COLLAPSE OF TEXAS TOWER NO. 4 21 
made a special analysis to determine whether or not the replaced diag- 
onals on the A-B side were functioning. This analysis led to the con- 
clusion that the upper tier of bracing on the A—B side was not func- 
tioning and this, in turn, prompted an analysis of the strength of the 
tower under this condition and the amplitude of motion which might 
indicate danger. It was estimated that, if the tower leg steel were 
stressed to the yield point, the tower could stand a 125 mile per hour 
wind combined with a 36 foot high wave or an 87 mile per hour wind 
combined with a 67 foot wave. The horizontal deflection at the same 
time would be about 6 inches. Because of this motion and the fact that 
the tower had not yet experienced a hurricane, the tower was totally 
evacuated of personnel in advance of Hurricane Daisy in August of 
1958. 
The Brewer Engineering Laboratories, Inc., of Marion, Mass. re- 
ceived a subcontract from Hallicrafters Co. to conduct a motion study 
of the tower during the fall of 1958 and winter of 1959. The Brewer 
study had as its purpose— 
(a) To experimentally measure the translational (horizontal) 
and rotational (twisting) excursions and corresponding frequen- 
cies (the number of times per minute it did each) of the tower 
platform from aerodynamic and hydrodynamic forces ; 
(6) To measure the caisson bending stresses at the lower deck ; 
and 
(c) To investigate the integrity of the subsea truss work (the 
functioning of the underwater braces). 
Prior to undertaking the experiment, two conferences were held: 
(a) At the Air Force Cambridge Research Center in Bedford, 
Mass., where it was revealed that the Air Force was interested 
in rotational motions and frequencies of the platform because of 
these influences on radar search equipment; and 
(6) At the offices of Moran, Proctor, Mueser & Rutledge, who 
were interested in caisson bending at the lower deck and knowl- 
edge as to the integrity of the upper tier of bracing in the A-B 
plane. 
At both of these conferences the integrity of portions of the under- 
water truss work was questioned. It was revealed at that time that— 
the 8-inch LD clevis holes were bored one-eighth inch oversize to facilitate 
assembly. Moreover, two clevis brackets were broken off in tower transit to the 
installation site. A repair at sea was attempted by replacing the broken 
brackets with eared collars. These collars attempted to anchor the lower end 
of the diagonals in the upper frame of the A—B plane to caissons A and B, 
respectively. Considerable doubt was expressed regarding the success of this 
repair.” 
Mr. Brewer asserted that Mr. Kuss had told him that all he (Kuss) 
required was a measurement from Brewer of the natural frequency 
of the tower and Kuss could then compute all other facets of the 
tower’s functioning. 
The matter of the final tolerances authorized on the clevis joints was 
also unclear. In the meeting of November 12, 1958, Mr. Kuss indi- 
cated that tower motions of plus or minus 2 inches could occur with- 
out taking up known clearances of the pins in the first truss bay 
beneath the ocean surface. Commander Foster also stated that his 
16 Brewer Engineering Laboratories Report No. 173, pp. 5, 6. 
