Test apparatus for static simulation of earthquake response and verification of seismic design formulas

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A test apparatus was designed and assembled to simulate response of structures to an arbitrary seismic ground motion at loading rates much slower than actual seismic response velocity.The apparatus incorporates gears and threads to generate, magnify, and transmit force to a test specimen. Driving force is given by a conventional electric motor with brake.Rotational velocity of the motor is adiusted by a frequency inverter to which signals are sent from a conventional personal computer. The computer also retrieve data from displacement and load sensors through a digital strain meter.A typical time required to conduct a simulated seizmic response test for a selected earthquake ground motion was about one hour when the maximum restoration force was 1.0 ton, the maximum displacement was 6 mm, and the 10 seconds duration of earthquake was devided into 200 time interval steps. That required time corresponds to 18 seconds per one time step.The overall performance of the test apparatus was satisfactory. The threads ensures displacement control loading. Some slackness in the mechanical load tranmission paths requires corrections in determining displacements. Seismic simulation load tests are underway and will be continmed.