Ultra-deepwater tendon systems

Abstract

A tendon system for anchoring a floating platform to the seabed comprises composite tendon groups including one or more steel tendons in combination with tendons fabricated of synthetic materials. The synthetic composite tendons may be coaxially located within the steel tendons. Tendon resonance is inhibited by exerting damping forces through supplementary tendons/cables connecting a passive or active damping force system to the seabed. In another aspect of the invention, a passive tuned oscillator or an active driven mass oscillator provides damping of platform resonance motions.

1 . A tendon system for anchoring a floating platform to the seabed, comprising a tendon array including one or more steel tendons and one or more synthetic tendons.  
     
     
         2 . The tendon system of  claim 1  wherein said synthetic tendons are coaxially located within said steel tendons.  
     
     
         3 . The tendon system of  claim 1  wherein said synthetic tendons are carbon fiber composite tendons.  
     
     
         4 . The tendon system of  claim 2  wherein said floating platform is a single anchor leg mooring buoy anchored to the seabed by a single composite steel and carbon fiber composite tendon.  
     
     
         5 . The tendon system of  claim 1  including damping force means for inhibiting platform resonance motions, said damping force means connected to the seabed through steel or synthetic supplementary tendons or cables.  
     
     
         6 . The tendon system of  claim 5  wherein said damping force means is active.  
     
     
         7 . The tendon system of  claim 5  wherein said damping force means is passive.  
     
     
         8 . The tendon system of  claim 1  including passive tuned oscillator means for inhibiting platform resonance motions.  
     
     
         9 . The tendon system of  claim 1  includes active driven mass oscillator means for inhibiting platform resonance motions.