The modelling and prediction of dynamic responses of slender continua deployed in tall structures under long period seismic excitations

Tall buildings are susceptible to large sway motions when subjected to earthquake excitations. They are particularly affected by long period earthquake ground motions. These low frequency seismic waves resonate with the fundamental mode of the building structure which in turn causes resonance interactions with long slender continua such as lift suspension ropes, compensating ropes and overspeed governor ropes deployed in modular lift installations. Damage due to large resonance motions of suspension/ compensating ropes and cables during earthquake are one of the most common modes of failure in high-rise lift installations. In this paper an analytical model to predict the dynamic responses of suspension/ compensating/ governor rope system installed in tall buildings under seismic conditions is presented. The model is then used to predict the dynamic performance of the system under long period earthquake excitations. The predictions can then be used to develop suitable mitigating strategies and protective measures to minimize the earthquake damage.