Performance Identification of the Bi-Axial Dynamic Testing System

Performance Identification of the Bi-Axial Dynamic Testing System

The bi-axial dynamic testing system (BATS) was established in the Tainan Laboratory of the National Center for Research and Earthquake Engineering (NCREE) in 2017. It is presently one of the few advanced large-scale testing machines that possess dynamic compression and shear testing capabilities. It is globally beneficial for not only research and development of seismic isolation technology but also for performing prototype and production tests on full-scale seismic isolators. Identifying its essential parameters, including the effective mass and friction coefficients, and its dynamic performance in an explicit manner is imperative before it can service the public. Therefore, a series of tests, including triangle wave cyclic loading tests with varied horizontal displacements and velocities as well as sin wave cyclic loading tests with varied horizontal displacements and excitation frequencies, were conducted to clearly understand the crucial parameters and dynamic performance of the BATS. Three stages with different test conditions and specimens were schemed as follows: (1) Triangle wave and sin wave cyclic loading tests on the bare testing system without applying any compression load were performed to identify the relation between horizontal velocities and average friction coefficients as well as the effective mass of the BATS; (2) Triangle wave and sin wave cyclic loading tests on flat sliding bearings under different vertical compression loads were performed, and a simple linear regression method was adopted to identify the average friction coefficients of the BATS at different horizontal velocities; (3) Through comparing the identification results with the test results of full-scale friction pendulum bearings and further discussions, the rationality and applicability of the identified effective mass and average friction coefficients of the BATS can be further demonstrated.