Monitoring Displacement with Resensys Wireless Displacement SenSpot Sensors

Movements of structure members within certain ranges indicate the integrity and safe operation of that structure. The Resensys structural health monitoring (SHM) solution can be used for monitoring displacement in bridge and structure members. As an important application the displacement SenSpot can be used for crack monitoring which is an important part of SHM. Cracking may cause serious damage to the structure which deteriorates its integrity and safety. Resensys displacement SenSpots are able to monitor cracks in concrete, steel and composite materials. The displacement meter shown below consists of two parts which are to be installed on the two sides of the measurement spot. The relative distance between the moving and fixed sides of the SenSpot is measured with accuracy of one tenth of a millimeter. These SenSpots are available in different measurement sizes such as 1, 2, and 4 inches.

Steel girders of old bridges mostly suffer from fatigue cracks primarily due to non-functional bearings. In cases that the bridge bearings are not functioning properly, thermal expansions and contractions of the bridge deck cause a high level of cyclic strain to accumulate in the bridges structural elements. Such a strain level could result in damage in form of cracks or deformation. Resensys Displacement meters can be used to monitor the dynamics of existing cracks. A more comprehensive solution includes tilt and strain SenSpots that are able to monitor the direction of the movements and deformations to track the correct operation of the bridge.

Visual inspection is traditionally used for crack monitoring; however, this method is time and capital consuming. Moreover, visual inspections cannot be done frequently and in many cases the measurements are unreliable and inaccurate. Therefore, the need for a system that can continuously monitor displacements and cracks to capture the healthy operation of a structure is important. Wireless SenSpot sensors provide a wireless communication platform and versatile sensing for long term structural health monitoring; SenSpot sensors are capable of monitoring strain, vibration, tilt, inclination, displacement, temperature, and humidity. Using this technology, any potential problem in a structure is detected in an early stage before it becomes a major issue and leads to safety compromise and/or road closure.

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