A Proposal on Risk Control Method Focused on Liquid Height Control to Cope with Sloshing Response of Tanks

摘要

As the tank fires at Tokachioki earthquake in 2003 suggested the possibility of catastrophic disaster against the environment in case of large volume of its contents and due to the applied seismic design codes and standards not covering the floating roof of the tank, development of a procedure for the seismic risk management for the tanks is highly necessitated. The authors have already revealed that responses of the tanks at seismic events are affected by their volume of content, and have developed a framework concerning the risk control method for bulging responses of tanks using liquid height control. This paper is the next step of the former study, and aiming to propose the similar framework concerning the risk control method for sloshing responses of tanks using the liquid height control. Damage modes of single deck type floating roofs in the cylindrical storage tanks are extracted, and with corresponding damage levels and cost for repair, the conditional expected losses in case of assumed earthquakes are calculated by using event trees. Finally, an index of cost effectiveness, which is defined as the sum of seismic strengthening cost and operation cost considering liquid height control and conditional expected loss, is introduced, and it is verified by a case study that the most appropriate seismic countermeasure is able to be selected by this frame work.