Novel digital image correlation instrumentation for large-scale shake table tests

The identification of structural and seismic behavior using experimental methods has been the cornerstone for investigating the earthquake resistance capability of any types of structures. Traditionally, shake table tests are monitored using contact string potentiometers, strain gages, and/or accelerometers that are hooked up to a Data Acquisition system (DAQ). This procedure is usually time-consuming due to instrumentation attachments and setup and the results are usually obtained for limited locations. On the other, Digital Image Correlation (DIC) is a relatively new technology that can be used to provide non-contact full-field strain measurement and threedimensional (3D) point tracking. In this paper, the global behavior of several large-scale structures that include a steel frame building and a two-span bridge tested on the shake tables at the University of Nevada, Reno is captured and compared using DIC and conventional DAQ measurements. The objectives of this study are: (1) to demonstrate the validity of DIC for largescale and dynamic tests measuring with high-efficiency and high-accuracy comparable to existing instrumentation techniques; (2) to measure responses that are hard to capture using conventional measurements such as the tested bridge deck rotation. Several unidirectional and bidirectional earthquake tests are conducted using different ground motions on the different structures and the time histories of the structural response are generated by 3D DIC point tracking. The results from the DIC are compared to conventional instrumentation data collected from the DAQ. The results are very comparable which validates the DIC technology for large-scale dynamic tests measurements.