Efficiency of GFRP bars and hoops in recycled aggregate concrete columns: Experimental and numerical study

To develop a sustainable environment and to alleviate the problems of the large annual production of construction and demolition waste, the recycled aggregate concrete (RAC) has been used in the columns reinforced with glass fiber reinforced polymer (GFRP) bars. This study explores and compares the structural behavior of GFRP reinforced recycled aggregate concrete columns (GRAC columns) and steel bars reinforced recycled aggregate concrete columns (SRAC columns) under concentric and eccentric loadings. 18 circular concrete columns having a diameter of 250 mm and a height of 1150 mm were manufactured from which 9 samples consisted of GFRP reinforcement and the other 9 samples consisted of steel bars. The test measurements portrayed that the GRAC columns showed lower axial strength (up to 7.79%) with higher ductility indices (up to 4%) compared with SRAC columns. Both GRAC and SRAC columns showed similar failure modes and cracking patterns. Furthermore, both GRAC and SRAC columns presented significant reductions in the axial strength due to the loading eccentricities. The present study proposed a three-dimensional nonlinear finite element model (FEM) for predicting the structural response of GRAC and SRAC columns using ABAQUS 6.14. The simulation of RAC was carried out using a modified concrete damaged plasticity (CDP) model and that of GFRP bars was carried out using a linear elastic model. A theoretical model for predicting the axial strength of GRAC columns was given based on a large database of 270 GFRP reinforced concrete columns. The close agreements were observed among the experimental results, numerical simulations, and theoretical predictions for GRAC columns.

Automated summary

Through experimentation and simulation analysis of GFRP-reinforced recycled aggregate concrete columns and steel-reinforced recycled aggregate concrete columns, it was found that while GFRP-reinforced columns have lower axial strength, they exhibit higher ductility indices. There is good consistency observed among the experimental results, numerical simulations, and theoretical predictions for GRAC columns.