Shear strength model of reinforced concrete beams without stirrup used in the CIS countries

SNiP code is widely used in the so-called Post-Soviet Union or Commonwealth of Independent States (CIS) countries for the structural designs of reinforced concrete (RC) structures. The existing shear strength estimation model specified in SNiP code was initially developed about 90 years ago based on a semi-empirical approach, which means its accuracy and safety level significantly depends on the shear test results available at that time. In this study, a rational modification factor is derived to improve the accuracy of the shear design equation in SNiP code using a current up-to-date large shear database, and the key influencing factors of the shear resistance of RC beams, such as the size effect and tensile strength of concrete, were addressed. To verify the accuracy and safety level of the proposed models, detailed verifications are introduced with comparisons to the six different shear design models used in the international building codes, in which ACI-DAfStb shear database consisting of a total of 784 test results was utilized. According to verification results, the SNiP code model with the new modification factor provided a comparable analytical accuracy and reasonable safety level compared to the current international building code models.