Two-way Interface between Thermal Solid Elements and Structural Beam and Shell Elements (GetGo)

One of the recommendations of the National Construction Safety Team for the Federal Building and Fire Safety Investigation of the World Trade Center Disaster (NIST NCSTAR 1, 2005) is to enhance the performance-based capability of available computational software to predict the effects of fires in buildings, for use in the design of fire protection systems and the analysis of building response to fires. One of the general purpose software codes used in that analysis is capable of performing thermal and structural analyses, among other things. In its standard package, the transfer of temperatures from a thermal model to a structural model, or the transfer of deflections from a structural model to a thermal model can only be performed with compatible elements, i.e., solid to solid or shell to shell. The present paper seeks to remedy this situation: even though most thermal analyses are performed with solid elements, most structural analyses are not, as they make widespread use of beam and shell elements. The paper develops a procedure that allows temperatures anywhere within a solid thermal model to be transferred as load input to a wide variety of common beam cross sections and shells with various number of layers in a geometrically compatible structural model. The paper also develops a method to transfer deflections from a beam and shell structural model back to a solid thermal model, a step that is especially important in intense fires of long duration, when structural deflections may be significant enough to affect the thermal regime or damage the insulation.

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