Compressive membrane action in FRP strengthened RC members

- We propose a prediction model for FRP-strengthened RC beams when considering CMA.
- We examine effects of properties of FRP laminate, steel bar and concrete on CMA.
- CMA can effectively enhance the load bearing capacity of FRP-plated RC beams.
- Increasing area of FRP and steel bar will increase CMA effect.
- Increasing strength and ultimate strain of concrete will increase CMA effect.

This study focuses primarily on examining the compressive membrane action (CMA) in FRP (fibre reinforced polymer) strengthened reinforced concrete (RC) beams or one-way slabs. Considering a rigid-plastic mechanism, in combination with strain compatibility and force equilibrium, a model is proposed to predict the load bearing capacity of FRP strengthened RC members when considering CMA. Comparison with experimental tests proves the proposed model to be realistic and effective. A parametric study has been undertaken and an enhancement factor was used to qualify the CMA effect in FRP strengthened RC members. The parameters include the properties of FRP, steel reinforcement and concrete, and the span to depth ratio. The results indicate that CMA can effectively enhance the load bearing capacity of FRP strengthened RC members. Results also indicate that the effect of CMA increases with the increase of FRP area, steel reinforcement ratio, strength and ultimate strain of concrete but decreases with increasing span to depth ratio.