Structural Health Monitoring SHM

[edit] Introduction

Structural health monitoring (SHM - sometimes referred to as structural health and environmental monitoring) is an emerging technology used to document the viability and integrity of engineering projects such as bridges.

Christopher Beckett, lecturer in geotechnical engineering, University of Edinburgh, recognises the potential of SHM and sees it as "a burgeoning discipline" that could be "a possible solution to maintaining safety" using technology.

Beckett explains how sensors placed throughout a structure can be used to "monitor the condition of embedded reinforcement, accelerations within the structure (e.g. under wind loads) and the formation and propagation of cracks, amongst many other indicators of damage. Timely intervention, targeting the worst-affected areas, may provide the Holy Grail of a cost effective, safe solution for construction without needing to abandon coastal areas."

[edit] Types of SHM

SHM is non-evasive. Information that has been gathered through SHM can be used for maintenance purposes, but it is primarily used to detect systems that may have been compromised.

Passive SHM relies on inference or interpretation of operational data to provide the evaluation of the structural health of the project.

Active SHM attempts to detect the actual presence and extent of structural damage rather than extrapolate the condition based on interpretation.

[edit] Expanding role of SHM

SHM can now be used to record changes - or the absence of changes - in the characteristics of materials and structures. It can also be used to estimate the degradation of infrastructure, either due to age or extreme events such as floods, earthquakes, explosions and so on.

SHM systems can include wired or wireless sensors (over wired or wireless sensor networks) that are embedded into structures. These sensors record all types of movement so that it can be analysed.

[edit] SHM and bridges

When applied to bridges, SHM can produce valuable data sets that can aid key decisions about current performance, margins of safety, actual loading, stress history, extent of deterioration and residual life.

Long span bridges in particular can benefit from the sensing technology that is incorporated into SHM. The Queensferry Crossing (originally known as the Forth Replacement Crossing) across the Firth of Forth is one of the largest infrastructure projects of its kind. The 2.7 km structure is the longest three-tower, cable-stayed bridge in the world, as well as by far the largest to feature cables which cross mid-span. It was constructed with thousands of sensors as part of its SHM monitoring system. Since it opened in 2017, SHM professionals have been able to use a web-based system to access the data that has been collected by the sensors.

[edit] Related articles on Designing Buildings Wiki

• Assessing bridges.
• Building pathology.
• Civionics.
• Improving the energy efficiency of buildings.
• Queensferry crossing.
• Surfside condo collapse: climate change demands adaptation in design and approach.