Transient Dynamic Computation for Mega-High Rise Lifts

The megatrend of urbanization brings new challenges for the lift industry; the need for keeping the travel time short may conflict with the demand for safety and comfortable ride. In the case of a mega-high building, the performance of the lift system can be substantially affected by the response of the building to various excitation, such as strong winds. This paper focuses on the prediction of in-car vibrations for a specific lift configuration with various running parameters in the event of building sway, using a chain of multi-physic computation. The core of the computation is a direct transient dynamic finite element method where user subroutines were developed to accommodate installation accuracy in a range of millimetres for a travel in the range of 500 - 1000 m. Aerodynamic loads were considered by using a transient fluid dynamic computation. Behaviour of ropes while the lift is in motion with different building sway parameters and speed profiles were computed using a finite difference method. The computational results were validated in no-sway conditions and the computational method was used for predicting the in-car behaviour during sway conditions. The advantage of this approach is that the dynamics of the entire structure can be analysed for every lift component: car, sling, roller, roller’s stopper; for the entire travel and for different running parameters. This provides the opportunity of optimizing – for example – the lift speed, based on the targeted ride comfort class and lift system performance in various sway conditions. Finally, to demonstrate the one possible usage of this calculation method, the results of the multiphysic computation were combined with traffic analysis and the probability of various excitations to assess the long-term implication to the lift system performance. As a result, an enhanced sway operation of the elevator was developed, for which an optimized car speed profile was proposed instead of traditional high wind mode. Although no major improvement of handling capacity on a yearly level could be noticed, the service provided to lift users for highly windy days, will not go unnoticed.