AFCEC conducts CONEX dorm field testing

  • Published
  • By Susan H. Lawson
The Air Force Civil Engineer Center recently tested expeditionary CONEX, or container express, dorms for progressive collapse at Tyndall Air Force Base, Florida.

CONEX-based relocatable barracks are a common sight at many U.S. and coalition bases worldwide. Cost-effective, readily available and robust, CONEX containers are designed so they can be stacked, connected together and modified to create relocatable barracks for troops and other base personnel.

While CONEX-based structures are a quick and effective means to provide shelter from environmental elements, it was unclear how the barracks would respond to a sudden column loss during attack or disaster.

In an earlier study, the Department of Defense evaluated CONEX-based barracks for progressive collapse per Unified Facilities Criteria, or UFC, and determined a substantial risk for progressive collapse existed and that a structural retrofit was needed to bring CONEX-based barracks into compliance with UFC.

However, an AFCEC Reachback Center request revealed bad assumptions made during original structural analysis, such as how CONEX-to-CONEX connections were made, CONEX-to-ground connections and rigidity provided by corrugated sheathing. To properly evaluate the structures, AFCEC engineers reevaluated the findings indicating progressive collapse concerns and commissioned a three-phase program to perform dynamic full-scale column removal tests matching the exact specifications from a facility currently in theater. The program consisted of three distinct phases.

Phase one was a preliminary structural analysis using CSI SAP2000 to determine response of the CONEX-based structure to column removal at various locations. Phase two was to construct a representative test dorm and perform a controlled dynamic testing regimen using a system of hydraulically controlled structure jacks to document structure response to sudden column removal. Phase three was to detonate a 155-millimeter artillery shell in contact at the area deemed most critical during phase two and measure the structural response.

“I had originally approached the U.S. Central Command and the U.S. Army Corps of Engineers for this evaluation,” said Lt. Col. Michael Brannon, deputy of the AFCEC Operations Directorate, an originator of the reach-back request and former deployed squadron commander. “Neither organization had the expertise or resources to do the tests, but AFCEC was both willing and able! I was able to send pictures of my dorm and come to Florida after deployment to see the full-scale replica.”

The results of the program indicate no progressive collapse concerns as described by the UFC exist to CONEX-based relocatable barracks structures currently in theater when constructed to the specifications evaluated.

“These results mean deployed forces can use containers three-high without fear of collapse, and either greatly reduce the perimeter they must protect or increase stand-off from the perimeter,” said Jeff Nielsen, AFCEC antiterrorism subject matter expert.

AFCEC hopes to receive more input from warfighters to find lasting solutions to real problems.

For more information on CONEX, contact the AFCEC reach-back center at or 850-283-6995.