Yoshihiro Dozono

Shaking-Table Control by Real-Time Compensation of the Reaction Force Caused by a Nonlinear Specimen

An improved shaking-table control method has been developed. This method compensates the reaction force caused by a nonlinear specimen in real time, and thus maintains a desired table acceleration. To do so, it identifies the difference between the desired and the actual transfer characteristics of the shaking table, then compensates for the difference. Because the required time for this combination of identification and compensation is less than one second, the method can compensate, in real time, for the disturbance caused by a nonlinear specimen. By means of a series of experiments, it is confirmed that the method can maintain a desired table acceleration even when a nonlinear specimen is under excitation.

DISTURBANCE OBSERVER-BASED PRACTICAL CONTROL OF SHAKING TABLES WITH NONLINEAR SPECIMEN

Abstract This paper presents a practical control methodology of shaking tables for earthquake simulators. Reaction force generated by a nonlinear specimen on the shaking table generally deteriorates the motion performance of the table, resulting in the lower control accuracy of the seismic tests. In order to provide the precise table motion, therefore, a disturbance observer-based control approach is adopted, where the unknown disturbances in the table can be compensated in real time manner. The proposed compensation algorithm has been verified by experiments using an actual shaking table system.

Disturbance Observer-Based Reaction Force Compensation in Shaking Table Systems

This paper presents a practical control methodology of the shaking tables for earthquake simulators. Reaction force generated by a nonlinear specimen on the shaking table generally deteriorates the motion performance of the table, resulting in the lower control accuracy of the seismic tests. In order to provide the precise table motion, therefor, a disturbance observer-based control approach is adopted, where the unknown disturbances of the table can be compensated in real time manner. The proposed compensation algorithm has been verified by experiments using an actual shaking table system.

Visual and Versatile Hybrid Seismic Testing System Incorporated With Non-Linear Finite Element Analysis

Hybrid simulation/testing systems have been developed incorporating a non-linear finite element method with a pseudo-dynamic test. In order to ensure stability and efficiency for time integration, the incremental formulation of the α-OS method has been implemented on this system. Visualization system has also been integrated to recognize both numerical simulation for whole systems and laboratory testing for local parts. Numerical hybrid examinations of the soil structure interaction problem have been conducted on this system. By these results, validity and effectiveness of this system has been demonstrated.Copyright

Verification Test for Hybrid Seismic Experimental Method Using Nonlinear Finite Element Method

An improved substructure hybrid seismic experimental method has been developed. This method consists of numerical computations using a general-purpose nonlinear finite element analysis tool and a pseudo-dynamic vibration test. Therefore, it enables seismic testing of large-scale structures that cannot be loaded onto a shaking table. The method also visualizes both data measured by sensors placed on the specimen and the results of the numerical analysis, and it helps us to understand the behavior of an entire structure consisting of a specimen and a numerical model. We performed verification tests for a piping system, in which we used a numerical model including supports, valves, and a branch pipe, and a specimen including two elbows. As results of tests, we conclude that the developed system has enough accuracy to be used as a seismic testing method.Copyright