BEHAVIOR OF NONSTRUCTURAL COMPONENT SUPPORTED BY HANGER BOLTS UNDER SEISMIC EXCITATIONS BY SHAKING TABLE TEST

Abstract

During the Great East Japan Earthquake of March 2011, nonstructural components, such as pipe systems, ducts, cable racks and ceilings were severely damaged while main structural members in the building were not damaged seriously. Pipes, cable racks, apparatus and ducts’ hanger bolts were ruptured causing the equipment to fall down. Because of these damages, buildings cannot be used for a long period of time and one person was killed by pipe’s falling in Japan. In this study, the behaviors of nonstructural components are investigated by conducting shaking table tests to verify the cause of damage. More specifically, damage to hanger bolts is investigated by simulating its rupturing mechanism through shaking table test. To simulate the real installation condition of nonstructural components, apparatus-duct-pipe system supported by hanger bolts is selected as specimen. Roof floor response wave at the actual 5-story steel building under the Great East Japan Earthquake and sweep wave are used for the input waves. The maximum response acceleration was about 4 G in X direction under response wave 75% and the damage occurred at the metal fitting which is the connection part between braces and hanger bolt. And without installing braces, the upper hanger bolts at the fixed supporting part were ruptured easily since the natural frequency of the specimen closed to those of target building during excitations and the response became huge.