The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Mechanical Properties of Structural Steels at High Temperatures and After Cooling Down

Jyri Outinen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Civil and Environmental Engineering for public examination and debate in Auditorium R1 at Helsinki University of Technology (Espoo, Finland) on the 20th of April, 2007, at 12 noon.

Overview in PDF format (ISBN 978-951-22-8608-9)   [789 KB]
Dissertation is also available in print (ISBN 978-951-22-8605-8)

Abstract

Behaviour of mechanical properties of different steel grades at elevated temperatures need to be well known to understand the behaviour of steel and composite structures in fire. Quite commonly simplified material models are used to estimate the structural fire resistance of steel structures. In more advanced methods, for example in finite element or finite strip analyses, it is important to use accurate material data to obtain reliable results.

To study thoroughly the behaviour of certain steel structure at elevated temperatures, one should use the material data of the steel obtained by testing. Extensive experimental research has been carried out in the Laboratory of Steel Structures at Helsinki University of Technology in order to investigate mechanical properties of several structural steels at elevated temperatures by using mainly the transient state tensile test method.

In this thesis a collection of test results of the behaviour of mechanical properties of different steel grades at elevated temperatures is presented with analysis of the test results. The tests have been carried out at Helsinki University of Technology during the past about 12 years. The aim of these tests has been to evaluate the accuracy of existing design values for the mechanical properties of structural steel and to support other different research projects aimed at studying the behaviour of steel or composite structures in fire.

The results are presented with a comparison to the European design standard (EN1993-1-2) for structural fire design of steel structures, which is already the officially accepted standard in the EU countries and certainly will be largely in use in the near future. The results are quite well adopted and referred in other different research projects. The main aim of this research was to provide results to other researchers and design engineers in the field of structural fire engineering to improve structural fire safety in the future.

This thesis consists of an overview and of the following 8 publications:

  1. Outinen J., Kesti J., Mäkeläinen P., Fire design model for structural steel S355 based upon transient state tensile test results, Journal of Constructional Steel Research, Vol. 42, No. 3, pp. 161-169, Elsevier Science Ltd, 2/1997. © 1997 Elsevier Science. By permission.
  2. Mäkeläinen P., Outinen J., Kesti J., Fire design model for structural steel S420M based upon transient-state tensile test results, Journal of Constructional Steel Research, Vol. 48, No. 1, pp. 47-57, Elsevier Science Ltd, 8/1998. © 1998 Elsevier Science. By permission.
  3. Mäkeläinen P., Outinen J., Mechanical properties of an austenitic stainless steel at elevated temperatures, Journal of Constructional Steel Research, Vol. 46, Nos. 1-3, pp. 455, Elsevier Science Ltd, 2/1998. Full paper published in the Proceedings of the Second World Conference on Steel Construction, San Sebastián, Spain, 1998. © 1998 Elsevier Science. By permission.
  4. Outinen J., Kaitila O., Mäkeläinen P., A study for the development of the design of steel structures in fire conditions, Proceedings of the 1st International Workshop on Structures in Fire, Copenhagen, Denmark, 2000, pp. 267-281. © 2000 by authors.
  5. Outinen J., Mäkeläinen P., Effect of high temperature on mechanical properties of cold-formed structural steel, Puthli R., Herion S. (editors), Tubular Structures IX, Proceedings of the Ninth International Symposium and Euroconference on Tubular Structures, Düsseldorf, Germany, 3-5 April 2001, A.A. Balkema Publishers, The Netherlands, 2001, pp. 439-444.
  6. Outinen J., Mäkeläinen P., High-temperature strength of structural steel and residual strength after cooling down, M. Ivanyi (editor), Proceedings of the International Colloquium on Stability and Ductility of Steel Structures, Budapest, Hungary, 2002, Budapest University of Technology and Economics, pp. 751-760.
  7. Outinen J., Mäkeläinen P., Mechanical properties of structural steel at elevated temperatures and after cooling down, Fire and Materials, Vol. 28, Nos. 2-4, pp. 237-251, John Wiley & Sons, 2004.
  8. Outinen J., Mechanical properties of structural steel at elevated temperatures and after cooling down, Proceedings of the 10th International Fire and Materials Conference, San Francisco, USA, 29-31 January 2007, Interscience Communications Limited, 2007, Delegates handbook, pp. 125-126, full article in included CD. © 2007 Interscience Communications. By permission.

Keywords: fire, steel structures, material testing, high-temperature testing, transient state, mechanical properties, elevated temperatures

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© 2007 Helsinki University of Technology

Last update 2011-05-26