Abstract
Elevators are essential for means of vertical transportation. In recent year, elevators to be installed in high-rise buildings are long stroke, thus the elevator ropes are longer. High-rise buildings have longer natural period than conventional buildings. As elevator ropes become longer, the natural period of the elevator ropes become longer as well, and get closer to the natural period of the building. Consequently, the elevator ropes are hooked to the equipment in the hoistway when the elevator ropes vibrate by an external force, such as a strong wind and earthquake. Secondary damage such as containment of passengers and elevator service stop may occur. It has become a problem. For example, the 2011 off the Pacific coast of Tohoku Earthquake, 2215 cases such as catch and damage of elevator ropes have been reported. However, operations of elevators after earthquakes are required. Therefore, in this research, we aim to design elevator that can be operated even after the earthquakes. Conventional research has confirmed that dividing lift stroke install multiple elevators is effective for reducing the response of the rope. In this method, the lift stroke is equally divided. However, the displacement of the upper elevator becomes larger. Therefore, in this report, we examined the effectiveness of the case of changing the division ratio of lift stroke. The analysis and probabilistic risk assessment, changing the division ratio confirmed that displacement and probability of catching rope of the upper elevator are reduced.
