Explanation of jumping behavior of Chozu-sha in view of dynamics of discontinuous system

Abstract

At Kumamoto earthquake on April 16, 2016, at 1:25 AM, the jumping behavior of the unanchored wooden structure named Chozu-sha was reported. To explain it in view of dynamics of discontinuous systems, the Chozu-sha is modeled by two-story rigid rectangular block, and its equations of motion are derived. Employing a corresponding recorded accelerogram, its jumping motion is computed. Comparison of the jumping distance computed with that reported yields that the proposed procedure may explain a major mechanism of the jumping of the Chozu-sha. Its essence is that the jumping distance is elongated if the horizontal acceleration which is larger than the rocking commencement acceleration but is smaller than the maximum acceleration lasts longer.