Power Attached FRP Technology for Rapid Strengthening of Alabama's Bridges

摘要

The objective of this research is to provide ALDOT with a new low-cost and rapid strengthening technique for bridges. In the proposed technique, pultruted CFRP strips having bearing strength and longitudinal strength and stiffness will be attached to the concrete surface using closely spaced stainless steel Power Actuated Fasteners (PAF). During installation, an FRP strip is placed against the concrete surface, then using a commercially available high power gun the fasteners will be embedded into concrete through the FRP to mechanically attach the CFRP to concrete structure. The increase in strength due to the attached FRP is generated by the composite action where the load will be transferred to the CFRP through the powered actuated fasteners. The advantages of the proposed technique are: (1) Blasting, cleaning and smoothening of the surfaces are not required. (2) The proposed strengthening system can be applied to severely damaged surfaces with large cracks or potholes. Also unskilled workers can perform the proposed strengthening technique. (3) The proposed strengthening technique can applied regardless the moisture condition of the concrete surface and the weather conditions. (4) Concrete members strengthened with the proposed technique will have strength similar to those strengthened with epoxy bonded FRP, except that in the proposed system the increase doesnt depend the integrity of the interface between the FRP and concrete. (5) The proposed strengthening technique can be applied while the bridge is open to the traffic. (6) The proposed strengthening technique is extremely inexpensive with an expected cost of $10/ft2 including materials, labor and equipment. The proposed system can be applied in few hours for large structures. (7) Unlike epoxy bonded FRP, concrete members strengthened with the proposed system will exhibit ductile failure with warning.