Effects of PVC and CFRP on confinement of reinforced concrete columns under eccentric load

This work presents the empirical research on the confined reinforced concrete columns (CRCC) subjected to eccentricity force. The studying of CRCC using polyvinyl chloride (PVC) and carbon fiber-reinforced polymer (CFRP) is to explain the effect of PVC and CFRP on the bearing capacity and lateral stress of columns under eccentric load. This study was conducted on 2 unconfined circular reinforced concrete columns (control specimens) and 14 circular reinforced concrete columns confined by PVC and CFRP (two specimens for each variable). The diameter and height of the columns are 100 mm and 300 mm, respectively. Three of CRCC are confined by PVC (PVC-CRCC) with 2.5, 3 and 4 mm thicknesses. The rest of them are confined by CFRP laminates and PVC (CFRP-PVC-CRCC) with a constant PVC thickness (2.5 mm) and different numbers of CFRP laminates (2, 3, 4 and 5). According to test results, the PVC-CRCC and CFRP-PVC-CRCC bearing capacity increased in the range of 8–133% depending on the PVC thickness and the number of CFRP laminates. Using of PVC led to improve the lateral confined stress from 2.75 to 4.4 MPa, while the improvement in lateral confined stress which occurred by CFRP varied from 3.7 to 11.8 MPa. The results also showed that PVC-CRCC failed due to the cracking of PVC tubes, whereas cutting and fracturing of CFRP laminates as well as cracking of PVC tubes have been noticed for the CFRP-PVC-CRCC. The prediction of confined stress for PVC-CRCC and CFRP-PVC-CRCC is achieved with good agreement according to the previous literature data and data measured from this study. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2023.