Stress-Strain Behaviour of Confined Rubberised Concrete

Large reinforced concrete (RC) structures can be subjected to significant lateral loads and deformations. To prevent the development of large moments, highly deformable and high strength elements can be utilised, such as elastomeric bearings. These elements are currently expensive and not as durable as the structure itself. Extensive research carried out at The University of Sheffield propose a novel and cost-effective alternative solution, which is utilising FRP-confined rubberised concrete (CRuC).
Since the determination of deformation in RC depends on knowledge of the stress-strain characteristics, this research aimed to develop a comprehensive understanding of the stress-strain behaviour of CRuC and develop effective modelling methods that can be used for the development of high-strength high-deformability concrete elements.
Notched three-point bending tests are used to characterise the Mode I fracture behaviour of rubberised concrete (RuC). Test result shows that rubber particles enhance energy absorption capacity and ductility of concrete. The tensile stress-strain curves of RuC are obtained through inverse finite element analysis.
The compressive behaviour of CRuC in circular and non-circular sections is examined experimentally under uniaxial compression. Test results show that the confinement effectiveness in RuC elements is better than in regular concrete. An analytical model is proposed based on a new definition of the effective confinement area.
The shear behaviour of CRuC is assessed by axisymmetric four-point bending tests. Test results indicate that CRuC shows ductile and stable performance that allows the development of high shear deformations. By adopting a nonlinear numerical approach for the practical implementation of the smeared, fixed-angle crack approach in finite element analysis, the shear response of CRuC can be correctly predicted.
The experimental results support the idea that CRuC can be effectively used to develop highly ductile RC structural components for deformable elements and structures located in high seismicity regions. The proposed constitutive relations and models provide the necessary information for the development of design tools.