Potential and limits using the DAD method for condition assessment of bridge structures

Abstract

In the last years, the age of the bridge contingent is in all countries constantly increasing while in addition the bridges are solicited by an increased load level and an increased load frequency. This leads to an urgent need for defining efficient bridge structure condition assessment methods. Here, the Deformation Area Difference (DAD) method has already proven to be reliable and practicable. This has been shown in recent research in which it has been tested on real bridge structures using photogrammetry and compared with other highly precise measurement techniques. In order to further develop this method and to analyze the potential and limits of the DAD method in practical experiments, in the present study different parameters are varied such as e.g., the loading position along the longitudinal axis of the bridge structure, the damage position along the longitudinal axis of the bridge structure and the damage position in the cross-section. In addition, the method is analyzed on different bridge structure types. The results of the current study allow to determine set-ups for in-situ experimental investigations of existing bridge structures using the DAD method. A novel DAD Influence Line (DAD IL) is introduced to identify necessary load positions for the experiments. The Damage Detection Range depends on different damage levels, precisions, and deflection values. It is found that for local damage only one measurement line for the cross-section is not sufficient.