Ductility in high performance concrete structures : an experimental investigation and a theoretical study of prestressed hollow core slabs and prestressed cylindrical poles

Abstract: The thesis presents results from a project dealing with ductility in high performance concrete structures. The main objectives were to investigate the material and structural ductility/brittleness of prestressed structural elements of High Performance Concrete (HPC). The aim was to get a better understanding of the fracture process and to study sudden and brittle failures formed by shear stresses. The project was split into three parts: (I) Torsion of cylindrical pole elements, (II) Shear, torsion and bending of hollow core slabs, and (III) Shear, torsion and bending of cylindrical pole elements. Laboratory investigations were performed and displacements were carefully studied. The test results were compared with different code models and especially with the Modified Compression Field Theory(MCFT) proposed by Collins & Mitchell (1991). A computer program based on MCFT was written to calculate the interaction between shear, torsion and bending. One conclusion is that structures made of HPC can be as ductile as structures made of normal strength concrete. Another conclusion is that the strain-based modified compression field theory can represent failure processes in a correct way with good results.