Adaptive Motion Scaling Strategies for Seismic Performance Assessment in Shake Table Testing: Application to CFS-NHERI Wall-Line Tests

Shake table testing of large and/or full-scale structures has gained popularity in the earthquake engineering community due to its effectiveness in assessing the system-level seismic performance of structures. Test protocols for such experiments often involve a sequence of recorded earthquake motions with increasing intensities to progressively damage test specimens. To this end, this report summarizes a prediction-adjustment motion scaling methodology developed for a shake table test program of cold-formed steel (CFS) wall-line specimens with substantially varying structural behavior. The implemented procedure involves two separate stages, namely: (1) pre-test numerical analysis for preliminary motion scaling parameter prediction, and (2) adaptive (on-the-fly) motion scaling parameter adjustment accounting for the evolution of dynamic characteristics of the specimens during the test sequence. Although the structural behavior of the specimens considered in the pre-test numerical studies was estimated from prior experimental data on like-detailed specimens, the wall specimens tested herein achieved the intended performance during the earthquake test sequence using the proposed motion scaling strategy. Additionally, the energy dissipation and cyclic displacement demands of the test specimens during the shake table test sequence were comparable to similar specimens tested using a standard quasi-static cyclic loading protocol. The motion scaling procedure documented in this report intends to provide useful guidance for future applications of large and/or full-scale shake table experiments.

Structural Systems Research Report SSRP-24/02, University of California San Diego, La Jolla, CA