new technologies in timber buildingscanterbury.royalcommission.govt.nz/documents-by... · damage to...

Professor Andy BuchananUniversity of Canterbury

New Technologies in Timber Buildings

Canterbury Earthquakes Royal Commission

ENG.BUC.0001.1

Earthquake fundamentals

Design philosophy

Minor earthquake No damage

Moderate Repairable earthquake damage

Big earthquake No deaths. Damage is ok

We have to find a better solution

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Rebuild for damage resistance

1. Overdesign (expensive)

2. Base isolation

3. Energy dissipation

4. Rocking frames and walls

How do we do this with timber?

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Old Government Buildings, Wellington, 1870

Why not wood?

We have done it before

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New Technologies in Timber

Damage to houses and timber buildings

New wood materials

Plywood, LVL, CLT, piles

New fasteners

Epoxy, post-tensioning, screws, rivets

New structural systems

Base isolation, rocking systems

Examples

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Liquefaction damage

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Differential settlement

Differential settlement, veneer damage, timber structure OK

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Vertical accelerations

Roof shaken off

Timber housestructurally safe

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Internal linings

Gib plasterboard

Provided bracing for most houses

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Veneer failure

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Veneer ties

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Wall bracing failures

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Old timber building collapse

Before

After

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Before

Soft storey collapse

After

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Solid wood houses

Good performance despite differential slab movement

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Concrete slab floors

Lateral spreading

Differential sinking

No reinforcing

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Engineered timber buildings

Most performed very well

Lateral spreading of portal bases

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Shear cracks in column

Engineered timber buildings

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EXPAN building, UC campus

Engineered timber buildings

No structural damage. Immediate occupancy.

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New Technologies in Timber

Damage to houses and timber buildings

New wood materials

LVL, CLT, foundation piles

New fasteners

Epoxy, post-tensioning, screws, rivets

New structural systems

Base isolation, rocking systems

Examples

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LVL - Laminated veneer lumber

Veneers 3mm thick

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CLT - Cross laminated timber

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New Technologies in Timber

Damage to houses and timber buildings

New wood materials

LVL, CLT, piles

New fasteners

Epoxy, post-tensioning, screws, rivets

New structural systems

Base isolation, rocking systems

Examples

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Epoxied steel rods

Robert fairweather

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Post-tensioned timber frames

Post-tensioning solves the problem of moment connections for heavy timber

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Post-tensioned timber walls

U

U

U

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New Technologies in Timber

Damage to houses and timber buildings

New wood materials

LVL, CLT, piles

New fastening techniques

Epoxy, post-tensioning, screws, rivets

New structural systems

Base isolation, rocking systems

Examples

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Base isolation

L’Aquila, Italy. 2009

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Base isolation

L’Aquila, Italy. 2009

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Re-levelable buildings

Light building

Adjustment

Strong foundation

Concrete foundation

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Light building

Adjustment

Strong foundation

Concrete foundation

Re-levelable buildings

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Light building

Adjustment

Strong foundation

Concrete foundation

Re-levelable buildings

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Light building

Adjustment

Strong foundation

Concrete foundation

Re-levelable buildings

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CLT buildings

7 storey CLT building, London

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7 storey CLT shake test

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Light timber frame

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Light timber frame test

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Post-tensioned beams

Long spans (draped tendons)

Fewer columns

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Post-tensioned timber building

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Post-tensioning

Post-tensioned timber building

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Post-tensioned timber

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Post-tensioned timber walls

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Post-tensioned timber frames

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9 storeys – London(CLT panels)

International

6 storeys – Switzerland(Light timber frame)

7 storeys – Berlin(Glulam)

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International

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Photos of St Elmo, Vic St.

Re-building Christchurch

Sheppard and Rout Architects, Kirk Roberts Engineers

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Rick Proko Architects, Ruamoko Engineers

Re-building Christchurch

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Conclusions

New wood materials

LVL, CLT

New fasteners

Epoxy, post-tensioning

New structural systems

Base isolation, rocking systems

Timber solutions are available

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