Structural Health Monitoring ( SHM) system
- 1. Sanjivani Rural Education Society’s Sanjivani College of Engineering, Kopargaon (An Autonomous Institute, Affiliated to Savitribai Phule Pune University, Pune) NAAC ‘A’ Grade Accredited , ISO 9001:2015 certified Subject: Structural Audit and Health Monitoring FY Mtech Introduction Presented By, Miss. Shinde Bharti M. (Assistant Professor) Department of Civil Engineering Email- shindebharticivil@sanjivani.org.in 1
- 2. Syllabus • Unit 1: Structural Health • Factors affecting Health of Structures, Causes of Distress, Regular Maintenance. • Unit 2: Structural Health Monitoring • Concepts, Various Measures, Structural Safety in Alteration. • Unit 3: Structural Audit • Assessment of Health of Structure, Collapse and Investigation, Investigation Management, SHM Procedures. Non- destructive testing of concrete, steel structures, Various NDT tests, codal provisions, Proof Load testing. • Unit 4: Static Field Testing • Types of Static Tests, Simulation and Loading Methods, sensor systems and Hardware requirements, Static Response Measurement. • Unit 5: Dynamic Field Testing • Types of Dynamic Field Test, Stress History Data, Dynamic Response Methods, Hardware for Remote Data Acquisition Systems, Remote Structural Health Monitoring. • Unit 6: Introduction to Repairs and Rehabilitations of Structures • Case Studies (Site Visits), piezo–electric materials and other smart materials, electro–mechanical impedance (EMI) technique, adaptations of EMI technique.
- 3. Unit 2: Structural Health Monitoring
- 4. • In 19th century, vibration monitoring is used as performance evaluation technique. These techniques nowdays are utilized to detect the damages in the structure, and then a new field emerged namely Structural Health Monitoring. • The process of implementing a damage detection and characterization strategy for engineering structures is referred as Structural Health Monitoring.
- 7. Pattern of SHM: • Operational Evaluation, • Data Acquisition and Cleansing, • Feature Extraction & Data Compression, and • Statistical Model Development for Feature Discrimination
- 8. Operational Evaluation: • Under which operations, the structure services and damage. • Life safety and economic justification for performing SHM. • Limitations of acquiring data in SHM.
- 9. Data Acquisition: • This parts deals with: number of sensors, types of sensors, selecting their excitation methods & data storage techniques.
- 10. Data Normalization: • separating changes in sensor readings from damage to those caused by varying operational & environmental conditions.
- 11. Feature Extraction: • Feature extraction gives the technical literature to distinguish between damaged and non damaged items of buildings.
- 12. Statistical Model Development: • Statistical Model Development is used for determining damaged and undamaged structures.
- 13. Embedment of sensors during construction and measurement of structural responses during service will enable condition assessment and remaining life estimation easy and convenient Monitoring scheme helps to gather data on the realistic performance of the structures, which in turn will help to design better structures for the future.
- 14. Saptha Suthras: • All materials have inherent laws or defects • The assessment of damage requires a comparison between two system states • Identifying the damage differs than the type and vulnerability of the damage, which requires skill.
- 15. • Sensors cannot measure damage. Feature extraction and statistical classification is required to convert sensor data to damage information. • Damage information depends upon the intelligence of sensor’s feature extraction.
- 16. • There is a trade-off between the sensitivity to damage of an algorithm and its noise rejection capability. • DS α 1/RE (damage size) α (1/ frequency range of excitation) Parameters to be monitored in SHM: Deflection, strain, rotation, temperature, acceleration, corrosion, pre stressing force, etc
- 17. Components: • Structure • Sensors • Data acquisition systems • Data management • Data transfer • Data interpretation and diagnosis
- 18. TRADITIONAL METHODS OF STRUCTURAL HEALTH MONITORING • The short-term projects typically involve a relatively large number of sensors, many hundreds of metres of cable and a multi-channel recording system. This can take many days to set up. • For long term monitoring projects, typically from one to three accelerometers are installed at key points within the structure and possibly cabled together. The reason for this small number of sensors is the cost of the equipment and its installation and operation. Data from these sensors is usually collected manually, following an event of interest, and taken back to a laboratory for analysis.
- 19. RECENT ADVANCED METHODS FOR SHM Development in • Electronics • Sensors • Communication systems
- 20. Wireless Sensor Networks (WSN) Many sensors (tens or hundreds) are installed in a relatively small area. Each sensor device is small, low cost and low power. Each sensor includes a means of wireless communication. Each sensor able to communicate with its neighbors providing many benefits. Like the communications range of each sensor need only be sufficient to reach a small number of neighbors who can pass information back to a central collection point or gateway. It also opens up the possibility of collaborative decision making where each sensor contributes some information to a joint decision making process.
- 21. SHM using Wireless Sensor Networks (WSN) WSN allow a structure to be monitored at many points, allowing detailed information about real structures to be determined. A typical SHM system consists of at least two different types of components. The first is the sensor itself with associated electronics and radio and the second component is the gateway that collects the data from the sensors in the network. Each sensing node can perform some processing, decision making and data buffering to minimize communication, and thus power requirements. The SHM problem is often treated as a System Identification problem. That is, the measurements are used to determine parameters for a model of the structure. It is then a matter of determining these parameters on a regular basis and checking for trends or discontinuities. A variety of techniques are being used for this, from standard Box- Jenkins models to complete finite element models.
- 22. Difficulties in SHM using WSN • Time Synchronization • Data Volume • Network Topologies and Communications • Power Consumption
- 23. Sensors: • Sensors measure the physical quantity of damage and sends it to computer. Good Sensor : • Is sensitive to the measured property • Is insensitive to any other property likely to be encountered in its application • Does not influence the measured property.
- 26. DA systems: • Data acquisition is the process of sampling signals that converts the resulting samples into digital numeric values. • Sensors • Signal conditioning circuitry • Analog-to-digital converters
- 27. • Data management system manipulates the management of data obtained from sensors. • Data transfer systems are used to transfer the data to systems which help in predicting the failures of structures.
- 28. Alteration Alteration can be defined as: ‘Work intended to change the function or appearance of place.’ Ref Conservation Principles, Policies and Guidance, For the sustainable management of the historic environment, Existing buildings often undergo alterations during their life to change, modify or improve their performance or the nature of their use. •Total or partial change of use. •Extension. •Partial demolition. •Linking or separating spaces. •Making or closing openings. •Retrofitting a new a component or feature. •Refurbishing an existing a component or feature. •Renovating an existing component or feature. •Repairing an existing component or feature. •Maintenance. •Decoration.
- 29. Structural Alteration It means any replacement or change in the type of construction or in the shape or size of a building or of the supporting members of a building or structure such as bearing walls, columns, beams, arches, girders, floor joists, or roof trusses, beyond ordinary repairs and maintenance.
- 30. It means painting, wallpapering, the installation of carpeting, bookcases, shelves, partitions, non-load bearing walls, paneling, furniture or moveable fixtures, or the hanging of pictures or other decorative items which can be removed without permanent damage to the applicable surface, or computer/telecommunications wiring or re- wiring within the Premises which does not affect Building Systems. Non- Structural Alteration
- 31. Key requirements are: •Survey and assessment •Preventing structural collapse •Arrangements for demolition •Consulting building control departments