Blast and Impact Loading and Response of Structures
Full Session with Abstracts
An analysis tool used to analyze MiTek Ultra-Span® cold-formed steel (CFS) trusses is described and compared to data obtained via full-scale arena blast testing performed on Ultra-Span® CFS trusses. The tool consists of a nonlinear multiple-degree-of-freedom solver capable of performing analysis on Ultra-Span® CFS trusses generated by MiTek’s truss design program. Truss information such as member size, member layout, truss geometry, and bracing is extracted from an input file for a truss designed for environmental loads. The tool then discretizes the truss by assigning degrees of freedom at truss member intersection points and at additional top and bottom chord locations. The response of each degree of freedom is based on an internally-computed peak stress that is based on the controlling limit state computed according to American Iron and Steel Institute (AISI) S100. Unique peak stresses are defined in both tension and compression. Blast loads are computed including the effects of angle of incidence and applied considering shock front time of arrival. Positive-phase-only and positive-plus-negative-phase load cases are explicitly considered by the tool. Additionally, trusses that are supported by girder trusses are loaded by the dynamic reactions computed for dependent trusses. The output from the tool consists of member deflections, dynamic reactions at points of bearing support, maximum computed ductility in both tension and compression, and the required number of screws at each web-chord intersection. To demonstrate the efficacy of the tool, the paper compares the output generated by the tool with data obtained via full-scale arena blast testing performed on Ultra-Span® CFS trusses. The comparisons consider shock fronts of various magnitudes oriented parallel and perpendicular to the truss’s span. Additionally, the comparisons consider trusses of different types (i.e., monoslope, girder, jack, etc.), member sizes, bracing, and superimposed dead weight.