"The rapid growth of infrastructure in the UAE has caused a proportional growth in the transportation system. Bridges are among the major elements in the transportation system that requires continuous monitoring and maintenance over time. Replacement of bridges is expensive; hence it is desirable to assess damage using a cost effective maintenance strategy. Therefore, nondestructive testing techniques provide an efficient and feasible method for detecting defects in bridges in a quick manner. Several surveys have shown that ground penetrating radar (GPR) has the potential to be adopted as a non-destructive inspection technique. This work presents an experimental investigation of mix variation, and environmental conditions effects on the detectability of defects using GPR."--Abstract.

Ground-penetrating imaging radar (GPIR) is proposed for large-area inspection of concrete and concrete/asphalt composite bridge decks and roadways. This technique combines ground-penetrating radar (GPR) with unique image reconstruction algorithms developed for identification and characterization of subsurface flaws and structural features. New data acquisition hardware and image reconstruction techniques, under development at LLNL, offer the possibility for reliable and efficient, high-resolution subsurface imaging through the use of improved ultra-wideband transmitters, antennas, and arrays, and enhanced image- and signal-processing software. A field test of a limited-capability prototype system is planned for FY-93, as is completion of a conceptual design for a practical inspection system. A follow-on program for FY-94 would focus on development and demonstration of an advanced bridge inspection system prototype based on the conceptual design completed during FY-93.

Inspecting high-value structures, like bridges and buildings using Ground Penetrating Radar (GPR) is an application of the technology that is growing in importance. In a typical inspection application, inspectors use GPR to locate structural components, like reinforcing bars embedded in concrete, to avoid weakening the structure while collecting core samples for detailed inspection. Advanced GPR, integrated with imaging technologies for use as an NDE tool, can provide the capability to locate and characterize construction flaws and wear- or age-induced damage in these structures without the need for destructive techniques like coring. In the following sections, we discuss an important inspection application, namely, concrete bridge deck inspection. We describe an advanced bridge deck inspection system concept and provide an overview of a program aimed at developing such a system. Examples of modeling, image reconstruction, and experimental results are presented.

"The present study is comprised of two separate GPR case studies on a bridge deck and a concrete pavement respectively. These typical concrete structures were investigated using GPR with several objectives: 1) to find the reason of discrepancies between GPR results and the results of the other tests through bridge deck inspection, 2) to investigate the bridge deck under various weather conditions, 3) to determine the relative spatial locations of the imbedded dowel bars in the new concrete pavement, and finally 4) to evaluate the present capabilities of GPR technology including survey scheme and analysis through these two case studies."--Abstract, p. iii.

Effective maintenance of bridge structures comprises a broad spectrum of plans for repairs and services implemented to enable bridges to perform their intended function. These include in-depth inspection, fatigue analysis, design of mitigation measures and construction to avert component deterioration. Several incidents of in-service and under construction bridge failures have recently taken place. These dramatic failures emphasize the importance of risk-based inspections and analysis of real-life data to evaluate reliability of bridges. To effectuate benefits of reliability analysis in bridge maintenance, work on theoretical reliability must be equipped with practical analytical tools. Such an approach must underscore risk elements and identify processes to manage risk and avoid unexpected outcomes of failures and service disruption of bridges. The devastating earthquakes of February 6, 2023, in the southern region of Turkey near the northern border of Syria, which claimed tens of thousands of lives, caused enormous structural damage and staggering economic losses. These seismic events brought to focus on the vitality of instilling infrastructure routes that must accommodate emergency management plans to integrate the influx of medical and rescue response teams. The safe operation of bridges along these routes is indispensable for mobilization and deployment of rescue teams, medical personnel, humanitarian assistance, and the supply of food and water. The reliability of access routes and bridges is defined by their ability to adequately function as planned to effectuate emergency management plans, in the event of a similar seismic event, anywhere in the world. Risk-Based Strategies for Bridge Maintenance contains selected papers presented at the 11th New York City Bridge Conference (New York City, USA, 21-22 August 2023), and discusses issues of reliability, risk assessment, management, maintenance, inspection, monitoring, design, preservation, and rehabilitation of bridges. The book is aimed at bridge engineers.

" TRB's second Strategic Highway Research Program (SHRP 2) Report S2-R06A-RR-1: Nondestructive Testing to Identify Concrete Bridge Deck Deterioration identifies nondestructive testing technologies for detecting and characterizing common forms of deterioration in concrete bridge decks.The report also documents the validation of promising technologies, and grades and ranks the technologies based on results of the validations.The main product of this project will be an electronic repository for practitioners, known as the NDToolbox, which will provide information regarding recommended technologies for the detection of a particular deterioration. " -- publisher's description.

"This study is a GPR-based assessment of three bridge decks, two with a hot bituminous wearing surface and one with a bare concrete slab. The primary objectives of this study were: 1) to assess the integrity of the three bridge decks using a 1.5 GHz ground-coupled GPR antenna, and 2) to evaluate the utility of the 1.5 GHz ground-coupled antenna for bridge deck investigations. Core control (chloride ion concentration data and core integrity data) and visual inspection were used as interpretive constraint. The acquired GPR data were interpreted, and two plan view maps were generated. One depicts the magnitude of the reflections from the uppermost mat of rebar, and the second shows the arrival time of these reflections. Analysis of the GPR data and core control indicates that the magnitude of the reflected GPR signal from the uppermost mat of rebar is a direct function of concrete integrity. Higher magnitude reflections indicate higher quality concrete. To a lesser extent, the arrival time of the reflected energy is also indicative of concrete quality. Faster arrival times generally indicate higher quality concrete. Exceptions to this rule occur where the depth to the top layer of rebar varies. In this study, relative reflection amplitudes of less than 3000 on the bare concrete bridge and less than 5000 on the bituminous surface bridges indicate severe deterioration. Core control data was interpreted based on chloride ion corrosion threshold. Corrosion of rebar occurs once chloride ions content adjacent to the rebar reaches a threshold of approximately 0.033% to 0.04% by weight of concrete (or 330 ppm to 400 ppm). The GPR data correlates well with the core control, indicating that the 1.5 GHz antenna is an effective tool for assessing the condition of bridge decks"--Abstract, leaf iii

Advanced nondestructive inspection techniques like stress wave timing and resistance microdrilling have been used to successfully inspection timber bridges, but it is most effective on girder style bridges. There is a noted need to develop additional inspection techniques for longitudinal deck/slab timber bridges, which comprise about 20% of the national bridge inventory. One technique that holds potential is ground penetrating radar, a recognized nondestructive testing technique that has been used effectively for many different environmental and transportation applications. It has been utilized successfully to identify buried objects, internal defects and material changes. The objective of this research was to assess the potential for using GPR to identify and assess simulated deterioration in longitudinal timber deck timber bridges. GPR scans were completed in the longitudinal and transverse directions of a screw laminated timber bridge deck before and after a bituminous layer was added to assess embedded defects that simulated voids, decay, insect damage and horizontal shear splitting. Assessment of the GPR wave energy signal was completed using visualization software that was provided with the commercial GPR unit used for the testing. The radar signal was analyzed in both the longitudinal direction (antenna front to back) and the transverse direction (antenna side to side). Interpretation of the radar signals allowed for the identification of various internal defects present in the deck. Based on the results, GPR has the potential to identify internal defects in timber bridge decks before and after a bituminous layer was added. Large, rectangular void defects (at least 6‐ by 12‐ by 5 in. (15.2‐ by 30.4‐ by 12.7 cm)) that were hollow, filled with foam, or filled with sawdust/adhesive were most easily identified under all scanning conditions. The addition of a bituminous layer, common to slab bridge construction, damped the signal response and made it more difficult to identify defects. Several smaller defects that were found in the deck without a bituminous layer were not identified in scanning completed after the bituminous layer was added.

The safety, maintenance and repair of bridges and buildings depend on effective inspection and monitoring techniques. These methods need to be able to identify problems often hidden within structures before they become serious. This important collection reviews key techniques and their applications to bridges, buildings and other civil structures.The first group of chapters reviews ways of testing corrosion in concrete components. Given their continuing importance and vulnerability to decay, the next series of chapters describes ways of testing wood components within civil structures. A final group of chapters looks at visual and acoustic techniques and their use to assess bridges in particular.Inspection and monitoring techniques for bridges and civil structures is an invaluable reference for civil engineers involved in safety inspection, maintenance and repair of bridges and civil structures. - Reviews key inspection and monitoring techniques and their applications to bridges, building and other civil structures - Edited by a leading authority in the field