Implementing slack cables in the force density method

Abstract

Purpose – The purpose of this paper is to present a solution strategy for the analysis of cable networks which includes an extension to the force density method (FDM) in an attempt to support cable elements when they become slack. The ability to handle slack cable elements in the analysis is particularly important especially in cases where the original cable lengths are predefined, i.e. the cable structure has already been constructed, and there is a need for further analysis to account for additional loading such as wind. The solution strategy is implemented in a software application. Design/methodology/approach – The development of the software required the implementation of the FDM for the analysis of cable networks and its extension to handle constraints. The implemented constraints included the ability to preserve the length in the stressed or the unstressed state of predefined cable elements. In addition, cable statics are incorporated with the development of the cable equation and its modification to be able to be handled by the FDM . Findings – The implementation of the solution strategy is presented through examples using the software which has been developed for these purposes. Originality/value – The results suggest that for cable networks spanning large distances or cable elements with considerable self-weight the neglect of the cable slackening effects is not always conservative.