Infrared Thermography For Civil Structural Assessment: Demonstrations With Laboratory And Field Studies

A detailed investigation of infrared thermography (IRT) for civil structures is presented by considering different technologies, data analysis methods and experimental conditions in the laboratory and also in the field. Three different types of infrared (IR) camera were compared under active IRT conditions in the laboratory to examine the effect of photography angle on IRT along with the specifications of cameras. It is found that when IR images are taken from a certain angle, each camera shows different temperature readings. However, since each IR camera can capture temperature differences between sound and delaminated areas, they have a potential to detect delaminated area under a given condition in spite of camera specifications even when they are utilized from a certain angle. Furthermore, a more objective data analysis method than just comparing IR images was explored to assess IR data, and it is much easier to detect delamination than raw IR images. Specially designed laboratory and field studies show the capabilities, opportunities and challenges of implementing IRT for civil structures

Investigation Of Effective Utilization Of Infrared Thermography (Irt) Through Advanced Finite Element Modeling

Infrared thermography (IRT) has been used experimentally for concrete delamination detection. The past studies were conducted with limited experimental conditions, which make a difference in delamination detection. As a result, there are inconsistencies in the results reported in the literature. In this study, heat transfer models of concrete blocks with artificial delamination used for a previous test are developed and analyzed to explore sensitive parameters for effective utilization of IRT. After these FE models are validated, critical parameters and factors of delamination detectability such as the size of delamination (area, thickness and volume), ambient temperature and solar irradiance conditions (different seasons), and the depth of delamination from the surface are explored. This study presents that the area of delamination is much more influential in the detectability of IRT than thickness and volume. It is also found that there is no significant difference depending on the season when IRT is employed. This study shows a potential to bring significant improvement to IRT use in the field for subsurface damage detection for concrete structures

A Data Processing Methodology For Infrared Thermography Images Of Concrete Bridges

This study presents a methodology to improve the usability and efficiency of infrared thermography (IRT) for subsurface damage detection in concrete structures. A practical and more objective approach to obtain a threshold for IRT data processing was developed by incorporating finite element (FE) model simulations. Regarding the temperature thresholds of sound and delaminated areas, the temperature of the sound part was obtained from the IR image, and the temperature of the delaminated area was defined by FE model simulation. With this methodology, delaminated areas of concrete slabs at 1.27 cm and 2.54 cm depths could be detected more objectively than by visually judging the color contrast of IR images. However, it was also found that the boundary condition affects the accuracy of the method, and the effect varies depending on the data collection time. On the other hand, it can be assumed that the influential area of the boundary condition is much smaller than the area of a bridge deck in real structures; thus, it might be ignorable on real concrete bridge decks. Even though there are some limitations, this methodology performed successfully paving the way towards automated IRT data analysis for concrete bridge deck inspections

Effect Of Defect Size On Subsurface Defect Detectability And Defect Depth Estimation For Concrete Structures By Infrared Thermography

This study aims to reveal the effect and correlation of delamination size and defect shape for using infrared thermography (IRT) through FE modeling to enhance the reliability and applicability of IRT for effective structural inspections. Regarding the effect of delamination size, it is observed that the temperature difference between sound and delaminated area (Δ T) increases as the size of delamination increases; however, Δ T converges to a certain value when the area is 40 × 40 cm and the thickness is 1 cm. As for the shape of delamination, it can be assumed that if the aspect ratio which is the ratio of the length of the shorter side to the longer side of the delamination is more than 25%, Δ T of any delaminations converges to Δ T of the same area of a square/circular-shaped delamination. Furthermore, if the aspect ratio is 25% or smaller, Δ T becomes smaller than the Δ T of the same area of a square/circular-shaped delamination, and it is getting smaller as the ratio becomes smaller. Furthermore, this study attempts to estimate depths of delaminations by using IRT data. Based on the correlation between the size of delamination and the depth from the concrete surface in regard to Δ T, it was assumed that it was possible to estimate the depth of delamination by comparing Δ T from IRT data to Δ T at several depths obtained from FE model simulations. Through the investigation using IRT data from real bridge deck scanning, this study concluded that this estimation method worked properly to provide delamination depth information by incorporating IRT with FE modeling

An analysis of the prevalence of malaria in Turkey over the last 85 years

Background: Affecting 106 countries, malaria is a major global burden. Though intensive antimalaria efforts in Turkey have been successful in bringing down the number of cases, historically malaria was a serious public health concern

Experimental And Numerical Studies For Suitable Infrared Thermography Implementation On Concrete Bridge Decks

Capturing the temperature difference between sound and defective parts under ambient conditions is key for infrared thermography (IRT) on concrete bridges. This study explores the favorable time windows for concrete bridge deck inspections by IRT through field experiment and finite element model simulations. Based on the numerical simulations and experimental IRT results, the preferable thermal contrast to detect defects occurs during both daytime and nighttime. However, available time span during daytime is much shorter than that of nighttime due to interchange periods between cooling and heating cycles in the morning and in the evening. Furthermore, IRT is affected by sunlight during the daytime resulting in possible misdetections. Moreover, effects of clouds and radiative cooling are observed, and it is found that the clear sky is a preferable condition for IRT. Therefore, optimal conditions for IRT implementation on concrete bridge decks can be concluded that nighttime application under the clear sky condition. In addition, the effect of obstacles on a bridge surface such as gravel, wood chips that bring additional challenges to IRT are also evaluated experimentally

A Review Of Field Implementation Of Infrared Thermography As A Non-Destructive Evaluation Technology

The aging of highway infrastructure is a serious problem worldwide. As important constituents of this infrastructure, bridges have usually been inspected by visual inspection techniques and hammer sounding methods. In addition to these existing methods, different non-destructive evaluation technologies are also being developed and are expected to be utilized for effective management of highway structures. This study focuses on exploring and enhancing the usability of infrared thermography as a viable non-destructive evaluation technology. In this research, an experimental study was conducted to determine the most thriving time window to collect data from an object by using an infrared camera. The same setup was utilized to obtain data from existing structures. The results have shown that the night time was a better option to gather data from an object. It was also observed that infrared thermography could detect subsurface anomalies

Utilizing infrared technologies as a non-destructive evaluation for maintenance of concrete structures

The aging of road infrastructure is becoming a serious problem worldwide. Although the number of aged structures is increasing rapidly, inspection and maintenance for them cannot catch up with the speed due to the limited budget. Under these circumstances, infrared thermography method has been developed as one of non-destructive evaluation methods to implement inspections efficiently and effectively. This study is focusing on exploring enhancing the usability of infrared method as a viable non-destructive evaluation technology. In this research, infrared technology was applied to existing structures to prove the reliability and usability as a non-destructive inspection, and an experimental study was conducted to determine the most thriving time window to collect useful data from an object by using an infrared camera. Three infrared cameras with different specifications were also utilized both in a lab test and on an existing bridge. The results have shown that infrared thermography could detect subsurface anomalies in an existing bridge, and also indicated that night time was a better option to gather data from an object. The results of camera comparison showed the efficiency of the infrared thermography technique for bridge inspection although there were some discrepancies due to different camera types

A Review of Field Implementation of Infrared Thermography as a Non-Destructive Evaluation Technology

The aging of highway infrastructure is a serious problem worldwide. As important constituents of this infrastructure, bridges have usually been inspected by visual inspection techniques and hammer sounding methods. In addition to these existing methods, different non-destructive evaluation technologies are also being developed and are expected to be utilized for effective management of highway structures. This study focuses on exploring and enhancing the usability of infrared thermography as a viable non-destructive evaluation technology. In this research, an experimental study was conducted to determine the most thriving time window to collect data from an object by using an infrared camera. The same setup was utilized to obtain data from existing structures. The results have shown that the night time was a better option to gather data from an object. It was also observed that infrared thermography could detect subsurface anomalies

Utilizing Infrared Technologies As A Non-Destructive Evaluation For Maintenance Of Concrete Structures

The aging of road infrastructure is becoming a serious problem worldwide. Although the number of aged structures is increasing rapidly, inspection and maintenance for them cannot catch up with the speed due to the limited budget. Under these circumstances, infrared thermography method has been developed as one of non-destructive evaluation methods to implement inspections efficiently and effectively. This study is focusing on exploring enhancing the usability of infrared method as a viable non-destructive evaluation technology. In this research, infrared technology was applied to existing structures to prove the reliability and usability as a non-destructive inspection, and an experimental study was conducted to determine the most thriving time window to collect useful data from an object by using an infrared camera. Three infrared cameras with different specifications were also utilized both in a lab test and on an existing bridge. The results have shown that infrared thermography could detect subsurface anomalies in an existing bridge, and also indicated that night time was a better option to gather data from an object. The results of camera comparison showed the efficiency of the infrared thermography technique for bridge inspection although there were some discrepancies due to different camera types