STRUCTURAL HEALTH

MONITORING

M. MayurS.I.E.T.K Puttur.

Contents:

Definition… What is SHM? Pattern of SHM Importance of SHM Components Conclusion.

Structure:

Types:

Damages Due to:

mismanagement in construction,

lack of quality in control,

temperature conditions……

Damages such as surface cracks, segregation, settlements etc…

Damage:

Changes in:

geometric properties , boundary conditions , system connectivity…

which adversely affect the structure’s performance.

What should we do?

In 19th Century:

rail road wheel tappers - used the sound of a hammer when striked against the wheel of train to detect the damage.

In rotating machinery, vibration monitoring is used as performance evaluation technique.

Then, these techniques are utilized to detect

the damages in the structure, and then a new

field emerged namely Structural Health

Monitoring.

What is Structural Health Monitoring?

The process of implementing a damage detection and

characterization strategy for engineering structures is

referred as Structural Health Monitoring.

(in short…)

Pattern of SHM: Operational Evaluation,

Data Acquisition and Cleansing,

Feature Extraction & Data Compression, and

Statistical Model Development for Feature Discrimination

Operational Evaluation:

Under which operations, the structure services and damage.

Life safety and economic justification for performing SHM.

Limitations of acquiring data in SHM.

Data Acquisition:

This parts deals with:

number of sensors, types of sensors, selecting their excitation methods & data storage techniques.

Data Normalization:

separating changes in sensor readings from

damage to those caused by varying

operational & environmental conditions.

Feature Extraction:

Feature extraction gives the technical

literature to distinguish between damaged and

non damaged items of buildings.

Statistical Model Development:

Statistical Model Development is used for

determining damaged and undamaged

structures.

Importance of SHM: SHM improves - safety & functionality of

structures.

Monitoring - develop innovative design methodologies - timely warning of impending failures.

Structural condition monitoring and assessment are required for timely and cost-effective maintenance.

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.

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.

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.

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)

Components:

Structure Sensors Data acquisition systems Data management Data transfer Data interpretation and diagnosis

Why SHM?

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.

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

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.

SHM monitoring for a dam in China:

Conclusion:

There is always no particular conclusion for any technology related concept.

But, this concept ends with conclusion with that even structures have life and we (civil engineers) are here to protect it from various diseases.

Thank you...