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Results of a New Challenge

Original Post - 19 Jun 2020 - Michael H. Scott

Visit Structural Analysis Is Simple on Substack.

After proposing a modeling challenge for linear-elastic analysis of a strongback frame, I proposed a second challenge for linear-elastic analysis of the Ziemian frame. There were eight participants in this challenge, an increase from five for the first challenge.

Due to the light gravity loads on the frame, whether or not the analysis included self-weight made a significant difference in the requested roof displacement. Of the eight participants, four also computed roof displacement that accounted for the self-weight of the frame members.

The results are shown below, along with the median values among the submissions–0.31 mm with self weight and 0.12 mm without. Temporarily forsaking OpenSees, I analyzed the Ziemian frame in G2 and (fortunately) obtained the median results. You can find the G2 input file here.

Eyeball statistical analysis reveals some variance in the results, but not enough to worry about. The variations are most likely due to small differences in the input section and material properties.

In forthcoming challenges, we’ll move beyond linear-elastic analysis with a pushover analysis of the strongback frame and a push-down analysis of the Ziemian frame. Also, nonlinear analysis of a reinforced concrete beam has been suggested for a future challenge, but let’s take it one step at a time. Stay tuned!