Influence of seismic orientation on the statistical distribution of nonlinear seismic response of the stiffness-eccentric structure

This research presents the influence of varying seismic orientations on the statistical distribution of nonlinear seismic response considering a numerically validated stiffness-eccentric structural model. Firstly, the experimental results were utilized for the validation of the numerical model. The experimental results were obtained through shaking table test where stiffness-eccentric reinforced concrete (RC) structure was exposed to progressive seismic excitations. The asymmetric structure experienced inelastic deformations under high seismic excitations, which eventually caused the transformation of the structure from a state of elastic deformation to a state of highly inelastic deformation. The experimental observations were compared with numerical illustrations for each stage of the seismic excitation from elastic to in-elastic state of the structure. Then, based on the validated numerical models, the numerical investigation was extended for nonlinear seismic response under varying seismic orientations. Seismic responses of the flexible and stiff edges of the stiffness-eccentric structure were compared under varying seismic excitation to present the influence of asymmetry, response variability and their statistical distribution. The results were further investigated from seismic uncertainty viewpoint to evaluate the response variability and design shortcomings. It has been concluded that the stiffness-eccentric structures are more sensitive towards the rotational seismic response as compared to the translational seismic response. Similarly, the relative rotational response at the stiff edge of the structure proved to have more response variability than the flexible edge of the structure under varying seismic orientations.