No abstract

The wide use of cold-formed sections (CFS) in the field of steel constructions, favored by the multiple advantages they offer (lightness, ease of installation, etc.), has led us to reflect on a new process for manufacture of metal beams allowing the design of very large span hangars and a reduction in instability problems. This paper presents a study of the theoretical and numerical behavior of a large span CFS beam with different webs, a solid web, a triangular corrugated web, and a trapezoidal corrugated web. These beams are stressed by a concentrated bending load at mid-span. Numerical modeling was done using the finite element software ABAQUS. The results were validated with those theoretically found, based on the effective width method adopted in standard EN1993-1-3. The load capacity and failure modes of the beams were discussed. According to numerical and analytical analysis, corrugated web beams perform better than all other sections.

Le béton à hautes performances (BHP) est un béton innovant largement utilisé dans la construction moderne. De nouvelles techniques de formulation et de conception du HPC ont permis d'obtenir des performances mécaniques et une durabilité remarquables par rapport au béton conventionnel. Les principaux avantages du HPC sont liés à sa faible porosité, sa très haute résistance mécanique et son excellente durabilité. La facilité d'application du HPC est obtenue par l'utilisation combinée de superplastifiant et d'ajout de minéraux, ce qui se traduit par une augmentation significative de la résistance à la compression tout en améliorant la maniabilité et la durabilité. L'utilisation d'un liant ternaire (ciment, fumée de silice et laitier granulé de haut fourneau broyé) dans la fabrication du HPC est une nouvelle avancée dans la construction durable qui offre des avantages économiques, techniques et écologiques. L'objectif de ce travail de recherche était d'améliorer les propriétés physico-mécaniques du HPC à base de liant ternaire en étudiant l'influence du remplacement du ciment par du laitier granulé et des fumées de silice. Les résultats des tests mécaniques montrent que les performances du HPC réalisé avec ces liants ternaires sont similaires au HPC témoin sans laitier granulé. Enfin, il est conclu que l'utilisation de tels liants est très bénéfique pour diminuer les problèmes environnementaux et améliorer la durabilité du HPC.

The valorization of local by-products in the manufacture of a new range of sand concrete and the improvement of their properties, will lead to seek an arrangement between performance and cost in order to achieve a resistant material. Waste recycling affects two very important affect namely the environmental impact and the economic impact. The main objective of our work is to contribute to optimize the formulation of sand concrete as part of the recovery of waste, which is harmful to the environment given its bulky and unattractive nature, it is waste plastic. Most PET bottles become waste after use, causing environmental problems. To solve this problem, a method for recycling PET bottles as fibers to strengthen concrete is proposed. Two types of plastic waste are added to sand concrete; the first concerns the recycling of post-consumer bottles in PET, in the form of polyester fiber supplied by the company RET-PLAST and the second type concerns the packaging belts made of polyethylene terephthalate (PET). The properties in the fresh state (workability and density) and in the hardened state (compressive strength, tensile strength and water absorption) of the various produced concretes are analyzed and compared against their respective controls. From the experimental results, it can be concluded that the reinforcement of the cement matrix with PET fibers with a rate of 1% improves the mechanical properties of sand concrete as well as a remarkable decrease in its water absorption capacity.