Integration of CFRP strips as an internal shear reinforcement in reinforced concrete beams exposed to elevated temperature

In this study, an innovative application was implemented in which CFRP strips were integrated as internal shear reinforcement for reinforced concrete beams. The intent was to assess the CFRP strips' contribution to the shear strength and thus evaluate the effectiveness of using them as main or supplemental shear reinforcement before and after exposure to elevated temperature. Internal application of CFRP strips does not require an epoxy for attaching them, as they can be cut without difficulty to any width/length and then attaching them to the main steel bars. Similar to the steel shear stirrups, the CFRP strips work integrally with the beam concrete and steel reinforcement as the concrete confines them. The proposed technique applies only to new reinforced concrete (RC) elements and not as retrofitting existing members' strategy. Instead, externally bonded CFRP strips represent a popular strategy for structural retrofitting purposes. The investigated parameters include the area and number of layers of CFRP strips and different elevated temperatures. By demonstrating an outstanding structural performance with significant enhancement in the ultimate strength, ultimate deflection, stiffness, and toughness, this paper's findings strongly attest that CFRP strips can be effectively utilized as internal shear reinforcement in reinforced concrete beams exposed to elevated temperatures. A new guideline is proposed for predicting the damage level and shear strength of heated damaged RC beams internally reinforced with CFRP composites taking into consideration the influence of the number of CFRP strips and elevated temperature