204 COLLAPSE OF TEXAS TOWER NO. 4 



underwater braces were ineffective. Did I understand you correctly ? 



Mr. Brewer. That is correct. The motions, in other words, from 

 the measurements we were able to conduct above the water, which 

 were measuring stresses in these legs above the water, and measuring 

 the motions from the accelerometers, we were able to calculate that 

 the tower behaved as if there were no bracing whatsoever under the 

 water. 



Senator Saltonstall. Your work was to determine the motion of 

 the tower? 



Mr. Brewt2r. That was our primary purpose. 



Senator Saltonstall. In your opinion, was the motion of the tower 

 increased or diminished by the bracing above the water that is shown 

 in red on the model ? 



NO measurements made after X-bracing installed 



Mr. Brewer. We never measured it after that. I suggested that 

 that would be a worthwhile endeavor, but we were never commissioned 

 to do that, so we have never been on the tower since the bracing was 

 put in. 



Senator Saltonstall. But you did have an opinion that the bracing 

 above water would not strengthen the bracing below, if the bracing 

 below was ineffective ? 



Mr. Brewer. That is correct. All it could do was reduce some- 

 what the motions of the tower. 



Senator Saltonstall. Yes. 



One other question : You went into this analogy of the diving board, 

 and a 10- to 12-foot wave, as opposed to the 35-foot wave. 



What would be the effect on the bracing above the water, as shown 

 in red on the model, as affecting the length of the wave, and striking 

 the legs of the tower, if any ? 



Mr. Brewer. Actually what we were speaking of, where it hits all 

 legs simultaneously there would be no force change provided the 

 waves didn't hit the bracing. I said there would be no difference. 



Senator Saltonstall. No difference. 



Mr. Brew^er. As long as it didn't hit the bracing, as long as it 

 didn't hit the bracing. 



Senator Saltonstall. In other words, the effect of a 10- foot wave 

 on the tower, the dynamic movement, to use your expression 



Mr. Brewer. Yes. 



Senator Saltonstall (continuing). Would not be affected by the 

 bracing above the water. 



Mr. Brewer. Well, the movement would, but not the stresses. Per- 

 haps I did not understand your question. I would expect that with 

 the 10-foot waves, and with the bracing, the tower would not move 

 as much as it did without the bracing. But I would expect the stresses 

 would be very much the same; that is, you would not change the 

 stresses in the steel, but you would reduce the motion somewliat, pro- 

 vided the waves didn't hit or were not suflficiently large to hit, the 

 bracing. 



Senator Saltonstall. One final question: Did the motion of the 

 tower increase, during that winter wlien you were makinr^ tliese 

 examinations? You made them betw^een jSTovember and March, didn't 

 you? 



