Axial performance of hybrid fiber reinforced concrete columns having GFRP longitudinal bars and spirals

The literature is deficient in the investigation of the structural behavior of hybrid fiber reinforced concrete (HFRC) columns having GFRP longitudinal bars and spirals. This research study has been performed to explore the behavior of GFRP-reinforced concrete (RC) columns consisting of hybrid fibers (GHC columns) and to compare them with the steel-RC columns consisting of hybrid fibers (SHC columns) constrained with spirals and exposed to various loading conditions. A total of six (6) GHC circular specimens and six (6) SHC circular specimens were manufactured having 250 mm diameter and 1150 mm height. The experimental results revealed that the GHC columns have low axial strength (AS) than SHC columns by 8.68% but GHC columns presented higher ductility than SHC columns by 19.71%. Both GHC and SHC specimens presented similar failure modes. The eccentric loading led to a substantial loss in the AS of all columns. A theoretical analysis was also performed to propose a new equation for the AS of GHC columns by comparing it with the previous models. It was concluded from the theoretical analysis that the AS of GHC columns can be accurately predicted by assuming the axial influence of GFRP bars and the transverse confining mechanism of GFRP spirals.

Automated summary

The study investigated the behavior of GFRP-reinforced concrete columns with hybrid fibers, comparing GHC columns with SHC columns in terms of axial strength and ductility. It was found that GHC columns had lower axial strength but higher ductility compared to SHC columns, with both showing similar failure modes. Eccentric loading led to significant decrease in axial strength of all columns. A theoretical analysis proposed a new equation for predicting the axial strength of GHC columns based on the influence of GFRP bars and confining mechanism of GFRP spirals.