2020 年 86 巻 888 号 p. 20-00187
To investigate the failure behaviors of piping systems under extremely large seismic loads, which should be considered in beyond design basis events (BDBE), a new experimental procedure was proposed that used pipes made of a simulation material. In the proposed procedure, destructive experiments were carried out with the use of pure lead (Pb) as the simulation material, owing to its considerably low strength compared with that of steel. As the first step of the structural experiment, shaking table tests on simple piping system models, which included an elbow pipe made of Pb were conducted. Then, through excitation tests using various sinusoidal inputs, failure modes such as “ratchet and subsequent collapse,” “excessive deformation by one cycle,” and “no failure after considerable large number of inputs” were obtained. The failure modes appeared to be affected by steady loads such as self-weight, input seismic load, and the relation between input motion’s frequency and specimen’s natural frequency. The proposed procedures seemed to be effective for studying mechanical failure behaviors with large plasticity under excessive seismic load, which is difficult to achieve by experiments on steel pipes.