38 COLLAPSE OF TEXAS TOWER NO. 4 
the tower. It was the source of structural deterioration from which 
further numerous defiicencies developed. Repairs could not keep 
ahead of the progressive structural deterioration and developing de- 
ficiencies. The culmination of these deficiencies weakened the tower 
to the point of collapse. 
2. The structural design engineers in the redesign of the collar 
attachments by November 1957, as a fix for the diagonal struts lost 
prior to the tip-up of the template, placed too much reliance upon 
underwater diver-repairmen working under adverse conditions. 
3. When the tower was accepted from the contractor by the Navy 
and at the time the Navy turned it over to the Air Force in Novem- 
ber 1957, the tower possessed an unknown structural deficiency in the 
failure of the Dardelet bolts of the collar connections and was in a 
weakened condition. 
4. Before the deficiency in the collar connections was discovered 
in the fall of 1958, and corrected in May 1959, the tower, in its weak- 
ened condition, was exposed to the effects of storms of two winters re- 
sulting in exceptional dynamic impact stress concentrations on other 
foundation connections. 
VII 
Findings.—The design configuration of the tower in the use of three 
legs of minimum diameter with no auxiliary legs was based on the 
concept of keeping the resistance to wave passage toa minimum. In 
early 1960, a diver inspection revealed that there were loose pins and 
worn connections in the upper two panels of braces on the A-B side, a 
condition which necessitated emergency repairs prior to the 1960 hur- 
ricane season. The structural design engineers issued a second warning 
of the hazardous condition and probable loss of the tower and advo- 
cated the installation of above-water X bracing. Upon its completion, 
the structural design engineers certified on August 10, 1960, that the 
tower had been restored to its original design strength. No attempt 
was made to repair the loose pins and worn connections in the under- 
water braces. 
Committee conclusion.— 
1. The X bracing above water, aside from materially increasing the 
stresses exerted against the tower, was contrary to and militated 
against the original design concept in keeping resistance to wave pas- 
sage to a minimum and, in fact, these braces were placed in an area 
where the force of the passing waves was greatest. 
2. The subcommittee cannot understand how the tower could be 
certified as having been restored to its original design strength merely 
upon the installation of the X bracing in the absence of the repair of 
the worn pin connections underwater. 
VIII 
Finding —Additional and serious damage was inflicted on the tower 
by Hurricane Donna in September 1960, at which time the design 
criteria was admittedly exceeded. The original builder immediately 
began inspection and repair of the tower. On October 3, 1960, the 
structural design engineers, under subcontract with the original 
builder, agreed to evaluate the remaining strength of the tower in 
