Dynamic response control of multi-story structures by isolators with multiple plane sliding surfaces: A parametric study

Recently, a type of simple and cost effective sliding isolator, namely the uplifting sliding bearing (UPSS), had been developed for ensuring the seismic performance of multi-span continuous bridges. The objective is to control the large horizontal displacement of the conventional rubber bearings using this new sliding device which has a high potential in reducing the horizontal displacement due to the uniqueness of its geometrical configuration. The UPSS device consists of multiple sliding surfaces connected together, based on the PTFE and SUS interface; one horizontal and two inclined surfaces. This paper aims to investigate the efficiency of using the multiple-slider bearing based on the concept of UPSS to isolate multi-story shear type structures. The principles of operation and force displacement relationship for the isolator are introduced. The seismic behavior of the base isolated building by the multiple-slider bearing subjected to seismic excitation is investigated, comparing with conventional rubber bearing and pure friction slider isolating systems. Moreover, extensive parametric investigations are performed in order to achieve an optimum performance of the isolator with respect to three main properties which define the device: clearance length, the inclination angle and the friction coefficient. The results show the effectiveness of the multiple-slider bearing in minimizing the damage from earthquakes. The multiple-slider bearing proves to have a high potential in minimizing the effect of the ground displacement pulses through its operation mechanism and its unique feature that permits the use of different set of friction coefficients on each sliding surface. In addition, a principle to define the optimum value of the friction coefficient is developed.