| Resumo: |
The main objective of this project is the development of sustainable, innovative composite and highly efficient structural solutions achieved through the combination of concrete made of recycled rubber with high strength structural steels. According to the European Tire Recycling Association, it is estimated that about 300.000.000 scrap tires reach their end-of-life each year in the 27 member states of the European Union. It is reported that only 30% of these tires are recycled into recovered materials and the remaining 70% have already accumulated in uncontrolled stockpiles. Waste tire stream represents therefore a significant environmental, human health and aesthetic problem. Solutions must therefore be developed to solve this problem. One leading sustainable solution is to use shredded rubber chips and crumb rubber to modify concrete. Laboratory tests have shown that the introduction of waste tire rubber increases toughness, impact resistance, and plastic deformation of concrete, offering a significant potential for the concrete to be used in sound-crash barriers, retaining structures and pavements. However, almost all research studies have identified a considerable decrease in concrete strength. In some cases, strength became so low that concrete lost its ability to carry any meaningful structural load, making it impossible to use it alone in structural members. The present project envisions the use of waste tire rubber modified concrete encased by steel tubes, thus solving the lower strength problem of rubberized concrete, using it in primary load carrying structures, and increasing the sustainability of composite structures. In addition, replacing plain concrete by rubberized concrete would lead to enhanced ductile behaviour of steel-concrete composite columns, a major advantage for seismic resistant structures.
Probably, one of the most successful composite structural systems is the concrete-filled steel tubular (CFST) column. In CFST columns, the steel t  |
Resumo
The main objective of this project is the development of sustainable, innovative composite and highly efficient structural solutions achieved through the combination of concrete made of recycled rubber with high strength structural steels. According to the European Tire Recycling Association, it is estimated that about 300.000.000 scrap tires reach their end-of-life each year in the 27 member states of the European Union. It is reported that only 30% of these tires are recycled into recovered materials and the remaining 70% have already accumulated in uncontrolled stockpiles. Waste tire stream represents therefore a significant environmental, human health and aesthetic problem. Solutions must therefore be developed to solve this problem. One leading sustainable solution is to use shredded rubber chips and crumb rubber to modify concrete. Laboratory tests have shown that the introduction of waste tire rubber increases toughness, impact resistance, and plastic deformation of concrete, offering a significant potential for the concrete to be used in sound-crash barriers, retaining structures and pavements. However, almost all research studies have identified a considerable decrease in concrete strength. In some cases, strength became so low that concrete lost its ability to carry any meaningful structural load, making it impossible to use it alone in structural members. The present project envisions the use of waste tire rubber modified concrete encased by steel tubes, thus solving the lower strength problem of rubberized concrete, using it in primary load carrying structures, and increasing the sustainability of composite structures. In addition, replacing plain concrete by rubberized concrete would lead to enhanced ductile behaviour of steel-concrete composite columns, a major advantage for seismic resistant structures.
Probably, one of the most successful composite structural systems is the concrete-filled steel tubular (CFST) column. In CFST columns, the steel tube enhances the compressive strength and ductility of the concrete by providing continuous confinement in addition to acting as formwork. The concrete core enhances the overall capacity of the column by providing stability against inward local and overall buckling of the steel tube. Nowadays, the use of CFST columns is extensive in regions of high seismicity, where structures are expected to exhibit high energy dissipation capacity.
With the recent emergence of innovative production technologies, new materials for engineering applications have been developed. Nowadays, high performance concrete and high strength steel are widely disseminated in construction. However, the design codes for composite structures did not follow this path as the design rules currently prescribed in EC4 are applicable only to composite members made of typical steel grades and concrete classes. It is thus mandatory that design codes are updated in order to prescribe design rules for composite columns made of high performance materials. A large number of experimental and numerical research studies have been performed in the last decade in order to overcome this code limitation. Most of these works considered different types of steel in combination with several types of concrete. The scientific community has been focused on the characterisation of the stiffness and strength of CFST columns. However, few studies have been conducted on the characterisation of the cyclic behaviour of CFST columns with innovative materials, which is essential for a reliable consideration of this type of structural members in seismic resistant structures.
The major objective of this project proposal is the development of sustainable and innovative CFST columns with improved ductility for use in regions of high seismicity. The scope of this project is the characterization of the monotonic and cyclic behaviour of rubberized CFST columns through experimental testing and numerical modelling. |