Studies in Advanced Structural Design

Structural design is an essential part of the architecture of buildings

Studies in Advanced Structural DesignEmanuele Marfisi | Chris Davies


06 - Timber Structures

• Material properties

• Traditional timber structures

• Engineered Wood Products

• Benefits of Timber

• Fire behaviour

• Composite systems (timber and concrete / timber and

steel)

• Timber connections

• Panels systems

• Timber grid-shells

• Case Study – Labs

• Workshop

m1

m2

m3Wood


Material properties



Softwood Structure


Grade Bending Strength

(N/mm2)

Mean Modulus of Elasticity || to grain

(N/mm2)

Characteristic density

(kg/m3)

C16 16 8000 310

C24 24 11000 350

GL28h 28 12600 410

Timber

Material Properties - EN 338 Table 1


Traditional Timber

Structures


Traditional Timber Structural Forms – King Post



Engineered Wood

Products - EWP


Raw Materials


The ‘Cross Lamination’ Process




Material Comparisons

Manufacturers


Timber Products


Product Use Dimensions

Sawn timber Small structural framing, studs and joists, general

carcassing, door panels, joinery

Length: up to 5.4m

Width: 25-75mm

Depth: up to 250mm

Finger-jointed

softwood

Floor and roof joists, ceilings, loadbearing studs,

cladding

support, prefabricated multi-span ‘cassette floors’,

laminations for glulam members

Length: up to 20m

Width: 38-75mm

Depth: up to 250mm

Glulam Large structural elements, beams, columns, trusses,

bridges, portal frames, post and beam structures

No theoretical limits to size length or

shape.

Common size range: 60 to 250mm

wide

by 180mm to >1000mm deep

‘Massive’ or cross

laminated timber

(CLT)

Floor slabs, roofs, beams, columns,

load bearing walls, shear walls

Length: up to 20m

Thickness: 50-300mm

Width: up to 4800mm

Laminated veneer

lumber

(LVL)

Beams, columns, trusses, portal frames, post

and beam structures, structural decking, I-joist

flanges, stressed skin panels

Length: up to 20m

Width: 19-200mm

Depth: 200mm up to 2500mm

Oriented strand

board (OSB)

& plywood

Structural sheathing and decking Board materials typically available

in 1220mm x 2440mm sheets and

thickness ranges from 9 to 25mm

I joists Floor and roof joists, formwork, ceilings, loadbearing

studs, cladding support, prefabricated ‘cassette

floors’

Length: up to 20m

Width: 38-97mm

Depth: 200-500mm






Benefits

FULL MODELLING

COORDINATION

EARLY COORDINATION OF

DESIGN

FACTORY PRECISION

FABRICATION

QUICK ERECTION FOR CLIENTS




(900 C02 kg/m3)

WHY TIMBER?

Modern method of construction

High quality finishes

An exciting alternative

Carbon negative



Fire Performance


Structural Resistance Integrity Insulation





Timber connections



Glulam Connections


CLT Connections




Hybrid timber


Cork Airport

HOK + Buro Happold

Glulam tie roof beam

Flitched beam / truss



Panel systems


Structural Stability

Using rigid panels on the 3 planes.


Structural Stability

Using rigid panels on the 3 planes.


Braced Systems

Portalised Systems


Cellular Frame Single Plane Single Plane with Rigid Frames




Construction Drawings


Furness Academy, UK – Architect Halliday Clark, Engenuiti Engineers


The Hive, Worcester, UK – Fielden Clegg Bradley Architects – Hyder Engineers


Cross laminated timber half lap connections


Gridshells


Timber gridshells

A gridshell is a structure, which derives its strength from its double curvature and is constructed of a grid or lattice of elements that work predominantly in compression.

The ‘optimal’ shape can be found as a catenary or using form finding techniques.

The material needs to be used ‘predominantly’ in compression so does not need bending capacity.

The ‘flexibility’ of timber can be used to create curved shapes using straight elements.


Weald and Downland museum

connection detail of the two

layer timber lattice structurearchitect edward cullinan architects structural engineers buro happold


exhibition hall, mannheim

a timber lattice shell clad with a fabric

membrane architect carlfried mutschler with frei ottp structural engineers arup


exhibition hall, mannheim

internal view showing the timber grid shell structure

the fabric cladding stressed over the timber lattice provides both skin and stability

diagonal bracing cables lock the geometry of the grid shell by providing shear

stiffnessarchitect carlfried mutschler with frei ottp structural engineers arup


Metz Pompidou Centre, FR – architect Shigeru Ban Architects structural engineers – Arup Engineers


Metz Pompidou Centre, FR – architect Shigeru Ban Architects structural engineers – Arup Engineers




Savill Centre, UK – architect Glenn Howells Architects structural engineers – A Anthony Hunt Engineers



CASE STUDY


� Design Brief

� Design loading

� Choice of materials

� List of structural components

� Stability system

� Structural calculations

� Connection details / analysis

� Production of construction documents (drawings etc..)


NOTTINGHAM

LABS


Steel and timber hybrids



WORKSHOP

Workshop Question Student AccommodationClient’s requirements

1. A new halls of residence for a university based on the edge of a regional city. Consisting of three floors of accommodation centred around a courtyard. SeePlan.2. The building is to have strong architectural style, and floors are required to stepout 300mm on the external perimeter. The internal perimeter must have awalkway that is column free and the architect wishes to see glulam beams at900mm c/c in the rooms.3. The maximum permitted overall height of the building is 9.0m.4. Clear minimum internal floortoceiling heights of 2.3m are required. A 200mmservice zone is required above each structural slab to enable an acousticdampener to be installed.5. No columns are to be visible within each student room, and large windows arerequired on the external perimeter.

Imposed loading

Roof 1.5kN/m2 Residential floor loading 2.5kN/m2

Site conditions

Ground conditions vary linearly with the existing slope surface. Ground level – 1.0m Topsoil and fill 1m to 3m+ gravels increasing strength to a allowable bearing stress of 170kN/m2Ground water was not encountered.

Omit from considerationDetailed design of the lift/elevator shafts and stairs.

OUTPUTS

a. Prepare a design appraisal with appropriate sketches indicating a viablesolution for the proposed structure including the foundations.

Indicate clearly the functional framing, load transfer and stability aspects of eachscheme.

b. After the design has been completed the client wishes to replace three roomswith a junior common room at ground. Provide structural solutions.

Courtyard

Room

Student Accommodation

1:200 @ A4

3,400 mm

5,268

mm

EACH ROOM 3.6m x 5.665m (min)

No columns oninternal courtyard line

1,800

mm

5,655 mm

9,000

mm

3,000

mm Courtyard

Steppedoutfacadeline

1:200 @ A4

1,800 mm

NoColumnson innercourtyard

2.5m windowon external

Student Accommodation


CHURCHILL

COLLEGE








References:

IStructE The Structural Engineer March 2013B&K StructuresEngenuiti Partnership

6a Architects


Studies in Advanced Structural Design

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