Fatigue behavior of adhesively connected pultruded GFRP profiles

Fatigue experiments on adhesively connected pultruded profiles were performed in a laboratory environment. The first objective was to determine if fatigue limits exist and if so, how their magnitude is compared to real shear stress amplitudes in GFRP bridge structures subjected to fatigue loads. A further objective was to evaluate measurement methods with respect to a possible detection of damage initiation and progression. For the investigation, a symmetric full-scale double-lap connection geometry was chosen in order to eliminate scale effects and to minimize peeling stresses. The experiments showed a fatigue limit at about 25% of the static failure load at 10 million cycles. This corresponds to an average shear stress amplitude in the connections of 2.0 MPa. This value can remain far above average shear stress amplitudes due to fatigue loading in adhesive connections of GFRP bridges. During the experiments, damage initiation and progression were not detected with the chosen set-up. Failures always occurred in a very brittle manner without warning in the adherents. Keywords