fire safety engineering - unece · datum fire safety engineering dr. michael klippel email:...

Datum

Fire safety Engineering

Dr. Michael Klippel

Email: [email protected]

ETH Zurich, Switzerland – Institute of Structural Engineering

74th session of the ECE Committee on Forests and the Forest Industry

Geneva, 19th of October, 2016

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What are the key barriers

for timber constructions?

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Key barriers for timber constructions

?

Education

Costs

Regulations/

laws

It burns!

And few more…

DurabilityExperience

4


Why is the fire behaviour of timber a key barrier?

… timber burns.

… I do not want to live in a

building that might burn.

Yes, it burns! I agree. But

let me explain why this is a

great behaviour:

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Description

Charring rate

Char layer

And many more…

Fire behaviour

Pyrolysis

Timber behaviour in fire – some basics

Pyrolysis:

Thermal degradation of wood

producing combustible gases

and accompanied by a loss in

mass

Timber burns,

but totally

predictable

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Description

Char layer

And many more…

Fire behaviour


Pyrolisis

Charring rate

Charring rate:

Ratio between charring depth

dchar and fire time t (in mm/min)

min7.0min71

50mm

mm

t

dchar

Char layer

Fire time

t = 71 minCharring rate

is constant!

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Description

And many more…

Fire behaviour


Pyrolisis

Char layer

Charring rate

Char layer protects the

residual cross-section from

high temperatures

The inside of the cross-section

is “cold“ and load-bearing

850

700

580

400

200

20

Temp. [°C]

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Zeit [min]

Tem

pera

tur

[°C

]

Mode of action: intumescent systems expand at a temperature of about

200°C by a factor of 30 to 60 and form a compact insulating layer.

Time (min)

Tem

pera

ture

(°C

)

Intumescent coating systems on steel members

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[°C

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Time (min)

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pera

ture

(°C

)


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0 10 20 30 40 50

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“Modern manmade

intumescent materials

applied to steel structural

elements are in essence an

attempt to replicate what

timber does naturally.”

From paper “Overview of design issues for tall

timber buildings”, I. Smith, A. Frangi,

Structural Engineering International SEI 2/2008

Intumescent coating systems

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Steel girders cannot take

any loads anymore

Timber beam still has a

residual load-bearing capacity

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Timber behaviour in fire – Fire resistance

Use of massive

cross-sections

Increase of cross-sections by

charring depth

Protection of the timber

elements with non

combustible materials

Basic strategies

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?

Education

Costs

Regulations/

laws

It burns!

And few fmore…

DurabilityExperience

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... we are not allowed

… we are not able

… we do not have the

knowledge

Yes, but regulations and

education as well as

assistance from experts

are the key!


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So, what is the situation

in your country?

Can you help me?

Yes, with pleasure.

Cooperation and best

practice experience is

important.


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Fire safety regulations in Switzerland

New fire safety regulations in Switzerland since 1st of January 2015

1Timber as a construction material can be used in all categories of

buildings (low-rise, medium-rise and high-rise buildings).

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New fire safety regulations in Switzerland since 1st of January 2015

1Timber as a construction material can be used in all categories of

buildings (low-rise, medium-rise and high-rise buildings).

2With regard to requirements of fire resistance, there is no difference

between combustible structural elements and non-combustible

structural elements.

3Structural elements in wood needs to be designed for a fire

resistance of 60 minutes.

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A fire resistance of

60 minutes only?

We have good experience

with 60 minutes combined

with good engineers and a

good fire brigade

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A fire resistance of

60 minutes only?

And: We help the

engineers to design a

building with standards,

handbooks etc.

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Important tool in planning,

execution and implementation

for architects, engineers, fire

authorities and contractors.

Is recognised by the fire

authority as state of the art.

Lignum Documentation

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Use of products or components given in

the Swiss Fire Safety Register

Use of standardized components

(according to Lignum documentation)

Verification by calculation using

recognized calculation methods

(according to Lignum documentation)

How to design a building

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Revision every 10 years

Same format as previous fire regulations

Implementation of state of the art

Economic optimization

Principals of the regulations

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I understand that you

have great documents.

Anything else of

importance?

A big YES!

A good quality management

system is essential!

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Fire safety plan with all fire safety measures

Careful planning and detailing

Professionally implementation

of fire safety measures

during the construction

Periodic controls and

maintenance

The intensity of maintenance and controls must be set

depending of the type of structures and the type and

importance of the building


Quality management system:

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Wow, but this is very

expensive! Do you have

this for all types of

buildings?

Of course, this depends on

the type of building, the

materials, the location, etc.

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And what type of

timber buildings do you

build in Switzerland?

Let me show you some

examples.

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Zürich, 7 storeys (Switzerland)

Lugano, 6 storeys

(Switzerland)Baar, 5 storeys (Switzerland)

Steinhausen, 6 storeys (Switzerland)

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Trends for timber structures in Switzerland

More and more buildings in the city

ZugZürich

Lugano

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House of Natural Resources

ETH Zürich, 2015

More and more hardwood (?)

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More and more digital fabricated (?)

ArchTecLab

ETH Zürich, 2016

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More and more exposed to weather

Studentenwohnheim

ETH Zürich, 2016

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How tall is the tallest

timber building?

What is the market

share of timber?

The tallest timber building

will be a 10 storey

building. It is currently

under construction.

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…and the market share:

Residential

Multi-family

Non-residential

Non-residential

Multi-family

Development of market share of timber (new buildings)

Load-bearing structures

Multi-family

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Identified requirements to reduce barriers:

Requirements with regard to fire safety engineering:

• Good education of engineers

• Good documents for engineers (standardized products, handbooks)

• Help each other and learn from fire experts

• Establish an effective quality management system for fire safety

• Reasonable and adequate regulations /laws (fire safety, design loads) considering the

building environment (education, documents, knowledge, experience) in each country

• Identify risks and be careful. One fire in a timber building might have an enormous

negative impact!

• Do not overestimate your abilities. With increasing complexity of a building more

experienced (fire) engineers should be involved

• Clarify that a burning material like timber has a predictable, foreseen fire behavior

General requirements:

• Consider a timber solution for your building in a very early state of planning!

• Reduce costs, use standardized products (do not reinvent the wheel every time!)

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Conclusions

Sustainability is not a

trend, it is a necessity

Timber construction

= sustainable construction

To burn timber for heating

is a pity

Bring together people and

ideas to gain the greatest

benefit of timber as

building material

We are in the era of timber

fire safety engineering - unece · datum fire safety engineering dr. michael klippel email:...

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