Shen-En Chen

Small-Format Aerial Photography for Highway-Bridge Monitoring

Small-format aerial photography (SFAP) is a low-cost solution for bridge-surface imaging and is proposed as a remote bridge-inspection technique to supplement current bridge visual inspection. Providing top-down views, photos taken from airplanes flying at 305 m (1,000 ft) allow for the visualization of subinch (i.e., large) cracks and joint openings on bridge decks or highway pavements. An onboard global positioning system can help geo-reference images collected and allow automated damage detection. However, the site lighting, surrounding tree shades, and highway surface reflectivity may affect the quality of the images. Several examples of bridge evaluation using SFAP are presented to demonstrate the capability of remote sensing as an effective tool for bridge-construction monitoring and condition assessment. A deck condition rating technique for large crack detection is proposed to quantify the condition of the existing bridge decks.

An interactive visual analytics system for bridge management

Bridges deteriorate over their life cycles and require continuous maintenance to ensure their structural integrity, and in turn, the safety of the public. Maintaining bridges is a multi‐faceted operation that requires both domain knowledge and analytics techniques over large data sources. Although most existing bridge management systems (BMS) are very efficient at data storage, they are not as effective at providing analytical capabilities or as flexible at supporting different inspection technologies. In this paper, we present a visual analytics system that extends the capability of current BMSs. Based on a nation‐wide survey and our interviews with bridge managers, we designed our system to be customizable so that it can provide interactive exploration, information correlation, and domain‐oriented data analysis. When tested by bridge managers of the U.S. Department of Transportation, we validated that our system provides bridge managers with the necessary features for performing in‐depth analysis of bridges from a variety of perspectives that are in accordance to their typical workflow.

3D LiDAR Scans for Bridge Damage Evaluations

High resolution ground-based optical-photonic images generated from laser scans provide detailed geometric information about a structure and simple algorithms can be used to retrieve damage information from the geometric point cloud data. Also called terrestrial 3D LiDAR, the laser scanning technology has great potential for bridge condition assessment, in particular, for damage evaluations. This paper describes several studies on quantification of concrete material damages using 3D LiDAR including mass losses due to vehicle collisions, reinforcement corrosion and surface erosions. The computed information can provide engineers critical measurements for further damage analysis, which were not previously available using photogrammetry or plan photographic techniques.

LiDAR Scan for Blasting Impact Evaluation on a Culvert Structure

This paper summarizes a case study of using three-dimensional (3D) light detection and ranging (LiDAR) scanner technology in bridge postblast geometric assessments. Terrestrial 3D LiDAR scanners can generate dense point clouds of position information that can be used to establish baseline geometric information for structures and to establish critical dimensional footprints for before and after event comparisons. For close range blast effects, the preblast and postblast scans of a bridge are proposed to establish blasting induced effects and damage information. The Colony Road culvert bridge was monitored for a nearby construction blasting, where full-scale 3D scans of the bridge have been conducted before and after blasting. The critical sections and geometries are then compared to ensure the safety of the bridge.

Three-Dimensional Terrestrial LIDAR for Operational Bridge Clearance Measurements

AbstractThis paper reports the outcomes of a study of the vehicle crossing effects on a terrestrial light detection and ranging (LIDAR) scan on highway bridges for underclearance measurements. Ground-based or vehicle-mount terrestrial LIDAR scanners, which recreate the bridge structure as a three-dimensional point cloud of thousands of position data points, have been found to be ideal for bridge clearance measurements. To determine the effects of ambient overhead vehicle crossing and seasonal temperature variation on clearance measurements, periodic monitoring of the Harris Road Bridge has been conducted. A simplistic but practical correlation analysis is performed, which shows that operational LIDAR scanning is a viable technique for bridge clearance measurements.

Lidar based edge-detection for bridge defect identification

Previous visual damage detection on bridge structure based on eye-ball method is arbitrary and time-consuming for bridge management due to its heuristic nature. Commercial remote sensing (CRS), which has remarkable applications for geometric quantification, is suggested to supplement visual bridge inspection. Ground-based LIDAR is one of the remote sensing tools that have been successfully used in bridge evaluation. Most of the early measurement algorithms are developed based on the spatial information contained from the LIDAR data; this paper explores the potential of applying another important feature of the scan data: the reflectivity, to enhance the defect detection program. The addition of reflectivity in damage diagnostics is particularly useful for defect detection of curved surfaces. A damaged joint area and concrete beam were selected to verify the method. The study shows that the reflectivity of the LIDAR could be used to support the automatic defect detection in bridges by combining it with the current position-based only image processing algorithms.

3D terrestrial lidar for operational bridge clearance measurements

This paper reports the outcomes of a study of the vehicle crossing effects on terrestrial LiDAR scan on highway bridges for underclearance measurements. Ground-based or vehicle-mount terrestrial LiDAR scanners, which recreate the bridge structure as 3D point cloud of thousands of position data points, have been found to be ideal for bridge clearance measurements. To determine the effects of ambient overhead vehicle crossing and seasonal temperature variation on clearance measurements, periodic monitoring of the Harris Road Bridge has been conducted. A simplistic but practical correlation analysis is performed which shows that operational LiDAR scanning is a viable technique for bridge clearance measurements.

Mode I Fatigue of the Carbon Fiber‐Reinforced Plastic–Concrete Interface Bond

As the reinforced concrete infrastructure continues to decline, the engineering community is turning to rehabilitative methods as cost effective alternatives to replacement. One such method, that has gained popularity over the last few decades, is the use of wet-layup fiber reinforced polymers (FRP) adhered to the concrete surface. The application of FRP consists of a fibrous material (carbon, glass, Kevlar), which when impregnated by an epoxy, may then be bonded to the surface of a reinforced concrete structure. The experimental fracture mechanics approach known as the Single Contoured-Cantilever Beam (SCCB) was herein utilized to investigate the fatigue behavior of the bonded interface between the externally reinforcing CFRP composite member and the underlying concrete under Mode I failure. The research outcome made it possible to establish a modified Paris law relationship for the CFRP-concrete interface bond as a predictive means of ascertaining the expected mechanical life cycle of such externally reinforced structures.

The role of terrestrial 3D LiDAR scan in bridge health monitoring

This paper addresses the potential applications of terrestrial 3D LiDAR scanning technologies for bridge monitoring. High resolution ground-based optical-photonic images from LiDAR scans can provide detailed geometric information about a bridge. Applications of simple algorithms can retrieve damage information from the geometric point cloud data, which can be correlated to possible damage quantification including concrete mass loss due to vehicle collisions, large permanent steel deformations, and surface erosions. However, any proposed damage detection technologies should provide information that is relevant and useful to bridge managers for their decision making process. This paper summaries bridge issues that can be detected from the 3D LiDAR technologies, establishes the general approach in using 3D point clouds for damage evaluation and suggests possible bridge state ratings that can be used as supplements to existing bridge management systems (BMS).

Comparative study of bridge management programmes and practices in the USA and China

The bridges of the USA and China are inventoried, inspected and maintained by governmental agencies, promoting efficient national infrastructure and safety through the development of bridge management technology. This paper provides a brief comparison between the USA and China concerning the ability to implement foreign bridge management technology by analysing the regulatory practices in the bridge management process and the bridge management systems in each country. The goal is to investigate possible synergistic approaches to enhance bridge monitoring through comparing the two largest bridge inventories in the world.