NZ EXPAN Post-Tensioned Timber Buildings - June 2013 ...assets2.expan.co.nz/assets/NZ-EXPAN-Post-Tensioned...2013-presen… · 6/7/2013 1 Post-Tensioned Timber Buildings - Design

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Post-Tensioned Timber Buildings -Design Guide

University of CanterburyJune 2013

A design guide for Expan multi-storey timber buildings incorporating Pres-Lam technology

Post-Tensioned Timber Buildings -Design Guide

Part 1- Overview Andy Buchanan

Part 2 – Seismic Design Stefano Pampanin

Part 3 – Gravity design Alessandro Palermo

Main authors

Other contributorsContributing authors:

Wouter van Beerschoten Daniel Moroder James O’Neill Francesco Sarti Tobias Smith Ben Sporn Christopher Watson

Earlier research contributors: Structural engineering Fire, environmental

Dr Massimo Fragiacomo Dr David Carradine Dr Michael Newcombe Dr David Yeoh Dr Asif Iqbal Dr Manoocher Adalany Dr Felice Carlo Ponzo Dr Antonio Di Cesare Domenico Nigro

Simona Giorgini Denis Pino Jesus Menendez Bruno Dal Lago Claudio Dibenedetto Tom Armstrong Andrew Dunbar Norhayti Ghafar Daniela Bonardi

Dr Dion Marriott Dr Kam Weng Laurent Pasticier Philip Loock Mitchell Le Heux Michael Cuseil Tiziana Cristini Pasquale Riccio Simon Wessellman Florian Ludwig.

Stephen John Dr Nicolas Perez Gordon Grant Kevin Tsai Phillip Spellman Reuben Costello Ricky Wong

Timber industry contributors:

Hank Bier, Warwick Banks, Cameron Rodger Andy van Houtte, Jason Guiver Peter Law Robert Finch

Carter Holt Harvey Woodproducts Nelson Pine Industries Wesbeam Structural Timber Innovation Company Ltd

Research partners:

Professor Pierre Quenneville Professor Keith Crews

University of Auckland University of Technology Sydney

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Other contributors

1 Introduction2 Post‐tensioned structural systems3 Seismic behaviour of Pres‐Lam technology4 Diaphragms7 Design for gravity loading8 Design for wind loading9 Floors and roofs10 Fire safety11 Supply chain and construction12 Durability, Sustainability14 Recent Expan buildings

Part 1- Overview

Part 2 – Seismic Design

1 Introduction2 Lateral force design3 Force Based Design (FBD)4 Direct Displacement Based Design (DDBD)5 Corrected Force Based Design (CFBD)6 Design example of a beam‐column joint7 Post‐tensioned single wall8 Post‐tensioned coupled walls9 Diaphragm design10 Fire Design

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1 Introduction2 Methodology

2.1 Design of PT beams2.2 Design of PT frames2.4 Long‐term behaviour and losses

3 Design of case study building3.2 Design of PT columns3.3 Design of PT beams3.5 Design of PT frames3.6 Design of PT walls3.7 Design of diaphragms3.8 Fire resistance

Part 3 – Gravity Design

TODAY’S TALK

1. Why wood2. Materials3. Pres‐Lam technology4. Recent Expan buildings with Pres‐Lam tech.5. Seismic Design Methods (FBD, DBD)6. Pres‐Lam frames for seismic loading7. Pres‐Lam walls for seismic loading8. Diaphragms9. Supply chain and construction

Re-building Christchurch

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What kind of city do we want?

Warren and Mahoney

Old Government Buildings, Wellington, 1876

Wood is part of the solution

WOOD is GREEN


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Advantages of timber

• Constructability

• Sustainability

• Availability

• Weight

• Cost

• Fire safety, durability, acoustics, energy

Overall performance:

As good as (or better than) other materials

New technology• New materials

o Glulam

o LVL

o CLT

• New fasteners

o Screws

o Rivets

• New structural concepts

o Post-tensioning

Rivets Screws

New fasteners

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Glulam

LVL - Laminated veneer lumber

Veneers 3mm thick

LVL changes Radiata Pine from a commodity to a top class engineering material

X-Lam factory in Nelson, New Zealand

CLT - Cross laminated timber

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Melbourne - 10 storeys CLT

TODAY’S TALK


Rocking Concrete SystemsPRESSS (PREcast Seismic Structural Systems)University of California, San Diego

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Rocking Concrete Systems

U.S. PRESSS (PREcast Seismic Structural System), coordinated by Prof. M.J.N. Priestley, University of California, San Diego

Frame and wall systems with dry connections characterised by lumped ductility at the rocking section

Cortesia di S. NakakiCortesy of S. Nakaki

Hybrid System or with “controlled rocking”

MM

Self-centring Capacity

Unbonded post -tensioned cables/bars

Dissipation Capacity

M

Mild steel or dissipation devices

Advantages of “Controlled Rocking” behavior:Reduced level of damage in the structural elements

Negligible residual (permanent) deformations

Rocking Concrete Systems

PRESSS TechnologyThe hybrid Connection

•Dissipation design is a trade-off between amount of energy

Effect of Dissipation on Post-tensioned System

•Dissipated and re-centering capability

•Dissipation also adds moment resistance

Rocking Timber Systems – PRES-LAM technology

Application to Timber (Palermo et al. 2005)

• Combines post-tensioned cables and mild steel dissipation• Developed for concrete• Material independent

c/o Miss S. Nakaki Palermo et al. 2005

Hybrid Connection

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Material properties of LVLLaminated Veneer Lumber

Extension to LVL multi-storey seismic resistant buildings

Post-tensioned timber frames

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

Post-tensioned timber walls

U

U

U

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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 0,05Drift

Top

-lat

eral

For

ce [

kN]

fp0 = 0.6fpy

Testing at Canterbury University

50 mm

INTERNAL DISSIPATERS

Internal epoxied dissipaters (deformed bars with or without necked and taped fuses for unbonded length of 50 mm)

INTERNAL DISSIPATERS

-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

-lat

eral

For

ce [

kN]

fp0 = 0.8fpy

Hybrid specimen 1 - HY1

-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

-lat

eral

For

ce [

kN]

fp0 = 0.8fpy

Hybrid specimen 2 – HY2


Beam to Column Joint (Smith 2011)

Testing at UNIBAS, Italy in collaboration with Canterbury University

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Frames WallsPost-tensioningtendons


Post-tensioningUniversity of Canterbury laboratories (Newcombe et al. 2010)


Expan Head Office

Architect: Thom Craig

Engineer: Holmes Consulting

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Earthquake 22 Feb 2011No structural damage. Immediate occupancy.

Expan Head Office

“A design guide for Expan multi-storey timber buildings incorporating Pres-Lam technology”

Expan is the Trade Mark of STICSTIC IP is managed by EWPAA.

Pres-Lam technology is owned byPrestressed Timber Ltd (UC spin-off company)

Licenced for free use in Australia and NZ.

Terminology

TODAY’S TALK


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NMIT Building, Nelson

NMIT Arts and Media Building, Nelson.

ISJ Architects, Aurecon, Davis Langdon, Arrow International

NMIT, Nelson

NMIT Building, Nelson

Rotated timber to avoid compr perp in columns

Massey University, Wellington

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Massey University, Wellington.


Beam-column connection tested in UC lab

• UC


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TCC floor, precast off site


Carterton, Wellington

Portal frames with post-tensioned columns

BRANZ, Wellington

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ISJ Architects, Aurecon

Hereford St, Christchurch

Rick Proko Architects, Ruamoko Engineers

St Elmo, Christchurch

St Elmo, Christchurch

Base-isolated building. Frames both directions with concrete columns and post-tensioned LVL beams.

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Sheppard and Rout Architects, Kirk Roberts Engineers

Merritt, Christchurch

Post-tensioned frames



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Opus International Architects and Engineers

Trimble, Christchurch


Trimble walls


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Post-tensioned CLT with LVL

Museum, library, council offices, Kaikoura

Kaikoura District Council

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All timber. No concrete. LVL floor cassettes. CLT walls.

Kaikoura District Council

TODAY’S TALK


Seismic Design Methods

3D view -Seismic Design Worked Example

Typical floor plan, frame elevation and beam and column sections.

Case Study

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Seismic Design Methods

wall elevation and wall base section

Case Study

Seismic Design MethodsForce Based DesignElastic (5% damped) acceleration spectrum in accordance to NZS1170.5 to be used for the case study building (Z=0.3, 1/500 year, Soil D)

Common-Practice Force-Based Design (FBD) Procedure (adapted from (Sporn et. al 2013)

Check MCE level (roughly 1.5 ULS) – Expected rupture of dissipaters but no yielding of tendons!

• Frames: yielding drift around 1%, ULS-ductility = 2-2.5 (maximum design drift 2-2.5%)

• Walls: yielding drift around 0.5%, ULS-ductility = 2.5-3 (maximum design drift 1-1.5%)

Hierarchy of strength for post-tensioned timber frames and walls

Seismic Design MethodsDispacement Based Design (modified from Priestley et al., 2007)

Check MCE level (roughly 1.5 ULS) – Expected rupture of dissipaters but no yielding of tendons!

• Frames: ULS = maximum design drift 2-2.5%

• Walls: ULS = maximum design drift 1-1.5%

Sequence of Steps for Direct Displacement Based Design

Displacement Profile

n

i

w

iyyi H

H

l

H

31

2

cpwymwnypnyndn LllH /0.2/0.1

ipw

ym

n

ii

w

ypiyii HL

lH

HH

l

2

312

Yield Displacement

0 0.2 0.4 0.6 0.8 1

Displacement Ratio

0

0.2

0.4

0.6

0.8

1

Hei

gh

t R

atio

(H

i/H

n)

yn dn

yi pi

Yield Critical Drift(top wall)

wnynyyn lHH /0.12/

Critical Total Drift (top wall)

p

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Seismic Design MethodsDispacement Based Design (modified from Priestley et al., 2007)

Sequence of Steps for Direct Displacement Based Design

Transformation from MDOF to SDOF according to a DDBD approach

Seismic Design MethodsFrames: ULS = maximum design drift 2-2.5%

Displacement Profile

n

i

w

iyyi H

H

l

H

31

2

cpwymwnypnyndn LllH /0.2/0.1

ipw

ym

n

ii

w

ypiyii HL

lH

HH

l

2

312

Yield Displacement

0 0.2 0.4 0.6 0.8 1

Displacement Ratio

0

0.2

0.4

0.6

0.8

1

Hei

ght

Rat

io (

Hi/

Hn)

yn dn

yi pi

Yield Critical Drift(top wall)

wnynyyn lHH /0.12/

Critical Total Drift (top wall)

p

Walls: ULS = maximum design drift 1-1.5%

TODAY’S TALK


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Pres-Lam frames for Seismic loading

1. Location and size of post-tensioning (bars or tendons?)

2. Location and type of dissipaters (mini-BRB, dog bone.. Viscous dampers etc.)

3. Anchorages4. Corbels5. Reinforcing of the column-

panel joint (screws, plates and rods)

6. Post-tensioning losses

Pres-Lam frames for Seismic loadingLocation and type of dissipaters (mini-BRB, dog bone.. Viscous dampers etc.)

Anchorages - beams

Internal

External


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Anchorages - beams


Anchorages - Frames


Wood block Custom-made steel

Deviators - beams


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Corbels

Steel corbels. May need fire protection


Column reinforcing


Steel

Screws

Rotated LVL

Pres-Lam frames for Seismic loadingColumn reinforcing

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Pres-Lam frames for Seismic loadingPost-tensioning lossesInstantaneus

Long-term

Effect of post-tensioning losses on frame-performance

t=0

t=oo

Summary of post-tensioned timber design procedure

Pres-Lam frames for Seismic loadingCapacity design

MMBA nomenclature for a beam-column joint

MMBA nomenclature for a wall-foundation jointMore complex for frames!

• The Modified Monolythic Beam Analogy (MMBA) Palermo 2004, Newcombe 2008, 2010

Capacity design


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• Extension to Timber 2008

• Elastic portion of MMBA based on strain gauge evidence

• Use of an empirically based E modulus connection redution factor end effect factor 0.55

• Significant contribution of elastic deformation to frame response also recognised

PRESS LAM: Design Tools

Timber ModificationsCapacity designPres-Lam frames for Seismic loading

Frames Walls

Results

Predictions

Capacity design


TODAY’S TALK


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Pres-Lam walls for Seismic loading

Isolated wall Coupled wall Core wall

1. Location and size of post-tensioning (bars or tendons?)2. Location and type of dissipaters (mini-BRB, dog bone..

Viscous dampers etc.)3. Anchorages4. Post-tensioning losses


1. High strenght bars are preferrable to strands 2. Similar dissipaters to beam-column joints can be

used but their locations should be more centred otherwise the dissipater will fail prematurely in tension or, if too long it will fail prematurely in compression

3. Anchorages are similar to frames. It’s important to design thickness of the steel plate to diffuse the load. The plate must have the sam width of the timber wall.

4. Sheark keys at wall-to-foundation (no dowel action!)

5. Post-tensioning losses are less critical then frames (only timber loaded perpendicular to the grain


Location of dissipaters and bars

Location of shear key

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Equilibrium for a post-tensioned beam-column joint (top) and wall (bottom)

Pres-Lam for Seismic loadingQuick design

Dimensioning reinforcement assuming

0.3-0.4d as c (neutral axis)

Capacity:

Ductility/rotation: check strain in dissipaters and tendons (/L)


Details of the fuse dissipater (Plug&Play)

Case study

Section and elevation view of the post-tensioned single wall with external dissipaters

Section and elevation view of the configuration for the coupled walls

Pres-Lam walls for Seismic loadingCase study

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TODAY’S TALK


Lateral load resisting system

Diaphragms

Diaphragms

Definitions

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Timber-Concrete-Composite

notched coach screw connection

joists

panel

cast-in-situ reinforced concrete

(Yeoh 2010)

Diaphragms

(Dolan 2003)

Boards or panels on joists

(Brignola 2009)

(Legno Trento 2013)

Diaphragms

Stressed Skin Panels

(PotiusTM)

Diaphragms

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Solid or modular panels

(Lignatur®)(Kaufmann)

Glulam

Modular floorCLT

(Kaufmann)

Diaphragms

Diaphragms

Girder analogy

Strut and tie model

Diaphragms

Irregular diaphragm

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Diaphragms

Displacement imcompatibility for frames and walls and interaction with the diaphragms

Diaphragms

Connections between timber floor panels

Diaphragms

Connections for TCC floors

collector beamor edge joist

ductile meshnotched joistconnection

starter bars

drag bar

sheetingpanel

coach screw

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Testing at University of Canterbury

Diaphragms

Diaphragms

TODAY’S TALK


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The Supply Chain

Logs

Wood products

Structural elements

Structural skeleton

Whole building

Forest owner

Processor

Fabricator

Erector

Contractor

Building owner

They all may have to take some risks

The Whole Building

• System

• Frames

• Walls

• Floors

• Connections

• Penetrations

• Envelope

• Foundations

The Design Team

Structure Structural engineer, architect

Fire Fire engineer, architect

Acoustic Acoustic engineer

Thermal Building services engineer, architect

Durability Façade engineer, architect

Environmental Architect, environmental consultant

Cost control Quantity surveyor

Construction Project manager1. They must have some understanding of wood2. They all need confidence to proceed

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Conclusions

• We have the technology, more coming

• We have the materials, hybrids coming

• We have the structural systems

• We have the enthusiasm

• The hard part is putting it all together

Let’s work together to reduce the risk

For a sustainable timber future

Documents

NZ EXPAN Post-Tensioned Timber Buildings - June 2013 ...assets2.expan.co.nz/assets/NZ-EXPAN-Post-Tensioned...2013-presen… · 6/7/2013 1 Post-Tensioned Timber Buildings - Design