seismic design of timber buildings - wood-works · 10/25/2014 1 prestressed timber limited –...

10/25/2014

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PreStressed Timber Limited – [email protected]

Pull-over test of timber framed school building

Testing conducted by: Aurecon Group, BRANZ

T. Smith, 29th October 2014

Seismic Design of Timber BuildingsDr. Tobias Smith

University of Canterbury, Christchurch, New Zealand

10/25/2014

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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. 2014


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.

Program Education Credit Information

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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

Christchurch New ZealandCourtesy of D. Moroder

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Countries strong in Timber Engineering

Courtesy of D. Moroder


Countries with Timber Framed Houses


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Countries strong in Seismic Design



Seismic Timber Design…


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And why is that?

Japan

Chile

Vancouver

New Zealand

www.earthobservatory.sg


Seismicity of ‘The Shakey Isles’

Movement of fault = 40mm per year

Geoffrey Cox

The Restless Country

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Seismicity of ‘The Shakey Isles’• M7.8 1929

• M7.8 1931

• M7.6 1934

• M7.2 1942

• M7.1 1968

• M6.5 1987

• M7.8 2009


The Christchurch Earthquake

Main quake:

4 September 2010, 4.30am. M 7.1.

No deaths www.all-geo.org

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The Christchurch EarthquakeGround accelerations, 2010



Main quake:

4 September 2010, 4.30am. M 7.1.

No deaths

Aftershock:

22 February 2011, 1 pm. M 6.3

182 deaths

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The Christchurch EarthquakeGround accelerations, 2011



Design spectrum1.0

0.5

1.5

0.0

Sp

ect

ral

acc

ele

rati

on

(g

)

0.0 1.0 2.0 3.0 4.0

Building period (s)

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The Christchurch EarthquakeDamage to the city – Unreinforced Masonary


The Christchurch EarthquakeDamage 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

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The Christchurch EarthquakeDamage 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 EQTimber 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

Courtesy of A. Buchanan


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Timber Structures in the CHCH EQTimber Housing – Drywall lining

Most of the residential building stock, performed very well but costly to repair




Timber Structures in the CHCH EQTimber Housing – External Veneer

Heavy external veneers performed poorly in many cases, especially near epicenter


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Timber Structures in the CHCH EQTimber 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 EQTimber Housing – Rockfall and Liquefaction

Blah Blah Blah Blah

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Timber Structures in the CHCH EQTimber Housing – Rockfall and Liquefaction

Liquefaction damage due to use of shallow,

occasionally unreinforced, foundation slabs




Timber Structures in the CHCH EQTimber 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


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Timber Structures in the CHCH EQTimber Housing – Soft Storey



Timber Structures in the CHCH EQEngineered Timber Buildings

Their was not a significant

stock of engineered

timber buildings in CHCH,

however, all performed

very well



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Timber Structures in the CHCH EQEngineered Timber Buildings

Shear DamageCourtesy of A. Buchanan


Timber Structures in the CHCH EQWhat does Christchurch look like now?

Courtesy of W. Y. Kam

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Courtesy of W. Y. Kam

PreStressed Timber Limited – [email protected] of M. Taylor

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Courtesy of M. Taylor


Current seismic design practiceOur current design choices

Earthquake engineering philosophy

Minor earthquake No damage

Moderate earthquake Repairable damage

Big earthquake No deaths, Damage is ok

Not good enough

Society wants more

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‘Bad’ Behavior ‘Good’ Behavior

This saves lives, but it is not good enough



This building displayed almost

prefect ‘good’ seismic behavior

Courtesy of S. Pampanin


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Current seismic design practiceThis was our choice for Christchurch following a major earthquake

Repair is just too expensive,

and people are nervous about the results



Current seismic design practiceDamage to timber connections…

‘Bad’ Behavior

Seim and Vogt 2013 Seim and Vogt 2013 Lauriola 2006

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Current seismic design practiceDamage to timber connections…

Lauriola 2006 Lauriola 2006 “Versuche zur DIN 1052”

‘Good’ Behavior

But how do we repair it and what would it cost?


We need to shift the goal postsUpdating 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)


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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

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PREStressed – LAMinated Timber:

GLUe – LAMinated: GLULAM

CROSS-LAMinated: CROSS-LAM

Smith et al.


Pres-LamDamage 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

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“Bill and Ben at 10” TVNZondemand


Demolish

Repair

Pres-LamDamage Limiting System

Pres-Lam changes the way in which a system remains following earthquake loading, replacing

damaged reinforcing following a major event

Courtesy of S. PampaninCourtesy of A. Buchanan

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Pres-Lam for framesDamage Limiting System

Post-tensioning provides moment connectionsCourtesy of A. Buchanan


Pres-Lam for wallsDamage Limiting System

U

U

U


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Pres-LamSystem Performance

Hybrid specimen 3 – HY3

-20

-15

-10

-5

0

5

10

15

20

-0,05 -0,04 -0,03 -0,02 -0,01 0 0,01 0,02 0,03 0,04 0,05

Drift

Top-late

ral F

orc

e [k

N]

fp0 = 0.6fpy

Pres-Lam separates good seismic

performance from system damage

Smith et al.


The Flag-shaped hysteresis loopDuctility without Damage

Self-centering

F

D +F

D

F

D =

Energy Dissipation A Hybrid System

Unbonded Post-

tensioned (PT) tendons

Internal or External

reinforcing

Combination of PT

Tendons and Reinforcing

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Pres-Lam Timber WallUnder Lateral Loading

Courtesy of F. Sarti




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Testing of Pres-Lam SystemsGravity Frames

Pres-Lam not only provides excellent seismic performance but it can also reduc beam

heights and achieve longer bay lengths

Van Beerschoten et al.


Testing of Pres-Lam SystemsWall systems

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.

Sarti et al. Moroder et al.

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Testing of Pres-Lam SystemsMoment Frames in LVL and Glulam

Frame testing has been performed in both LVL and Glulam.

Numerous connection details and reinforcing methods have been investigated as well as

reinforcing techniques

Armstrong et al.

Smith et al.


Testing of Pres-Lam SystemsComplete Building System

Post-tensioning TendonsNewcombe et al.

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Testing of Pres-Lam SystemsComplete Building System – Shaking Table Testing

Frame subjected to 200% of

design earthquake loading with

no damage

Smith et al.


Testing of Pres-Lam SystemsMoment Cross-Lam Stairwell

Dunbar et al.

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Pres-Lam in PracticeRelocation 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 PracticeThe first Pres-Lam Building in the World


Architect: Irving Smith Jack, Engineer: Aurecon

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Photo: Irving Smith Jack Architects




Courtesy of A. Buchanan Courtesy of A. Buchanan


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Pres-Lam in PracticeThe first Pres-Lam Auditorium in the World


Architect and Engineer: Opus International




Photo: Opus International

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Photo: Carterton District Council


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Pres-Lam in PracticeA gravity dominated Pres-Lam Frame


Architect: Athfeild Architects, Engineer: Dunning Thornton Consultants


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


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Pres-Lam in PracticeA gravity dominated Pres-Lam Frame

Architect: Athfeild Architects, Engineer: Dunning Thornton Consultants

Photo: Trends Magazine NZ

Photo: Trends Magazine NZ


Pres-Lam in PracticeThe Largest Pres-Lam Building

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.



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Photo: Conorboyd Photography






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Pres-Lam in PracticeOther Examples of Pres-Lam

Concrete Columns,

Timber Beams and

Base Isolated

Cross-Lam Panels

incorporating

sections of LVL

Pres-Lam Frames only

Architect: Rick Proko, Engineer: Ruaumoko

Architect: Design Base, Engineer: Nelson Timber Solutions

Architect: Sheppard and Rout, Engineer: Kirk Roberts


Current Trends in Timber DesignThe World’s getting Taller

Reiulf Ramstad Arkitekter Asmgb ARCHITECTURE + DESIGN Equilibrium,

LMDG Ltd, BTY GroupSOM Skidmore Owings and Merrell

Norway Canada USA

Barentshus Tower Tall wood proposal Timber Tower Chicago

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Current Trends in Timber DesignThe World’s getting Taller

What type of connections do we want?


We want more Timber BuildingsESPECIALLY 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

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We want more Timber BuildingsESPECIALLY 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

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Photo: Irving Smith Jack Architects


• 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

Questions/ Comments?

92

Dr. Tobias Smith

[email protected]

seismic design of timber buildings - wood-works · 10/25/2014 1 prestressed timber limited –...

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