Load bearing behavior of concrete encased composite columns with high‐performance materials

The use of steel‐concrete composite columns, such as concrete‐encased steel columns have increased in the construction of high‐rise buildings and longspan structures. In particular, the use of high‐performance materials in composite columns is expanding, enabling optimisation of the column dimensions, theultimate load capacity, improve economic design and resource efficiency. However, high‐strength concrete shows a more brittle behaviour compared to normal concrete compression strength classes that may limit the development of plastic strains in the encased steel section. In addition concrete spalling is a serious issue that may become decisive for the determination of the ultimate resistance. Therefore, to extend the design methods for composite columns using high‐performance materials, the ideitified knowledge gaps need to be filled. For this reason an experimental campaign has been performed consisting of nine concrete‐encased steel composite column test specimens; five specimens with circular and four with rectangular cross‐sections. The testing campaign was carried out in a 20 MN servo‐hydraulic universal testing machine at the Ruhr‐Universität Bochum.

Abaqus^® FEM software has been used to develop numerical models able to reproduce the behavior of the tested specimens. The comparisons of the experimental and numerical results show a very good correlation. The numerical analysis enable more detailed understanding of the tests results and behavior of the columns.