Seismic damage analysis of reinforced concrete structures with substandard detailing

The goal of this study is to investigate seismic behaviour of existing R/C buildings designed and constructed in accordance with standards that do not meet current seismic code requirements. In these structures, not only flexure, but also shear and bond-slip deformation mechanisms need to be considered separately and in combination. To serve this goal, a finite element model developed previously by the writers for individual non-ductile beam-column members is extended herein in order to cope with inelastic seismic analysis of complete planar R/C frames. The proposed finite element is able to capture gradual spread of inelastic flexural and shear deformations as well as their interaction in the end regions of R/C members. Additionally, it is capable of predicting shear failures caused by degradation of shear strength in the plastic hinges of R/C elements, as well as pullout failures caused by inadequate anchorage of the reinforcement in the joint regions. The finite element is fully implemented in the general inelastic finite element code IDARC2D. Then, the numerical model is calibrated against experimental data coming from three experimental plane frame structures with non-ductile detailing. It is shown that, in all cases, satisfactory correlation is established between the model predictions and the experimental evidence. The analytical results are in agreement with the experimental values in terms of stiffness, strength and displacement demands. The failure mechanism is predicted accurately for all experimental specimens. Finally, parametric studies illustrate the significance of each deformation mechanism in the seismic response of the experimental frames. It is concluded, that all deformation mechanisms, as well as their interaction, should be taken into consideration in order to predict reliably seismic damage of R/C structures with substandard detailing.