Damage detection using the discrete wavelet transformation (DWT) of temperature field recorded on the surface of a plate structure is discussed. Defects in the form of voids and inclusions of various magnitude are considered. Computer-simulated experiments including the ones accounting for white noise and real thermal experiments are applied. Transient heat transfer problems are analysed. The efficiency of DWT in damage detection is studied by way of a number of examples. Haar, Daubechies 4, 6 and 8 wavelets in 1D and 2D DWT are used. The usefulness of the Lipschitz exponent evaluated with the use of DWT is discussed. The issue of denoising the thermal response signals using the soft threshold shrinkage procedure is also taken up.

Standard procedures for carrying out the inspection of the bridge or the assessment of its technical condition and suitability for use, rely on visual assessment made by the inspector and are in a certain part subjective. The main objective of the article is to analyze the applicability of IR as a tool to support the inspections of the structure and equipment elements of bridges. We are looking for the relationship between temperature distribution on an element surface (registered by an infrared camera) and hidden defects, which may be associated with, among others, moisture, discontinuity or delaminations in concrete structures. The study was divided into three parts: numerically simulated experiments of transient heat transfer, laboratory tests of reinforced concrete (RC) slab and some in-situ tests of a real bridge. To improve the effectiveness of damage detection, discrete two-dimensional wavelet transformation was applied.

Damage detection by the analysis of steady-state or transient thermal response of a structure is studied. 2D-wavelet transform is employed. Measurement noise in temperature field is accounted for. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The paper deals with a class of problems, where localised damage is detected using static and dynamic tests. Response of a structure is analysed employing discrete wavelet transformation as a tool for signal processing. The localised damage in beam structures was modelled as bending stiffness reduction. The efficiency of static and dynamic tests is studied. The minimal number of experimental measurement data and the precision of measurements required for the successful damage localisation is discussed by several numerical examples.

This study presents a numerical analysis of a prefabricated prestressed concrete beam subjected to a three-point bending test. The beam has a span length of 4600 mm and cross-section of 240 x 400 mm, and was prestressed with a single 7-wire strand with a diameter of 15.2 mm. In order to ensure the propriety and reliability of the numerical model of the studied beam, a parametric analysis of the influence of selected model components on the determined results was carried out. Using the finite element method (FEM) software Abaqus/CAE by Simulia, the following parameters were analyzed: a) the effect of mesh size and meshing method, b) the type and shape of elements, c) the method of transferring the prestressing force, d) the effect of passive reinforcement. To check the reliability and effectiveness of the model, the obtained numerical results were compared and contrasted with analytical solutions, assessing the sensitivity of FEM factors. The results presented in the paper demonstrate high agreement between numerical simulations and analytical calculations for the prestressed concrete beam, encompassing the deflection and stresses in both the elastic and characteristic states of inelastic ranges.

The aim of the article is to analyze the applicability of infrared thermography as a diagnostic tool to support the inspections of the structure and equipment elements of bridges. Infrared thermography consists of recording the power of electromagnetic radiation emitted by the surface of a given body. Thanks to the IR camera, the energy of the infrared radiation is converted into an electrical signal whose value depends on the temperature of the object. The starting point is the assumption that the distribution of temperature anomalies, recorded by IR camera, may be associated with located under the surface hidden defects. In-situ and laboratory tests were performed to document the use of this NDT tool in bridge diagnostics.