Experimental Testing and Analysis of S50 Beam with Finite Element Modeling of Splice Connection

Abstract

Large Area Maintenance Shelters, LAMS, are commonly used as deployable shelters by the US Air Force to store and maintain equipment. This work is specific to the LAMS located at Tyndall Air Force Base manufactured by Clamshell Buildings. This type of LAMS has recently experienced multiple failures at wind speeds below the specified design wind speed. This has resulted in expensive repairs, injuries, and one fatality. In this work, experimental testing is conducted on the S50 beam, which is the main structural element of the LAMS that makes up the structural frame. The objective of this testing was to collect data to compare the structural response between a spliced S50 beam versus a continuous S50 beam. Testing showed that the continuous beams performed similar to the theoretical structural response, but the spliced beam had significantly lower stiffness and less load capacity. The continuous beams were significantly stronger and stiffer than the spliced beam. The S50 beam and splice connection were modeled with finite elements using SAP2000 V21. The continuous S50 beam experimental test and model were verified using beam theory and virtual work. Once the continuous beam was confidently modeled, the splice beam was created. The splice connection was modified to match the experimental testing displacements by decreasing the effective splice moment of inertia. The spliced model was also verified with beam theory and virtual work once it followed the experimental testing displacements. The modified splice was implemented into subsystem models to compare the differences between a fully continuous S50 frame line and one that included the splice connection. The analysis proved that the splice connection added considerable flexibility to the structure, which could contribute to the recent causes of the collapses. A strength check was conducted, which proved the splice connection could result in failures due to internal forces.