Ruicong Han

Initial Validation of Mobile-Structural Health Monitoring Method Using Smartphones

The structural health monitoring system has made great development nowadays, especially on bridge structures. Meanwhile, most SHM systems reported were designed, integrated, and installed into large-scale infrastructures by professionals and equipped with expensive sensors, data acquisition devices, data transfer systems, and so forth. And it is impossible to install SHM system for every civilian building. For this status, a kind of new idea for structural health monitoring using smartphone is introduced in this paper. A smartphone, with embedded responding SHM software and inner sensors or external sensors, can be used not only as a single wireless sensor node but also as a mini-SHM system. The method is described in detail, and then the swing test, cable force test in laboratory, and cable force test on an actual bridge based on the iPhone were conducted to validate the proposed method. The experimental results show that Mobile-SHM using smartphone is feasible. The realization of Mobile-SHM method using smartphones may be considered as a milestone in making SHM popular in the lives of people.

A Cyber-Physical System for Girder Hoisting Monitoring Based on Smartphones

Offshore design and construction is much more difficult than land-based design and construction, particularly due to hoisting operations. Real-time monitoring of the orientation and movement of a hoisted structure is thus required for operators’ safety. In recent years, rapid development of the smart-phone commercial market has offered the possibility that everyone can carry a mini personal computer that is integrated with sensors, an operating system and communication system that can act as an effective aid for cyber-physical systems (CPS) research. In this paper, a CPS for hoisting monitoring using smartphones was proposed, including a phone collector, a controller and a server. This system uses smartphones equipped with internal sensors to obtain girder movement information, which will be uploaded to a server, then returned to controller users. An alarming system will be provided on the controller phone once the returned data exceeds a threshold. The proposed monitoring system is used to monitor the movement and orientation of a girder during hoisting on a cross-sea bridge in real time. The results show the convenience and feasibility of the proposed system.

Experimental Research on Quick Structural Health Monitoring Technique for Bridges Using Smartphone

In the recent years, with the development and popularization of smartphone, the utilization of smartphone in the Structural Health Monitoring (SHM) has attracted increasing attention owing to its unique feature. Since bridges are of great importance to society and economy, bridge health monitoring has very practical significance during its service life. Furthermore, rapid damage assessment of bridge after an extreme event such as earthquake is very important in the recovery work. Smartphone-based bridge health monitoring and postevent damage evaluation have advantages over the conventional monitoring techniques, such as low cost, ease of installation, and convenience. Therefore, this study investigates the implementation feasibility of the quick bridge health monitoring technique using smartphone. A novel vision-based cable force measurement method using smartphone camera is proposed, and, then, its feasibility and practicality is initially validated through cable model test. An experiment regarding multiple parameters monitoring of one bridge scale model is carried out. Parameters, such as acceleration, displacement, and angle, are monitored using smartphone. The experiment results show that there is a good agreement between the reference sensor and smartphone measurements in both time and frequency domains.

Cable force monitoring system of cable stayed bridges using accelerometers inside mobile smart phone

Cable force is one of the most important parameters in structural health monitoring system integrated on cable stayed bridges for safety evaluation. In this paper, one kind of cable force monitoring system scheme was proposed. Accelerometers inside mobile smart phones were utilized for the acceleration monitoring of cable vibration. Firstly, comparative tests were conducted in the lab. The test results showed that the accelerometers inside smartphones can detect the cable vibration, and then the cable force can be obtained. Furthermore, there is good agreement between the monitoring results of different kinds of accelerometers. Finally, the proposed cable force monitoring system was applied on one cable strayed bridge structure, the monitoring result verified the feasibility of the monitoring system.

Shaking table tests for evaluating the damage features under earthquake excitations using smartphones

Earthquake can cause severe damage to structures, the assessment of structural performance, before, during, and after an extreme event, is critical for ensuring their safe operations and resiliency to potentially catastrophic events. However, the conventional monitoring methods need complicate sensors, acquisition devices and data transmission system, it’s difficult to obtain the real-time response of the structures during earthquake. Moreover, current damage assessment always relies on the numerical simulation, the monitoring data is rare to apply on the damage detection due to the difficult SHM system implementation during earthquake. Furthermore, the displacement was particular difficult to be monitored. In this work, the objective was to extract the damage features such as the modal frequencies variation and residual displacement using smartphone data in a three-story steel frame structure subjected to shaking table earthquake excitations, and study the acceleration integration method in frequency domain to obtain the displacement more convenient and quickly with higher precision. First, a discussion of experimental details, including test structure, test plan and damage cases was introduced. Then the modal frequencies variation and residual displacement in different cases were obtained with the conventional and smartphone monitoring data. Third, the integration techniques for obtaining displacements from acceleration raw data based on one-story measured displacement were investigated to reduce the errors caused by uncertain cut-off frequencies.

Research on multi-parameter monitoring of steel frame shaking-table test using smartphone

The numerical simulation promises an effective method to assess seismic damage of high-rise structure. But it’s difficult to determine the input parameters and the simulation results are not completely consistent with the real condition. A more direct approach to evaluate the seismic damage is the structural health monitoring (SHM), which is one complex set of various kinds of sensors, devices and software, and always needs professionals. SHM system has achieved great development over recent years, especially on bridge structures. However it’s not so popular on high-rise building due to its difficult implementation. Developing a low-cost and convenient monitoring technique will be helpful for the safety maintenance of high-rise building. Smartphones, which embedded with sensors, network transmission, data storage and processing system, are evolving towards crowdsourcing. The popularity of smartphones presents opportunities for implementation of portable SHM system on buildings. In this paper, multi-parameter monitoring of a three-story steel frame on shaking table under earthquake excitations was conducted with smartphone, and the comparison between smartphone and traditional sensors was provided. First, the monitoring applications on iOS platform, Orion-CC and D-viewer, were introduced. Then the experimental details were presented, including three-story frame model, sensors placement, viscous dampers and so on. Last, the acceleration and displacement time-history curves of smartphone and traditional sensors are provided and compared to prove the feasibility of the monitoring on frame under earthquake excitations by smartphone.

Emergency Communication and Quick Seismic Damage Investigation Based on Smartphone

1School of Civil Engineering, Dalian University of Technology, Dalian 116024, China 2State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China 3School of Electronic Science and Technique, Dalian University of Technology, Dalian 116000, China 4School of Software Technology, Dalian University of Technology, Dalian 116000, China 5School of Civil Engineering, Harbin Institute of Technology, Harbin 150000, China

Research on quick seismic damage investigation using smartphone

Quick seismic damage investigation in earthquake zone is significant to provide guidance for emergency response and rescue after disaster. In this paper, the damage investigation software is developed, which integrates the functions of questionnaire and picture collection for phenomenon register and image acquisition. The software has been updated to online version, all the information collected can be uploaded to the website with their GPS information, and demonstrated on a map. The expert can evaluate the seismic damage by analyzing the photos and recordings collected, which reduce the waste of human and time.

Public-participant quick cable force investigation method using smartphone for bridges in disaster area

Numerous infrastructures, especially the bridge, require some safe inspection and assessment at the soonest when hit by a disaster like catastrophic earthquake. However, plenty of bridges within disaster area and limited resources for inspections may lead to the traffic delays and hampering the quick post-disaster assessment and rebuilt. In this article, a public-acceptant method, where cable force of bridges can be investigated quickly based on ubiquitous smartphones, was proposed to raise the efficiency of inspection and assessment in post-disaster emergency. First, public-participant post-disaster emergency disposal system was supported by the developed mobile software Orion-CC. Second, the lab’s comparison experiment was conducted with the mature wireless monitoring method, which verified the feasibility of the above-mentioned method. Third, the field experiment in totally three bridges in Dalian including Hualu Bridge which used three iPhones demonstrated the feasibility, practicability, high efficiency, and stability of the novel method, and showed its huge potential for the application in bridges’ quick health investigation. Besides, utilizing the smartphone-based cable force investigation method as the breakthrough, the data collection network and the framework of public-participant post-disaster emergency disposal system were preliminary established.

Displacement Monitoring of Structures Using Laser Image Displacement Method

Based on image processing technology, a laser spot identification method of bridge displacement monitoring was proposed. A laser device is affixed on the monitored object and projects a laser spot onto a projection panel. When the object moves, the laser device and the laser spot move along with it. The motion trail of the laser spot on the projection panel is recorded by a webcam. The displacement of the object is obtained by analyzing the motion trail of the laser spot. Many experiments had been conducted; the results show that this method has high accuracy. We hope to find a low-cost and high accuracy method for bridge displacement monitoring by