Structural Health Monitoring

Campbell Scientific data acquisition systems' versatile capabilities make them ideal for structural health monitoring. Our dataloggers applications range from simple beam fatigue analysis, to structural mechanics research, to continuous monitoring of large, complex structures. Campbell systems provide remote, unattended, portable monitoring for highway overpasses, roads, buildings, retaining walls, bridges, and amusement park rides. They make reliable structural measurements, even in harsh environments.

Read more

Dataloggers used in Structural Monitoring and Control

The versatility of our datalogger systems allows them to be customized for each application. We offer a range of dataloggers from the most basic system with just a few channels, to expandable datalogger systems that measure hundreds of channels. Scan rates can be programmed from a few hours to 100,000 times per second, depending on the datalogger model. Measurement types, recording intervals, and processing algorithms are also programmable. Dataloggers not only provide advanced measurement capabilities, but can also control external devices.

On-board processing instruction sets contain programmed algorithms that process measurements and output results in the desired units of measure. For example, data can be displayed as rainflow or level crossing histograms. These rainflow and level crossing algorithms allow processing for extended periods of time, not just a limited number of cycles. The instruction sets also allow for triggered output with pretrigger data capture capability. Triggers can be based on sensor output, time, and/or user control. For example, if an overpass is being monitored, data collection can be triggered by a sensor detecting the approach of a car, an earthquake, pre-programmed times, or by pushing a button.

The control functions of our dataloggers combined with their programmability allow them to sound alarms, actuate electrical devices, or shut down equipment based on time or measured conditions. Systems can also call out to phones, pagers, radios, and other devices to report site conditions. Voice-synthesized modems are available, so the system can actually call and tell you what is happening.

Sensors used in Structural Monitoring

Because our dataloggers are compatible with nearly every commercially available sensor, you can use the sensors that best meet your application. Typical sensors used for structural and seismic monitoring by our systems include:

1. Carlson strain meters
2. vibrating wire strain gauges
3. foil strain gauges (set up in quarter, half, or full bridge strain configurations)
4. inclinometers
5. crack and joint sensors
6. tilt sensors
7. piezoresistive accelerometers
8. piezoelectric accelerometers
9. capacitive accelerometers
10. borehole accelerometers
11. servo force balance accelerometers

Because our dataloggers have many channel types and programmable inputs, all these sensor types can be measured by one datalogger. Channel types include analog (single-ended and differential), pulse counters, switched excitation, continuous analog output, digital I/O, and anti-aliasing filter. Using switched or continuous excitation channels, our dataloggers provide excitation for ratiometric bridge measurements.

Our configurable datalogger models, the CR9000X and CR9000XC, allow you to customize a system with the channel types that best fit your application. The number and type of channels on most of our dataloggers are expandable using multiplexers and other measurement peripherals. Our dataloggers have input resolutions to 0.33 microvolts, allowing strain measurements with a resolution of a single micro-strain.

Communications

The availability of multiple communications options for retrieving, storing, and displaying data also allows systems to be customized to meet exact needs. On-site communication options include direct connection to a PC or laptop, PC cards, storage modules, and datalogger keyboard/display. Telecommunication options include short-haul, telephone (including voice-synthesized and cellular), radio frequency, multidrop, and satellite.

Software

Our Windows-based software simplifies datalogger programming, data retrieval, and report generation. The datalogger program can be modified at any time to accommodate different sensor configurations or new data processing requirements.

Example Application: Monitoring an Overpass

Campbell Scientific's monitoring systems are used for a variety of structural and seismic applications. Monitoring possibilities on an overpass include: