Automated crackmeters were part of the instrumentation GEO installed during work at the Kennedy Center for the Performing Arts.
GEO deployed twelve automated crackmeters on the facade of Boston’s Old South Church during repair of a 70 foot crack.
GEO automated ten crackmeters to monitor a National Park Service building at Charleston Naval Yard, home of the USS Constitution.
Crackmeters are used to monitor movement at cracks and joints in concrete structures or rock. Typical applications include:
- Monitoring joints to provide early warning of performance problems
- Monitoring joints and cracks in structures that could be affected by nearby construction activities.
- Monitoring cracks in structures that have experienced seismic activity.
Automated monitoring goes beyond simple data logging. It includes automated retrieval of data, automated processing, automated alarms, and automated distribution of reports and graphs via a project website.
Installation & Operation
The crackmeter consists of a displacement sensor and a set of anchors. The anchors are installed on opposite sides of the crack. The sensor is then fixed to the anchors via ball joints, which accommodate movement in other planes.
Signal cable from the crackmeter is connected to a wireless data logger or a wireless node, either of which obtains readings at regular intervals and transmits them offsite to GeoCloud servers for processing.
The initial reading establishes the baseline width of the crack. Subsequent readings are compared to the baseline to determine changes.
In processing the readings, the GeoCloud server applies any calibration factors, converts readings to the desired engineering unit, and checks the reading against alarm thresholds.
Alerts are sent to smartphones and desktop PCs by text message or email. All readings are then used to update trendplots and planviews on the project website.
Vibrating Wire Crackmeter
Standard Ranges: 1, 2, 4, and 6 inch.
Resolution: 0.025% FS.
Accuracy: ± 0.1% FS.
Linearity: < 0.5% FS
Operation: -20 to +80 °C.
Linear Potentiometer Crackmeter
Available ranges: 1, 2, 4, 6 inch
Resolution: 0.0015% FS.
Accuracy: ± 0.15% FS.
Operation: -40 to +85 °C.
Vibrating wire crackmeters can be connected to a GeoCloud-enabled datalogger or GeoCloud wireless node.
Linear Potentiometer with GeoCloud wireless node.