We recently came across an article related to the U.S. Minuteman Ballistic Missile System Program. Engineers William J. Hartdegen and John A. Quigley published their configurations for 150 subterranean missile facilities located near the Grand Forks Air Force Base, North Dakota. The pod-like launch and control facilities were comprised of several layers of #18 rebars (top) that were designed to withstand "the high, dynamically applied pressure resulting from a nuclear attack." Dynamic strength capability tests conducted at the University of Illinois suggested that all splices of reinforcing bars of #11 and larger size required butt-welding. The pods were additionally lined with 1/4-inch steel plate in order to provide electromagnetic pulse (EMP) and radio frequency interference (RFI) shielding. A typical launch facility with a 90-foot launch tube and its adjacent capsule-shaped equipment storage space is depicted in the lower image.
Travelers to North Dakota can now visit the Ronald Reagan Minuteman State Historic Site, and journey down an elevator shaft to enter the last* post-disarmament launch control center. Learn more here.
To read more about the construction & view more images, see: Hartdegen & Quigley. "Welding Solves Problems in Multibillion-Dollar Minuteman Program." Chap. in Modern Welded Structures, Vol. III (Cleveland, OH: The James F. Lincoln Arc Welding Foundation, 1970), pp. I-16 to I-20. Available in the Southeastern Architectural Archive.
*Post-Script: As part of the Strategic Arms Reduction Treaty, most of these siloes have been imploded. Read more here.