2.1. Test specimens
A total of 27 circular CFFTs, including 15 SFRHSCFFTs, 3
HSCFFTs, 3 SIFCONFFTs and 3 unreinforced SIFCONFFTs were
manufactured and tested under axial compression. In addition,
27 unconfined control specimens, with the same materials and
geometric properties to the CFFTs they were companion to, were
tested to establish the mechanical properties of unconfined concretes.
The specimens were 152.5 mm in diameter, measured at
the concrete core, and 305 mm in height. The test parameters
included: type of concrete (i.e., SFRHSC or SIFCON), shape of steel