Experience with Structural Damage Identification of an Experimental Bridge Model

Abstract

The paper is devoted to structural health monitoring using a non-destructive method based on the method of direct stiffness determination combined with the model updating method. The primary aim of the paper is to determine the change in bending and torsional stiffnesses. In the first part of the work it was necessary to prepare a simple experimental scale model of the bridge which was made from two materials – wood and plaster boards. The same bridge model was created in the finite element commercial codes RFEM5 - Dlubal (a more detailed 3D analysis) and ANSYS (a 2D analysis). The last numerical model consists of beam elements with lumped mass elements. The modal analysis was made and these results were used as a comparative base for measurements. In either case data for the original and the damaged models were acquired. Analysis of the measurement data led to the identification of vertical and torsional mode shapes. Last part of the paper is devoted to identification of the damage by application of the direct stiffness calculation method.

The approximation function of bridge deck vibration derived from the measured eigenmodes

“…These methods are suitable, e.g., for structural health monitoring (SHM), when repeated tests of the dynamic responses have to be compared and even small variations in results can lead to damage identification. In SHM of bridges it is necessary to know higher derivatives of eigenmodes in order to, e.g., assess stiffness using the direct method (Maeck and De Roeck, 1999a;1999b) or for increasing the speed of iterations (Sokol et al, 2015).…”

Impact analysis of input parameter for damage detection code

“…The FEMU method is also applied to damage detection with neglecting damping of structure in a simple self-developed code. The used version of the code has been customized in comparison to its published version in [10]. The paper is devoted to analysis of input data and their impact on accuracy of damage assessment and analysis of minimum degree of possible damage that can be detect on a numerical model of a steel bar.…”

Choice of Appropriate Control Values for Effective Analyses of Damage Detection

“…The theoretical basis and a detailed description of the operation of the program was described by Sokol et al (2015). However, it has been slightly modified for this case.…”

“…All of the calculations ran in a while-loop cycle. The limit value of the auxiliary error (indicated by LIMIT in accordance with Sokol et al (2015)) is the only condition which determines the calculations in a way that the vector of the calculated displacements corresponds to the desired state of the measured mode-shape, i.e. when the FAULT value is equal to or smaller than LIMIT value.…”

“…The FEMU method is applied for damage assessments by neglecting structural damping and using the measured modal parameters in a simple program in MS Office Visual Basic for Applications (Excel VBA). The program has been slightly modified compared to its last published version in Sokol et al (2015). In this work, the emphasis was placed on an analysis of the input data and its impact on the accuracy of the damage detection.…”