Abstract: The behaviour of torsionally coupled structures isolated using a Multiple-variable frequency pendulum system (MVFPI) is discussed (Recently developed advanced friction base isolator). Because of the constant isolator period and restoring force features of the friction pendulum system (FPS), this MVFPI overcomes these restrictions. Most presently available methods, such as the friction pendulum system (FPS) and the pure friction (PF) system, however, have practical limits and are ineffective when the input excitation level differs greatly from the design level. A novel technology dubbed the multiple variable frequency pendulum isolator (MVFPI) has been designed to address these constraints while maintaining the benefits. To integrate the seismic performance of MVFPI with varied seismic intensities, the sliding surface of MVFPI was specified as a continuous piecewise function. Newmark's step-by-step technique is used to construct and solve the governing equations of motion of the building-isolation system, assuming linear acceleration change over tiny time intervals. In this research, six pairs of near-fault ground movements are used as input ground motions. The response ratio between the peak responses of the torsionally linked structure with and without the MVFPI is used to measure the efficiency of the base isolation utilizing the MVFPI. For chosen earthquake ground movements, the coupled lateral-torsional response is calculated using various parameter modifications. Furthermore, a parametric investigation of MVFPI-isolated structures was compared to FPS. The parametric study's numerical findings aid in understanding the torsional behavior of the MVFPI-isolated structure. The MVFPI is proven to perform much better than the FPS in terms of reducing base shear and torque responses. Also square model has been compared with rectangle model for different parameters.

Keywords: Multiple-variable frequency pendulum system, base isolation, near-fault ground motion, asymmetric building, eccentricity ratio, the torsional coupling, uncoupled time period.

| DOI: 10.17148/IARJSET.2022.9591