Performance assessment of drilled shaft using Embedded Sensor Technology.
Smart Structures introduces the fastest, most precise, and easiest-to implement performance assessment solution for drilled shafts combining sophisticated software with embedded sensors to provide improved levels of accuracy, reduced uncertainty, and accelerated testing of drilled shaft performance. Smart Structures solutions for drilled shafts are configurable for both dynamic and static load testing. The solution architecture consists of calibrated sensors installed on the drilled shaft rebar cage, a portable data logger, and a data acquisition workstation pre-loaded with Smart Structures analytics software. The hardware portions of the solution have been engineered to work reliably in the harsh environment of concrete.
Using Smart Structures IoT solution in Drilled Shafts determines:
- Static Load measurements at various locations along the shaft and shaft cap
- Changes in shaft strain during live load, dead load and service loads
- Temperature of concrete at various stages of the shaft and shaft cap construction and post construction
- The load transfer along the shaft
Typical solution architecture
Smart Structures presents a completely new and tested solution for determining driven pile capacity; obtain pile resistance with accuracy that is comparable with static load testing. Perform pile testing smoothly and easily with minimum disturbance to construction activity and environment. Take the guesswork and subjectivity out of pile resistance assessment.
Smart Structures sensor packs consisting of Strain Gages and Accelerometers are installed onto the rebar cage at various levels. For dynamic load testing, they are typically installed onto the top and tip of the rebar cage while static load testing calls for only strain sensors to be placed at multiple levels. Sensor data is wired through to the top of the drill shaft where the cables are connected to the Portable Data Logger. The Data Logger beams the data out wirelessly to the Smart Structures workstation. The preloaded analytics software provides real-time analytics on the live data stream to assist operators assess the drilled shaft performance and load capacity to a far greater degree of accuracy, precision, and with great ease.
Dynamic Load Testing
With the strain sensors and accelerometers in place on the rebar cage, the concrete is poured in, eventually curing around the sensors. Drop hammer blows are then applied to create an impulse. The data provided by the embedded sensors is analyzed by the workstation software and provides:
- True wave speed for modulus determination
- Detection of early reflections indicating voids or material defects
- Measurement of load transfer at the tip
- Measurement of settlement at the tip and assessment of the presence of loose or soft material
Static Load Testing
Only strain gages are used for static load testing and these are placed at the top, tip, and intermediary positions along the rebar cage. As in the case of dynamic testing, the data cables are drawn through the height of the rebar cage and exit at the top to be connected to the portable data logger.
The Smart Structures workstation receives the data wirelessly and monitors static load at various levels along the drilled shaft. Changes in shaft strain during static load, dead load, and testing load scenarios are also recorded.
The Smart Structure workstation with its proprietary data analytics software is the brains of the performance assessment solution for drilled shafts. The recorded data combines the unique radio address, sensor calibration details, and time stamp with a structure element location (e.g. pile top, pile tip). The software provides multiple views of the sensor data for detailed analysis of location specific as well as performance assessment. The software is built around sophisticated algorithms for both dynamic and static load testing.
Monitoring of Concrete Curing
A common practice is to include temperature sensors within some of the embedded sensor packs to establish a curing profile for the concrete. Beneﬁts of the Smart Structures solution for Drilled Shafts
- No setup time
- Auto-configuration of calibrated sensors
- Accurate readings using embedded instrumentation
- Operator software ensures proper data collection and reporting