Comparative analysis of EC2-04 and ACI318-19 strength provisions for reinforced concrete beams under pure torsion

While the EC2-04 and ACI318-19 provisions use almost the same philosophy to evaluate the torsional strength of reinforced concrete beams, some important details and limitations in these two approaches differ greatly. The objective of the present study is to investigate the differences between these codes and their accuracy by how well they estimate the torsional strength of experimentally tested beams. The predicted torsional strengths based on EC2-04 and ACI318-19 approaches were compared with the results of 120 tested reinforced concrete beams under pure torsion. The inclination angle of the concrete compression struts of the idealized space truss model is chosen to be equals to 45°. It was observed that the ACI318-19 approach is more conservative than the EC2-04 approach in predicting the torsional strength of the tested beams. The graphical comparisons of the predicted to tested torsional strength ratios shows that the EC2-04 approach gives approximately normal distribution curve with a peak at a strength ratio of about 0.85. (paper)