A bridge bearing is a component of a bridge which typically provides a resting surface between bridge piers and the bridge deck. The purpose of a bearing is to allow controlled movement of  the structure and thereby reduce the stresses involved. Possible causes of movement are thermal expansion and contraction, creep, shrinkage of/within the structure, or fatigue due to the properties of the material used for the bearing. For instance, abnormal movements in the bearing/expansion joint may cause abnormal movement in the piers of a bridge.
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An expansion joint or movement joint is an assembly designed to hold parts together while safely absorbing temperature-induced expansion and contraction of building materials, and vibration, or to allow movement due to ground settlement or seismic activity. They are commonly found between sections of buildings, bridges, sidewalks, railway tracks, piping systems, ships, and other structures. Bridge expansion joints are designed to allow for continuous traffic between structures while accommodating movement, shrinkage, and temperature variations on reinforced and pre-stressed concrete, composite, and steel structures. They stop the bridge from bending out of place in extreme conditions, and also allow enough vertical movement to permit bearing replacement without the need to dismantle the bridge expansion joint.

The Resensys Wireless Displacement and Tilt SenSpot sensors data analysis can be used for bridge bearing/expansion joint monitoring. Resensys wireless displacement and tilt sensors are designed to provide accurate small scale displacement/tilt measurements over long periods of time, allowing them to provide base-level data and also continuously monitor for changes that could indicate changes in the effectiveness of these important bearings or joint functionality. Ensuring that these bearings/joints are functioning as designed can pre-empt expensive repairs or structural failures or other structural damage. This can allow for improved asset management decisions. By utilizing ultra-low power, wireless technology, Resensys decreases installation and maintenance costs of monitoring these elements.

The applicable, measurable and monitorable quantities for bridge bearing and expansion joint measuring are displacement, tilt and ambient temperature. Resensys SenSpots are able to monitor these structural quantities in concrete, steel and composite materials under wet, humid and extreme weather conditions. The product is corrosion resistant and can withstand salty environments.

A Resensys Bridge Bearing/Expansion Joint Monitoring solution comprises wireless Displacement SenSpot sensor and/or wireless Tilt SenSpot sensor on the location of bearings/expansion, a SeniMax Gateway to transmit data away from the site and the SenScope display user-interface.