Brittle fracture: Selection of steel sub-grade to BS EN 1993 1-10

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This page is about the following publication:

  • Brittle fracture: Selection of steel sub-grade to BS EN 1993 1-10
  • Authors:
    • D. G. Brown & T. C. Cosgrove
  • ISBN: 978‑1‑85942‑224‑3
  • Year: 2017

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SUMMARY

Brittle fracture and the selection of a steel sub-grade are covered by BS EN 1993 1-10. The UK National Annex makes various modifications, where allowed, to the Eurocode. The provisions of the UK National Annex are implemented and presented in PD 6695‑1‑10, which contains straightforward look-up tables of limiting thickness.

The scope of the Eurocode includes structures where fatigue is a design consideration, noting that the limiting thicknesses may be conservative for structures where fatigue is not a significant design consideration. The definitive background document to the Eurocode confirms that the limiting thicknesses may be “extremely safe-sided” if used for non-fatigue structures.

In an effort to reduce the declared conservatism for structures where fatigue is not a design consideration – so called quasi-static structures – this guide follows the procedures, based on fracture mechanics, which were used to develop BS EN 1993‑1‑10, but modifies the contribution from fatigue. The result is increased values of limiting thickness which are appropriate for quasi-static structures.

Section 1 provides a very basic introduction to fracture mechanics. Section 2 demonstrates the process used to develop the limiting thickness data provided in BS EN 1993‑1‑10. Section 3 describes the simple modification to the calculation process in order to develop limiting thicknesses for quasi-static structures. Section 4 describes the important adjustments imposed by the UK National Annex and Section 5 presents the results of those adjustments with tables of limiting thicknesses for use in the UK.

Numerical examples of the calculation process are presented in the Appendix.

For structures where fatigue is not a design consideration, the limiting thicknesses presented in Section 3 may be used as a substitute for the values given in Table 2.1 of BS EN 1993-1-10. For construction in countries other than the UK, it is very important that the relevant National Annex is consulted to identify any effect on these values. For construction in the UK, the limiting thicknesses presented in Section 5 may be used.

The guidance in this guide is limited to quasi-static structures, in which fatigue is not a design consideration. For other structures, the guidance in BS EN 1993-1-10 and the relevant National Annex should be followed.

CONTENTS

FOREWORD

SUMMARY

1 BRITTLE FRACTURE – INTRODUCTION

1.1 Fracture mechanics
1.2 Basic concepts
1.3 Eurocode procedures for sub-grade selection
1.4 Evaluation using fracture mechanics

2 DEVELOPMENT OF EUROCODE GUIDANCE

2.1 Detail types
2.2 Crack size
2.3 Crack growth
2.4 Stress intensity factor
2.5 Limiting temperature, TEd
2.6 Numerical example

3 GUIDANCE FOR QUASISTATIC STRUCTURES

3.1 Modified calculation process
3.2 Numerical example – quasi-static structures
3.3 Modified thickness limits

4 UK NATIONAL ANNEX PROVISIONS

4.1 UK NA adjustments
4.2 Modified thickness limits for use with quasi-static structures and the UK NA

5 IMPLEMENTATION OF THE UK NA PROVISIONS FOR QUASI-STATIC STRUCTURES

6 BIBLIOGRAPHY

7 REFERENCES

8 CREDITS

APPENDIX A - NUMERICAL EXAMPLES

A.1 Example from BS EN 1993-1-10, for an element subject to fatigue
A.2 Modified example for quasi-static structures
A.3 Application of the UK National Annex provisions applied to quasi-static structures