Necessity of Considering Bolt Slip and Applicability of Incremental and Direct Iteration Methods in Load Bearing Analysis of Transmission Towers with Base Displacement

Abstract

Load bearing deterioration of existing transmission towers due to base displacement is estimated by numerical analyses and on-site measurements. However, the accuracy and efficiency improvement of the practical analysis technique is inevitably requested, because of a lot of anxiety towers that should be diagnosed. The purpose of this paper is to propose incremental and direct iteration methods considering bolt slip, paying attention to the most appropriate ratio of construction error to total base displacement and bolt slipping stress. It is clarified that the proposed methods are remarkably improved from the viewpoint of accuracy and efficiency improvement compared with the conventional method not considering bolt slip. And it is also clarified that the direct iteration method is worth using from the practical standpoint, such as computer run-time and on-site computation, compared with the incremental method.