RockRebar® Design Considerations
Recommendations for maximum deflection and shear of concrete elements reinforced with fiber reinforced polymer (FRP) rebar are presented in ACI 440.1R-06 (2006), Guide for the Design and Construction of Structural Concrete Reinforced with FRP Bars. Generally, the design methodology for FRP-reinforced concrete members follows that of steel reinforcing, however designing concrete structure to exploit the non corrosive and light weight attributes of FRP reinforcement must take into account the linear elastic or non-ductile nature of these material by using an FRP material reduction factor, and controlling the stress and strain at the serviceability limits for a given structure. RockRebar® mechanism for failure being either rupture of the reinforcement itself or crush of the concrete.
A direct substitution of RockRebar® into a concrete structure that was designed for steel rebar may not always be possible. While RockRebar® is several times stronger than steel it may be necessary to redesign the size and placement of RockRebar® within the concrete member in order to mitigate potential for excessive deflection of the panel or beam. A RockRebar® reinforced concrete structure should be designed to accommodate its required strength, keeping in mind that the stress-strain relationship exhibited by all FRP reinforcements is different than that of steel.
RockRebar® is based on continues basalt fiber reinforced epoxy polymer BFRP. As such exhibits linear stretch up to failure. In compliance with the ACI 440.1R-06 (2006) all FRP reinforced concrete elements including RockRebar® should be engineered so that sustained stress is kept below 25% of its guaranteed tensile strength. The physical strength of RockRebar® rods from 4 mm to 25 mm diameters rods change as the diameter goes up, with smaller diameter rods generally having higher tensile strength.