SAUFNAY Loris PhD
New production technologies and high performance materials
By contrast with the conveyed image, the construction sector regularly evolves with a constant concern for quality, safety and, of course, for economic efficiency. As a matter of fact, steelmakers are, nowadays, able to produce more resistant steels through more efficient processes. In recent years, the research interest is focused on two particular aspects which are: the impact of new production processes on member stability and the economic benefit in using high strength steel in steel structures.
The first part focuses on the impact of new processes such as the roller-straightening process or the oxy-cutting on the resistance of members. Indeed, such processes may reduce the amplitude of residual stresses at flange tips that could lead to an increase in the column bearing capacity, in particular of the member sensitive to instabilities. However, up to now, these possible positive effects have not yet been deeply studied and still need to be mastered. It is proposed to perform the required investigations within the thesis with the objective of highlighting the possible positive effects of these processes and to propose analytical methods to account for these effects.
The second part focuses on the economic interest in using high strength steels in steel structures. The use of such high strength steels can lead to lighter structures requiring smaller foundations, lower transportation and construction costs and so can result in a global economy on the project. However, the interest in using such steel is not necessarily obvious as phenomena such as buckling, fatigue or deflection requirements considerably limit the advantage of high strength steels. It is for this reason that the designer is sometimes reluctant in using them as, up to now, he has no clear indications when the use of such steels is of interest. Various steel sections subjected to various loading investigations which are regularly met in steel structures will be considered so as to clearly identify the domains for which the use of high strength steels present an economic benefit.
Example of a chart displaying the weight ratio between an optimized solution using “classical” S355 steel and an optimized high strength S500 steel. From this weight ratio, it is then possible to highlight the zone of economic benefit in using S500 steel solutions