Lift Guide Rail – Counterweight/Car - Suspension Systems under Seismic Excitations: the Dynamic Behaviour and Protection Measures

Lift systems are susceptible to damage when buildings are subjected to strong earthquake motions. The counterweight - guide rail and car guide rail systems suffer from earthquake-induced vibrations. The most common mode of failure is the counterweight derailment. This paper reviews that dynamic phenomena and presents a model to study, to predict and to mitigate the effects of the seismic responses of guide rail – counterweight/ car – suspension systems. The application of a Tuned Mass Damper (TMD) is a convenient method to reduce the guide rail-counterweight/ car response and to control the system operating under seismic conditions. In the TMD arrangement vibrations of the counterweight/ car can be suppressed and the stresses in the guide rails reduced by the application of an auxiliary spring – damper - mass system attached to the main structure. In the counterweight system a part of the counterweight mass can be used as the auxiliary mass. The performance of the TMD can be improved by the application of an actuator force determined by a suitable feedback control algorithm.