286 COLLAPSE OF TEXAS TOWER NO. 4 



useless since the bracing is of the "K" type, and the stresses in the two inner 

 connecting diagonals are equal. This is a serious condition. 



In July we made a study of the strength of the tower if such a condition 

 should exist. The results of this study were reported to you by letter of July 3, 

 1958, and indicated that with an allowed increase in stresses up to the yield 

 point, the tower would stand moderately heavy weather. At that time we had 

 no real reason to believe that the braces were not working, and since the stormy 

 season was still some time off, we made no great issue of the subject except 

 to recommend in our report that a diver be employed to inspect the bolted collars 

 and that a program be inaugurated to measure tower deflections. As things stand 

 now the diver inspection has been made with a resulting discouraging report, 

 and also the beginning of the hurricane season has come. We are concerned that 

 the tower cannot safely withstand a major hurricane with the braces in the 

 present loose condition. We recommend that every possible effort be made to 

 tighten the bolts connecting the two halves of the collars holding the tv.'o replace- 

 ment braces. 



If possible the tightening of each bolt should be to a torque of 1,300 foot-pounds 

 using a winch to pull the wrench. The collars should be tightened to a point 

 where they do not move with respect to the legs, even if some bolts are broken 

 and have to be replaced in the process. Only then can the problem of restoring 

 shear bolts or connections be met. 



In the meantime, and if the collars cannot be tightened and the shear bolts 

 replaced, we are compelled to warn you that a definite hazard exists to the safety 

 of the tower and the personnel aboard in the event of a major hurricane passing 

 directly over the tower location. 

 Very truly yours, 



MoRAN, Proctor, Mueser & Rutledge. 

 Theodore M. Kuss. 



October 8, 1958. 

 From : Officer in Charge of Construction, Texas tower. 

 To : Air Force Installations Representatives Office, New England Region, Boston, 



Mass. 

 Subject : Stability of Texas tower No. 4. 

 End: (1) Report of OICC conference of October 1, 1958. same subject. 



1. This letter confirms information reported to Commander, 4604th Support 

 Squadron on September 24, 1958. regarding the stability of Texas tower No. 4, 

 and reports subsequent developments from that date to October 3, 1958. 



2. The governing criteria (max.) for the design of the tower was as follows: 



Wind velocity : 125 miles per hour. 

 Wave height : 35-foot breaking or 60-foot nonbreaking. 



Resulting allowable stress: (1/SC -f50 percent, not to exceed 29,000 

 pounds per square inch. 



3. After reports from the using activity that the tower seemed to move to a 

 greater degree than the previous towers, the A. & E. was requested to compute 

 the conditions under which the tower could be considered safe presuming that 

 the upi>er bay of bracing in the A-B plane is inoperative. The results of this 

 study are tabulated below : 



(a) 125 miles per hour wind plus 36-foot wave nonbreaking, or 

 (&) 87 miles per hour wind plus 67-foot wave nonbreaking, with maximum 

 resulting stress 30,000 pounds per square inch, 



4. A recent inspection disclosed the following discrepancies : 



(a) The pin connecting the top strut to the B leg was partially retracted, 

 althoiigh it appeared to be in full bearing against the fish plates. An emergency 

 stop has been applied to this pin to prohibit further movement until equipment 

 to make permanent repairs can be obtained. 



(b) The collar which connects the K brace to the A leg at elevation 65 was 

 not tight around the leg. The 2-inch bolts did not exhibit the required torque, 

 and the Dardelet bolts were sheared off. In effect, while these conditions pre- 

 vail, this particular bracing panel is not functioning, and the modified stability 

 conditions given in paragraph 3, (a) and (6) , above would apply. 



5. During the inspection the 2-inch bolts were tightened to the designed 

 torque. Hence, at present, the tower is safe for greater wind and wave condi- 

 tions than those quoted, but until the Dardelet bolts are replaced, will not reach 

 the original design condition. 



