practice The Largest Pres-Lam Building Photo: Opus International Architect and Engineer: Opus International 42

43 Pres-Lam in Practice Other Examples of Pres-Lam Architect: Rick Proko, Engineer: Ruaumoko Concrete Columns, Timber Beams and Base Isolated Cross-Lam Panels incorporating sections of LVL Architect: Design Base, Engineer: Nelson Timber Solutions Architect: Sheppard and Rout, Engineer: Kirk Roberts Pres-Lam Frames only Current Trends in Timber Design The World s getting Taller Barentshus Tower Tall wood proposal Timber Tower Chicago Norway Canada USA Reiulf Ramstad Arkitekter As mgbarchitecture + DESIGN Equilibrium, LMDG Ltd, BTY Group SOM Skidmore Owings and Merrell 43

44 Current Trends in Timber Design The World s getting Taller What type of connections do we want? We want more Timber Buildings ESPECIALLY in Seismic areas What are the barriers? RISK Who carries it? We have to lower the risk, for many players What are the key strategies? 1. Collaboration 2. Skills and knowledge 3. Successful projects 44

45 We want more Timber Buildings ESPECIALLY in Seismic areas Collaboration Researchers Timber industry Engineers, Architects, QS Builders, developers Skills and knowledge Design guides Education Websites Software Successful projects Working together on real buildings Testing of prototypes Learning from design and construction Conclusions We have the technology, more coming We have the materials, hybrids coming We have the structural systems Excellent seismic performance The hard part is putting it all together Reduce the risk for all stakeholders by working together For future timber buildings 45

46 Photo: Irving Smith Jack Architects Questions/ Comments? This concludes the: American Institute of Architects Architectural Institute of British Columbia Engineering Institute of Canada Continuing Education Systems Program Seismic Behavior of Timber Buildings Dr. Tobias Smith 92 46