Fundamental Study on Rope Vibration Suppression by Middle Transfer Floor using Risk Information

Lifts are essential for means of vertical transportation. Recently, the lifts installed in the high-rise buildings are long travel, thus the lift ropes are becoming longer. The natural period of the high-rise buildings is longer than that of the conventional buildings [1] and in addition to the lift rope becoming longer, the natural period of the lift ropes has also become longer. Accordingly, the natural period of the lift ropes gets closer to the that of the building. Consequently, the lift ropes might be hooked to the equipment of wall when the lift ropes vibrate by an external force, such as a strong wind or an earthquake. Furthermore, secondary accidents such as containment of passengers and lift service stop may occur. In the 2011 Great East Japan Earthquake, over 2000 problems such as the catch and the damage of lift ropes were reported [2]. Operation of lifts after earthquakes is required for the security of the refuge course. Accordingly, the analytical method for comparative evaluation is investigated in this study. Furthermore, a method to prevent a catch by vibration reduction of the lift ropes is investigated. In the previous research, it was confirmed that the division of the lift stroke is effective for reducing the response of the rope. When the lift stroke was equally divided, the displacement of the upper lift became larger than that of the other lift and so the effectiveness of the division ratio of lift stroke was examined in this report. The catching of the lift rope using differential analysis and risk assessment was investigated and as the result, the displacement of the upper lift was decreased by the apposite division ratio. The probability of catching rope of the upper lift is reduced. Furthermore, it was confirmed that the risk of the catching rope reduces in probabilistic risk assessment.