A problem of inherent stability
at Texas Tower 4 loomed so large at this time that it overshadowed all previous
Texas Tower problems. Ever since TT-4 was towed to site in mid-1957, it
had become an engineering nightmare. To begin with, supports for TT-4 had
been made somewhat differently from those fabricated for TT-2 and TT-3,
chiefly because of the extra depth involved. Whereas TT-2 and TT-3 stood
firmly in relatively shallow waters, 56 and 80 feet, respectively, TT-4
stood in water two to three times deeper, 185 feet to be exact. A series
of underwater bracing-s were made to compensate for the extra stresses incurred.
But in the process of towing TT-4 to site in June-July 1957, two diagonal
braces, vital to lacing the three legs snugly together, were lost. The contractor
and the Bureau of Yards and Docks decided to improvise repairs on the spot,
rather than return to shore for reworking defective portions. The
original design strength, consequently, was not restored.
From the time it was erected,
Texas Tower 4 wobbled some when under stress caused by brisk winds and waves.
Platform motion became the rule rather than the exception. The Navy, in
late 1958, conducted underwater surveys of TT-4’s supports, resulting in
the discovery that certain collar connection bolts either had sheared or
worn loose. The problem was aggravated because the defective portion weakened
not only its immediate area, but also shifted considerable stress onto non-defective
members. From late 1958 to May 1959, with at least six interruptions due
to storms, the contractor effected repairs that stabilized the platform
for several months. Four successive storms struck in the winter of 1959-1960,
which threatened to undo tower stability all over again.