Operation UPSHOT-KNOTHOLE Nevada Proving Grounds, March-June 1953. Project 3.4. Tests on the Loading of Truss Systems Common to Open-Framed Structures. Report to the Test Director,
WRIGHT AIR DEVELOPMENT CENTER WRIGHT-PATTERSON AFB OH
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This report deals with pre- and post-test work on the Air Force Structures Test Project 3.4, Tests on the Loading of Truss Systems Common to Open Frame Structures. The over-all objective of the test was to determine the blast loading on open-framed structures, and to compare these loads with the results of steady-state wind-tunnel tests on model structures where possible. The items tested were a section of a plate girder bridge, a center section of a truss bridge, the upper chord and lower chord of this bridge, and a typical isolated structural member as represented by an I-beam. All items were at 2000 ft intended from ground zero in both Shots 9 and 10. Thirteen of eighteen strain gages provided usable records in Shot 9, and no usable records were obtained in Shot 10 even those records classified as usable appeared to have significant baseline shifts. For the most part, the strain data did not yield any interpretable results, and therefore none of the stated test objectives has been achieved. In view of the limited and uncertain nature of the strain data obtained, it is very doubtful if the test objectives could have been realized in any event. However, the anticipated methods of analysis were unsuccessful for the data obtained, and it is clear that additional work remains to be done with regard to the data-reduction problems associated with net force measurement systems such as employed on the present test.
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