This paper investigates axial and flexural behaviour of circular reinforced concrete (RC) columns strengthened with reactive powder concrete (RPC) jacket and fibre reinforced polymer wrapping. The experimental results of 16 circular RC column specimens have been presented. The specimens were divided into four groups of four specimens. Column specimens of the first group were the reference RC specimens without any strengthening, specimens of the second group were strengthened by wrapping with two layers of carbon fibre reinforced polymer (CFRP), specimens of the third group were jacketed with a 25 mm thick layer of RPC and specimens of the fourth group were jacketed with a 25 mm thick layer of RPC then wrapped with a single layer of CFRP. Test results demonstrated that jacketing with a thin layer of the RPC enhanced significantly the ultimate axial and flexural loads as well as energy absorption of circular RC column specimens. Wrapping the RPC jacketed specimens with CFRP improved the ultimate axial load, ductility and energy absorption of the specimens.

Mechanical properties of steel, glass, and hybrid fiber reinforced reactive powder Mechanical properties of steel, glass, and hybrid fiber reinforced reactive powder concrete concrete

This paper presents a new strengthening technique for square-reinforced concrete (RC) columns by circularisation with reactive powder concrete (RPC) and wrapping with fibre-reinforced polymer (FRP). RC column specimens were tested, divided into four groups of four specimens based on the strengthening technique: four reference square specimens (150mm side length) without any strengthening, four were wrapped with two layers of carbon fibre-reinforced polymer (CFRP) and the remaining eight were strengthened by changing the square cross-section to a 240mm diameter circle with RPC jacket. Four of the RPC jacketed specimens were left unwrapped, while the last four were wrapped with two layers of CFRP. From each group, one specimen was tested under concentric axial load, two were tested under eccentric axial load and one was tested under four-point bending. It was found that using the RPC for circularisation and strengthening of existing square RC columns is an effective technique to significantly increase their axial carrying capacity, ultimate flexural load and energy absorption. Wrapping the circularised RC columns with CFRP prevented the failure of the RPC jacket at the corners of the existing square RC columns under the axial load, and improved the ultimate load as well as the energy absorption of the circularised RC columns.

No abstract

Cross-sectional analyses of circular and square reinforced concrete (RC) columns strengthened with reactive powder concrete jacketing and fibre-reinforced polymer (FRP) wrapping were undertaken. The stress block method was used to determine theoretical axial load–bending moment (AL–BM) interactions of the columns. These were then compared with experimental results and found to be in very good agreement. A parametric study was also undertaken to investigate the most important factors that influence the AL–BM capacity of circular and square strengthened columns. Finally, a group of theoretical AL–BM interactions for circular and square strengthened columns was produced. These can be used in a wide range of applications for strengthening RC columns with high-performance concrete jackets and FRP wraps.