COLLAPSE OF TEXAS TOWER NO. 4 193 



accelerometer measurement, even if it only obtained the frequencies, 

 would enable him to calculate the tower stresses by analytic means. 



Mr. French. Did you have any discussion with reference to the 

 extent of platform movement which could occur before the known 

 tolerances in the pins were taken up ? 



Mr. Brewer. Yes, we did. I am not certain whether it took place 

 at that meeting. If you will excuse me, I have some notes of that 

 meeting. 



Not at the first meeting, at least I do not see it here on a quick 

 examination ; but we had a second meeting on November 12, 1958, in 

 Boston, and at that time Mr. Kuss, who was in attendance, stated 

 that the tolerances, in other words, the clearance between the pins 

 and bracing here — there are pins that join this bracing to the legs, 

 and those pins, if they fit in a large hole, obviously they will permit 

 some motion of this bracing, which means the entire tower could 

 then go back and forth without utilizing its bracing until the pin 

 fetches up against the other side of the clevis. 



MOTION or PLATFORM PERMITTED BY TOLERANCES 



Now, the tolerances at that time, as they were given to me, were 

 about an eighth of an inch, and Mr. Kuss computed that would allow 

 about a 2-inch motion at the platform ; that is to say, the tower 

 could move 2 inches back and forth before these pins would take up 

 against the known clearances that were allowed in the design. 



Commander Foster at that time stated that during construction of 

 the tower it had been necessary to enlarge these clevises somewhat 

 to permit mechanical assembly, so there were some that were larger 

 and had a greater clearance than an eighth of an inch, which meant 

 it could move, presumably, more than 2 inches before these pins 

 would take up — that is, before the tower would be completely rigid. 



So what we discovered on our first measurements was that the tower 

 behaved as if there were no bracing at all. In other words, the tower 

 moves back and forth at a frequency indicated from our instruments 

 that would be the same as if there were no bracing whatsoever under 

 the water, and during that entire winter, where we recorded motions 

 and stresses and waves periodically, we never found excursions suf- 

 ficient enough to make the tower behave as if the structure down be- 

 low were indeed clamped tightly. 



Senator Stennis. Pardon me. Repeat that, will you, Mr. Brewer? 



Mr. Brewer. During the winter we left the instrumentation above 

 the tower for the entire winter, and Air Force personnel ran it for us. 



Senator Stennis. Yes. 



Mr. Brewer. And this instrumentation recorded the wave height, 

 the wind velocity, wind direction, the stresses in three legs, and ac- 

 celerometers at three points — all of this information was simultane- 

 ously recorded on a graph like the cardiogram. 



Senator Stennis. Yes. 



Mr. Brewer. Now, from an analysis of that you can tell, and we 

 were able to tell, what the period of m.otion, that is, the frequency, 

 how many times a minute, the tower oscillates back and forth, and 

 that frequency never changed appreciably during that winter, and 

 that, very briefly, means that the tower bracing down below never 

 came into effect as far as we could determine above the water. 



