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JRC report: Choice of steel material for bridge bearings to avoid brittle fracture
The EN Eurocodes are a set of European standards which provide common rules for the design of construction works to check their strength and stability against live and extreme loads such as earthquakes and fire.
With the publication of all of the 58 Eurocodes parts in 2007, the implementation of the Eurocodes is extending to all European countries and there are firm steps towards their adoption internationally. The Commission Recommendation of 11 December 2003 stresses the importance of training in the use of the Eurocodes, especially in engineering schools and as part of continuous professional development courses for engineers and technicians, noting that they should be promoted both at national and international levels.
In light of the recommendation, DG JRC is collaborating with DG ENTR and CEN/TC250 'Structural Eurocodes' and is publishing the report series ‘Support to the implementation, harmonisation, and further development of the Eurocodes’ as JRC scientific and technical reports. Editorial work for this report series is assured by the JRC together with partners and stakeholders when appropriate. The publication of the reports type 3, 4, and 5 is made after approval for publication from the CEN/TC250 Co-ordination Group.
Influence of temperature on toughness and risk of brittle fracture
Due to a significant decrease of toughness properties of structural steel with decreasing temperatures, there is a risk that structural steel components may, under low temperatures, be susceptible to brittle fracture. EN 1993-1-10 provides a method to avoid such brittle fracture by an appropriate choice of steel grade.
The background of this method is a fracture mechanics safety assessment for a particular accident scenario that includes extremely low temperatures, the presence of crack-like flaws at critical hot spots that have grown by fatigue effects, the presence of nominal stresses, and material properties as specified in EN 10025.
The purpose of this report is to adapt the method in EN 1993-1-10 used for normal steel structures to the specific case of steel components of structural bearings that are produced according to EN 1337 and are subject to specific design, fabrication, and installation methods. In this adaptation, the specific shapes of components generally machined from plates, and the particular loading and verification models for the design of the components have been taken into account, so that eventually selection tables as in EN 1993-1-10 could be established. In case a Finite-Element analysis is applied in the design of the components of bearings, the appropriate method to determine the reference stress is a hot spot stress as defined by Dong.
For usual dimensions of bearings, a simplified procedure is offered that refers to nominal values as the surface stress from the linear bending theory.
A worked example illustrates the use of the simplified procedure.
This Joint Research Centre (JRC) scientific and technical report deals with the choice of steel material for the production of bearings to avoid brittle fracture of the steel components of these bearings under low temperature conditions.
This report was initiated by the VHFL-Vereinigung der Hersteller von Fahrbahnübergangen und Lagern für Bauwerke (Association of Producers of Transition Joints and Bearings for Civil Engineering Works).
The objective was to prepare a tool on the basis of the procedure in EN 1993-1-10 – Choice of material to avoid brittle fracture - for normal steel fabrication that allows for the selection of suitable steels for the various components of bearings such that the regulatory requirements for safety under low temperatures are met.
As this JRC report is connected with product standards for bearings - in particular EN1337- it has been prepared in cooperation with experts from CEN/TC 250, CEN/TC 167, and invited metallurgists.
The purpose of this report is to serve as information and guidance and also to be used for the further development of EN 1337 and EN 1993.
This report has been published with the support of the European Convention for Constructional Steelwork (ECCS) which is the federation of the National Associations of Steelwork industries and covers a worldwide network of industrial companies, universities, and research institutes.
ArcelorMittal Europe is a member of ECCS.
© European Union, 2012. Reproduction is authorised provided the source is acknowledged.