1. M. Z. Bezas, Th. N. Nikolaidis, C. C. Baniotopoulos
Sustainable Synergies from Buildings to the Urban Scale Thessaloniki, 2016
Fire protection and sustainability of structural steel buildings with double-shell brickwork cladding
M. Z. Bezas, Th. N. Nikolaidis, C. C. Baniotopoulos
address:
SBE16 Thessaloniki

2. Passive fire protection and sustainability
This research work focuses on the sustainability of steel-framed buildings, in the case of a double-shell brickwork cladding, assessed under passive fire protection criteria.
Passive fire protection is critical to the stability and integrity of a steel member exposed to the accidental situation of fire.
The use of fire insulating materials is one of the most common passive protection methods of a steel-framed member (column, beam or diagonal bracing) against fire.
In this work not only the fire insulating materials but the influence of all opaque construction elements of the building’s envelope (bricks, coatings etc.) are considered and evaluated.

3. Passive fire protection and sustainability
More specifically, the passive fire protection of a steel-framed building envelope configurations take into account the bearing capacity of the structural members, the type of the insulation materials, the varying thickness of insulation, the position of insulation, and the type/thickness of the assumed coatings.
And last but not least, it is important during a fire event any passive protection system taken into account in the design of the envelope be adequately maintained.

4. SYNERGY research program
This work focuses some topics of the research that have been done by the research project SYNERGY, Research and development on a system of high energy-efficient building elements, under integrated protection criteria and life-cycle design aspects,
The project where scientific responsible and coordinator was prof. D. Bikas has been elaborated with the collaboration of two Laboratories of the Aristotle University of Thessaloniki and two enterprises:
1. Lab. of Building Construction and Physics, A.U.Th. (Coordinator)
2. Lab. Of Metal Structures, A.U.Th.
3. FIBRAN S.A.
4. TESSERA Multimedia S.A.
It was a holistic approach in designing and evaluating the building elements of new and existing constructions, with regard to their energy, hydrothermal, fire and environmental performance.

5. Sustainability Indicators
In the proposed analysis, three sustainability indicators of a steel-framed building exposed to fire have been taken into account: 1. Safety and resistance of the structure The indicator of impact to the society 3. The indicator of life-cycle aspects to the environmental protection of the used materials to the building’s envelope.

6. Sustainability Indicators
(1. Indicator of the Safety and resistance of the structure )
The 1st indicator of the Safety and resistance of the structure influenced by two different levels of reliability: ) Life safety and no-collapse requirement No-collapse requirement impact means that the structural performance is valuated to avoid local or global failure and collapse ) Design of fire resistance of steel-framed structures with damage limitation This is an evaluation in respect to the limitation of damages and the costs that would be very high in comparison with the costs of the structure itself.

7. Sustainability Indicators
(1. Indicator of the Safety and resistance of the structure )
During a fire event, the load bearing capacity of a steel member decreases
at elevated temperatures.

8. Critical temperatures of steel elements exposed to fire
Eurocode 3.1 proposes reduction factors for the effective yield strength fy,θ and modulus of Elasticity Ea,θ at elevated temperatures, (see Tab. 3.1) The critical temperatures according to the design procedures for a steel members are: a) Temperature of 400οC (red. factor of yield strength ky,θ =1.0) b) Temperature of 600οC (red. factor of yield strength ky,θ ≈0.5)

9. Structural details catalogue
Have been designed under this work an integrated catalogue with numerous constructional details of steel-framed buildings with double-shell brick cladding. (It’s a sub-catalog as part of a general catalogue that has been produced under the framework of the research project "SYNERGY“). The costructional details of this catalogue provide information regarding their fire protection system and materials, thermophysical, hydrothermal and environmental properties. The general scope of this catalogue is to obtain an optimal estimation about the form and position of building materials.

10. Fire-thermal behavior of building materials exposed to fire
- All structural details based on requirements and regulations (Eurocodes) and energy standards (Regulation of Energy Performance of Buildings). - Reduction of thermal bridges for residential buildings Variety of steel-frame element position.

11. Fire-thermal behavior of building materials exposed to fire
Internal side
Internal side
1st case: Column cross-sections configurations of double-shell brickwork cladding with respect to the position of the steel-framed column.

12. Fire-thermal behavior of building materials exposed to fire
Internal side
Internal side
1st case: Column cross-sections configurations of double-shell brickwork cladding with respect to the position of the steel-framed column.

13. Fire-thermal behavior of building materials exposed to fire
Internal side
Internal side
2nd case: Beam cross-sections configurations of double-shell brickwork cladding with respect to the position of the steel-framed beam.

14. Typical fire curve at residential buildings
Fire simulation
In this analysis the performance of steel-framed elements is checked by two fire curves: 1st : The fire curve defined in Eurocode 1, Part nd : The fire curve of an advanced FDS (Fire Dynamic Simulator), using a software simulation. Both fire curves are used to investigate the heat transfer on external shell and the effect of increasing the temperature of the connected with the cladding steel member.
Typical fire curve at residential buildings

15. 1st Fire simulation model is the Eurocode fire curve
It’s a temperature to time fire distribution defined in Eurocode 1

16. 2nd Fire simulation by a development FDS (Fire Dynamic Simulation) fire curve
Is a computational fluid mechanics program which forms a fluid flow model driven by fire and solves numerically a form of Navier-Stokes equations. The fire model is obtained by the numerical solution of the partial differential equations giving, in all points of a compartment, the thermodynamical and aerodynamical variables. The thermal flow guidance is supplemented with data from smoke emissions and heat transfer due to the fire.

17. 2nd Fire simulation by a development FDS (Fire Dynamic Simulation) fire curve
Have been established a common and representative fire compartment with dimensions of 12X5 meters of typical steel building model with residential use.

18. 2nd Fire simulation by a development FDS (Fire Dynamic Simulation) fire curve
Temperature-time fire distribution due to FDS simulation to the top and to the bottom of the fire compartment.

19. Fire simulation – Comparison of both fire curves
Temperature-time fire distribution defined in Eurocode 1 and FDS model

20. Finite element analysis – Model and software
A certain part of a detail including shell in connection with a steel element is discretized and analyzed as a 3-D Finite Element Model using ANSYS computer program under a thermal solution scheme.
3-D FEM model of a typical double-shell brickwork cladding.

21. Finite element analysis – Model and software
Input data in FEM are: 1) all thermodynamic characteristics and properties of the materials 2) geometry of each layer (solid model) 3) conditions of connections between neighbouring layers 4) temperatures-time curve The analysis is parametric and easily can be modified.

22. Finite element analysis – Results for EC fire curve
Internal side
Critical temperature distribution due to fire on a complex structural detail configuration (left) using thermal analysis (right).

23. Finite element analysis – Results for EC fire curve
Using the same model we obtain critical temperature distribution due to fire on a steel member using the thermal analysis (right).

24. 5.2 Finite element analysis – Results for EC fire curve
Internal side
The same thermal analysis for another complex structural detail configuration where the position of the steel member is in the middle of the cladding (left) using thermal analysis (right).

25. 5.2 Finite element analysis – Results for EC fire curve
Using the same model we obtain critical temperature distribution due to fire on the steel member using the thermal analysis (right).

26. Finite element analysis – Results for EC fire curve
Internal side
The same thermal analysis for another complex structural detail configuration where the position of the steel member is in the external side of the cladding (left) using thermal analysis (right).

27. Finite element analysis – Results for EC fire curve
Internal side
Using the same model we obtain critical temperature distribution due to fire on the steel member using the thermal analysis (right).

28. Finite element analysis – Results for FDS fire curve
Internal side
Critical temperature distribution due to fire on a complex structural detail configuration (left) using thermal analysis (right).

29. Finite element analysis – Results for FDS fire curve
Using the same model we obtain critical temperature distribution due to fire on the steel member using the thermal analysis (right).

30. Finite element analysis – Comparison of results with different fire curves
Internal side

31. Finite element analysis – Comparison of results with different fire curves
Temperature-time fire distribution defined in Eurocode 1 and FDS software compared with the temperature of steel element

32. Thank you for your attention!