Infrared thermography for condition monitoring – A review

Review of Unmanned Aerial System (UAS) applications in the built environment: Towards automated building inspection procedures using drones

Nondestructive test methods for concrete bridges: A review

Electrical Resistance Tomography Imaging of Concrete

The high profile failure of the Malahide Viaduct in Dublin, Ireland, which is a part of the EU TEN-T network of critical transport links, was caused by foundation scour. Scour is a common soil-structure interaction problem. In light of current changes in climate, increasing frequency of flooding, coupled with the increasing magnitude of these flood events, will lead to a higher risk of bridge failure. Monitoring scour is of paramount importance to ensure the continued safe operation of the aging bridge asset network. Most monitoring regimes are based on expensive underwater instrumentation that can often be subjected to damage during times of flooding, when scour risk is at its highest. This paper presents a critical review of existing scour monitoring equipments and methodologies with a particular focus on those using the dynamic response of the structure to indicate the existence and severity of the scour phenomenon affecting the structure. A sensitivity study on a recently developed monitoring method is also undertaken.

https://researchrepository.ucd.ie/bitstream/10197/6521/1/UCDLukePrendergast_ScourReview.pdf

A review of bridge scour monitoring techniques

Within recent years there has been an increase in the use of NDT methods to detect defects and anomalies in various civil engineering structures. Infrared thermography, which has been successfully used in the USA in civil engineering applications, is being increasingly applied in the UK as an NDT technique. For example, the technique is now included in the Building Regulations for the assessment of thermal insulation for all new non-domestic buildings from April 2002. One of the perceived limitations of infrared thermography is that in temperate climates it is too cold to use this technique since there is rarely the extreme solar exposure that has enabled the successful use of thermography to detect render debonding and concrete spalling utilising solar heating. However, with the advancements in modern technology it is now possible to detect smaller changes in temperature (down to 0.08 °C). This paper shows that even with the low ambient temperatures experienced in Europe it is possible to use infrared thermography to identify correctly known areas of delamination in a concrete bridge structure and also to investigate the internal structure of a masonry bridge.

Application of infrared thermography to the non-destructive testing of concrete and masonry bridges

Scour around bridge piers and abutments has resulted in many structural failures over the past decade and considerable research has been carried out to develop methods which can be used to evaluate the risk of scour affecting the integrity of these major structures. Traditional site investigation methods based on borehole core and samples of the riverbed sediments are expensive and time-consuming and may not always give a complete assessment of the lithological variation in the riverbed sediments. Geophysical methods can be used to determine the riverbed profile beneath the water in a river and may also be of value for obtaining the previous scour history below the riverbed level. Trials of ground penetrating radar (GPR) have indicated that this geophysical method is particularly effective in determining the sub-bottom geological structure in a shallow freshwater environment. In this presentation the results from a number of scour surveys using GPR are presented and discussed. It is concluded that GPR surveys can be effective in determining both the water depth and sub-bottom geological structure near bridge piers and abutments provided that the correct instrumentation and operational procedures are adopted.

Radar measurement of bridge scour

Laboratory experiments were undertaken to identify and characterise the dielectric properties of railway track ballast using Ground Penetrating Radar (GPR). Better results were obtained with lower frequency antennas. Clear distinctions were obtained between wet and dry and clean and spent ballast. The laboratory experiment is described in detail and sample radar scan plots given — the final analysis of dielectric constants is also given. The implications of the findings for radar velocity are discussed. The application to identifying defects in railway track bed is discussed.

Electromagnetic properties of railway ballast

This paper will evaluate Ground Penetrating Radar (GPR) as a Non Destructive Test (NDT) technique for the assessment of railway track bed ballast. Ballast and tracked deterioration is responsible for the majority of differential settlement of tracks, resulting in poor track geometry. Traditionally ballast is only replaced when it has visually deteriorated, resulting in the planning and programming of maintenance and renewals currently being condition driven. There is a significant potential cost saving if ballast deterioration can be detected earlier. GPR can survey large lengths of track ballast in a relatively short space of time. This paper will show how GPR can be used to quickly identify the degree of track bed ballast deterioration and detect the ballast/formation interface.

The application of time domain ground penetrating radar to evaluate railway track ballast

A theoretical study was undertaken to determine if infrared thermography is an appropriate method to identify the condition of railway track ballast. Within this study the optimal conditions for an infrared survey were established. A laboratory experiment was undertaken to identify clean and spent ballast using an infrared camera. By cooling the ballast and watching it heat up to room temperature over time a difference in the rate of heat transfer between the two types of ballast was observed. A field trial of the infrared camera was undertaken over an operational track as part of the work within a normal track maintenance possession. The field trial identified an area of dirty ballast within a section of clean ballast and the findings were also confirmed by using ground penetrating radar and a trial pit. The laboratory and fieldwork are described in detail and sample infrared images as well as visual images of the same area are given — along with calculated values for the emissivity. The findings proved that it is possible to calibrate an infrared camera so that it can determine the condition of the ballast. Also from the success of the field trial it was shown that infrared thermography is a suitable method of identifying the condition of ballast on an operational track

M. R. Clark

Papers

Application of infrared thermography to the non-destructive testing of concrete and masonry bridges

Radar measurement of bridge scour

Electromagnetic properties of railway ballast

The application of time domain ground penetrating radar to evaluate railway track ballast

Infrared thermographic investigation of railway track ballast