Experimental Investigation of an FRP Wind Turbine Blade for use as a Bridge Girder

Fiber reinforced polymer (FRP) composite materials have been used in a variety of civil and infrastructure applications since the early 1980s including in wind turbine blades. The world is now confronting the problem of how to dispose of decommissioned blades in an environmentally sustainable manner. One proposed solution is to repurpose the blades for use in new structures (www.re-wind.info). One promising repurposing application is in pedestrian and cycle bridges. This paper reports on the experimental investigation conducted on a wind blade to be used in the construction of a bridge for a greenway in Cork, Ireland in late 2021. Two LM 13.4 blades originally manufactured by LM Windpower (Kolding, Demark) will be utilized as girders for the bridge. A detailed reverse-engineering investigation of the as-received, previously used, blade was conducted to obtain material and structural properties for use in the structural design of the bridge. The material tests included physical (volume fraction and laminate architecture) and mechanical tests (tension and compression) at multiple locations. Full-scale testing of a section of the blade was performed to determine the load carrying capacity and the failure modes when loaded in flexure similar to that which will be experienced in the bridge. Key details of the testing conducted and the results are provided. The results of the testing revealed that the FRP material is still in excellent condition and that the blade has the strength and stiffness in flexure to serve as a bridge girder for the bridge to be constructed.