2025 Volume 25 Issue 2 Pages 2_42-2_49
Sinusoidal loading test is used to evaluate the performance of devices for seismic isolation and supplemental damper. If a sine wave is input as it is, the velocity and acceleration will be large at the start and end of the loading, resulting in an impact and / or a delay in the loading. Desirable test results may not be obtained. An additional part of input waveform (tapered portion) is often applied to mitigate the above effects; however, that increase the cumulative deformation in the test. From the viewpoint of influence on the specimen and restrictions on the accumulated deformation of the machine, it needs to minimize the cumulative deformation increment due to the tapered portions as much as possible. We investigated the increase in acceleration and cumulative deformation due to the additional tapered portion and proposed a rational setting method. The method is based on constant-acceleration excitation, and the displacement and velocity can be continuous at the connection point. It is shown that this method can reduce the cumulative displacement increment to about 28% compared to the conventional method using a cosine-square type filter.
