266 COLLAPSE OF TEXAS TOWER NO. 4 



(The letter referred to is as follows :) 



MoBAN, Proctor, Mueser & Rutledge, 



New York, N.Y., April 1, 1960. 

 Re motion of Texas tower No. 4 and condition of bracing connections. 



Maj. James Phelan, 



Commander, 460Jith Stipport Squadron (TT), 



Otis Air Force Base, Mass. 



Dear Sir: As a result of the diver inspection of the underwater bracing be- 

 tween the legs of Texas tower No. 4 and from reports of experience of personnel 

 on the tower, we wish to make comments and recommendations. 



The diver's findings were reported to Air Force representatives in a meeting 

 at Otis Air Force Base on February 9. 1960, and subsequently the findings were 

 sumniarizod on a drawing prepared by the Air Force and titled "Underwater 

 Structural Deficiencies. Texas Tower No. 4" (drawing OTS-14()-061), dated 

 February 11, 1960. The findings indicate that on the A-B side there are loose 

 pin connections on all of connections of the horizontal liraces at elevations 

 ±25 and ±76. Also the main bolts of the collars connecting replacement braces 

 to the legs just above elevation ±76 are not tight. 



The loose pin connections are a very serious matter since there seems to be 

 no way of satisfactorily remedying this condition. Furthermore, the ccmdi- 

 tion is one which will tend to worsen at an increasing rate with time. This is 

 because the looseness induces impact stresses in the pins and pin plates which are 

 greater than for the nondynamic design assumptions and will become increas- 

 ingly greater as the play in the joint enlarges. 



There are no circumstances which would tend to alleviate these conditions if 

 corrective measures are not undertaken. Due to the complexity of the pin con- 

 nections (multiplicity of plates involved, etc.), there seems to be no practical 

 way of restoring the defective connections to their originally conceived con- 

 dition. It would be exceedingly dangerous to remove the pins for replacement. 

 Even if the pins could be removed, however, it woiild be necessary to ream the 

 holes to a larger circular shape to fit new oversize pins and we believe this to be 

 impossible. After careful and long consideration we have concluded that the 

 only practical cure for the situation is the addition of new above-water braces 

 which we have advocated and designed. We recommend this type of bracing 

 for all three sides because the requirement of their being entirely above water 

 does not provide an ideally effective depth and the bracing on the A-C and B-C 

 sides reduces bending components from these sides almost to zero, thus increas- 

 ing the factor of safet.v in the A-B system. The bracing on the three sides will 

 also reduce the general motions of the tower, including rnt»ition and will diminish 

 the tendency to develop impact on all of the bracing pins, including tliose which 

 have not as yet shown any distress. 



Time is of the essence in the program for erecting new braces. The liurricane 

 season has been pretty well established as beginning after the first week of August 

 and the schedule for construction to be reasonably sure of accomplishment 

 should be essentially complete by that time. If the new braces are not secure 

 by then and are lost due to hurricane action the tower would be forced to vmder- 

 go another winter's exposure and it is very doubtful if the deteriorating pin 

 connections will survive. This means that a contract should be let immediately 

 so that fal)rication can be started by May 1. Allowing 5 weeks for fabrication 

 and 8 for erection brings the completion date to the beginning of the danger 

 period. 



Due to the above-discussed urgency, and the contingencies inherent in the 

 type of construction involved, it would appear that a cost-plus-fee contract 

 would be most ideal for the accomplishment of the work. This would permit 

 the Government to assume the hazards which would otherwise be generously in- 

 cluded as contingencies in competitive bidding. It would enable the Govern- 

 ment to ask for extra expediency measures, if necessary, and it would permit 

 the Government to negotiate with the contractor who built the tower (J. Rich 

 Steers Co.) and who is most familiar with all of the conditions attendant upon 

 the work. 



We trust that the foregoing makes our position clear, but will be glad to 

 furnish further information if desired. As you are aware, we have made every 

 effort to expedite the plans and specifications pending a formal A. & E. contract 

 and these are now available for initiating the work. 

 Very truly yours, 



MoBAN, Proctor, Mueser & Rutledge, 

 By Theodobe M. Kuss. 



