Ravi Shukla, HBM Test and Measurement
Eighteen channels of sensor data from strain gauges attached to girders supporting bridge decking helped U.S. Army Corps of Engineers technicians monitor and record stresses on a decking structure of a new portable bridge.
The work took place at the Corps’ Engineer Research and Development Center (ERDC) in Vicksburg, Miss. Their technicians used a six-month test with a heavy vehicle simulator (HVS) to see how 20 years-worth of traffic would affect pavement and decking on a test section of the bridge. The objective of the project was to gauge the durability of the proposed bridge deck design by stressing it to failure, then evaluating the structural changes in the bridge segment. Accelerating the testing process allowed quick experiments with different materials or engineered structures.
The bridge segment tested for the project was approximately 15 ft wide and 51 ft long, with a 40-ft long test area. Strain gauges went to two HBM QuantumX Model MX1615B 16-channel strain gauge bridge amplifier modules. Corps electronics technicians Tommy Carr and Tony Brogdon say they chose the QuantumX system because of its durability, modular architecture, application flexibility, its ability to withstand high humidity, and compatibility with multiple sensor types.
Data was initially stored locally on a QuantumX CX22B data recorder running catman AP data acquisition, visualization, storage, analysis, and reporting software. This instrument can not only store data locally but also stream it via Ethernet to a PC running catman AP. This remote PC sat in a control room in the Pavement Testing Facility, which allowed the research team to monitor data visually as it was acquired.
Carr and Brogdon say they chose catman AP software to interface with the QuantumX system because it required little programming knowledge; catman automatically triggered the system to take data whenever the HVS moved, then stop automatically when the vehicle stopped. The technicians have acquired data at a rate of 300 samples/sec multiplied by 18 strain gauges over the course of several months, generating a massive amount of data that is still being analyzed.
The QuantumX hardware remains in regular use though the data acquisition portion of the bridge project is complete. Most recently, it helped monitor the levels of vibration produced by concrete breaking equipment like jackhammers.
The portable bridge project took place at the Airfields and Pavements branch of the ERDC’s Geotechnical and Structures Lab, one of four ERDC labs in Vicksburg. Projects in the Airfields and Pavements Branch often involve testing a variety of engineered products used in geotechnical applications, like roadways, airfields, railroads, etc.