Structural Behavior of GFRP-Reinforced Circular HFRC Columns Under Concentric and Eccentric Loading

The previous research is rich in plain concrete columns reinforced with glass fiber-reinforced polymer (GFRP) bars, but it is deficient in GFRP-reinforced concrete columns incorporating hybrid fibers. The present study aims to explore and compare the structural behavior of steel and GFRP-reinforced concrete columns having hybrid fibers (SHFC and GHFC columns). Two types of fibers, i.e. steel fibers and polypropylene fibers, were used to develop the hybrid fiber-reinforced concrete. A total of 18 circular concrete columns (9 SHFC columns and 9 GHFC columns) having a height of 1150 mm and a diameter of 250 mm were constructed and tested under axial loading at various eccentricities. The test measurements portrayed that the SHFC columns presented a better performance in terms of axial strength (about 20% higher) and ultimate deflections. The GHFC columns presented higher ductility indices compared with SHFC columns. Both steel and GHFC columns showed similar failure modes and similar reductions in the axial strength when subjected to eccentricities. The newly developed empirical model for the prediction of the axial strength of GHFC columns showed a close agreement with the experimentation. Thus, the comparative study solidly substantiates the application of the proposed empirical model.

Automated summary

This study compares the structural behavior of steel-reinforced concrete columns and GFRP-reinforced concrete columns with hybrid fibers, showing that SHFC columns have better axial strength and ultimate deflections while GHFC columns exhibit higher ductility indices. The failure modes and reductions in axial strength under eccentricities are similar between steel and GHFC columns. The newly developed empirical model for predicting the axial strength of GHFC columns shows close agreement with experimental results, supporting the proposed model's application.