Structural Fire Performance of Steel Portal Frame Buildings (KET0060)

Structural Fire Performance of Steel Portal Frame Buildings

Contents

1. Introduction

1.1 Steel Portal Frame Buildings in New Zealand

1.2 Impetus for the research

1.3 Objectives of this research

1.4 Scope of this research

1.5 Organisation of this report

2. Literature review

2.1 Introduction

2.2 Design Codes and Standards

2.2.1 New Zealand Building Code

2.2.2 Approved Document for New Zealand Building Code

2.2.3 Building Code of Australia

2.2.4 Steel Structures Standard NZS 3404

2.2.5 Concrete Structures Standard NZS 3101

2.2.6 New Zealand Loading Code NZS 4203

2.2.7 Australian/New Zealand Loading Standard AS/NZS 1170.0

2.2.8 Revision of the Concrete Structures Standard NZS 3101

2.2.9 Eurocode

2.3 Behaviour of Steel Portal Frames and Concrete Walls subjected to elevated temperatures

2.3.1 Steel Portal Frames

2.3.2 Concrete Walls

2.3.3 Connections between Wall Panels and the Supporting Structure

3. Properties of materials at elevated temperatures

3.1 Introduction

3.2 Properties of Structural Steel at elevated temperatures

3.2.1 Components of Strain

3.2.2 Thermal Strain, WK
3.2.4 Stress-UHODWHG 6WUDLQ
3.3 Steel Mechanical Properties in SAFIR

3.3.1 Ambient Properties of Steel

3.3.2 Steel Properties at elevated temperatures

3.4 Steel Thermal Properties in SAFIR

3.4.1 Thermal Conductivity, D

3.4.2 Specific Heat, ca

3.4.3 Thermal Elongation, ¨OO

3.5 Steel Structures Standard NZS 3404:1997

4. Behaviour of industrial buildings and concrete walls in fires

4.1 Introduction

4.2 Industrial Buildings in New Zealand

4.2.1 Typical Industrial Buildings

4.2.2 Recent Industrial Buildings

4.2.3 Connections between Tilt-up Walls at vertical joints

4.2.4 Connections between Tilt-up Walls and Roof

4.3 Fires in Industrial Buildings

4.3.1 Small Enclosure Fire

4.3.2 Large Compartment Fire

4.3.3 Fire Concepts

4.4 Behaviour of Industrial Buildings at elevated temperatures

4.4.1 Structural Fire Behaviour by Newman (1990)

4.4.2 Structural Fire Behaviour by O’Meagher et al. (1992)

4.4.3 Structural Fire Behaviour by Lim (2000)

4.4.4 Structural Fire Behaviour by Wong et al. (2000) and Wong (2001)

4.5 Concrete Walls

4.5.1 Thermal bowing

4.5.2 Behaviour of Concrete Walls at elevated temperatures

4.5.3 External Concrete Wall Design Considerations

4.5.4 FIREWALLS

4.6 Design of Connections between Concrete Walls and Supporting Structure

4.6.1 Design Philosophy adopted in Australia

4.6.2 Design of Connections in New Zealand

4.7 Connection Details at Column Base

4.8 Reports of Fire Incidents in Warehouse and Industrial Buildings

4.8.1 Real Fire Incidents

4.8.2 Spalling

5. Analysis method

5.1 Introduction

5.2 SAFIR

5.2.1 Introduction

5.2.2 Analysis Procedure

5.2.3 Beam Element

5.2.4 Sign Conventions

5.2.6 Common Features in all Analyses

5.3 The New Version of SAFIR (SAFIR 2004)

6. Design of building according to NZS 4203:1992 and NZS 3404:1997

6.1 Introduction

6.2 Building Description

6.3 Load Cases according to NZS 4203:1992

6.4 Design of Purlin and Brace Channel

6.5 Design of Steel Portal Frame

7. Modelling of parts of the steel portal frame building

7.1 Introduction

7.2 Cross Sections of the Steel Elements

7.2.1 Discretisation of the Sections

7.2.2 Thermal Analysis

7.3 Gravity Load

7.4 Structural Analysis

7.4.1 2D Analysis of the Frame (2D Frame)

7.4.2 3D Analysis of the Frame with no Purlins (3D Frame)

7.4.3 3D Analysis of the Purlin with no Lateral Restraint

7.4.4 Purlins supported on Fully Fixed Beams

7.4.5 Two Bay Portal Frame Structure

7.4.6 Conclusions

8. Fire analysis of the whole building

8.1 Introduction

8.2 Description of the Analytical Models

8.3 Location and Severity of Fire

8.3.1 Results of Analyses

8.3.2 Discussion

8.4 Eurocode External Fire

8.4.1 Results of Analyses

8.4.2 Discussion

8.5 Out-of-plane Restraints to Columns

8.5.1 Results of Analyses

8.5.2 Discussion

8.6 Passive Fire Protection to Columns

8.6.1 Results of Analyses

8.6.2 Discussion

8.7 Partially Fixed Frames

8.7.1 Results of Analyses

8.7.2 Discussion

8.8 Other Analyses

8.8.1 Geometrical Imperfection

8.8.2 Half of the Building exposed to the fire

8.9 Further Discussion on the Steel Connections between the Side walls and the Supporting Frames

8.10 Summary

8.11 Conclusions

9. Conclusions and recommendations

9.1 Introduction

9.2 The Building

9.3 SAFIR

9.4 Fire Analysis of the Whole Building

9.4.1 Axial Restraint of Purlins

9.4.2 Support Conditions at the column base

9.4.3 Location and Severity of Fire

9.4.4 Out-of-plane Restraints to Columns

9.4.5 Passive Fire Protection

9.4.6 Eurocode External Fire

9.5 Design Recommendations

9.6 Recommendations for future research

10. REFERENCES

APPENDIX

Appendix A Bending Moment Diagrams

Appendix B Axial Force Diagrams

Appendix C Load-displacement curves for Purlin without lateral restraint under cold conditions

Appendix D Load-displacement curves for Purlin without lateral restraint under hot conditions