Numerical characterization and mathematical modeling of RNC isolator

The results of an extensive series of numerical simulation tests to identify the mechanical characteristics of the recently proposed roll-n-cage (RNC) isolation bearing are presented. Several different configurations of a 1/10 reduced scale prototype are included in a deep parametric study. Cyclic horizontal displacement tests considering varying test parameters of shear displacement amplitude, axial load, and loading frequency were performed. The RNC isolator shear stiffness and damping properties were investigated in terms of the different test parameters. Ultimate level tests consisted of monotonic shear loading up to the maximum displacement limit of the RNC isolator at several different axial loads were performed. The RNC isolator is subjected to a tensile axial load to check its tension capacity. Attempts were done to analytically match the resulting force-displacement relationships using the versatile hysteretic Bouc-Wen model 2 EVACES 2011 – Experimental Vibration Analysis for Civil Engineering Structures finite element formulation by Tsai et al. (2008). Another proposed isolation system consists of high damping rubber bearings strengthened with glass fibre fabrics was studied by Mordini and Strauss (2008) and a wide parametric numerical investigation through finite element analysis was carried out in order to develop and verify analytical models for that isolation device. In this paper, the mechanical characterization of a recently proposed seismic isolation device called roll-n-cage (RNC) isolator, Ismail et al. (2008) and (2009), is performed by means of numerical simulation using an available finite element software. The RNC isolator provides in a single unit all the necessary functions of rigid support, horizontal flexibility with enhanced stability and energy dissipation characteristics. Figure 1 : The 1/10 reduced Scale RNC isolator.