Loris Saufnay

In recent years, significant production improvements have been observed in the field of steel structures allowing for a constant increase in the yield strength and consequently for a reduction in the weight of structures. However, considering the required production techniques for high‐strength steels, which are sometimes more demanding in terms of energy as well as more demanding in terms of alloy content, the manufacturing cost generally increases with the yield strength. Accordingly, designers and engineers are sometimes reluctant to consider higher steel grades as they do not know in which cases their use presents an economic benefit. Evaluating reliable relative prices for higher grades is seen as a necessity to realise a prospective study and prove their economic benefit but, looking to the literature, only a few publications address this topic. Thus, this article aims to establish relative price‐strength relationships for different section typologies to help practitioners in choosing cost‐effective steel grades for their applications. These investigations are based on previously available producer price lists to establish relative price intervals for existing and future emerging steel grades. The results of this article demonstrate the base price dependency and the key features which govern the relative prices and thus the economic benefit of such grades.

This paper presents the results of 10 laboratory tests performed on closely spaced built-up members fabricated from hot-rolled angle sections. Such members are of special interest in the construction and reinforcement of steel lattice towers used for telecommunication or electrical transmission lines. The angle sections used in this study were star-battened with pinned support conditions. In particular, two configurations were studied: star-battened angles with equal sections (SBE) (composed of two chords with the same section), and star-battened angles with unequal sections (SBU) (composed of two chords with different sections). The influence of connection spacing along the members and different types of connections (fully preloaded bolts, partially preloaded bolts) were also studied. In addition, the important influence of geometric imperfections on failure load and failure mode were analyzed. In this paper, a numerical model is introduced after the laboratory tests are presented. The model was built in ANSYS version 18.2 and was validated based on the results obtained during the experimental campaign. The numerical results highlighted the sensitivity of failure modes to initial imperfections (out-of-straightness, load eccentricity). Last, the validated numerical model is thought to be used in a wider parametric study with the aim of developing new design recommendations.

The present work aims at studying the field of interest of high strength steel rolled sections (f_y>460 MPa) for steel structures from an economic point of view. Whilst these high strength steel profiles do not exist yet, steelmakers are able to produce more resistant steels through more efficient production processes and a future emerging of these particular steel profiles is likely to occur. The use of this kind of steels can lead to a significant material saving. So, the use of high strength steel leads to lighter structures requiring smaller foundations, lower transportation and construction costs but also emitting less CO₂. However, buckling, fatigue or deflection requirements often reduce the advantage of high strength steels. It is for this reason that the designer is sometimes reluctant to use them. A study establishing the areas of economic benefit of high strength steel tubes in steel and composite structures had already been carried out at the University of Liège [8]. The goal of the present is to extend this study to rolled sections (H‐shape and I‐shape). It therefore consists in providing methods in order to help the designer determining the economic benefit of high strength steel for structural elements subjected to different loadings. These ones are then used to determinate the areas of economic benefit of the high strength steels in comparison to regular steel, depending on their relative costs.