This paper proposes a novel method for bridge inspection that essentially digitises bridges using Light Detection and Ranging (LIDAR) so that they can be later inspected in a virtual reality (VR) environment. The work uses conventional terrestrial LIDAR together with affordable VR hardware and freely available software development kits originally intended for authoring computer games. The resulting VR app is evaluated for a case study involving a typical masonry bridge, comparing the proposed technique with traditional inspection methods. The new approach promises to be highly effective in terms of interpretation of results, accessibility to critical areas and safety of inspectors. The work represents an important step towards the creation of digital twins of important assets in the built environment. Recent bridge collapse incidents have affected local economies, traffic congestion, and in some extreme cases led to a loss of life. The work is timely as law making agencies are paying greater attention to structural rehabilitation. This paper will be of particular interest to bridge engineers, construction professionals and law makers and could lead to future revisions of bridge inspection processes and standards. ARTICLE HISTORY

Recent high profile collapses coupled with an aging bridge stock, increased loading and the pressures of climate change have led to a greater focus on bridge management by policy makers. To prevent any negative socio-economic impacts, timely inspection of bridges becomes of prime importance. Visual inspection is standard practice around the world but is subjective in nature and is influenced by many factors that can affect the accuracy of results and future decisions. The research presented here critically compares the conventional Visual Inspection approach with a Virtual Reality (VR) Inspection technique that combines Lidar and VR, applied for the first time to bridges made of reinforced concrete. Inspection of the Mancunian Way, an elevated motorway in Manchester, UK, is performed by the conventional visual approach and the VR approach. Digital virtual twins of the bridge are developed. Lidar is used to capture a 3D image of the geometric surface of the bridge incorporating all its defects. The image is post-processed and a virtual reality application is created using Unity, a software development kit, for inspection of bridges in an immersive 3D virtual environment. The resulting VR app is evaluated subjectively by conducting a critical comparison between both methods. The results demonstrate promising improvements over the conventional inspection technique. It is intended that this research will benefit civil engineers in inspecting bridges as well as policy makers who may revise bridge inspection codes and procedures.

Background:In recent years, numerous reinforced concrete buildings have been constructed in Iraq and some developing countries. Fire accidents occur in wooden formwork especially during the summer season due to problems associated with the construction procedure and on-site management. And fires can erupt during the construction stage of buildings. Introduction:Generally, if fire accidents occur in a wooden formwork, in these situations the concrete in the field is at an early age (i.e., "young"). The internal structure and chemical composition of early-age concrete are different from that of the carrier due to incomplete hydration at an early age. This study aimed to evaluate the strength of reinforced concrete frames at early ages when exposed to natural fire. The evaluation of existing buildings is an important issue that involves researchers and engineers in many countries. Methods:The experimental program consisted of constructing three full-scale reinforced concrete frames that are then exposed to natural fire. When the concrete age reaches three and five days by firing its formwork, the concrete quality of the structure was evaluated via ultrasonic pulse velocity as a nondestructive measurement. Core test was used as a destructive technique to implement a relationship between compressive strength and nondestructive measurements. Results:The results showed that the frame exposed to natural fire early was generally more affected than the other frame, and its compressive strength was reduced close to 33%. The results also showed that the ultrasonic pulse velocity test for the structural elements was smaller than those of the core test. Conclusion:It can be concluded that the current assessment methodology must be evaluated to provide practical suggestions that can enhance the reliability of assessing the in situ strength of existing concrete structures by nondestructive tests and cores.

Although concrete abrasion damage is a major maintenance challenge for coastal structures fronted by beaches with hard coarse sediments, there are no readily available field studies that have measured abrasion damage of known concrete mixtures under defined exposure conditions. The objective of this investigation is to evaluate the abrasive exposure conditions of the concrete revetment armour units at Cleveleys on the Fylde coast of the U.K. and examine the feasibility of using terrestrial laser scanning (TLS) to measure concrete abrasion damage in field conditions. It was found that the concrete elements at Cleveleys are exposed to a macro-tidal environment, which experiences significant wave heights that vary from 0.42 to 1.92 m, whilst the peak wave periods range from 3.7 to 6.5 s. The beach sediments have a mean size of 26 mm and are moderately sorted. TLS provides a dense point cloud of abraded surfaces suitable for quantitative assessment of concrete abrasion in the field. Based on the measured abrasion depths and exposure durations, the peak concrete abrasion rates at the site varied from 3.5 to 4.5 mm/year, and severe abrasion was concentrated in the region between mean high-water springs and mean high-water neaps, wherein the highest beach levels were also found during the survey. Finally, the abraded surfaces exhibited a polished texture with no visible craters; thus, the mechanism of concrete material loss was by grinding/polishing due to rolling/sliding sediments.