Sunday, February 25, 2018


Scope of Work
Cianbro constructed a 112,000 sf, interstitial mezzanine level below a section of the first floor of the Pentagon after damages caused by the attacks on September 11, 2001.

Project Details
  • Constructed the interstitial level 15 feet above slab on grade and five feet below the first floor
  • Attached 248 six hole steel plates to concrete columns containing spiral rebar
  • Welded shear plates to the steel plates
  • Bolted steel I-beams to the steel plates
  • Installed bar joists on the beams at approximately five foot intervals
  • Installed corrugated decking
  • Installed stairs, railings, and miscellaneous metal to anchor walls and other building structures
Using an FS10 ferrous scanner, the Cianbro team employed the latest magnetic imaging resonance technology to locate and maintain the integrity of spiral rebar in the concrete columns.

Unique Challenge

Working within a high security area with an extremely limited lay down area and a 48-hour notice for all deliveries, the Cianbro team managed material deliveries in coordination with the construction schedule, allowing the right materials to be in the proper place at the appropriate time.

Project Information


Type of Project:
Commercial & Institutional

Construction Schedule:
Completed December 2002

Washington, DC
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