effects of bi-directionl loading on ductility capacity of high strength rc piers

It has been observed that considerable simultaneous bi-directional moment and torsion demand is inevitable in the rc piers of curved or skewed bridges. this has resulted in reduction of ductility of the single piers within the nonlinear response in earthquakes. however sufficient data is not available yet on the response of high strength rc (hsrc) piersin such condition. in this research, numerical models of hsrc piers have been developed in abaqus finite element software to study different parameters affecting the ductility of the element during several loading protocols. variation in section and element aspect ratio, concrete characteristic strength, longitudinal reinforcement ratio and transverse reinforcement ratio are considered in the defined samples. cyclic axial and cyclic biaxial lateral loading protocols (diamond & butterfly) simultaneously with torsion were applied in the model.