Stress-strain model for spiral confined fibre reinforced high strength concrete columns

摘要

A stress-strain model has been developed for steel fibre reinforced high strength concrete confined by circular spirals. The proposed model incorporates all the relevant parameters of spiral confinement and steel fibres. To calibrate the model, an experimental study was carried out involving concentric testing of steel fibre reinforced high strength concrete short columns confined by circular spirals under monotonically increasing compression. A total of 72 confined and 4 unconfined specimens were tested under this test program. The test variables included aspect ratio and volume fraction of crimped steel fibres and volumetric ratio and yield strength of transverse spiral reinforcement in addition to volumetric ratio of longitudinal steel and concrete strength. The contribution of steel fibres towards strength and ductility improvements of confined concrete has been included in the proposed model by defining an equivalent fibre confinement index.