As part of the U.S.-Japan Cooperative Research Program Utilizing Large Scale Testing Facilities, a study was conducted on the simulation capacity of the pseudo dynamic testing in the earthquake response behavior of structural systems. For this purpose, two structural models: a two story steel unbraced frame model and a two story steel braced frame model, were prepared. For each model, two identical specimens were fabricated, and one was tested using a shake table device, while the other using the pseudo dynamic testing technique.

Through direct comparison between the responses obtained from the shake table and pseudo dynamic tests, it was found that, in general, the pseudo dynamic test has a great capacity on simulating the earthquake response behavior of structural systems. Minor differences between the two responses were also observed with respect to the plastic flow in the displacement time history as well as to the shear force in the range where the braces started carrying the force.

Numerical models which would represent the tested specimens were formulated using the system identification technique. The ability of the numerical models to simulate the experimental responses was demonstrated. Using the models, possible effect of the simplifications included in the pseudo dynamic testing on the overall response was calibrated, and it was found that those simplifications had at most the secondary effect.

It was indicated that the difference in hysteresis was the major source that had caused the difference in the response. Using the numerical models, possible differences in hysteresis were examined.There was indication that the loading rate played some role on changing the hysteresis but that the degree was by no means high.

^*1 Head, Production Department
^*2 Research Engineer, Production Department