Abstract:
This article describes a finite element analysis (FEA) code translation methodology developed by the National Institute of Standards and Technology (NIST) for its World Trade Center (WTC) disaster investigation. A key challenge was that the original engineering documents for the WTC twin towers were in the form of large text files designed to be executed by a commercial FEA software package called SAP2000. Because SAP2000 is limited to linear elastic analysis, NIST needed to translate these files into a format compatible with more advanced FEA software, namely ANSYS and LS-DYNA. These codes have the capability to simulate non-linear phenomena such as impact, thermal-structural interactions, buckling, creep, fracture, and ultimate collapse—all essential for understanding the WTC buildings' failure. The translation process involved developing a two-option methodology to convert SAP2000 files into ANSYS, and a simplified version for LS-DYNA, with the help of a parametric FEA translator code called TrueGrid. To ensure the accuracy of the translation, a five-criteria verification specification and a suite of five benchmarks were created. This methodology facilitated the analysis of complex structural details and represented a crucial step in the WTC investigation.
