Structural integrity of tied arch bridges affected by instability phenomena

Abstract

A numerical study is developed to investigate out-of-plane buckling instability of tied arch bridges due to vertical loads. In particular, a numerical model is implemented to evaluate initial configuration under dead loads and nonlinearities due to nonlinear geometric effects in bridge components arising from instability phenomena. The main aim of the paper is to identify the most relevant bridge components, which are affected out-of-plane instability behavior of the structure. The nonlinear behavior of tied arch bridges is evaluated by means of a three-dimensional finite element model, in which several wind bracing system layouts and cable system configurations are considered. A comparative analysis between Elastic Buckling Analysis and Nonlinear Elastic Analysis methodologies is developed to achieve a more accurate evaluation of the maximum capacity of the structure against instability phenomena. Comparisons in terms of buckling assessment between numerical evaluations and simplified methodologies reported in current codes on bridge structures are proposed. Results show that the simplified methodologies overestimate the instability capacity in most of the bridge configurations, which have been dimensioned according to the preliminary design rules commonly adopted in current applications.