Earthquake Response of Structure-Elevator System

Abstract

This paper studies the seismic response of structure-elevator systems. Dynamic models are developed to represent the structure and elevator counterweight subsystems, with nonlinear contact elements between the counterweight and the guide rails. The computational output is given in terms of maximum rail stresses, relative elastic deflections, and interaction forces between counterweight and guide rails. Numerical methods are developed and analysis is performed to study the seismic response of the combined system. The structure subsystem is represented by six flexural modes (i.e., three for each of two horizontal axes), while the counterweight subsystem is modeled with four degrees of freedom. A nonlinear contact element with air gaps, viscous damper, Coulomb friction, and variable stiffness of guide rail is developed to model the dynamic interaction between structure and counterweight subsystems. Nonlinear time-history dynamic analysis was carried out using step-by-step integration of the 20 first-order differential equations using the Runge-Kutta fifth-order method. It was observed that contact forces and rail stresses depend on the mass of the counterweight, width of gaps, cross-sectional properties of rails, vertical motion velocity, and intensities of earthquake excitations. Dynamic contact between the counterweight and guide rails introduces large forces that may endanger the elevator system.