Study on the fatigue performance of GFRP connectors in sandwich insulated composite wall panels

To study the fatigue performance of the anchorage between GFRP connectors and concrete, a sandwich insulation composite wall panel with GFRP connectors was designed and fabricated. Static tensile tests and tension-compression fatigue tests under constant amplitude loads were conducted on it. This study investigates the fatigue life characteristics, failure progression mechanisms, failure mode classifications, and tension-compression stiffness evolution of specimens under cyclic loading with upper amplitude limits of 0.4 F y , 0.6 F y , 0.8 F y (where F y denotes the ultimate bearing capacity). A fatigue damaged model of sandwich insulation composite wall panel with GFRP connectors is proposed based on stiffness degradation. The results indicate that the failure mode of the specimen under uniaxial tension is characterized by the pull-out failure of the connector from the concrete slab. When the load amplitude upper limit increases from 0.4 F y to 0.8F y , the fatigue life is reduced by 54.7 %. Compared with the initial stiffness, the stiffness in the first stage is degraded by 15.7–42.1 %; and the stiffness in the second stage is degraded by 82.4–88.9 %. In the derived three-stage fatigue damage model, the fatigue times in each stage account for 7 %, 87 %, and 6 % of the fatigue life respectively. This model can characterize the damage degree of sandwich insulation composite wall panel with GFRP connectors under different loading times.