fire resistance of metal framed historical...
TRANSCRIPT
![Page 1: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/1.jpg)
Fire Resistance of Metal Framed Historical Structures
Chrysanthos Maraveas
Supervisors: Professor Yong Wang, Thomas Swailes
Steel in Fire Forum meeting Institution of Structural Engineers, London
21 April 2015
![Page 2: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/2.jpg)
Research Background
• Strict Building Codes -> High fire resistance requirements -> applied in refurbishment of historical structures
• Many Cast Iron Structures still in use in UK, Central/West Europe and USA
• Metal structures vulnerable to fire attack
• No systematic research on the subject exists
![Page 3: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/3.jpg)
Typical 19th century metal structures
Cast iron columns
Beams: Cast iron Wrought iron Mild steel
Masonry arches: Brick + Mortar
“Early Concrete” (great variety of materials): Aggregate: coke, clinker (incl. coal or coke), breeze, cinders, broken brick, burnt clay, limestone or rubbish. Cement: lime, Roman or Portland cement.
![Page 4: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/4.jpg)
Cast iron Brittle material – asymmetric σ-ε diagram
Graphite flakes
Flaws open in tension Thermal conductivity:
Different depending of flakes direction
![Page 5: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/5.jpg)
Structure of work
• Elevated Temperature Material Properties
– Material properties from literature
– Sensitivity analysis
– Experimental investigation
• Behaviour of Structural Elements in Fire
– Moment capacity of cast iron beams exposed to fire, material safety factor estimation
– Fire resistance of cast iron columns
![Page 6: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/6.jpg)
Literature Review
• Collates thermal and mechanical properties of metals & thermal properties of the ‘‘insulation’’ from literature. Data compared with Eurocode’s expressions for contemporary materials to assess the applicability of the Eurocode expressions for the 19th century fireproof flooring systems.
![Page 7: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/7.jpg)
Thermal properties of cast iron
![Page 8: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/8.jpg)
Mechanical properties an thermal expansion of cast iron
![Page 9: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/9.jpg)
Thermal properties of masonry units
![Page 10: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/10.jpg)
Sensitivity analysis
• Effect of material properties variations
• Variations placed with upper and lower bounds
• Thermal properties->Thermal analysis -> temperature variations->structural response
• Mechanical properties->Structural analysis -> structural performance/resistance
• Estimate the governing material properties
![Page 11: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/11.jpg)
Thermal properties of metals
![Page 12: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/12.jpg)
Mechanical properties of metals
![Page 13: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/13.jpg)
Analysis of arch jack system
![Page 14: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/14.jpg)
Effect of thermal properties of insulation
![Page 15: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/15.jpg)
Effect of thermal properties of cast iron
Analysis number Thermal
Conductivity Specific Heat
1 Upper bound EC3-1-2
2 EC3-1-2 EC3-1-2
3 Lower bound EC3-1-2
4 EC3-1-2 Upper bound
5 EC3-1-2 Lower bound
![Page 16: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/16.jpg)
Structural response Effect of thermal properties and thermal
expansion
![Page 17: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/17.jpg)
Structural response Effect of mechanical properties
![Page 18: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/18.jpg)
Conclusions-1
• The thermal properties of steel per EN1993-1-2 can be used for all metals
• Sensitive to mechanical properties of metals (especially of strength) and thermal expansion
• Thermal properties of insulation can be taken as concrete per EN1992-1-2 (lower bound thermal conductivity)
![Page 19: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/19.jpg)
Experimental investigation of elevated temperatures mechanical
properties of cast iron
![Page 20: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/20.jpg)
For temperatures >400oC moderately brittle fracture
![Page 21: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/21.jpg)
Stress-strain diagram in tension
![Page 22: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/22.jpg)
Proposed model for tension
![Page 23: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/23.jpg)
Stress-strain in compression
![Page 24: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/24.jpg)
Proposed model in compression
![Page 25: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/25.jpg)
Coefficient of Thermal
Expansion
![Page 26: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/26.jpg)
Conclusions -2
• A stress strain temperature relationship for cast iron has been proposed
• Large uncertainties remain – material safety factor should be estimated
• The thermal expansion relationship of steel per EN1993-1-2 can be used for cast iron
![Page 27: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/27.jpg)
Cast iron columns in fire
• Six fire tests performed in US has been simulated
• FEA software: Abaqus, FE brick DC3D8
• Thermal properties and thermal expansion according EN1993-1-2 for steel
• The proposed σ-ε-Τ model used
• Applied fire curve according the fire test report
![Page 28: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/28.jpg)
Thermal response
![Page 29: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/29.jpg)
Structural response
![Page 30: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/30.jpg)
Structural response
![Page 31: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/31.jpg)
Utilization and critical temperature (γfi=3.0 for cast iron column)
![Page 32: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/32.jpg)
Design buckling resistance
![Page 33: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/33.jpg)
Conclusions -3
• The fire resistance of cast iron columns is higher than steel columns
• The cast iron columns have similar behaviour with steel columns and EC3-1-2 procedures can be used (where fy is the 0.2% proof stress of cast iron)
![Page 34: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/34.jpg)
Moment capacity of cast iron beams exposed to fire
• For cross section analysis, a fiber model developed and verified against FE models
• 4 cross sections studied:
![Page 35: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/35.jpg)
Fiber analysis results
![Page 36: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/36.jpg)
Unprotected sections
![Page 37: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/37.jpg)
Simplified method
Temperature profile can be estimated with use of equations for slim floors (Zacharia and Franssen (2012))
εc and εt from empirical equations
![Page 38: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/38.jpg)
Conclusions -4
• The arch jacked cast iron beams are R60+ in terms of moment capacity
• The EN1993-1-2 can be used for unprotected cast iron beams
• A simplified method which is giving quite accurate results have been proposed
![Page 39: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/39.jpg)
Material safety factors estimation
• For arch jacked cast iron beams (non linear temperature profile)
• A reliability method used for target reliability index 3.8 • 8 random parameters -> statistical/analysis-distribution
-> monte carlo simulation -> randomized σ-ε-Τ relationship
• Calculation of Moment capacity distribution for various cross sections with use of the fiber analysis model
• Material safety factor for fire design of arched jack cast iron beams estimated
• For failure probability 10-1, 10-2, 10-3, 10-4 the corresponding safety factors are 1.5, 2.5, 4.5 and 5.5
![Page 40: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/40.jpg)
Detailed information:
•C. Maraveas, Y.C. Wang, T. Swailes, G. Sotiriadis, An experimental investigation of mechanical properties of structural cast iron at elevated
temperatures and after cooling down, Fire Safety Journal, Vol. 71, 2015, pp 340-352.
• C. Maraveas, Y.C. Wang, and T. Swailes, Fire resistance of 19th century fireproof flooring systems: a sensitivity analysis, Construction and
Building Materials, Vol. 55, pp 69-81, 2014.
• C. Maraveas, Y.C. Wang, T. Swailes, Thermal and mechanical properties of 19th century fireproof flooring systems at elevated
temperatures, Construction and Building Materials, 48: 248-264, 2013.
• C. Maraveas, Y.C. Wang, T. Swailes, Moment capacity of cast iron beams in jack arched construction exposed to fire, Constructional Steel
Research.
•C. Maraveas, Y.C. Wang, T. Swailes , Elevated temperature behaviour and fire resistance of cast iron columns (in preparation)
•C. Maraveas, Y.C. Wang, T. Swailes, Probabilistic determination of material safety factor for cast iron beams in jack arched construction
exposed to fire, CONFAB 2015-The First International Conference on Structural Safety under Fire & Blast, Glasgow, UK.
•C. Maraveas, T. Swailes, Y.C. Wang, Modeling of insulation in 19th century metal framed structures, 2nd International Conference on
Protection of Historical Constructions, Antalya, Turkey, pp 257-261, 2014.
•C. Maraveas, T. Swailes, Y.C. Wang, Sensitivity of fire resistance of 19th century fireproof flooring systems to thermal and mechanical
properties of masonry, 2nd International Conference on Protection of Historical Constructions, Antalya, Turkey, pp 475-481, 2014.
![Page 41: Fire resistance of Metal Framed Historical Structuresfire-research.group.shef.ac.uk/steelinfire/downloads/CM... · 2015-04-29 · Fire Resistance of Metal Framed Historical Structures](https://reader030.vdocument.in/reader030/viewer/2022040303/5e8f9f7574d34034f22676ee/html5/thumbnails/41.jpg)
Thank you!