Structural Monitoring and Evaluation Tools at Caltech: Instrumentation and Real-Time Data Analysis

This paper presents a summary of the structural monitoring tools available at the California Institute of Technology (Caltech) and selected research using these tools. The Caltech Online Monitoring and Evaluation Testbeds (COMET) site is an educational and research tool that archives real-time data from the Southern California Earthquake Data Center (SCEDC) stations MIK (Millikan Library) and CBC (Broad Center). The COMET site allows users to view and download real-time data, as well as perform dynamic analysis using Caltech's MODEID software. Ambient analysis of data from Millikan Library has revealed a change in dynamic properties based on weather conditions, especially rainfall and windstorms. During heavy rains, the fundamental E-W and Torsional frequencies of Millikan Library can increase by 3-5%. Strong winds can decrease all fundamental frequencies by 2-4%. Results such as these have important implications in the development of structural health monitoring methods that use changes in modal parameters to infer damage.