Edge-computed Shaking Intensity Parameters and Structural Damage Detection: Application to the Community Seismic Network (CSN)

Monica D. Kohler, Richard Guy, Eliseo Banda, Robert W. Clayton, Ellen Yu, Allen L. Husker, Shane Zhang, Huiyun Guo, Shokrullah Sorosh, Charlie Zhang, & Tara Hutchinson

Submitted September 7, 2025, SCEC Contribution #14522, 2025 SCEC Annual Meeting Poster #226

The Community Seismic Network (CSN) continues to expand in southern and northern California and consists of over 1200 permanent 3-component accelerometers that report in near-real-time to the Amazon cloud. We present findings from two new developments: 1) testing of several fast, real-time, recursive algorithms to compute spectral accelerations for implementation in the seismic station software; and 2) preliminary findings about building damage from a recent deployment of 75 sensors at the 10-story cold-formed steel building that was constructed and tested at the large, outdoor NHERI@UCSD shake table during June 2025 (cfs10.ucsd.edu; lead PI: Tara Hutchinson).

Real-time Spectral Accelerations (SAs): We present comparisons of efficiency and accuracy of four recursive algorithms that solve the SDOF differential equation of motion in real time to compute SAs in-situ at individual sensor sites, i.e. at the edge. Each CSN station is a low-cost MEMS sensor coupled to a microcomputer (Raspberry Pi) connected to the Internet. All shaking intensity parameters computed at the sensor-microcomputer site (PGA, PGV, SAs) are formatted into ground motion packets and transmitted to an AQMS import server. Once it receives notification of an earthquake, ShakeMap can then query the AQMS database for CISN and CSN amplitudes associated with that event to create ShakeMaps. Test ShakeMaps for recent southern California earthquakes indicate an order of magnitude improvement in spatial resolution when the high-density CSN data are added.

10-Story Steel Building Shake Tests at UCSD Shake Table: Continuous CSN data recorded on 75 accelerometers at the 10-story steel building constructed at the large outdoor shake table at UC San Diego presented a real-world test of the structural health monitoring capabilities of the CSN hardware and software architecture. Eighteen shake tests using scaled earthquake ground motion inputs were conducted at the 10-story on the shaketable. Multiple resonant modes of the building are identified from both quiet and shake test times. During shaking, building resonant frequencies drop transiently by as much as 50% and then recover, though often not to pre-shaking levels, suggesting permanent damage. At least three shake tests were large enough to produce a significant amount of damage throughout the building. Across all tests, a permanent reduction of 10-20% accumulated in the fundamental, first, and second overtones of the building’s resonant frequencies.

Citation
Kohler, M. D., Guy, R., Banda, E., Clayton, R. W., Yu, E., Husker, A. L., Zhang, S., Guo, H., Sorosh, S., Zhang, C., & Hutchinson, T. (2025, 09). Edge-computed Shaking Intensity Parameters and Structural Damage Detection: Application to the Community Seismic Network (CSN). Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions (GM)