Program Summary
S-lynks is a wireless vibration measurement and data processing solution that is used to aid inspections by identifying the current dynamic status of bridges. S-lynks provides high quality and reliable information regarding overall dynamic and wind performance for both long and short span bridges regardless of their material composition. Stay cable forces, resonant frequencies of bridge members along with damping ratios and mode shapes are accurately identified and used in establishing the baseline dynamic performance. Identified forces and dynamic parameters are tracked at each inspection or scheduled intervals to determine changes in bridge behavior or can be incorporated in calibrating the existing finite element models for more accurate strength and serviceability analysis.
Contact Information
Ozan Celik, PhD, PE Structural Monitoring Lead
Geocomp, Inc.
O: 978-635-0012 | D: 978 893 1227 | C: 407 575 0864
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www.geocomp.com
Detailed Description of Program
Describe your product/technology:
S-lynks is a distributed wireless measurement and data analysis solution that consists of a group of MEMS-based wireless triaxial accelerometers, and data processing software. It allows to collect acceleration data from structures under operational and ambient loads for the following applications:
- Estimation of cable forces and assessing the effectiveness of cable dampers on cable stayed bridges.
- Full characterization of frequencies, mode shapes, and damping.
- Torsional dynamic characterization of long span bridges for wind and seismic loads.
- Tracking of modal parameters (frequency, damping, modal shapes) to assess the deterioration, reveal anomalies and validate performance after construction, after extreme events, and periodically during the structure’s lifetime .
- Assessment of floor vibrations and resonance under human induced loads or machinery.
- Modal verification of buildings in seismic zones and acceleration information to be used in story drifts.
- Finite Element Model (FEM) verification and providing information for FE updating.
Why is it innovative?
S-lynks is a passive measurement system eliminating the need to excite the system externally to capture all the critical modes in the data. Through its wireless technology and easy deployment, it allows the data collection to be completed in hours to a few days even for large signature bridges. Cable measurements do not require cable plucking or pulling and the data can be recorded for a much longer time ensuring much better frequency resolution and removing the bias induced by forcing the cable compared to traditional excitation methods. As a result, force and damping estimation is the most accurate. The web-based software platform allows to build the geometry, upload the data, and do the processing right after the partial or full system measurements are completed. The data analysis is powered by the Stochastic Subspace Identification (SSI) algorithm, which is the most advanced and the most convenient to automate with the availability of uncertainty estimation.
What would a field demonstration entail?
Depending on client needs, field demonstration includes the temporary deployment of measurement nodes on deck, towers, cables or other elements of concern followed by data collection. Data collection is typically done by roving up to 20 measurement nodes along discretized measurement points and collecting data in 20-min long durations at 250 samples per second. This is a repeated process that does not require hard mounting on the structure and continues until the entire structure or structural element is covered. The quality of data is verified after each measurement. Data processing and visualization are done using the dedicated software either on-site or after the completion of data collection. As a reference, a long span bridge with a main span length of 1250ft can be completed within a day.
For cable force estimation, S-lynks nodes are strapped around the circumference of the cables along the free longitudinal length of the cable or group of cables. Rugged metal brackets are used to position the sensor. Once the measurement node is in place, data is collected for a pre-set interval of 10-20 minutes. Data collection is completely passive and does not require any sort of external cable excitation such as plucking or pulling. Up to 40-50 cables can be done in a single day.