Real Geometrical Imperfection of Bow-String Arches—Measurement and Global Analysis

In order to analyse the buckling behaviour of existing bow-string arch bridges, it is necessary to deal with the imperfections that influence the global stability of their superstructures. Direct quantification of the material imperfections represents an extremely difficult task for this type of structure. On the other hand, the geometrical imperfections can be measured in more detail by using special scanners or high-accuracy surveying instruments. This contribution represents a beginning part of the research activities focusing on the real values of geometric imperfections of existing steel arch bridges using three-dimensional (3D) scanning. The possibility of using these data for further theoretical and numerical analysis based on the finite element method (FEM) and for further creating the building information modelling (BIM) of the bridges is proposed. When verifying the stability of bow-string arch bridges, much higher attention has to be paid to the out-of-plane stability of the arches. The numerical models of an existing bridge superstructure were developed to execute a nonlinear analysis with geometrical imperfections included. Both the theoretical and actual imperfections obtained by 3D scanning were taken into account. The obtained data, their comparison and the applicability of the presented method are finally discussed.