BASIS Damper System
Casper, Phillips & Associates Inc. (CPA) designed a new seismic isolation system on two quayside container cranes in a major seismic activity zone in Asyaport, Turkey. The cranes have a 100 ft. (30.48m) gantry span, 223 ft. (68m) outreach, 66 ft. (20m) back-reach, and 152 ft. (46.3m) lifting height above the gantry rail.
Asyaport has a different seismic isolation system on its existing STS cranes. Crane operators complained that hydraulic based seismic isolation systems affect the operation of the cranes, and the port wanted an alternative. The friction damper system in BASIS is designed to slip at a certain force, and to not slip during regular operation and the more common overload events like trolley emergency stops.
BASIS was designed using nonlinear time history analysis (NLTHA) to protect the crane main structure from damage in seismic events. The Asayaport cranes were designed using three sets of ground acceleration records (D3 level) provided by Asayaport. A D3 level earthquake is a maximum considered earthquake that is expected to occur once in approximately every 2500 years; that is a 2% probability of being exceeded in 50 years.
A revolutionary seismic isolation system—provided by Casper, Phillips & Associates Inc. (CPA)—has been installed on two quayside container cranes for the first time this year.
The BASIS crane isolation system is designed to offer earthquake protection for a crane structure at a reasonable cost and without affecting the stiffness of the crane in normal operations.