nfrastructure elements, especially reinforced concrete bridges and viaducts, are exposed to a combination of degrading processes throughout their life cycle, such as corrosion and fatigue. The combined effects of both processes are known to be more harmful to the structure than the sum of both deterioration processes considered individually. Due to the limited amount of studies in this field, this research aims to evaluate, by experimental analysis, the combined effects of fatigue and corrosion on reinforced concrete beams. Eight beams measuring 7 x 14 x 130 cm were cast and divided in four groups of 2 beams each: one group for reference beams, one for corroded beams with a loss of mass of 10%, one for beams subjected to 200,000 cycles and the last for corroded fatigued beams. The results show that the combined processes drastically reduce the load capacity of the beams by less than half compared to the reference beams. It was also observed that fatigue life decreased and the failure mode changed to fragile.
Due to the nature of their use, concrete structures are typically subjected to various aggressive actions derived from the loads and the environmental agents, which make the concrete condition change over time. Constant monitoring of structures is a necessary procedure since the preventive detection of problems allows the use of more straightforward and cost-effective methods for evaluation and repair. In order to carry out continuous monitoring of the state condition of concrete elements, there are many tools available. Nondestructive Testing (NDT) applications are a new strategy to monitor the state of concrete structures continually. Recent advancements in NDT technologies are increasingly turning them into attractive and viable strategies to support this type of monitoring and visual inspection. In particular, besides been viable and attractive, ultrasonic tests are a relatively cheap alternative and represent a range of different methods, each one with its benefits, to analyze concrete structures. The Research Group of LEME-UFRGS has developed research and application of NDT methods in general, and ultrasonic based methods in particular, for the last 15 years. The research done by the group demonstrates that these methods can contribute to monitoring deterioration and the quality of concrete structures. The present study demonstrates particular cases involving ultrasonic pulse testing and ultrasonic tomography. The aim was to check for these technique improvements for the analysis of concrete elements. The results highlight the potentialities and shortcomings of each technique.
The tests of Brazilian Standard NBR 15575: 2013 are part of the knowledge of the civil construction industry, but the heat and thermal shock test is innovative and does not have a consolidated history. The research objective is to analyze the testing critically and present proposals based on data meta-analysis. Results showed that the test is very inaccurate in describing the procedure and equipment. This study proposed adjustments and innovations in the test to provide more reliable results, but it does not make propositions regarding visual inspection and the number of cycles. The study concluded that the lack of information on the testing has direct responsibility for the results and that the suggested proposals have the potential to be incorporated.
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