Experimental study of the flexural response of steel beams strengthened with anchored hybrid composites

• The performance of steel beams strengthened with anchored GFRP-CFRP laminates is investigated.
• Increasing the length of the FRP leads to slight improvement in the yield moment of the beam.
• Increasing the length of the FRP results in significant enhancement in the ultimate capacity.
• Increasing the thickness of the FRP leads to considerable increase in the load carrying capacity.
• Enough number of anchors should be used to connect FRP laminates and steel for optimum performance.

This paper proposes an innovative technique for flexural strengthening of steel beams using a special type of drillable fiber reinforced polymer laminates. The utilized laminates are hybrid carbon–glass fiber (CFRP–GRFP) pultruded strips that provide both high tensile and high bearing strengths. The current study explores experimentally the potential enhancement in the flexural capacity of steel beams strengthened with mechanically anchored CFRP–GFRP laminates. The experimental program involves flexural testing of eleven full-scale beams under three-point loading. The influence of various strengthening parameters including length and thickness of FRP laminates, and number of anchoring bolts on the behavior is investigated. The experimental results reveal that increasing length and/or thickness of the FRP laminates improves the ultimate capacity of the strengthened sections. Strengthened beams are shown to exhibit ductile response associated with high deflection if adequate number of anchors is used. Otherwise, a brittle failure takes place because of shear failure in the anchors connecting FRP laminates to the steel beam.