experiment set-up Urheberrecht: © STB

Efficient Lifting Equipment with Extra High Strength Steel

Short description

The overall objective of the "Efficient lifting equipment with extra high-strength steel" (LiftHigh) research project was to obtain improved utilisation of extra high-strength steels, in this context defined as steels with yield strengths in the interval 460 to 1 100 MPa, and thereby expand the limits for structural steels available for crane manufacturers as well as for other applications. The work within the project included actions focusing on fatigue resistance, resistance to global and local buckling, and the development of methods for advanced design with non-linear FEM. A specific aim of the project was to show that the use of extra high-strength steel makes it possible to obtain a 20 to 40 % reduction in weight for a given function. This aim is in accordance with the desire amongst crane users, indicated by an enquiry at the beginning of the project, that decreased crane weight should be the first priority for future development. The final report presents examples of how to use FEM for design as well as examples of the redesign of an existing trolley structure and a telescopic boom. Some of the conclusions show that it is possible to achieve substantial weight reduction by using extra high-strength steel. In the examples the weight reductions were 38 % and 18 %. Investigations focused on global and local buckling and gave no indication that the design models already in use, for instance in EN 1993-1-5, for steels with regular yield strengths cannot be applied also for high-strength steels with yield strength up to 1 100 MPa. However, as regards welded plates, the design rules in EN 1993-1-5 seem to slightly overestimate the resistance (if the modified slenderness is greater than ~ 0.9). For fatigue, it was concluded that the investigated steel grades fit the detail categories given in EN 1993-1-9 and can be classified as good as mild steels although, for some details, differences appear in the calculated slope of the S-N curves. Nevertheless, it has to be mentioned that with the same stress variation range, the fatigue loads of high-strength steels can be applied on a correspondingly higher level than is possible for mild steels. This fact does not arise from the classification in detail categories, as it is carried out in EN 1993-1-9.

Research program

RFCS - Research Fund for Coal and Steel


Luleå University of Technology - Division of Structural Engineering-Steel Structures - Sweden

CETIM - Centre Technique des Industries Mécaniques - France

Universität Karlsruhe (TH) - Versuchsanstalt für Stahl, Holz und Steine - Germany

Liebherr-Werk Ehingen - Germany

SSAB Oxelösund - Sweden

Duration of project

07/2002 - 06/2005