Determining initial tension of carrying cable in nonlinear analysis of bi-cable ropeway – Case study

Abstract

Abstract This paper presents a computational approach dedicated to determining the initial tension of the carrying cable of a bi-cable ropeway under in-service moving load in numerical analyses. A continuous model of a multi-span inclined cable pre-tensioned by a counterweight is considered and changes in geometry are found to be the source of nonlinearity in the cable behaviour. Special attention is paid to the influence of nonlinear effects on the displacement state and axial forces. The main part of numerical research is preceded by tests of the convergence of solutions due to the applied discretisation method. In the first step an original computational algorithm is used to verify the initial tension of the cable estimated on the basis of a simplified formula for a single-span cable. In a static analysis of cable and counterweight displacements, the linear and nonlinear solutions are compared depending on different values of the initial cable tension. The problem of the solutions’ convergence in numerical simulations regarding the influence of nonlinearity is also discussed. Afterwards a quantitative dynamic analysis is performed to assess the impact of nonlinear effects on representative dynamic responses of the structure. The need to reduce the level of these effects and vibration amplitudes becomes clearly evident. In this context the recommended value of the initial cable tension is determined for engineering application and a limit level of transverse cable displacements is proposed. The presented concept of numerical investigations for determining the initial cable tension in a nonlinear analysis can be useful for practical calculations of ropeway structures.