Rubberised concrete confined with thin-walled steel profiles: a ductile composite for building structures

Tyre components are high-quality materials, which can be utilised and disposed into construction projects. Despite its high ductility and impact resistance, rubberised concrete (RuC) with high rubber content has a strength much lower than that of conventional concrete. Previous research shows that confinement by a jacket material can significantly improve the strength of RuC. This paper presents how infilling RuC to cold-formed steel (CFS) sections improves strength of RuC and local-buckling-resistance of CFS thin-walled sections, resulting composite elements where the advantage of each material cancels out the disadvantage of another. In this research, the composite RuC-CFS elements are developed and tested with the purpose of using them for structural frames with high energy dissipation capacity under extreme loading conditions, while providing resource-efficiency by using lightweight CFS and recycled RuC materials. To enable infilling long steel hollow sections for beams and columns, the experimental RuC mixes are designed for self-compaction (SCC). The results reveal that 35 % rubber content (by volume) and 3 mm thickness of the CFS profile (S275 grade) gives the best performance of the composite by adding 19 % to the capacity of the individual constitute materials.