Effects of rotational components of earthquakes on seismic responses of triple concave friction pendulum base-isolated structures

Abstract

In this research, the effects of rotational components of earthquakes on seismic responses of Triple Concave Friction Pendulum (TCFP) base-isolated structures are investigated elaborately. Although it is common to ignore the influence of rotational components of earthquakes on structural analysis, this investigation demonstrates the significant effects of these components on seismic responses of isolated structures mounted on TCFP bearings. Extensive base-isolated structures models with different superstructure specifications such as slenderness and aspect ratios as well as isolation properties such as effective period and damping are investigated. Essential seismic responses such as base shear, roof acceleration, isolator displacement and base slab rotation are studied while isolated structures subjected to the translational components of earthquakes as well as the rotational and translational components of earthquakes simultaneously. The results demonstrate the sensitivity of seismic responses to the superstructure properties such as the slenderness ratio and plan aspect ratio in presence of rotational components; whereas it does not show such sensitivity to isolation properties. Generally, the roof acceleration and the base shear can be affected by the rotational components, tremendously. For instance the roof acceleration can be raised 220% in a structure when its plan length is three times more than its plan width and the base shear can be increased 33% for a 9-story building in presence of rotational components.