COST TU0904 @ Naples, June 2013

Behaviour in fire of high-performance CFRP (carbon fibre reinforced polymer) prestressed concrete structural elements

• High strength self-compacting concrete (silica fume, fly ash)

• CFRP tendons (non-corrosive, high strength)

• Slender structural elements (45mm thick)

• High prestress conditions (12 MPa)

• 2 kg/m3 of PP fibres

Potential to benefit the whole building construction industry...

• Develop products at a fraction of the economic and temporal cost

• Design for “real” fire (or fires!!)

• Move away from a pass-fail testing environment

• “Understand” materials’ and systems’ behaviour in fire

H-TRIS

How a napkin doodle became a testing methodology

What now?

Acknowledgments

• Luke Bisby, Giovanni Terrasi,

Michal Krajcovic, José Luis Torero,

Guillermo Rein, etc.

• Technical and Research Staff

• PhD and MEng students

• Interns

• Visitors

...what's next

• Further experimental validation - replicate thermal loading of the furnace test to a range of materials

• Time-history HF from fire models ("real" fires)

• Higher exposed surface & max higher incident HF

• And...

H-TRIS is a tool…

• Studies with statistical confidence

• Realistic and/or proper boundary thermal conditions

• High repeatability

• Low economical and temporal cost

Past Research

Heat-induced concrete spalling

• Polypropylene (PP) fibres

• PP fibre type (cross section, diameter) and dosage

• With and without compressive stress

• 11 concrete mixtures

• 30 days

60 min

7.9 min

10.6 min

16.3 min

16.36 kJ/m2

1.61 kJ/m2

2.22 kJ/m2

3.64 kJ/m2

Experimental Validation of the Inverse Heat Transfer Model

Factors related to the occurrence of

Heat-Induced Concrete Spalling

• In-service mechanical stress condition

• Moisture content

• Concrete strength (compressive, tensile)

Very complex

thermo-hydro-mechanical

phenomenon!!!

• Admixtures inclusion (fly ash, silica fume, etc.)

• Type of aggregate

• Type of cement

• Casting technique (vibrated concrete, SCC, spun concrete)

• Internal reinforcement (type, ratio, tie configuration)

• PP-fibre inclusion

• Structural form (shape, size, thickness, span, etc.)

Rational Study of

Heat-induced Concrete Spalling

• Heating rate

Understand and control the mode by which concrete “heats up”

Replicate thermal loading imposed by the furnace test

High precision and high repeatability

Low economic and temporal cost

Statistical assessment

The Concept

• Simply supported
• Four-point bending (decompression at the tension fibre in the central region)
• Rectangular cross-section (200x45 m2)

Heat-induced concrete spalling

Longitudinal splitting cracks and loss of bond

Furnace Tests

2009-2010

Size of the test specimen

• Identical cross section as the full size element
• 500 mm in length

Mechanical loading

• Replicate mechanical conditions near the anchorage zone

Thermal loading

• Replicate the thermal conditions of the furnace test using radiant panels

• Get the radiant panels as close as possible, as hot as possible

No Spalling!!

Incident HF

Why?

Absorbed HF

Kunio Kawagoe

Margaret Law

What's going on inside the furnace?

Tibor Harmathy

Philip Thomas

Plate Thermometer ('90s)

• Homogenization

• "Adiabatic Temperature"

• Gas, walls, burners, are all at one single temperature!!

Radiant panels

Loading rig

“We want to get it as nearly right as possible before it is finally adopted, because, after it is adopted by these various associations, it will be pretty hard to change it.”

Ira Woolson, 1917

Chairman of the NFPA Committee

on Fire-Resistive Construction

Inverse Heat Transfer Model

Control

thermal energy!!!

Linear motion system

H-TRIS

BRE Centre for Fire Safety Engineering

How a napkin doodle became a

testing methodology

Naples, 6-9 June 2013

COST Action TU0904 - Integrated Fire Engineering and Response

Cristián Maluk Zedán

The University of Edinburgh

H-TRIS

Heat-Transfer Rate Inducing System

?

Inverse Model

c.maluk@ed.ac.uk

BRE Centre for Fire Safety Engineering