Preliminary Design for Mid-rise

Timber Buildings

Alastair Woodard

• The importance of the concept / preliminary design phase

• The importance of working together as a team from the start

• The importance of knowing what you can (and can’t) do

• The importance of knowing who can help you

• Some of the important structural engineering considerations

you might not at first be considering

Today’s Presentation

Project: Library at the DockBy: LendleaseLocation: Docklands, Melb, VIC

Project :: 25 KingArchitects :: Bates SmartBuilder :: LendleaseLocation :: Brisbane, QldImage :: Bates Smart

International House, Sydney

Gulam post & beam

CLT floor plates

WORLD’S TALLESTTIMBER OFFICE

BUILDING

Gulam post & beam

CLT floor plates

Project :: 25 KingArchitects :: Bates SmartBuilder :: LendleaseLocation :: Brisbane, QldImage :: Bates Smart

Project :: 55 SouthbankArchitects :: Bates SmartBuilder :: Atelier ConstructionsLocation :: MelbourneImage :: Bates Smart

International House, Sydney

220 Room Vertical Hotel Extension2 Level Steel & Concrete Transfer Deck10 Level CLT Wall, Floor & Roof Structure

Project :: 55 SouthbankArchitects :: Bates SmartBuilder :: Atelier ConstructionsLocation :: MelbourneImage :: Bates Smart

International House, Sydney

220 Room Vertical Hotel Extension2 Level Steel & Concrete Transfer Deck10 Level CLT Wall, Floor & Roof Structure

Project :: 55 SouthbankArchitects :: Bates SmartBuilder :: Atelier ConstructionsLocation :: MelbourneImage :: Bates Smart

First CLT panels being lifted

Project –

Feb 2019

What do all these timber

projects have in common?

A very timber committed and

knowledgeable

project team

What do all these timber

projects have in common?

A structural engineer

prepared to design in timber

The design process

from a structural

engineering

perspective

Phase 3: Fabrication & Assembly

Step 10: Engineered timber systems fabrication (shop drawing review)

Step 11: On-site construction assembly supervision - certification

Phase 2: Detailed Design

Step 3: Vertical load – Roof and floor design

Step 4: Vertical load – Wall design

Step 5: Vertical movement design

Step 6: Lateral load – Stability design

Step 7: Check robustness

Step 8: Other engineering details for consideration

Step 9: Engineering drawings and documentation for certification

Phase 1: Preliminary Design

Step 1: Performance considerations and overall building layout

Step 2: Preliminary structural design – including Early Supplier

Involvement (ESI)

WS Design Guide 50 –

Due for release mid-2019

Phase 1: Preliminary Design

Step 1: Performance considerations and overall building layout

Step 2: Preliminary structural design

– including Early Supplier Involvement (ESI)

Preliminary Design Phase

Approving Authorities

Commissioning

Mid-rise Timber Building Design & Construction Chain

Concept

Design

Detailed

Design

Tender &

Fabrication

On-site Assembly

A wide range

of building

professionals

involved

Preliminary Design Phase – Work Together

✓ Design team (and Client)

✓ Early Supplier Involvement - ESI

✓ Early Contractor Involvement - ECI

Collaboration, communication and knowledge is the key to success

Preliminary Design Phase – Knowledge

Know what you can (and can’t) do

• NCC Provisions

• Timber system options

NCC 2019 – A Current Game Changer

The National Construction Code (NCC) is the regulatory framework for determining the minimum design and construction requirements for buildings in Australia.

NCC Volume OneBuilding Code of Australia 2019

for Class 2 to Class 9 Buildings is the document relevant to mid-rise timber

buildings

(hereon referred to simply as the NCC)

NCC 2019 Compliance Pathways

Two pathways are available under the NCC to demonstrate performance

Image of new WS Design Guide

NCC – Mid-rise Timber Construction Provisions

The 2016 NCC allowed under the Deemed-to-Satisfy (DTS) provisions the use of fire-protected timber construction systems in

✓ Class 2 (apartments),

✓ Class 3 (eg hotels) and

✓ Class 5 (offices) buildings

up to 25 metres in effective height

(hereon in termed ‘mid-rise construction’).

Mid-rise

THE 2019 NCC

HAS EXPANDED

DtS PROVISIONS

TO ALL BUILDING

CLASSES

2016 NCC – Timber Construction Provisions

NCC 2019 Changes for Timber Construction

Summary – NCC DTS Provisions

• The NCC DTS provisions cover both

• traditional ‘lightweight timber framing’ and

• new ‘massive timber systems’ such as CLT, GLT, LVL, NLT

Lightweight timber framing

CLT

Fire resistant plasterboard

consist of the use of appropriate layers of fire resistant plasterboard – to provide ‘fire- protected timber’ – the use of compliant automatic sprinkler systems, and cavity barriers.

NCC 2019: SPRINKLERS

FOR ALLBUILDING

MATERIALS

Summary of General Fire Design Principles

Mid-Rise Timber Buildings have a number of critical layers of fire protection

Thirdly, the use of cavity barriers to prevent fire or smoke spread through the cavities if the fire-grade plasterboard is breached

Firstly, the use of automatic fire sprinklersto suppress a fire before the timber structure is threatened

Fourthly, the use of non-combustible insulation to minimise fire spread in cavities if the fire-grade plasterboard is breached

Secondly, the use of fire-grade plasterboard to effectively ‘fire-protect’ the timber elementsin the low probability event that the sprinklers fail

Timber Construction Options for Mid-rise Timber Buildings

Design of Mid-Rise Timber Buildings

?

Timber Construction - Lots of Options

Structural Types

Massive Panel Walls

Massive Panel Floors

Massive Wood

Systems

Modular Systems

General Frames

Lightweight Frames

Heavy Timber Post

& Beam

Post-Tensioned

Frames

Portal Frames

Lightweight Timber Construction Options

Roof Systems

Wall Systems

Floor Cassette Systems

Massive Timber Construction Options

Glulam

(GLT)

Cross Laminated Timber

(CLT)

Laminated Veneer Lumber

(LVL)

Nail Laminated Timber

(NLT)

Massive Timber – Previous NCC 2016 Definition

Massive Timber – NCC 2019 Definition

Schedule 3 Definitions

Timber Construction Options

6-7 Storeys

12-14 Storeys

NCC Timber construction up to 25m under DTS

Hei

ght

(m)

Optimised Timber Construction Class 2 or 3

Multi-Res Apartments 1-6 Storeys Lightweight Timber

As load

increases

– use

more

studs

Concrete core Mass timber core

Optimised Timber Construction Class 2 or 3

Multi-Res Apartments 1-6 Storeys Lightweight Timber

As load

increases

– use

more

studs

Multi-Res Apartments 6 – 8 StoreysLightweight Timber + Massive Timber

Above 6

storeys use

Massive

Timber in

lower

storeys

(LVL, CLT)

Optimised Timber Construction Class 2 or 3

Multi-Res Apartments 6 – 12+ StoreysMassive Timber (CLT)

Project: Aveo NorwestBuilders: StrongbuildLocation: Baulkham Hills, NSW

Optimised Timber Construction – Class 5 Offices

Heavy Timber

Post & Beam

(Glulam, LVL)

Portal Frames

Glulam, LVL, Box-beams)

Vertical Extensions Using Timber Construction

Vertical Extensions using timber construction

above an existing concrete structure

55 Southbank Boulevard, Melbourne

CLT 10 storey additionImage: Bates Smart

Considerations Impacting on the Structural Engineering

Approach

Design of Mid-Rise Timber Buildings

Preliminary DesignNCC Performance Considerations

1.Structural performance - NCC Part B1 Structural Provisions

2.Fire performance - NCC Section C of the NCC

3.Acoustic performance - NCC multiple requirements

4.Robustness

5.Weatherproofing

6.Building services

7.Energy efficiency

Phase 1: Preliminary DesignNCC Performance Considerations

1.Structural performance

2.Fire performance

3.Acoustic performance

Structural

• Approach

• Design

Structural

• Loading

• Layout

NCC Fire-Protected Timber – Massive Timber

Massive Timber (Lower level of protection to timber)

• Fire protective covering required:• Element with appropriate layers

of fire protective covering, generally 1 layer of 16mm fire-grade plasterboard for walls and ceilings

Fire -grade plasterboard

Massive timber

• Minimum 75mm thickness of massive timber element, with required FRL, with no concealed spaces between plasterboard coverings and timber

e.g. Glulam - GLT, CLT, LVL, NLT

NCC Fire-Protected Timber – Lightweight Timber

General Timber (High level of protection to timber)

• Fire-grade plasterboard linings required (typical 90 min. solution):

• 2 x 13mm fire-grade plasterboard for walls, and

• 2 x 16mm fire-grade plasterboard for ceilings

Fire-grade plasterboard

Timber framing

• FRL lightweight timber-framed construction

e.g. 90, 120, 140 x 45mm

FIRE RATED

PROTECTIVE

LININGS IMPACTS

DEAD LOAD

CALCULATIONS

NCC Acoustics

Acoustic Requirements

- Mass (floor build-ups, wall lining)

- Suspended ceilings (resilient mounts)

- Separation

- Isolation (decoupling)

- Avoid sound bridges (flanking)

• Impact &

• Airborne

• Minimise

Flanking

Wall Design Considerations – Fire & Acoustics

Staggered stud wallsDiscontinuous walls

ACOUSTIC

REQUIREMENTS

WILL INFLUENCE

WALL LAYOUT

CONFIGURATIONS

Single stud walls + resilient mounts

Wall Design Considerations – Fire & Acoustics

Staggered stud wall

Discontinuous wall

Acoustic Wall Configurations

Acoustic Wall Configurations

Wall Design Considerations – Fire & Acoustics

Mass Air Mass Resonance

Small cavities in systems can dramatically affect the acoustic performance of a system even though the same amount of

material and overall width are the same

TAKE CARE WITH

STRUCTURAL

BRACING PANEL

PLACEMENT

Floor Design Considerations – Fire & Acoustics

• Structural loading • Floor depth

40 – 100 mm

300 – 450 mm

60 - 70 mm

100 - 200 mm

Acoustic overlay

Flooring material

Fire rated plaster

Suspended non-fire rated ceiling

Acoustic insulation

Impacts on

ISOLATING THE

CEILING LINING

FROM THE JOISTS

– PROVIDES THE

MAIN BENEFIT

>10dB improv

Resilient mounts

Floor Design Considerations – Fire & Acoustics

• Structural loading • Floor depth

40 – 100 mm

300 – 450 mm

60 - 70 mm

100 - 200 mm

Mass acoustic overlay on mat

Flooring material

Fire rated plaster & mounts

Suspended non-fire rated ceiling

Acoustic insulation

Impacts on

FOR

PRELIMINARY

DESIGN ASSUME

AT LEAST 40kg/m2

OF ADDED

OVERLAY MASS

Floor Design Considerations – Fire & Acoustics

• Structural loading • Floor depth

40 – 100 mm

300 – 450 mm

60 - 70 mm

100 - 200 mm

Mass acoustic overlay on mat

Flooring material

Fire rated plaster & mounts

Suspended non-fire rated ceiling

Acoustic insulation

Impacts on

FOR

PRELIMINARY

DESIGN ASSUME

AT LEAST 40kg/m2

OF ADDED

OVERLAY MASS

Sprinklers or downlights

Floor Design Considerations – Fire & Acoustics

45mm mineral

wool cavity

barrier or similar

Concrete screed or

high-density flooring

Acoustic mat upturned at

wall

Primary flooring layer

Optional – additional non fire-

rated ceiling allowing sprinklers

and wiring to be installed without

penetrating fire-protection layer

In-fill floor strip required to

provide diaphragm action in

floor plate

2/16mm fire rated

plasterboard or equivalent

with resilient mounts

Acoustic insulationeg: R2.0 non-

combustible 90 Gold

BattsTM

Floor/Wall Design Considerations - Acoustics

• Layout• Floor diaphragm actionImpacts on

STRUCTURAL

NEEDS MAY

INFLUENCE THE

ACOUSTIC

APPROACHES

Structural Engineering

Resources

Design of Mid-Rise Timber Buildings

WS Design Guide 46 Wood Construction Systems

COMPARATIVE

SPAN TABLES

FOR QUICK

PRELIMINARY

SIZING

Manufacturer Technical Literature

Think Timber Early

Approving Authorities

Preliminary

design phase

Detailed

design phase

Supply &

construction

Consider timber early

and engage with the

manufacturer /

supplier

Supply – Timber Framed Systems

Frame & Truss

Manufacturing SectorSpecialised

Suppliers

Supply – Heavy Timber Systems

Glulam

Manufacturers

and Suppliers

Supply – Massive Timber Panel Systems – CLT & LVL

CLT

Manufacturer/

Suppliers

LVL Manufacturer/Suppliers

WoodSolutions Mid-rise Team a FREE service to assist you

WS Mid-rise Advisory Team – Vic Pilot

• The concept / preliminary design phase is key

to timber being either IN or OUT

• Work together as a TEAM from the start

• Remember structural engineering

considerations will be impacted on by others

• Know what you CAN DO

• Know who can HELP you and use them

Conclusion

WS Design Guide 50 –

Mid-rise Timber Building Structural Engineering Design Guide

Due for release mid-2019

WS Design Guide 50 – Engineering Design Assistance

Preliminary Design for Mid-rise

Timber Buildings

Thank you for your

Attention