Non-destructive Evaluation Of Concrete Structures Using High Resolution Digital Image And Infrared Thermography Technology

As existing bridge structures age, they are susceptible to the effects of deterioration, damage and other deleterious processes. These effects hamper the capacity and efficiency of transportation networks and adversely impact local, regional and national economic growth. As a result, bridge authorities and other professionals have become more sensitive to maintenance issues related to this aging infrastructure. While highway bridge condition have been monitored by visual inspection, non-destructive evaluation (NDE) technologies have also been developing and they are expected to be utilized for effective management of highway bridges or other civil infrastructure systems. Efficient use of these technologies saves time spent or bridge inspections, and also helps the bridge authorities for management decision-making. One of the NDE technologies is the image-based technology. In this thesis research, image-based technologies using high resolution digital images (HRDI) and infrared thermography image (IRTI) are introduced, described and implemented. First, a review of the mechanisms of these technologies is presented. Due to the specific engineering utilization and recent technological development, there is a need to validate effectiveness of HRDI and IRTI for their practical use for engineering purpose. For this reason, a pilot project using these technologies was conducted at an in-service bridge and a parking structure with the support of Florida Department of Transportation District 5 and the results are presented in this thesis. Secondly, in order to explore and enhance the usability of infrared thermography technology (IRTI), experiments on campus and on another bridge were conducted to determine the best time to test bridges and the sensitivity of IRTI to delamination volume. Since the iv accuracy of damage detection using infrared thermography technology is greatly affected by daily temperature variation, it is quite important to estimate an appropriate duration for infrared thermography inspection prior to the inspection. However, in current practice, the way to estimate the duration is to monitor the temperature of the concrete surface. Since the temperature varies depending on the area or region, there is a need to visit the bridge before the actual test and monitor the temperature variation. This requires additional visits to the bridge site and also access to the bridge for measuring concrete temperature. Sometimes, this can be a practical issue. In this research, in order to estimate an appropriate duration without visiting bridges, a practical method is explored by monitoring and analyzing variation of concrete surface temperature at one location and projected to another location by also incorporating other factors that affect the concrete temperature, such as air temperature and humidity. For this analysis, specially-designed concrete plates of a few types of thickness and shapes are used and the regression analysis is employed to establish a relationship between environmental effects and temperature variation between two different sites. The results have been promising for this research study and it is shown that HRDI and IRTI are excellent technologies for assessing concrete structures in a very practical manner

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

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

Practical Identification Of Favorable Time Windows For Infrared Thermography For Concrete Bridge Evaluation

Infrared Thermography (IRT) is one of the nondestructive inspection techniques to detect delaminations in concrete bridge decks. These defects are identified by capturing the temperature gradient of concrete surfaces. In order for this technique to be effective in damage detection, IRT inspections should be conducted at certain time windows with favorable temperature conditions to get clear temperature gradients on inspected surfaces. This study is an experimental work examining the effects of ambient environmental conditions at different times of a day to locate subsurface delaminations and voids at a shallow depth, which is an additional influencing factor. This study also attempts to figure out a relationship between ambient environmental conditions and the temperature values of concrete surfaces to estimate the best time window with appropriate environmental conditions for IRT inspections. To this end, specially designed reusable concrete test plates with different thicknesses were manufactured to collect thermocouple sensor readings. Multiple regression analyses were employed to generate prediction models that seek a relationship between environmental conditions and temperature gradients on the test plates attached to a target bridge. Regression models also utilized sensor data collected at another location different than the target bridge location. It was found out that the most important aspect of sensor data collection was to accomplish a perfect contact of test plates with concrete bridge deck surfaces to get discernible temperature gradients. When this condition is not met, data analyses yield spurious results leading to futile conclusions. On the other hand, it was also observed that prediction models generated by regression analyses followed the same pattern as that of sensor readings. This makes it possible to have prediction equations based on sensor readings to determine suitable time window for conducting IRT inspections