STRUCTURAL AND ENVIRONMENTAL MONITORING TECHNOLOGIES. SOME RESULTS OF THE RESEARCH TEAM AT THE UNIVERSITY OF DA NANG – UNIVERSITY OF SCIENCE AND TECHNOLOGY

Assoc.Prof.Dr. Nguyen Lan, Engineer Pham Huy Hung

Danang Polytechnic Institute of Science and technology (DPIST)

1. Purpose of structural health monitoring

      Civil works, including bridges, buildings, tunnels, pipelines, dams and many others, provide very basic facilities for a society. Therefore, the safety and serviceability of these civil works are the basic elements of a civilized society and an efficient economy, as well as the ultimate goal of technical, academic and managerial communities [1].

   Structural Heath Monitoring (SHM) is an integration of Sensor System, Data Acquisition System, Data Storage and Processing System, Communication System and Modeling System and structural damage detection to gain knowledge of structural integrity during continuous use.

     The main objectives of the SHM are to monitor the current state of structural loads, assess the effects of different usage loads, check or update the rules used in the design phase, detect damage or deterioration, and guide the inspection and maintenance of the structure.

Figure 1: Comparison of aircraft monitoring system and human neuron

Figure 2: Architectural example of the structural monitoring system [2]

2. Initial research and application premises

     Projects to strengthen research capacity for the Faculty of Civil Engineering, University of Science and Technology, University of Danang (1998-2000) have invested in a number of modern construction measuring equipment systems at that time, such as: 6 node, 24 channel wireless structural load testing system of BDI – USA, Structural Response Dynamic Measurement System NI-USA, TDS 303 30-channel Structural Response Static Measurement System-Japan, 8-channel SDA830 Structural Dynamic Measuring System - Japan, GPS System with can be used to measure static, dynamic structures, ... that has motivated many lecturers who are passionate about research to exploit new devices for teaching, research and technology transfer. Scientific research project at the University of Da Nang "Research on diagnosis and health monitoring of large span bridges in Vietnam. Code B2010-TDA01-19-TRIG “ by Nguyen Lan (chaired), lecturer of  the Faculty of Road and Bridge Engineering, implemented and accepted in December 2011. The research results of the project have also been applied to short-term monitoring of bridge bearing displacement and evaluation of cable-stayed tension for construction of Tran Thi Ly bridge built at this time. The design, installation, and writing of software for collecting and processing large span bridge monitoring data at this time is still quite unfamiliar to bridge engineers in Vietnam. Most of the bridge monitoring systems in Vietnam at this time (before 2015) such as My Thuan-Can Tho Cable-Stayed Bridge, Bai Chay-Quang Ninh Cable-Stayed Bridge, Tran Thi Ly-Da Nang Cable-Stayed Bridge, .. are all implemented by foreign companies.

     In 2013, the Hue T-junction project started with a fairly fast construction progress, there were many construction vehicles causing wave propagation in the ground, affecting the surrounding works, requiring measurement experiments, short-term monitoring of vibration velocity intensity in the ground caused by construction vehicles. Certer for Science and Technology and Investment Consultancy – Danang University of Science and Technology (STIC) has been assigned by the Project owner and Da Nang City Departments to perform this task. With experience in using oscillometric equipment, writing software in Labview language and professional support for data processing and reporting measurement results from Dr. Tran Dinh Ngoc at Vietnam Institute for Building Science and Technology. The STIC’s engineering team has completed a system of equipment and software written in Labview language that allows connecting devices, setting configurations, collecting vibration monitoring data and automatically processing vibration monitoring results. This system has been applied to measure ground vibration in many projects in the Central region after that.

    Scientific research project "Study and clarify the characteristics and impacts of seismic waves caused by construction activities on soil types in Da Nang city, Code B2016-DNA-22-TT ” chaired by Lecturer Nguyen Lan and accepted in December 2018 has also developed a system and summarized more than 20 vibration measurement results of projects on many different geological backgrounds. The reference book "Soil vibrations due to construction activities" Construction Publishing House, 2019, ISBN: 978-604-82-2824-8 is one of the results of this project.

Figure 3: Architecture and interface of vibration measurement and monitoring system in the ground

     In addition to studying automatic monitoring systems, engineers of STIC have carried out semi-automatic monitoring projects for a number of projects such as: Geotechnical monitoring of embankment on soft soil on Extended Nguyen Tri Phuong street (2013), Monitoring of deep excavation pits of Da Lat Trade Center (2011), .. also contributed to promote the research and application of automatic monitoring systems later.

3. The first structural monitoring project

     Thuan Phuoc Suspension Bridge, Da Nang City is the longest span modern suspension bridge structure in Vietnam today. Thuan Phuoc Bridge crosses the lower Han River located on the National coastal route, is one of the architectural highlights of the coastal city of Da Nang. The bridge was built in 2003 and opened in 2009. By 2017, the bridge had some signs of deterioration, Da Nang City had installed an automatic bridge health monitoring system to promptly detect damage to have an appropriate bridge maintenance plan. Certer for Science and Technology and Investment Consultancy – Danang University of Science and Technology is trusted by the owner with the task of designing the system, providing equipment and monitoring software solutions for this special bridge (after winning the tender through open bidding). Under the chairmanship of Dr. Nguyen Lan and a team of experts from the Danang University of Science and Technology, STIC has successfully implemented the Thuan Phuoc bridge monitoring project. The system has been trained, handed over to the bridge management unit to automatically monitor the structural behavior due to different types of loads to assess bridge health in real time. Through the Thuan Phuoc bridge monitoring project phase 1 and phase 2, the monitoring software system has been improved and updated gradually and has been granted a copyright registration certificate by the Copyright Office No. 5523/2019/ QTG on September 11, 2019.

Figure 4: Certificate of software copyright registration “STIC Project Monitoring”

     From the experience of the projects, the research team has also formed the process of surveying the design of the structural monitoring system, the architectural foundations of the monitoring system and the experience of choosing highly reliable monitoring equipment for projects.

Figure 5: Example process and architecture of the bridge monitoring system implemented.

     The research team has also compiled operating procedures, equipment maintenance procedures to train and transfer to the bridge operator. The 2-year system warranty process is also the team's competitive advantage for the owner, the team always promptly warrants system failures and fixes them as quickly as possible. Some bridge monitoring systems in Vietnam provided by foreign companies previously did not work after the foreign contractor finished the project and returned home.

Figure 6: Operation and maintenance procedure of bridge monitoring system [3]

     The results of the implementation of the first bridge monitoring project (Thuan Phuoc Suspension Bridge) were highly appreciated by the Owner and fellow Experts as a motivation for the Research Team to continue to perfect the system. The Department of Transport of Da Nang City continued to entrust the STIC to carry out the project of automatic monitoring of Dragon Bridge and Tran Thi Ly Bridge after that.

Figure 7: Overview interface of monitoring software on workstations [3]

Figure 8: Vibration monitoring window and real-time FFT [3]

Figure 9: SDC Map 4D integrated monitoring website interface [3]

4. Structured, geotechnical and environmental monitoring projects have been implemented

     After the first automatic monitoring project of Thuan Phuoc suspension bridge, STIC continues to receive the trust of many owners assigned to carry out many projects as follows:

  - Monitoring Dragon bridge, Da Nang city

  - Monitoring Tran Thi Ly bridge, Da Nang city

  - Monitoring Alin B1 hydroelectric dam, Hue

  - Monitoring Song Than Dam, Ninh Thuan province

  - Monitoring Nam Kong 2 hydroelectric dam, Ataapeu province, Laos

  - Monitoring Nam Cum 2 hydroelectric dam, Lai Chau province

  - Monitoring Nuoc Bieu hydroelectric dam, Quang Nam Province

  - Monitoring Dakpokei Reservoir Dam, Kon Tum Province

  - Monitoring Cable-Stayed bridge across Hieu River, Quang Tri province

  - Monitoring Hoa Lien Reservoir Dam, Da Nang City.

Figure 10: Interface of the Dragon bridge monitoring system, Da Nang City [4]

Figure 11: Interface of Tran Thi Ly bridge monitoring system [5]

Figure 12: Monitoring interface of monitoring data of Alin Hydroelectric Dam [6]

   From the experience of structural and geotechnical monitoring systems that have been and are being implemented, the research team has collaborated with Environmental experts from the University of Danang to continue to develop automatic monitoring systems for wastewater, emissions, surface water, groundwater, weather monitoring, etc.

     The STIC won the bid for the wastewater monitoring project of the rubber latex processing plant of Company 75, Army Corps 15. The system is being deployed and installed and is expected to be completed in August 2021.

Figure 13: Architectural diagram of wastewater monitoring system of the company 75's rubber latex processing plant [7].

    Currently, the research team is continuing to research and apply automatic monitoring systems for different types of projects such as: High-rise buildings, Deep excavation pits, High embankment on soft soil, slope erosion, environmental monitoring, weather monitoring, etc. based on IoT technology and combined with automatic control.

5. Directions for Future Work

- The team continues to collaborate with experts and engineers at the University of Danang to develop the system, optimize equipment configurations, upgrade software to meet the requirements of the Owner and legal regulations to ensure the system operates sustainably and economically.

- Research and apply IoT technologies, new communication protocols, data processing algorithms applying artificial intelligence to automatically diagnose structural damage, predict and analyze data more efficiently and accurately.

REFERENCES

[1] You-Lin Xu, Yong Xia (2012). Structural Health Monitoring of Long-Span Suspension Bridges. Spon Press, First published 2012 by Spon Press 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN.

[2] https://dewesoft.com/applications/monitoring/structural-health-monitoring

[3] STIC (2017). Manual on operation and maintenance of Thuan Phuoc bridge monitoring system.

[4] STIC (2018). Manual on operation and maintenance of Dragon bridge monitoring system.

[5] STIC (2019). Manual on operation and maintenance of Tran Thi Ly bridge monitoring system.

[6] STIC (2017). Proposal file for monitoring system of Alin B1 Dam – Hue.

[7] STIC (2020). Design and installation of wastewater monitoring system for rubber latex processing plant of Company 75, Army Corps 15, Gia Lai province.

@Article by Assoc.Prof.Dr. Nguyen Lan, Engineer Nguyen Huy Hung celebrates Vietnam Science and Technology Day, May 18, 2021