The nonstationary, nonlinear dynamic interactions in slender continua deployed in high-rise vertical transportation systems in the modern built environment

This paper presents a nonlinear mathematical model and numerical results concerning the nonstationary lateral dynamic behaviour of long low tension slender continua deployed and moving at speed in high-rise vertical transportation systems installed in tall structures. The analysis presented in this study involves the identification of conditions for internal lateral resonances that can readily arise in the system when the slowly varying frequencies approach the fundamental or higher frequencies of the structure. The passage through the fundamental resonance leads to dangerously large displacements in the plane of the excitation. Due to the nonlinear (cubic) coupling, interactions between the in-plane modes and the out-of-plane modes occur. These interactions are studied numerically in order to predict and to examine the non-planar motions that may arise due to the autoparametric resonances. In order to suppress the internal resonance interactions higher speed levels and /or cable tension levels should be applied. Alternatively, an active tension control algorithm can be considered

On the Mechanical Interactions in Suspension Rope – Sheave / Pulley Systems

Steel wire ropes employed as suspension means in lift systems are subjected to bending when passing around rigid traction sheaves/pulleys. In this paper, a suspension rope is represented as a moving Euler-Bernoulli beam and its global mechanical behaviour and interactions at the contact area are described by a nonlinear Boundary Value Problem with an unknown boundary. The problem is solved numerically for a lift system with the car suspension in a 2:1 roping configuration. The solution yields the curvature values, slope angles and the distribution of tensile and bending stresses along the rope span. It is demonstrated that the boundary angles vary during the lift travel and the distribution of stresses over the transition arc is nonuniform

On the Mechanical Interactions in Suspension Rope – Sheave / Pulley Systems

Steel wire ropes employed as suspension means in lift systems are subjected to bending when passing around rigid traction sheaves/pulleys. In this paper, a suspension rope is represented as a moving Euler-Bernoulli beam and its global mechanical behaviour and interactions at the contact area are described by a nonlinear Boundary Value Problem with an unknown boundary. The problem is solved numerically for a lift system with the car suspension in a 2:1 roping configuration. The solution yields the curvature values, slope angles and the distribution of tensile and bending stresses along the rope span. It is demonstrated that the boundary angles vary during the lift travel and the distribution of stresses over the transition arc is nonuniform

Nonlinear Dynamics and Control of Moving Slender Continua Subject to Periodic Excitations

Tall structures often sway with large amplitude and low frequency due to resonance con-ditions induced by wind loads and long-period seismic excitations. These sources of exci-tation affect the performance of vertical transportation systems (VTS) deployed in these structures. The fundamental natural frequencies of tall buildings fall within the frequency range of the wind and seismic excitations and the sway motions form the excitation mech-anism which acts upon the VTS. Particularly affected are long moving slender structural components such as the suspension ropes, compensating cables and travelling cables. Complex nonlinear resonance interactions arise in the system when the frequency of the excitation is tuned to the natural frequencies of those elements. The methods to mitigate the effects of dynamic interactions in a high-rise VTS involve the application of passive and active control devices attached at the compensation sheave assembly. In this paper a numerical simulation model is presented to predict and analyse the resonance behaviour of the system equipped with a nonlinear damper-actuator system. The performance and characteristics of this device can then be optimized and adjusted to minimize the effects of adverse dynamic responses of the system

Evaluating a holistic energy benchmarking parameter of lift systems by using computer simulation

At present, there are benchmarking parameters to assess the energy performance of lifts, e.g. one in Germany adopted by VDI (4707-1/2), one internationally published by ISO (BS EN ISO 25745-2:2015), and the other in Hong Kong adopted by The Hong Kong Special Administrative Region (HKSAR) Government. These parameters are mainly checking the energy consumed by a lift drive without considering real time passenger demands and traffic conditions; the one in Hong Kong pinpointing a fully loaded up-journey under rated speed and the two in Europe pinpointing a round trip, bottom floor to top floor and return with an empty car, though including energy consumed by lighting, displays, ventilation etc. A holistic normalization method by Lam et al [1] was developed a number of years ago by one of the co-authors of this article, which can assess both drive efficiency and traffic control, termed J/kg-m, which is now adopted by the HKSAR Government as a good practice, but not specified in the mandatory code. In Europe, the energy unit of Wh has been used but here, Joule (J), i.e. Ws, is adopted to discriminate the difference between the two concepts. In this article, this parameter is evaluated under different lift traffic scenarios using computer simulation techniques, with an aim of arriving at a reasonable figure for benchmarking an energy efficient lift system with both an efficient drive as well as an efficient supervisory traffic control

Vibration Signature and the Application of Intelligent Pattern Recognition in Detection and Classification of Damage in Automatic Power Operated Lift Doors

The majority of faults in lift installations occur in the door (entrance) systems. Wear and tear of the door operator mechanism and the door system components/ subsystems will result in defects that lead to damage which in turn leads to faults, understood as a change in the door system that produces an unacceptable reduction in the quality of its performance. The research presented in this paper involved the development of an experimental lift door stand to collect vibration signature datasets corresponding to a range of typical damage classes that occur in lift door systems. The installation comprises single speed doors (single panel side opening and two panel centre opening) as well as two speed doors (two panel side opening and four panel centre opening). Once the data are collected the vibration features are extracted and used in supervised learning to train the artificial neural networks designed to recognize patterns and to classify damage. The results obtained demonstrate excellent performance of the network with very high percentage of correctly classified damage classes involved. The work completed so far forms the basis for the development of decision stage algorithms to analyze the results from the pattern recognition and to decide about appropriate maintenance actions required

Computer Simulation Aided Study of a Real-time Energy Benchmarking Parameter for Lift Systems under different Traffic Control Schemes

At present, there are benchmarking procedures to assess the energy performance of lifts, e.g. VDI (4707-1/2) adopted in Germany as a pioneer, then replaced by ISO (BS EN ISO 25745-1:2012 and 25745-2:2015) in Europe, and the other in Hong Kong adopted by The Hong Kong Special Administrative Region (HKSAR) Government. The Hong Kong procedure focuses on the design performance of lift drives. The ISO standard further estimates the annual energy. To facilitate real time monitoring of energy performance of lift systems, a holistic normalization method (So et al 2005, Lam et al 2006) was developed more than ten years ago, which can simultaneously assess both drive efficiency and traffic control performance on a real-time basis, termed which is the name of the parameter measured in unit, J/kgm, and is now adopted by the HKSAR Government as a good practice in the Technical Guidelines of the Energy Code, but not yet enforced in the mandatory code. Values, not just the procedures, for benchmarking are demanded. In this article, such a parameter is evaluated under different drives and lift traffic control scenarios by using computer simulations, with the aim of arriving at a reasonable figure for benchmarking an energy efficient lift system with both an efficient drive as well as an efficient supervisory traffic control. This parameter could also be used to compare the performance of different types of intelligent car dispatchers. The simulation suggested a value of 50 J/kgm as acceptable while 40 J/kgm as good

Vibration Signature and the Application of Intelligent Pattern Recognition in Detection and Classification of Damage in Automatic Power Operated Lift Doors

The majority of faults in lift installations occur in the door (entrance) systems. Wear and tear of the door operator mechanism and the door system components/ subsystems will result in defects that lead to damage which in turn leads to faults, understood as a change in the door system that produces an unacceptable reduction in the quality of its performance. The research presented in this paper involved the development of an experimental lift door stand to collect vibration signature datasets corresponding to a range of typical damage classes that occur in lift door systems. The installation comprises single speed doors (single panel side opening and two panel centre opening) as well as two speed doors (two panel side opening and four panel centre opening). Once the data are collected the vibration features are extracted and used in supervised learning to train the artificial neural networks designed to recognize patterns and to classify damage. The results obtained demonstrate excellent performance of the network with very high percentage of correctly classified damage classes involved. The work completed so far forms the basis for the development of decision stage algorithms to analyze the results from the pattern recognition and to decide about appropriate maintenance actions required