Shear unit and shear connection between structures

Claim 1

A CONCRETE TANK WHICH COMPRISES: (A) AN ANNULAR CONCRETE FOUNDATION, (B) AN ANNULAR STRESSED CONCRETE TANK WALL MOUNTED ABOVE SAID FOUNDATION, AND (C) A PLURALITY OF STRUCTURAL BASE SHEAR UNITS INTERPOSED BETWEEN SAID FOUNDATION AND WALL AT CIRCUMEFERENTIAL INTERVALS AND SUPPORTING THE LATTER FROM THE FORMER, EACH SAID SHEAR UNIT INCLUDING (1) A LOWER MEMBER FIXED TO SAID FOUNDATION AND INCLUDING AN ANTI-FRICTION PAD HAVING AN UPWARDLY DIRECTED SLIDE SURFACE, (2) AN UPPER MEMBER FIXED TO SAID WALL AND HAVING DOWNWARDLY DIRECTED SURFACE SLIDABLY SUPPORTED ON SAID SLIDE SURFACE AND BEING SLIDABLE IN THE RADIAL DIRECTION OF THE TANK WALL, AND (3) MUTUALLY ENGAGEABLE ABUTMENT ELEMENT ON SAID MEMBERS FOR RESTRAINING SLIDING MOTION THEREBETWEEN CIRCUMFERENTIALLY OF THE TANK WHILE PERMITTING FREE SLIDING MOTION RADIALLY OF THE TANK, SAID ELEMENTS BEING ELONGATED IN SAID RADIAL DIRECTION AND SUBSTANTIALLY UNOBSTRUCTED ALONG THEIR LENGTHS TO PERMIT RELATIVE RADIAL MOVEMENT BETWEEN THE MEMBERS.