https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/209936/error-the-rayleigh-frequency-1-13523e-06-is-less-than-0-00001-for-load-someone-who-can-help-me-with-this-i-am-trying-to-design-the-foundation-of-this-structure-for-which-i-use-the-reactions-of-the-plate-to-transfer-it-to-the-en-USTelligent Community 12https://communities.bentley.com/thread/634774?ContentTypeID=1Fri, 19 Feb 2021 00:49:45 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:b1e9120d-44f8-48c4-9123-a1625dc93b0cSye<p>The superstructure is not connected to the mat as the base nodes of your superstructure&nbsp;are not part of the nodes that belong to the plate mesh. See screenshot below</p> <p><img alt=" " src="/resized-image/__size/640x480/__key/communityserver-discussions-components-files/5932/pastedimage1613695492671v1.png" /></p> <p>If your intention is to take the reactions from the superstructure and design a mat foundation in STAAD Foundation Advanced, you may define FIXED supports at the column bases. take the reactions into SFA and create and design the mat in SFA itself</p><div style="clear:both;"></div>