The Earthquake Engineering Online Archive

Shaking table-structure interaction

Rinawi, Abdulkarim M.; Clough, Ray W.

UCB/EERC-91/13, Earthquake Engineering Research Center, University of California, Berkeley, 1991-10, 280 pages (550.2/R56/1991)

The 20 x 20 ft shaking table at the Earthquake Engineering Research Center of the Univ. of California at Berkeley is tested for interaction effects. The tests include three loading configurations: a bare table, a table loaded with 70 kips mass, and a table loaded with a 68 kips single degree-of-freedom structure with a height of 219 in. The shaking table has five degrees-of-freedom, one horizontal, one vertical, and three rotational. When loaded with heavy and tall structures, the shaking table undergoes pitching (rocking) motion even in the absence of a pitch command signal. This is mainly due to the flexibility in the pitch degree-of-freedom. Mathematical models are derived for analyzing the table-structure system. These include a shaking table with a horizontal actuator, a pitching actuator, and a passive pitch stabilizer. Simplified spring-mass-damper models are also discussed. Methods for avoiding modeling of the table flexibilities are presented. These include the use of a two-directional base input motion and the simpler unidirectional effective base motion. Interaction effects are studied using response spectra and the equivalent coupled single degree-of-freedom table-structure system.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-91-13.pdf (16 MB)