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- Non-destructive testing in civil engineering (4) (entfernen)
Active infrared thermography in civil engineering - quantitative analysis by numerical simulation
(2003)
The cooling-down process of building structures after heating-up with an external radiation source was analysed to detect voids inside and below the surface. Quantitative results of concrete test specimen containing voids with different sizes at various depths will be presented here. The experimental results were compared to numerical simulations performed with a Finite Difference program developed at BAM.
The structural safety, durability and performance of the infrastructure is of primary interest in every country. An efficient system for early and regular structural assessment as well as for quality assurance during and after the construction of new structures and of reconstruction processes is urgently required. At BAM, NDT methods to be applied in civil engineering are developed and their application improved. From the experience of on-site assessments, quality assurance systems and methodologies for regular inspections are elaborated. This work is mainly performed in the frame of externally funded research projects.
A research project is described involving a comparison of different non-destructive test methods for concrete bridges. A cooperative test series was started with the aim to compare and evaluate the performance and benefits of the latest technical developments in this field. For this purpose test specimens with localized defects were produced. Different modifications of radar, ultrasonic-echo and impact-echo methods were investigated. Including two- and three- dimensional reconstruction models. The experiments were accompanied by numerical simulation of the propagation of sound waves and microwaves. The results showed that the radar and the ultrasonic methods were efficient tools to locate the tendon ducts accurately if the reinforcing bars were not to narrowly spaced. The ultrasonic imaging methods were capable of identifying injection and compaction faults in a blind test. The good performance of the impact-echo method with regard to locating tendon ducts which was claimed in several publications could not be validated in the present investigations. The simulation models provided valuable information on how to improve the experimental test program and its evaluation.