Upgrading conventional cold-formed steel connections to protect against moderate blast events
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Most research in the area of blast resistant and retrofit designs has focused on high threat levels to meet the DOD and DOS needs. This report shows the need for moderate blast threat level protection and proposes ways to achieve that protection. Cold-formed steel stud wall systems are already used in many applications and could be effectively adapted to meet these threat levels. The objective of this report is to increase the strength of the connection of cold-formed steel stud-track systems to allow the studs to utilize part or all of the inherent tensile membrane resistance. The proposed solutions of upgrading stud-track wall connections with extra screws, larger screws, larger track and thicker track, etc. are evaluated and compared against each other and the current typical connection design. To accomplish this evaluation, four-foot long samples are constructed and loaded using a four-point loading tree. The results are compiled and trends are developed which are used to develop a matrix of full-length (ten-foot) samples. This study concludes that adding extra screws, along with stud thickness, are practical and efficient methods of altering the failure mechanisms and increasing the blast resistant characteristics of these wall systems. With these upgraded connections, lighter gauge sample show some tensile membrane behavior. Also discussed are the United Facilities Criteria (UFC) limits on deflection and data to support revising those criteria.
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