Swaged couplers for splicing GFRP reinforcing bars

Abstract

Fiber-reinforced polymer (FRP) reinforcing bars are used as reinforcement in concrete structures mainly due to their non-corrosive property. FRP bars are anisotropic and use a thermoset resin as a matrix to embed the fibers. Lap splicing is the conventional method for connecting or splicing FRP bars; however, it may result in significant construction challenges due to the long development length requirements of FRP reinforcement. Mechanical splices are alternatives where lap splicing is not practical or causes congestion. The lack of an efficient mechanical splice for FRP bars is a limitation for the full deployment of the composite reinforcement in concrete construction. This paper focuses on an experimental investigation conducted on splicing No. 4 (13 mm nominal bar diameter) Glass FRP (GFRP) bars using swaged steel couplers. The investigation only addressed short-term strength and did not cover the durability performance of the coupler. Three types of swaged steel couplers, four splice lengths, and three surface deformations for GFRP bars were studied. The ultimate strength of the spliced GFRP bars, the coupler’s strength, and failure modes were determined by conducting pull-out tests. The test results showed that spliced GFRP bars could achieve up to 97% of the guaranteed tensile strength as per ASTM D7957 when a 102 mm long low-carbon steel coupler is used and a pressure less than 20 MPa is applied for swaging.