Designing CLT BuildingsPresented By – Robert De Brincat

INTRODUCTION CLT Design Considerations• Optimum CLT Design & Building Applications• Strength / Serviceability / Vibration / Fire / Acoustics• Floor, Wall & Lateral Design

CLT Supply & Design Resources• CLT Material Properties & Supplier Involvement• Design Resources Available• Design, Construction & Importation Process• SmartStruct & Tilling Timber

CROSS LAMINATED TIMBER PROJECTS

• Optimum Slab Span – 4.5m to 5.5m• Simple Compartment & Wall Layouts• Minimal Load Transfer Between Floors• Optimum Building Height – 5 to 8 Levels• Residential & Commercial Developments• Lightweight Construction & Poor Foundations• Speed of Construction

Suitable Applications & Benefits

Affordable Housing - Austria

Das Post Hotel - Austria

Lee Valley Athletics Village

Lee Valley Athletics Village

Lee Valley Athletics Village

Lee Valley Athletics Village

Woodlands Trust

Woodlands Trust

Woodlands Trust

Woodlands Trust

Woodlands Trust

Woodlands Trust

CROSS LAMINATED TIMBERAvailable Finishes

• Architectural Visual Finish– Smoothly Edge Glued– Individual Boards Planned

• Industrial Visual Finish– Individual boards Sanded or Brushed

• Non-Visual Finish– Unexposed Panels

CROSS LAMINATED TIMBERAvailable Finishes

CROSS LAMINATED TIMBERAvailable Finishes

CROSS LAMINATED TIMBER

Floors – Walls – Shafts

Design Considerations

CLT FLOOR DESIGNTwo Way Slab Performance

CLT FLOOR DESIGNTwo Way Slab Performance

Wall Below CLT

CLT FLOOR DESIGNMoment Capacity

• Moment Capacity Relative to Member Size• Increased with Laminated Area• Increased with Material Area• Increase with Effective Area & Lever Arm

CLT FLOOR DESIGNMoment Capacity

• Moment Capacities Vary between CLT Products• Moment Capacity Provided by CLT Supplier

• Importance of Understanding Moment Capacity

– Longitudinal Shear Due to Bending– Rolling Shear Between Timber Layers– Effective Bending Stiffness

CLT FLOOR DESIGNLongitudinal Shear Due to Bending

Longitudinal Shear

Solid Section Non Laminated Section

CLT FLOOR DESIGN

Rolling Shear is Dependent on Many FactorsTimber Species; Cross Layer Density; Lamination Thickness; Moisture

Content; Sawing Pattern; Cross Sectional Size and Geometry

Rolling Shear

CLT FLOOR DESIGNRolling Shear

• Effective Bending Stiffness Dependent on Rolling Shear• Transverse Layers Modeled as Theoretical Connectors

Between Longitudinal Layers• ϒ Factor → Effective Moment of Inertia → Effective

Bending Stiffness. ϒ = 0 (No Connection) ϒ = 1 (Fully Rigid)

• Rolling Shear Modulus (GR) Predetermined by Supplier

CLT FLOOR DESIGNDesign Capacities

• Rolling Shear Modulus used to Calculate Effective Bending Stiffness

• Effective Bending Stiffness used to Calculate;– Moment Capacity– Shear Capacity– Deflection

Design Capacities Provided by CLT Manufacturer

CLT WALL DESIGNTwo Way Wall & Beam Performance

Beam Configuration Wall Configuration

CLT WALL DESIGNCompression Members

Applicable to both Wall & Column Applications

Pparallel ≤ F’c Aparallel

Pparallel = Load Applied Parallel to the Fibres

F’c = Adjusted Compression Strength

Aparallel = Area of Layers with Fibres Running Parallel to the Direction of the Load

CLT WALL DESIGNTension Members

Tension Loads can only be Resisted by the Layers where the Grain Runs Parallel to the Applied Load

Tparallel ≤ F’t Aparallel

Tparallel = Load Applied Parallel to the Fibres

F’t = Adjusted Tensile Strength

Aparallel = Area of Layers with Fibres Running Parallel to the Direction of the Load

CLT LATERAL DESIGNShear Walls & Diaphragms

• Resistance to Wind & Seismic Loadings• Wall & Floor Panels Designed as Shear Walls & Diaphragms• Panel Shear Strength will vary based on Fastener Size,

Fastener Spacing, Fastener Location, & CLT Shear Strength• Deflection Determined by Engineering Principles & Testing

CLT is a Suitable Substitute for Concrete in Lift Shaft & Building Core Design

CLT LATERAL DESIGNSeismic Design

• CLT Panel Connectors Provide Primary Source of Yielding while CLT Panel Remains Elastic

• Special Seismic Detailing Required for CLT– Fasteners Loaded in Shear– CLT Member Design at Connections– Nominal Connection Capacity– Fastener Withdrawal

CLT CONNECTIONSFloor Details

Single Surface Spline

Internal Spline

Half Lapped

Double Surface Spline

CLT CONNECTIONSWall/Concrete Floor Details

Metal Bracket Metal Plate Metal Shoe

CLT CONNECTIONSWall/Floor Details

Straight Screw

Straight Screw

Angled Screw

Steel Bracket

Steel Bracket

CLT CONNECTIONSWall/Floor Roof Details

Double Bracket

Bracket & Screw Bearing Angle

Block & Screw

CLT VIBRATION DESIGNMaterial Characteristics

• Damping is Approx. 1%• Area Mass is 50 – 150kg/m2• Fundamental Natural Frequency > 9Hz• Footstep Force causes Transient Vibrations which

can be controlled by the Stiffness & Mass of the CLT Floor Panel

• Span & Slab Depth Dependent

CROSS LAMINATED TIMBERFire Design

CLT Charring Rate~ 0.82mm/min

• CLT is NOT Timber Framed Construction• Fire Plasterboard Solutions Available

CROSS LAMINATED TIMBERFire & Acoustic Performance

FRL – 90/90/90Rw – 57Thickness – 284mm

FRL – 90/90/90Rw – 60Thickness – 290mm

CROSS LAMINATED TIMBERFire & Acoustic Construction

CROSS LAMINATED TIMBERFire & Acoustic Construction

Acoustic Layer

Plasterboard Ceiling

Ceiling Insulation

5 Layer CLT

2 x Layers Fire Check

70mm Concrete Topping

Wooden Floor Covering

CROSS LAMINATED TIMBERTermite Control

Termite Management is dealt with in accordance with AS3660.1 – 2000

CLT PROPERTIES & PERFORMANCEVariation Between Manufacturers

• CLT Design & Material Properties Predetermined and Provided by CLT Manufactures

• CLT Products Differ in Material Properties and Design Performance

• Importance of Obtaining Specific CLT Information from Local Australian Suppliers

• Importance of Early Involvement from Suppliers

CLT DESIGN RESOURCES• Supplier Specific Material Properties• Spanning & Pre-dimensioning Tables• Preliminary Design Software (EURO & AUS Codes)

• CADE Systems Engineering Design Software– New CLT Modeling Component– Based on the AUS Standards– Flexible CLT Sectional Analysis– Design Coordination with other Construction Materials

BALANCING ACT

Strength & Serviceability Vs. Fire & Acoustics Construction Depth Vs. Floor to Ceiling Height

Wall Height Vs. Importation CostPanel Optimisation Vs. Construction Time

EARLY CLT SUPPLIER INVOLVEMENT IS VERY IMPORTANT

CLT DESIGN & CONSTRUCTIONWhat Governs the Design?

CROSS LAMINATED TIMBERImportation Professionals

• Importation Capacity for Manufacture, Storage & Delivery• Importation Distance & Lead Time Management• Risk Management & Contingency Plans

What is SMARTSTRUCT?

Design – Fabrication – Supply – Construction

Design Tender Construct

COLLABORATION COLLABORATION COLLABORATION

SMARTSTRUCT CLT PROPOSAL SERVICE

Concept Design

Preliminary CLT Design

CLT Panel Optimisation

CLT Supply Cost

CLT Construction Cost

CLIENT

– Architectural Layout

– Material Wastage

– Transport Cost

– Construction Cost

CLT DESIGN & CONSTRUCTION PROCESS

CLT Delivery to SmartStruc

CLT Manufacture

Shop Drawing Approval

CLT Shop Drawings

CLT Delivery to Site & Install

PROJECT DESIGN

FINISH CONSTRUCTION

PROJECT TENDER

START CONSTRUCTION

Fire Engineered Solution

PCA

Acoustic Consultant

OCCUPATION CERTIFICATE

Building Inspections

SmartStruct Engineer

Architect Services

CLIENT