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CONTENTS
Volume 13, Number 6, June 2014
 

Abstract
Over the past several decades, substantial amounts of sensors and sensing systems have been developed for civil infrastructure systems. This special issue focuses on state-of-the-art robotics and automation technologies, including construction automation, robotics, instrumentation, monitoring, inspection, control, and rehabilitation for civil infrastructure. The issue also covers construction informatics supporting sensing, analysis and design activities needed to operate smart and sustainable civil infrastructure. Examples include robotic systems applied to civil infrastructure and equipped with various sensing technologies, such as optical sensors, laser sensors, wireless sensors, multi-sensor fusion, etc. This special issue is published in an effort to disseminate current advances of various robotics and automation technologies for civil infrastructure and built environment.

Key Words
civil infrastructure; structural health monitoring (SHM); sensing; inspection; robotics;automation

Address
Hyun Myung: Department of Civil and Environmental Engineering, KAIST, Daejeon, Republic of Korea
Yang Wang:School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA
Shih-Chung Jessy Kang:Department of Civil Engineering, National Taiwan University, Taipei, Taiwan
XiaoQi Chen:Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand

Abstract
The reliability of a Bridge management System depends on the quality of visual inspection and the reliable estimation of bridge condition rating. However, the current practices of visual inspection have been identified with several limitations, such as: they are time-consuming, provide incomplete information, and their reliance on inspectors\' experience. To overcome such limitations, this paper presents an approach of automating the prediction of condition rating for bridges based on digital image analysis. The proposed methodology encompasses image acquisition, development of 3D visualization model, image processing, and condition rating model. Under this method, scaling defect in concrete bridge components is considered as a candidate defect and the guidelines in the Ontario Structure Inspection Manual (OSIM) have been adopted for developing and testing the proposed method. The automated algorithms for scaling depth prediction and mapping of condition ratings are based on training of back propagation neural networks. The result of developed models showed better prediction capability of condition rating over the existing methods such as, Naïve Bayes Classifiers and Bagged Decision Tree.

Key Words
visual inspection; 3D visualization model; condition rating; neural networks; image analysis; depth perception; bridge defects

Address
Ram S. Adhikari, Ashutosh Bagchi and Osama Moselhi: Department of Building, Civil, and Environment Engineering, Concordia University, Montreal, Canada

Abstract
Structural displacement is an important indicator for assessing structural safety. For structural displacement monitoring, vision-based displacement measurement systems have been widely developed; however, most systems estimate only 1 or 2-DOF translational displacement. To monitor the 6-DOF structural displacement with high accuracy, a vision-based displacement measurement system with a uniquely designed marker is proposed in this paper. The system is composed of a uniquely designed marker and a camera with a zooming capability, and relative translational and rotational displacement between the marker and the camera is estimated by finding a homography transformation. The novel marker is designed to make the system robust to measurement noise based on a sensitivity analysis of the conventional marker and it has been verified through Monte Carlo simulation results. The performance of the displacement estimation has been verified through two kinds of experimental tests; using a shaking table and a motorized stage. The results show that the system estimates the structural 6-DOF displacement, especially the translational displacement in Z-axis, with high accuracy in real time and is robust to measurement noise.

Key Words
structural health monitoring (SHM); 6-DOF displacement; vision; unique marker

Address
Haemin Jeon, Donghwa Lee and Hyun Myung: Department of Civil and Environmental Engineering, KAIST, Daejeon 305-701, Republic of Korea
Youngjae Kim and Hyun Myung: Robotics Program, KAIST, Daejeon 305-701, Republic of Korea

Abstract
When subjected to fatigue loading, the main failure mode of partially prestressed concrete (PPC) structure is the fatigue fracture of tensile reinforcement. Therefore, monitoring and evaluation of the steel stresses/strains in the structure are essential issues for structural design and healthy assessment. The current study experimentally investigates the possibility of using fiber Bragg grating (FBG) sensors to measure the steel strains in PPC beams in the process of fatigue loading. Six full-scale post-tensioned PPC beams were exposed to fatigue loading. Within the beams, the FBG and resistance strain gauge (RSG) sensors were independently bonded onto the surface of tensile reinforcements. A good agreement was found between the recorded results from the two different sensors. Moreover, FBG sensors show relatively good resistance to fatigue loading compared with RSG sensors, indicating that FBG sensors possess the capability for long-term health monitoring of the tensile reinforcement in PPC structures. Apart from the above findings, it can also be found that during the fatigue loading, there is stress redistribution between prestressed and non-prestressed reinforcements, and the residual strain emerges in the non-prestressed reinforcement. This phenomenon can bring about an increase of the steel stress in the non-prestressed reinforcement.

Key Words
partially prestressed concrete (PPC); FBG sensor; fatigue; monitoring; strain

Address
Licheng Wang and Yupu Song: State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology,
Dalian, 116024, China
Jigang Han: Liaoning Provincial Communication Planning & Design Institute, Shenyang, 110179, China

Abstract
Hand-Arm Vibration Syndrome (HAVS) is a group of diseases caused by exposure of the hands to vibration while operating the hand held power tools such as road breaker, drilling machine, demolition hammer in construction works. In this paper, area-changed capacitive micro-accelerometer is designed to measure the vibration exposure on worker\'s hand when operating a drilling machine on various blocks such as clay block, paver block and solid cement block. The design process includes mathematical modelling of micro-accelerometer and simulations are done using INTELLISUITE 8.6. Experimental results are taken for various blocks surfaces using conventional and micro-accelerometer. Comparisons show that usage of area-changed micro-accelerometer for Hand-arm vibration monitoring provides better sensitivity, which in turn reduces the risk of HAVS in workers.

Key Words
accelerometer; hand arm vibration; area-changed capacitive type; drilling

Address
K. Gomathi, S. Shankar, S. Thangavel and R. Mohana priya: Department of Mechatronics Engineering, Kongu Engineering College, Erode, Tamilnadu, India
A. Senthilkumar: Department of Electrical and Electronics Engineering, Dr.MCET, Pollachi, Tamilnadu, India

Abstract
The objective of this study is to develop a reliable method for locating cracks in a beam using data fusion of fractal dimension features of operating deflection shapes. The Katz\'s fractal dimension curve of an operating deflection shape is used as a basic feature of damage. Like most available damage features, the Katz\'s fractal dimension curve has a notable limitation in characterizing damage: it is unresponsive to damage near the nodes of structural deformation responses, e.g., operating deflection shapes. To address this limitation, data fusion of Katz\' s fractal dimension curves of various operating deflection shapes is used to create a sophisticated fractal damage feature, the \'overall Katz;s fractal dimension curve\'. This overall Katz\'s fractal dimension curve has the distinctive capability of overcoming the nodal effect of operating deflection shapes so that it maximizes responsiveness to damage and reliability of damage localization. The method is applied to the detection of damage in numerical and experimental cases of cantilever beams with single/multiple cracks, with high-resolution operating deflection shapes acquired by a scanning laser vibrometer. Results show that the overall Katz\'s fractal dimension curve can locate single/multiple cracks in beams with significantly improved accuracy and reliability in comparison to the existing method. Data fusion of fractal dimension features of operating deflection shapes provides a viable strategy for identifying damage in beam-type structures, with robustness against node effects.

Key Words
damage detection; crack location; multiple cracks; operating deflection shape; data fusion; fractal dimension; laser measurement

Address
R.B. Bai, M.S. Cao and S.S. Wang:Department of Engineering Mechanics, Hohai University, Nanjing 210098, China
R.B. Bai: Department of Engineering Mechanics, Shandong Agricultural University, Taian, 271018, China
X.G. Song:School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
M. Radzieński:Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk, Poland
W.Ostachowicz:Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk, Poland;
Faculty of Automotive and Construction Machinery, Warsaw University of Technology, 84 Narbutta St., 02-524 Warsaw, Poland

Abstract
In civil engineering, revolving structures (RS) are a unique structural form applied in innovative architecture design. Such structures are able to revolve around themselves or along a certain track. However, few studies are dedicated to safety design or health monitoring of RS. In this paper, a wireless dynamic sensing system is developed for RS, and field tests toward a large revolving auditorium are conducted accordingly. At first, a wheel-rail problem is proposed: The internal force redistributes in RS, which is due to wheel-rail irregularity. Then the development of the sensing system for RS is presented. It includes system architecture, network organization, vibrating wire sensor (VWS) nodes and online remote control. To keep the sensor network identifiable during revolving, the addresses of sensor nodes are reassigned dynamically when RS position changes. At last, the system is mounted on a huge outdoor revolving auditorium. Considering the influence of the proposed problem, the RS of the auditorium has been designed conservatively. Two field tests are conducted via the sensing system. In the first test, 2000 people are invited to act as the live load. During the revolving process, data is collected from RS in three different load cases. The other test is the online monitoring for the auditorium during the official performances. In the end, the field-testing result verifies the existence of the wheel-rail problem. The result also indicates the dynamic sensing system is applicable and durable even while RS is rotating.

Key Words
revolving structure; sensing system; field test; dynamic addressing; wheel-rail; structural health monitoring; system development

Address
Yaozhi Luo, Pengcheng Yang, Yanbin Shen and Feng Yu: Department of Civil Engineering, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, Zhejiang Province, 310058, P. R. China
Zhouneng Zhong: Zhejiang Greenton Architectural Design Co., Ltd, Hangzhou 310007, P. R. China
Jiangbo Hong:Hanjia Design Group Co., Ltd, Hangzhou 310005, P. R. China

Abstract
The widening project on Freeway No.1 in Taiwan has a total length of roughly 14 kilometers, and includes three special bridges, namely a 216 m long-span bridge crossing the original freeway, an F-bent double decked bridge in a co-constructed section, and a steel and prestressed concrete composite bridge. This study employed in-situ monitoring in conjunction with numerical modeling to establish a real-time monitoring system for the three bridges. In order to determine the initial static and dynamic behavior of the real bridges, forced vibration experiments, in-situ static load experiments, and dynamic load experiments were first carried out on the newly-constructed bridges before they went into use. Structural models of the bridges were then established using the finite element method, and in-situ vehicle load weight, arrangement, and speed were taken into consideration when performing comparisons employing data obtained from experimental measurements. The results showed consistency between the analytical simulations and experimental data. After determining a bridge\'s initial state, the proposed in-situ monitoring system, which is employed in conjunction with the established finite element model, can be utilized to assess the safety of a bridge\'s members, providing useful reference information to bridge management agencies.

Key Words
bridge monitoring system; in-situ experiment; position sensitive detector

Address
Yi-Tsung Chiu:Department of Civil Engineering, National Taipei University of Technology, 1, Zhongxiao E. Rd. Sec. 3,
Taipei 106, Taiwan R.O.C.
Tzu-Kang Lin:Department of Civil Engineering, National Chiao Tung University, 1001, University Rd., Hsinchu 300, Taiwan R.O.C.
Hsiao-Hui Hung: National Center for Research on Earthquake Engineering, 200, Hsinhai Rd. Sec. 3, Taipei 10, Taiwan R.O.C.
Yu-Chi Sung:Department of Civil Engineering, National Taipei University of Technology, 1, Zhongxiao E. Rd. Sec. 3, Taipei 106, Taiwan R.O.C.;
National Center for Research on Earthquake Engineering, 200, Hsinhai Rd. Sec. 3, Taipei 10, Taiwan R.O.C.
Kuo-Chun Chang: National Center for Research on Earthquake Engineering, 200, Hsinhai Rd. Sec. 3, Taipei 10, Taiwan; R.O.C.
Department of Civil Engineering, National Taiwan University, 1, Roosevelt Rd. Sec. 4, Taipei 106, Taiwan R.O.C.

Abstract
This work introduces a two-module robotic pipe inspection system with ultrasonic NDE device to evaluate the integrity of pipe structures. The proposed robotic platform has high mobility. The two module mobile robot platform overcomes pipe obstacle structures such as elbow, or T-branch joints by cooperative maneuvers. Also, it can climb up the straight pipeline at a fast speed due to the wheel driven mechanism. For inspection of pipe structure, SH-waves generated by EMAT are applied with additional signal processing methods. A wavelet transform is implemented to extract a meaningful and specific signal from the superposed SH-wave signals. Intensity ratio which is normalized the defect signals intensity by the maximum intensity of directly transmitted signals in the wavelet transforms spectrum is applied to evaluate defects quantitatively. It is experimentally verified that the robotic ultrasonic inspection system with EMAT is capable of non-destructive inspection and evaluation of defects in pipe structure successfully by applying signal processing method based on wavelet transform.

Key Words
out- pipe robot; EMAT; wavelet transform; two-module climbing robot; non-eestructive test robotic system

Address
Jin-Hyuk Lee: Graduate School of Energy and Environment, Seoul National University of Science and Technology 232 Gongneung-ro, Nowon-gu, Seoul 139-743,Republic of Korea
Sangchul Han, Jaekyu Ahn and Hyungpil Moon:School of Mechanical Engineering, Sungkyunkwan University, Seoburo 2066, Jangan-gu, Suwon 440-746, Republic of Korea
Dae-Hyun Kim: Department of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul, 139-743, Republic of Korea

Abstract
Civil engineers always face the challenge of uncertainty in planning, building, and maintaining infrastructure. These works rely heavily on a variety of surveying and monitoring techniques. Unmanned aerial vehicles (UAVs) are an effective approach to obtain information from an additional view, and potentially bring significant benefits to civil engineering. This paper gives an overview of the state of UAV developments and their possible applications in civil engineering. The paper begins with an introduction to UAV hardware, software, and control methodologies. It also reviews the latest developments in technologies related to UAVs, such as control theories, navigation methods, and image processing. Finally, the paper concludes with a summary of the potential applications of UAV to seismic risk assessment, transportation, disaster response, construction management, surveying and mapping, and flood monitoring and assessment.

Key Words
unmanned aerial vehicle; UAV application; automatic control; artificial intelligence navigation; image processing and analysis; nuclear power plant; transportation; disaster response; construction management; mobile mapping; flood monitoring and assessment

Address
Peter Liu:Department of Electrical Engineering, Tamkang University, No. 151 Yingzhuan Rd., Tamsui Dist., New Taipei City 25137, Taiwan
Albert Y. Chen, Jen-Yu Han, Shih-Chung Kang, Tzong-Hann Wu and Ming-Chang Wen: Department of Civil Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd.,
Taipei, 10617, Taiwan
Jihn-Sung Lai:Hydrotech Research Institute, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei, 10617, Taiwan
Meng-Han Tsai:Center for Weather Climate and Disaster Research, National Taiwan University, No. 1, Sec. 4,
Roosevelt Rd., Taipei, 10617, Taiwan


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