Risk reduction by automatic seismic shutoff

Seismic shutoff devices are expected to automatically stop the flow of hazardous gases and liquids through distribution systems that may be damaged by earthquakes. There is some uncertainty in the actuation of these devices; they may actuate when not needed and they may not actuate when needed. Therefore, these devices can only reduce, and not eliminate, the risk of hazardous leaks. It is shown in this paper that shutoff devices can be deployed to meet specific performance goals in seismic design. A cost-benefit analysis is conducted to show that devices are most effective in reducing the risk to weak systems in highly seismic areas. The uncertainty in actuation diminishes the effectiveness of these devices. © 2016 American Society of Civil Engineers.