Evaluation of Modal Analysis for Time-Delayed Multi-Degree of Freedom Structures for Reliability Assessment of Real-Time Hybrid Simulation Results

Real-Time Hybrid Simulation (RTHS) presents an innovative technique for earthquake engineering research that enables researchers to assess structural performance through component tests.Servo-hydraulic dynamics induced time delay can lead to synchronization errors between the experimental and analytical substructures.This makes it necessary to perform reliability assessment of RTHS results to appropriately interpret structural performance subjected to selected ground motion.Research findings from previous studies on single-degree-of-freedom (SDOF) structures is not directly applicable due to multiple mode participation when the RTHS involves multiple-degree-of-freedom (MDOF) structures.Integrated with the engineering senior project at San Francisco State University and supported by the NSF BRIGE project, this study presents computational analysis of RTHS of a two-degree-of-freedom structure by a senior civil engineering student.Modal analysis developed for linear elastic structures is evaluated for timedelayed RTHS of nonlinear MDOF structures.Frequency response analysis is also utilized to decouple the MDOF into multiple SDOFs.It is demonstrated that modal analysis has potential for reliability assessment of RTHS involving multiple experimental substructures.The computational study presented herein exemplifies engaging engineering student into advanced earthquake engineering research to solve a real practical problem.The integration with senior design project provides an exploration for undergraduate institutions such as San Francisco State University to recruit and involve motivated engineering students into research and to prepare them for advanced degrees.