Behaviour of Concrete Sandwich Wall Panels in Flexure Using a Novel GFRP Shear Connector
This thesis examines the structural effectiveness of a new concrete sandwich panel with a shear connector made of glass fibre reinforced polymer (GFRP) pultruded channel sections intended to enhance composite action and flexural rigidity while minimizing thermal bridging. The flanges of the channel section are embedded in either wythe. Five half-scale panels (610x280x3050 mm) were tested in four-point bending, varying the connector configuration and type as well as the wythe reinforcement ratio. The connectors investigated were a continuous GFRP channel, a discrete GFRP channel consisting of multiple segments spaced apart and a control conventional steel truss. Ancillary push-off single shear tests were conducted on 500 mm long wall segments to examine GFRP shear strength and bond strength by varying boundary conditions. The panels with continuous and discrete GFRP channels achieved 2.8 and 1.3 times, respectively, the ultimate strength of that with a steel truss. The continuous GFRP channel contributed 59% of the total flexural capacity of the wall. As the wythe steel reinforcement ratio increased from 0.17 to 0.68% the ultimate load of panels with continuous GFRP channels increased by 33%. Failure modes were compressive flange crushing for the panels with continuous GFRP channel, web shear for the panel with discrete channel, and rupture of bottom wythe reinforcement for the panel with steel truss. An analytical model was developed in RESPONSE-2000 to evaluate the degree of composite action achieved by the GFRP shear connector. Both peak loads for theoretical fully composite and non-composite sections increased by 23%, as reinforcement ratio increased from 0.17 to 0.68%. Peak loads for specimens with discrete connector or truss connector were both only 45% and 20% of their fully composite and non-composite counterparts with a continuous connector. Specimens with continuous GFRP channel as shear connector exhibited higher degree of composite action (average of 38%) than the truss connector (32%). The GFRP-concrete bond strength was tested experimentally and was 0.28 MPa and the longitudinal shear strength of the channel was tested and found to be 39 MPa.