Seismic Response of Double Concave Friction Pendulum Base-Isolated Structures Considering Vertical Component of Earthquake

The current investigation has been conducted to examine the effect of vertical component of earthquake on the response of base-isolated structures using double concave friction pendulum (DCFP) system. The structure is idealized as a three-dimensional single-story building resting on a DCFP system. The coupled differential equations of motion are derived and solved in the incremental form using Newmark's step-by-step method of integration. Based on these equations, a computer program was developed to study the influence of vertical component of earthquake on the seismic response of isolated structure using DCFP system. To facilitate the investigation, an error function was defined and effect of various structural parameters on this function was studied under Tabas 1978, Northridge 1994 and Kobe 1995 earthquakes motions. The effect of vertical component of earthquake on the peak values of bearing displacement and base shear of the isolated structure is studied using the variation of essential parameters such as isolation period, superstructure period and friction coefficient of sliding surfaces. It is demonstrated that the maximum error caused by neglecting the vertical component of earthquake in determining the peak bearing displacement and base shear of the structure is 5 and 22 percent, respectively.