1st Edition

Designing Steel Structures for Fire Safety

Edited By Jean Marc Franssen, Venkatesh Kodur, Raul Zaharia Copyright 2009

    Structural design in fire conditions is conceptually similar to structural design in normal temperature conditions, but often more difficult because of internal forces induced by thermal expansion, strength reduction due to elevated temperatures, much larger deflections, and numerous other factors. Before making any design decisions it is essential to establish clear objectives, and determine the severity of the design fire. The art and science of designing structures for fire safety has grown considerable in recent years, accompanied by the development of sophisticated codes of practice such as the Eurocodes. The Eurocode documents now represent the best international consensus on design rules for structures exposed to fires. Similarly, codes and standards in the US and the rest of the world are being updated with rational design provisions for evaluating fire resistance of structures. One such example is the recent introduction of rational fire design approach in the latest edition of the American Institute of Steel Construction's steel design manual.

    Designing Steel Structures for Fire Safety provides guidance for those wishing to apply rational engineering methodologies for fire design of steel structures. Codes alone do not provide enough information for structural design, especially as they become more sophisticated and comprehensive. This book provides background material and serves as a design guide for the user. It should help the reader not familiar with the topic to make calculations of the fire resistance of steel structures according to the Eurocodes or other code provisions. The theoretical, technical or historical background is provided when this helps the user to understand more clearly the calculation methodologies, while examples on simple elements and guidance showing how a complete structure can be analyzed are included.

    Designing Steel Structures for Fire Safety is a major new contribution to the wider understanding of structural behavior in fires, and will be invaluable to professionals  in civil engineering and architecture, students or teachers in these disciplines, and building officials and regulators in all regions of the world.

    1.1 Fire safety design
    1.2 Codes and standards
    1.2.1 General
    1.2.2 Fire safety codes
    1.2.3 North American codes and standards
    1.2.4 European codes: the Eurocodes
    1.3 Design for fire resistance
    1.3.1 Fire resistance requirements
    1.3.2 Fire resistance assessment
    1.3.3 Eurocodes
    1.3.4 Scope of Eurocode 3 - Fire part
    1.4 General layout of this book

    2.1 Fundamental principles
    2.1.1 Eurocodes load provisions
    2.1.2 American provisions for fire design
    2.2 Examples
    2.2.1 Office building
    2.2.2 Beam for a shopping centre
    2.2.3 Beam in a roof
    2.3 Specific considerations
    2.3.1 Simultaneous occurrence
    2.3.2 Dead weight
    2.3.3 Upper floor in an open car park
    2.3.4 Industrial cranes
    2.3.5 Indirect fire actions
    2.3.6 Simplified rule

    3.1 Fundamental principles
    3.1.1 Eurocode temperature-time relationships Nominal fire curves Equivalent time Parametric temperature–time curves Zone models Heat exchange coefficients
    3.1.2 Eurocode localised fire, flame not impacting the ceiling
    3.1.3 Eurocode localised fire, flame impacting the ceiling
    3.1.4 CFD models in the Eurocode
    3.4.5 North American time-temperature relationships
    3.2 Specific considerations
    3.2.1 Heat flux to protected steelwork
    3.2.2 Combining different models
    3.3 Examples
    3.3.1 Localised fire
    3.3.2 Parametric fire–ventilation controlled
    3.3.3 Parametric fire–fuel controlled

    4.1 General
    4.2 Unprotected internal steelwork
    4.2.1 Principles
    4.2.2 Examples Rectangular hollow core section I-section exposed to fire on 4 sides and subjected to a nominal fire I-section exposed to fire on 3sides
    4.3 Internal steelwork insulated by fire protection material
    4.3.1 Principles
    4.3.2 Examples H section heated on four sides H section heated on three sides
    4.4 Internal steelwork in avoid protected by heat screens
    4.5 External steelwork
    4.5.1 General principles
    4.5.2 Example

    5.1 Level of analysis
    5.1.1 Principles
    5.1.2 Boundary conditions in a substructure or an element analysis
    5.1.3 Determining Efi,d 0
    5.2 Different calculation models
    5.2.1 General principle Tabulated data Simple calculation models Advanced calculation models
    5.2.2 Relations between the calculation model and the part of the structure that is analysed
    5.2.3 Calculation methods in North America
    5.3 Load, time or temperature domain
    5.4 Mechanical properties of carbon steel
    5.5 Classification of cross-sections
    5.6 How to calculate Rfi,d,t ?
    5.6.1 General principles
    5.6.2 Tension members
    5.6.3 Compression members with Class 1, 2 or 3 cross-sections
    5.6.4 Beams with Class1, 2 or 3 cross-section Resistance in shear Resistance in bending Uniform temperature distribution Non-uniform temperature distribution Resistance to lateral torsional buckling
    5.6.5 Members with Class 1, 2 or 3 cross-sections, subject to combined bending and axial compression
    5.6.6 Members with Class 4 cross-sections
    5.7 Design in the temperature domain
    5.8 Design examples
    5.8.1 Member in tension Verification in the load domain Verification in the time domain Verification in the temperature domain
    5.8.2 Column under axial compression Fire resistance time of the column with unprotected cross-section Column protected with contour encasement of uniform thickness
    5.8.3 Fixed-fixed beam supporting a concrete slab Classification of the section, see Table 5.2 Verification in the load domain Verification in the time domain Verification in the temperature domain Beam protected with hollow encasement
    5.8.4 Class 3 beam in lateral torsional buckling

    6.1 General
    6.2 Simplified procedure
    6.3 Detailed analysis
    6.3.1 Temperature of joints in fire
    6.3.2 Design resistance of bolts and welds in fire Bolted joints in shear Bolted joints in tension Fillet welds Butt welds

    7.1 General
    7.2 Introduction
    7.3 Thermal analysis
    7.3.1 General features
    7.3.2 Capabilities of the advanced thermal models
    7.3.3 Limitations of the advanced thermal models
    7.3.4 Discrepancies with the simple calculation models
    7.4 Mechanical analysis
    7.4.1 General features
    7.4.2 Capabilities of the advanced mechanical models
    7.4.3 Limitations of the advanced mechanical models
    7.4.4 Discrepancies with the simple calculation models

    8.1 General
    8.2 Continuous beam
    8.3 Multi-Storey moment resisting frame
    8.4 Single storey industrial building
    8.5 Storage building

    I.1 Thermal properties of carbon steel
    I.1.1 Eurocode properties
    I.1.1.1 Thermal conductivity
    I.1.1.2 Specific heat
    I.1.2 Thermal properties of steel according to ASCE
    Thermal conductivity
    Specific heat
    I.2 Thermal properties of fire protection materials
    I.3 Temperatures in unprotected steel sections (Eurocode properties)
    I.4 Temperatures in protected steel sections (Eurocode properties)

    II.1 Eurocode properties
    II.1.1 Strength and deformation properties
    II.1.2 Thermal elongation
    II.2 ASCE properties
    II.2.1 Stress strain relations for steel (Version 1)
    II.2.2 Stress strain relations for steel (Version 2
    II.2.3 Coefficient of thermal expansion

    Subject index


    Venkatesh Kodur, Jean Marc Franssen, Raul Zaharia