Dynamics of a Multibody Vertical Transportation System Under Seismic Excitation

EasyChair Preprint 13390

Abstract

The frequencies of long period seismic excitations fall within the range of the fundamental natural frequencies of tall structures and buildings. This results in resonance and large responses of the buildings and structures. Their resonance motions affect the modular vertical transportation (VT) systems operating in the buildings. A typical traction-driven VT system comprises a set of long slender continua (LSC) employed as a means of suspension of discrete masses, representing a car / conveyance and counterweight, that can be treated as rigid bodies (RB). Another set of LSC, referred to as compensating cables, is suspended from the beneath of the car to the beneath of the counterweight and is used to reduce, or eliminate the effect of the suspension rope mass transfer. To constrain the loop of the compensating cables a compensator pulley assembly is used. The lengths of the LSC elements vary when the VTS moves vertically within the host structure. Therefore, the natural frequencies of the system vary during the travel. Complex resonance interactions arise when the frequency of the seismic excitation is tuned to one (or more) natural frequencies of the system. In this paper an analytical model to predict the dynamic responses of the multibody VT system under seismic conditions is presented. The model is then used to develop a numerical simulation model to predict the dynamic performance of the system under long-period earthquake excitations. The results demonstrate the interactions of RB responses with the LSC resonance conditions when the frequency of the excitation is tuned to the natural frequencies of the LSC system. These in turn inform the development of resonance mitigating strategies to reduce the effects of the resonance conditions.

Keyphrases: Long period seismic excitations, Nonlinear ODE system, Nonlinear resonance interactions, Tall structures, Vertical transportation systems

@booklet{EasyChair:13390,
  author    = {Stefan Kaczmarczyk},
  title     = {Dynamics of a Multibody Vertical Transportation System Under Seismic Excitation},
  howpublished = {EasyChair Preprint 13390},
  year      = {EasyChair, 2024}}