Preliminary experimental study on prestressed grouted sleeve connection of FRP tubular members under compression

Superior properties of fibre-reinforced-polymer (FRP) composites, such as high specific strength and excellent corrosion resistance, make them as a potential substitute to traditional metallic materials in piping structures. Despite the advantages associated with FRP pipes, their joining methods are still not satisfactory. It is a known fact that joints are the weakest links of such composite piping structures. A new connection method is proposed in this paper, as the prestressed grouted sleeve connection. The connection transmits axial force by shear on the grout and FRP interface. Shear transfer can be enhanced by introducing radial prestress. The prestress is achieved by using an expansive additive (CSA) which expands the grout after setting. This paper investigates the effects of different CSA ratios on the load bearing capacity of the prestressed grouted sleeve connections in compression. It was found pre-load strain developed significantly in hoop direction which indicates the development of radial prestress. Results from compressive experiments indicate that a high CSA ratio enhances the load bearing capacity of the connection. Different failure modes were observed during the compression tests. Possible reasons are discussed based on the interpretation of strain results.