Innovation Report > Using Very Small Strain Analysis to Monitor Structures

It is quite common in the construction industry to monitor structures for potential damage from ongoing construction activities. Impact to retaining walls, foundations, adjacent buildings, abutments, etc. from ongoing construction are typically undertaken through the application of optical based laser surveys, crack gages, pre/post photographs, vibrating wire strain gages, accelerometers, and tilt meters. These tools are, of course, well-known across the North American construction industry and found on most job sites. It is recognized, however, that these traditional applications provide evidence of deformation or movement after it has occurred and it is then a matter of extrapolation and analysis to determine the effect of the movement on the structure. For example, if vibration readings from installed accelerometers are beyond accepted levels, what is the impact on the asset being monitored? Can we be sure there has been no damage to the asset? If there was movement, has the structure stabilized? Is there damage that may be accelerating? What are the inherent risks and how can they be managed or minimized?

These questions represent very real concerns to contractors and developers. Issues associated with progressive damage pose safety risks, scheduling risks and liabilities for project stakeholders.  They portend unforeseen costs. It is recognized that traditional approaches can often only demonstrate a change without providing demonstrable proof of what that change might mean to the project. STRAEN Inc. has been working in the US to introduce complementary tools to work with contractors, developers and engineers to provide immediate answers to these critical questions. Using new wireless fiber optic strands that can be installed in as little as fifteen minutes, contractors and engineers are able to benefit from new high resolution data that measures accumulated strain from an installed baseline level to any changes to the ongoing dynamic operating conditions of a structure.

Normal construction activities and their effect on monitored assets are measured dynamically as are any changes to normal operating conditions such as excessive vibration, blasting, drilling, excavation, collisions, etc., which may compromise the structural integrity of the asset. By continuously sampling at 50Hz, the technology measures the accumulation of strain on monitored structures, and provides immediate (alarmed) feedback if normal conditions have been exceeded, and how the structure has responded to the activity. Dynamic changes can be highlighted and the response of the structure is made available for immediate analysis. This high-resolution data illustrates the effect of the movement, if the structure has returned to its normal operating conditions, of if there are any changes (and where) to normal operating behavior.  The goal is immediate and objective data on critical issues.

While relatively new to North America, the technology was developed by French-based OSMOS SA and has been used across Europe and Asia for over ten years with over 4,000 installations globally. Landmark structures including the Euro Tunnel, Eiffel Tower, Manhattan Bridge and even the monitoring of adjacent buildings at Ground Zero post 9-11 demonstrate the wide-variety of uses for the instrumentation. With the introduction of the new wireless units developed by OMSOS SA, STRAEN Inc. anticipates a very rapid adoption of the technology in the US given the ease of installation and the significantly increased data available for managing risk on project sites.

STRAEN Inc. is focusing on the introduction of the new wireless sensors for the construction industry as an inexpensive contribution to the real questions needing to be answered onsite for contractors, developers, and engineers to manage risk proactively and avoid costly emergencies.


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2 Responses to Innovation Report > Using Very Small Strain Analysis to Monitor Structures

  1. Sujan says:

    This seems to be a great product in the field of Geotechnical Instrumentation and Monitoring (I&M). Based on my experience with I&M in major infrastructure projects in the US, similar I&M methodology is available; satellite based remotely controlled I&M technique is also used in projects in the US. I think what really is needed is the quick, if not instantaneous analysis of I&M data and generation of signals as to the degree of risk. If any kind of failure is possible, system must signal it well in advance of failure. I am not aware of any product that generates alarm signals related to risks almost instantaneously upon storing the data.

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