Comprehensive mechanics‐based virtual model of NHERI@UCSD shake table—Uniaxial configuration and bare table condition

Abstract

A mechanics-based virtual model of the NHERI@UCSD large high-performance outdoor shake table (LHPOST) in its uniaxial configuration and under bare table condition is presented. The virtual model includes: (i) a reprogrammed version (i.e., virtual replica) of the actual controller, (ii) a servovalve model including servovalve spool dynamics and two independent servovalve flow nonlinearities for each of the four servovalves of the system, (iii) an actuator model for each of the two single-ended actuators, (iv) two accumulators modeling the average supply pressure drop at the entrance of the servovalves, and (v) a one-degree-of-freedom mechanical subsystem model. Based on forced vibration test results for the foundation block, it was found that the soil-foundation compliance effects do not need to be included in the virtual model of the LHPOST. The virtual model presented is able to predict accurately the actual shake table platen response under narrow and broadband inputs with the controller gains set to the same values as on the actual shake table. Moreover, the fourth stage spool displacements and actuator driving force from actual tests are reproduced accurately by the virtual model. The mechanics-based virtual model presented in this article can be coupled with FE models of specimens to be tested on the LHPOST and can be used to improve the signal reproduction fidelity of the LHPOST and to develop more advanced model-based shake table controllers.

Frequency Seismic Response for EEWS Testing on Uniaxial Shaking Table

“…The performance evaluation of unidirectional shaking tables has been issued in much research, addressing the interaction effects with different loading configurations [ 27 ], the accuracy of a small-scale low-cost electrodynamic shaker [ 28 ] and the bearing capacity issues when reproducing sinusoidal ground motion with frequencies up to 10 Hz [ 29 ], or revealing synchronization and tracking control advances [ 30 ]. The shaking table test outlasts the seismic test closest to the real seismic response, exhaustively appraising the impact of damping natural vibration frequency in all types of investigations, from laboratory validations to practical studies for settling the dynamic behavior of a dry-joint masonry arch [ 31 ] or to evaluate the effectiveness of coupling between a 2-degree-of-freedom shear-type frame system and a rigid block [ 32 ].…”

Digital twins for the underwater shake table array facility

“…The estimated results of shaking table A are shown in Figure 8. For further information please refer to Ozcelik et al 8 and Conte and Trombetti 12 . By estimating, the nominal flow is shown in Table 5.…”

“…7 A digital twin is the best solution for the above issues. 8 At present, the application of servo-hydraulic shaking table around the world develop rapidly. Professional manufacturing companies such as MTS Corporation in the United States, ServoTest Corporation in the United Kingdom, and Mitsubishi, Hitachi, and Saginomiya Works in Japan, had conducted extensive cooperation with universities and scientific research institutions.…”

“…So, a simulation model should be created not only for planning future experiments and developing safety practices but also for the offline synthesis of the actuation system and optimization for specific test purposes 7 . A digital twin is the best solution for the above issues 8 …”

“…They mainly focus the nonlinear dynamic effects of oil column and servo‐valve time delay. Ozcelik et al 8,13 further developed the NHERI@UCSD shaking table uniaxial virtual model to facilitate the test. While nonlinear and mechanical properties such as unequal piston area, dynamics of servo‐valve, spool, actuator, and cumulator, and geometry kinematic transformation are taking into account, the virtual shaking table model is still hard to build 14 …”