Investigation of HFRC columns reinforced with GFRP bars and spirals under concentric and eccentric loadings

There is a lack of experiments and finite element analysis (FEA) on the structural behavior of glass fiber-reinforced polymer (GFRP) reinforced concrete columns with hybrid fibers. The main objective of the current study is to investigate and compare the structural performance of GFRP-reinforced concrete columns with hybrid fibers (GHC columns) and steel-reinforced concrete columns with hybrid fibers (SHC columns) confined with spirals and subjected to concentric and eccentric loading by performing experiments and the finite element modeling (FEM). Steel fibers (SF) and polypropylene fibers (PF) were used together to develop the hybrid fiber reinforced concrete (HFRC). Six GHC circular columns and six SHC circular columns were fabricated having a cross-sectional dimension of 250 mm and a height of 1150 mm. ABAQUS 6.14 was used for the FEA of the columns by using a modified concrete damage plastic (CDP) model for HFRC. The results from the present work depicted that both types of columns (GHC and SHC columns) show similar failure modes. The average axial strength of GHC columns was 91.32% of the axial strength of SHC columns. The GHC columns presented higher ductility (up to 19.71%) compared with SHC columns. The eccentric loading caused a significant reduction in the axial strength of columns. The newly developed theoretical equation performed well over the experimental results. The comparative study solidly substantiates the validity and applicability of the newly developed theoretical and FEA models for capturing the axial strength of GHC columns by considering the axial involvement of longitudinal GFRP bars and the confinement effect of transverse GFRP spirals.

Automated summary

The study compared the structural performance of GFRP-reinforced concrete columns and steel-reinforced concrete columns with hybrid fibers under concentric and eccentric loading, finding that GHC columns exhibited higher ductility and similar ultimate bearing capacity compared to SHC columns.