Size effect in high strength concrete beams

Recent research has identified size, longitudinal reinforcement and concrete compressive strength as significant factors influencing the shear behaviour of slender concrete beams. However, there are distinct differences in the treatment of factors in shear models developed by several research groups. Some research groups utilize an effective crack spacing parameter, consisting of aggregate size and member depth considerations, to represent size effect, while others adopt a depth parameter with varying exponentials. Furthermore, some models do not include a size effect parameter. Research has also indicated that the shear capacity model utilized in the current ACI 318-08 Code provide unconservative predictions for large slender lightly reinforced concrete members without stirrups, but conservative predictions for deep beams. Moreover, the ACI shear equation is limited to the use for concrete members with concrete strength equal or below 68.89MPa. To modify these problems in the ACI shear provisions, a new shear strength equation was developed through statistical analysis of previous experimental data for the formation of size effect, longitudinal reinforcement and concrete compressive strength parameters. The proposed equation was compared with ACI 318 Code, Eurocode 2, Canadian Code, Kim and Park’s equation, Lubell’s equation, and Cladera and Mari’s equation.Bachelor of Engineering (Civil