6/7/2013. Post-Tensioned Timber Buildings - Design Guide. Post-Tensioned Timber Buildings - Design Guide. University of Canterbury June 2013

6/7/2013

Post-Tensioned Timber Buildings Design Guide University of Canterbury June 2013

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

Post-Tensioned Timber Buildings Design Guide Main authors Part 1- Overview

Andy Buchanan

Part 2 – Seismic Design

Stefano Pampanin

Part 3 – Gravity design

Alessandro Palermo

Other contributors Contributing authors: Wouter van Beerschoten James O’Neill Tobias Smith Christopher Watson

Daniel Moroder Francesco Sarti Ben Sporn

Earlier research contributors: 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

Structural engineering 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.

Fire, environmental 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

Part 1- Overview 1 Introduction 2 Post‐tensioned structural systems 3 Seismic behaviour of Pres‐Lam technology 4 Diaphragms 7 Design for gravity loading 8 Design for wind loading 9 Floors and roofs 10 Fire safety 11 Supply chain and construction 12 Durability, Sustainability 14 Recent Expan buildings

Part 2 – Seismic Design 1 Introduction 2 Lateral force design 3 Force Based Design (FBD) 4 Direct Displacement Based Design (DDBD) 5 Corrected Force Based Design (CFBD) 6 Design example of a beam‐column joint 7 Post‐tensioned single wall 8 Post‐tensioned coupled walls 9 Diaphragm design 10 Fire Design

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Part 3 – Gravity Design 1      Introduction

2    Methodology 2.1 Design of PT beams 2.2 Design of PT frames 2.4   Long‐term behaviour and losses 3 Design of case study building 3.2 Design of PT columns 3.3 Design of PT beams 3.5 Design of PT frames 3.6 Design of PT walls 3.7 Design of diaphragms 3.8 Fire resistance

TODAY’S TALK 1. 2. 3. 4. 5. 6. 7. 8. 9.

Why wood Materials Pres‐Lam technology Recent Expan buildings with Pres‐Lam tech. Seismic Design Methods (FBD, DBD) Pres‐Lam frames for seismic loading Pres‐Lam walls for seismic loading Diaphragms Supply chain and construction

Re-building Christchurch

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Re-building Christchurch

Re-building Christchurch What kind of city do we want?

Warren and Mahoney

Re-building Christchurch Wood is part of the solution

Old Government Buildings, Wellington, 1876

WOOD is GREEN

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Advantages of timber

• Constructability • Sustainability Overall performance: • Availability As good as (or better than) • Weight other materials • Cost • Fire safety, durability, acoustics, energy

New technology

• New materials o Glulam o LVL o CLT

• New fasteners o Screws o Rivets

• New structural concepts o Post-tensioning

New fasteners Rivets

Screws

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Glulam

LVL - Laminated veneer lumber LVL changes Radiata Pine from a commodity to a top class engineering material

Veneers 3mm thick

CLT - Cross laminated timber

X-Lam factory in Nelson, New Zealand

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Melbourne - 10 storeys CLT

TODAY’S TALK 1. 2. 3. 4. 5. 6. 7. 8. 9.

Why wood Materials Pres‐Lam technology Recent Expan buildings with Pres‐Lam tech. Seismic Design Methods (FBD, DBD) Pres‐Lam frames for seismic loading Pres‐Lam walls for seismic loading Diaphragms Supply chain and construction

Rocking Concrete Systems PRESSS (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

Dissipation Capacity

Self-centring Capacity

Hybrid System or with “controlled rocking”

M

M

M







Cortesy Nakaki Cortesia diof S.S. Nakaki Unbonded post -tensioned cables/bars

Mild steel or dissipation devices

Advantages of “Controlled Rocking” behavior: Reduced with level of damage in the structural elements by lumped Frame and wall systems dry connections characterised Negligible residual (permanent) deformations ductility at the rocking section

Rocking Concrete Systems

PRESSS Technology The hybrid Connection

Effect of Dissipation on Post-tensioned System

•Dissipation design is a trade-off between amount of energy •Dissipated and re-centering capability •Dissipation also adds moment resistance

Rocking Timber Systems – PRES-LAM technology

Application to Timber (Palermo et al. 2005) Hybrid Connection

c/o Miss S. Nakaki

Palermo et al. 2005

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

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Extension to LVL multi-storey seismic resistant buildings

Material properties of LVL Laminated Veneer Lumber

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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Testing at Canterbury University Hybrid specimen 3 – HY3

20 Top-lateral Force [kN]

15 10 5 0 -5 -10 -15

fp0 = 0.6fpy

-20 -0,05 -0,04 -0,03 -0,02 -0,01

0 Drift

0,01

0,02

0,03

0,04

0,05

Testing at Canterbury University INTERNAL DISSIPATERS INTERNAL DISSIPATERS

50 mm

Hybrid specimen 1 - HY1

T op-lat eral Force [kN]

20 15 10 5 0 -5 -10 -15 fp0 = 0.8fpy

-20 -0,05 -0,04 -0,03 -0,02 -0,01

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

0

0,01

0,02

0,03

0,02

0,03

0,04

0,05

Drift Hybrid specimen 2 – HY2

T op-lat eral Force [kN]

20 15 10 5 0 -5 -10 -15 fp0 = 0.8fpy

-20 -0,05 -0,04 -0,03 -0,02 -0,01

0

0,01

0,04

0,05

Drift

Testing at UNIBAS, Italy in collaboration with Canterbury University Beam to Column Joint (Smith 2011)

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Testing at Canterbury University Post-tensioning tendons

Frames

Walls

Testing at Canterbury University

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

Expan Head Office

Architect: Thom Craig Engineer: Holmes Consulting

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Expan Head Office

Earthquake 22 Feb 2011 No structural damage.  Immediate occupancy.

Terminology “A design guide for Expan multi-storey timber buildings incorporating Pres-Lam technology” Expan is the Trade Mark of STIC STIC IP is managed by EWPAA. Pres-Lam technology is owned by Prestressed Timber Ltd (UC spin-off company) Licenced for free use in Australia and NZ.

TODAY’S TALK 1. 2. 3. 4. 5. 6. 7. 8. 9.

Why wood Materials Pres‐Lam technology Recent Expan buildings with Pres‐Lam tech. Seismic Design Methods (FBD, DBD) Pres‐Lam frames for seismic loading Pres‐Lam walls for seismic loading Diaphragms Supply chain and construction

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NMIT Building, Nelson

NMIT Arts and Media Building, Nelson. ISJ Architects, Aurecon, Davis Langdon, Arrow International

NMIT Building, Nelson

NMIT, Nelson

Massey University, Wellington

Rotated timber to avoid compr perp in columns

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Massey University, Wellington

Massey University, Wellington.

Massey University, Wellington

Massey University, Wellington

Beam-column connection tested in UC lab

• UC

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Massey University, Wellington

TCC floor, precast off site

Carterton, Wellington

BRANZ, Wellington Portal frames with post-tensioned columns

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Hereford St, Christchurch

ISJ Architects, Aurecon

St Elmo, Christchurch

Rick Proko Architects, Ruamoko Engineers

St Elmo, Christchurch

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

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Merritt, Christchurch

Sheppard and Rout Architects, Kirk Roberts Engineers

Merritt, Christchurch

Post-tensioned frames

Merritt, Christchurch

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Trimble, Christchurch

Opus International Architects and Engineers

Trimble, Christchurch

Trimble, Christchurch Trimble walls

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Trimble, Christchurch

Trimble, Christchurch

Kaikoura District Council Post-tensioned CLT with LVL

Museum, library, council offices, Kaikoura

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Kaikoura District Council

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

TODAY’S TALK 1. 2. 3. 4. 5. 6. 7. 8. 9.

Why wood Materials Pres‐Lam technology Recent Expan buildings with Pres‐Lam tech. Seismic Design Methods (FBD, DBD) Pres‐Lam frames for seismic loading Pres‐Lam walls for seismic loading Diaphragms Supply chain and construction

Seismic Design Methods Case Study

3D view -Seismic Design Worked Example

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

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Seismic Design Methods Case Study

wall elevation and wall base section

Seismic Design Methods Force Based Design Elastic (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)

• 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

Check MCE level (roughly 1.5 ULS) – Expected rupture of dissipaters but no yielding of tendons! Common-Practice Force-Based Design (FBD) Procedure (adapted from (Sporn et. al 2013)

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

• Frames: ULS = maximum design drift 22.5%

yn

dn

1

H e ig h t R a tio ( H i / H n )

• Walls: ULS = maximum design drift 1-1.5% 0.8

yi

pi

Yield Critical Drift (top wall)

0.6 0.4

 yn   y H n / 2  1.0 y H n / l w

0.2

Yield Displacement

0 0

0.2

0.4

0.6

0.8

1



yi



 y H i2  lw

Hi   1  3 H   n 

Displacement Ratio

Critical Total Drift (top wall) Displacement Profile

 dn   yn   pn  1.0 y H n/ lw  m  2.0 y / lw L p   c

p  i   yi   pi 

 y 2 2 y  H    Lp H i H i 1  i    m  lw l w   3H n  

Sequence of Steps for Direct Displacement Based Design

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

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

Transformation from MDOF to SDOF according to a DDBD approach

Sequence of Steps for Direct Displacement Based Design

Seismic Design Methods Frames: ULS = maximum design drift 22.5%

Walls: ULS = maximum design drift 1-1.5% yn

dn

H e ig h t R a tio ( H i / H n )

1 0.8

yi

pi

Yield Critical Drift (top wall)

0.6 0.4

 yn   y H n / 2  1.0 y H n / lw

0.2

Yield Displacement

0 0

0.2

0.4

0.6

0.8



yi



 y H i2  lw

1

Hi   1  3 H  n  

Displacement Ratio

Critical Total Drift (top wall) Displacement Profile

 dn   yn   pn  1.0 y H n/ lw  m  2.0 y / lw L p   c

p  i   yi   pi 

 y 2 2  H   H i 1  i    m  y  L p H i lw lw   3H n  

TODAY’S TALK 1. 2. 3. 4. 5. 6. 7. 8. 9.

Why wood Materials Pres‐Lam technology Recent Expan buildings with Pres‐Lam tech. Seismic Design Methods (FBD, DBD) Pres‐Lam frames for seismic loading Pres‐Lam walls for seismic loading Diaphragms Supply chain and construction

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Pres-Lam frames for Seismic loading

1. Location and size of posttensioning (bars or tendons?) 2. Location and type of dissipaters (mini-BRB, dog bone.. Viscous dampers etc.) 3. Anchorages 4. Corbels 5. Reinforcing of the columnpanel joint (screws, plates and rods) 6. Post-tensioning losses

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

Pres-Lam frames for Seismic loading Anchorages - beams

Internal External

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Pres-Lam frames for Seismic loading Anchorages - beams

Pres-Lam frames for Seismic loading Anchorages - Frames

Pres-Lam frames for Seismic loading Deviators - beams

Wood block

Custom-made steel

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Pres-Lam frames for Seismic loading Corbels

Steel corbels. May need fire protection

Pres-Lam frames for Seismic loading Column reinforcing

Pres-Lam frames for Seismic loading Column reinforcing

Steel Screws

Rotated LVL

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Pres-Lam frames for Seismic loading Post-tensioning losses Instantaneus

Long-term

t=0

t=oo Effect of post-tensioning losses on frameperformance

Pres-Lam frames for Seismic loading Capacity design Summary of post-tensioned timber design procedure

MMBA nomenclature for a beam-column joint

More complex for frames!

MMBA nomenclature for a wall-foundation joint

Pres-Lam frames for Seismic loading Capacity design

•

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

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PRESS LAM: Design Toolsfor Seismic loading Pres-Lam frames

Capacity design

Timber Modifications

•

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

Frames

Walls

Pres-Lam frames for Seismic loading Capacity design

Results Predictions

TODAY’S TALK 1. 2. 3. 4. 5. 6. 7. 8. 9.

Why wood Materials Pres‐Lam technology Recent Expan buildings with Pres‐Lam tech. Seismic Design Methods (FBD, DBD) Pres‐Lam frames for seismic loading Pres‐Lam walls for seismic loading Diaphragms Supply chain and construction

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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. Anchorages 4. Post-tensioning losses

Pres-Lam walls for Seismic loading 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

Pres-Lam walls for Seismic loading

Location of dissipaters  and bars

Location of shear key

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Pres-Lam for Seismic loading Quick design

Capacity: Dimensioning reinforcement assuming 0.3-0.4d as c (neutral axis)

Ductility/rotation: check strain in dissipaters and tendons (/L) Equilibrium for a post-tensioned beam-column joint (top) and wall (bottom)

Pres-Lam frames for Seismic loading Case study

Details of the fuse dissipater (Plug&Play)

Pres-Lam walls for Seismic loading 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

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TODAY’S TALK 1. 2. 3. 4. 5. 6. 7. 8. 9.

Why wood Materials Pres‐Lam technology Recent Expan buildings with Pres‐Lam tech. Seismic Design Methods (FBD, DBD) Pres‐Lam frames for seismic loading Pres‐Lam walls for seismic loading Diaphragms Supply chain and construction

Diaphragms

Lateral load resisting system

Diaphragms

Definitions

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Diaphragms Timber-Concrete-Composite cast-in-situ reinforced concrete

joists

panel

notched coach screw connection (Yeoh 2010)

Diaphragms Boards or panels on joists

(Brignola 2009)

(Legno Trento 2013)

(Dolan 2003)

Diaphragms Stressed Skin Panels

(PotiusTM)

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Diaphragms Solid or modular panels Glulam

Modular floor (Kaufmann)

CLT

(Lignatur®) (Kaufmann)

Diaphragms

Strut and tie model

Girder analogy

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

drag bar notched joist connection

collector beam or edge joist ductile m esh

coach screw

sheeting panel starter bars

Connections for TCC floors

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Diaphragms

Testing at University of Canterbury

Diaphragms

TODAY’S TALK 1. 2. 3. 4. 5. 6. 7. 8. 9.

Why wood Materials Pres‐Lam technology Recent Expan buildings with Pres‐Lam tech. Seismic Design Methods (FBD, DBD) Pres‐Lam frames for seismic loading Pres‐Lam walls for seismic loading Diaphragms Supply chain and construction

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The Supply Chain  Forest owner Logs

 Processor Wood products

 Fabricator Structural elements

 Erector Structural skeleton

 Contractor Whole building

 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 manager

1. They must have some understanding of wood 2. 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

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