Leg Assembly For an offshore structure

Abstract

The invention relates to a leg assembly for an offshore structure, such as a self-elevating jack-up rig. The leg assembly has a pair of parallel leg chords divided into a plurality of sections by transverse bracing members. A unit of angular bracing members is secured within each such section. The unit has four angular members defining a rhombus, with each angular bracing member attached to a transverse bracing member and an adjacent leg chord. The braces are connected at four points to each other. The leg assembly is free from obstructing, drag-increasing auxiliary braces.

We claim:  
     
         1 . A leg assembly for offshore structures, comprising: 
 at least a pair of elongated parallel leg chords;    a plurality of transverse bracing members extending between said leg chords and dividing said leg chords into a plurality of leg sections defined by adjacent transverse bracing members;    a first pair of angular bracing members secured to a midpoint of a first transverse bracing member, each of said first pair of angular bracing members having a free end secured to a leg chord at a midpoint of a leg section below said transverse bracing member; and    a second pair of angular bracing members secured to the midpoint of said first transverse bracing member, each of said second pair of angular bracing members having a free end secured to a leg chord at a midpoint of a leg section above said first transverse bracing member, said angular bracing members being secured to said transverse members at four attachment points, said leg assembly being free from drag-increasing auxiliary braces.    
     
     
         2 . The apparatus of  claim 1 , wherein an obtuse angle is formed by said first pair of angular bracing members.  
     
     
         3 . The apparatus of  claim 1 , wherein an obtuse angle is formed by said second pair of angular bracing members.  
     
     
         4 . A leg assembly for an offshore structure, comprising: 
 a pair of elongated parallel leg chords divided into a plurality of sections by transverse bracing members; and    a plurality of inclined bracing members secured in sections between said transverse bracing members, said inclined bracing members defining a rhombus-shaped bracing unit within each of said sections, said inclined bracing members forming a four-point connection with their respective transverse bracing members, said leg assembly being free from obstructing auxiliary braces.    
     
     
         5 . The assembly of  claim 4 , wherein each of said inclined bracing members is secured to an adjacent leg chord and to a transverse bracing member.  
     
     
         6 . The assembly of  claim 5 , wherein a first pair of said inclined bracing members is fixedly attached to a midpoint of a transverse bracing member and extends downwardly from said bracing member.  
     
     
         7 . The assembly of  claim 6 , wherein a second pair of said inclined bracing members is fixedly attached to a midpoint of an adjacent bracing member and extends upwardly from said adjacent bracing member.  
     
     
         8 . The assembly of  claim 6 , wherein said first pair of bracing members defines an obtuse angle, with an apex of said angle being at a point of attachment of said first pair of bracing members to said transverse member.  
     
     
         9 . The assembly of  claim 7 , wherein said second pair of bracing members defines an obtuse angle, with an apex of said angle being at a point of attachment of said second pair of bracing members to said adjacent transverse member.  
     
     
         10 . A leg assembly for an offshore structure, comprising: 
 at least a pair of parallel leg chords divided into a plurality of sections by transverse bracing members;    an angular bracing unit positioned in each of said sections, said angular bracing unit comprising a first angular bracing member extending downwardly from a first transverse member, a second angular bracing member extending downwardly from said first transverse member, a third angular bracing member extending upwardly from a second transverse bracing member located immediately below said first transverse bracing member, and a fourth angular bracing member extending upwardly from s aid second transverse bracing member, said first angular bracing member and said second angular bracing member being fixedly attached to a midpoint of said first transverse bracing member, said third angular bracing member and said fourth angular bracing member being fixedly attached to a midpoint of said second transverse bracing member , said leg assembly being free from obstructing auxiliary braces between said transverse bracing members and said angular bracing members.    
     
     
         11 . The assembly of  claim 10 , wherein a free end of said first angular bracing member is fixedly attached to a fist leg chord at midpoint between said first transverse bracing member and said second transverse bracing member.  
     
     
         12 . The assembly of  claim 10 , wherein said second angular bracing member is fixedly attached to a second leg chord at a midpoint between said first transverse bracing member and said second transverse bracing member.  
     
     
         13 . The assembly of  claim 10 , wherein said third angular bracing member is fixedly attached to said first leg chord adjacent to a point of attachment of said first angular bracing member.  
     
     
         14 . The assembly of  claim 10 , wherein said fourth angular bracing member is fixedly attached to said second leg chord at a point adjacent to a point of attachment of said second angular bracing member.