https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/203993/natural-frequency-errorI&#39;m sure this is something simple but I&#39;ve got a model that runs fine without inputted masses. My goal is to determine the period/natural frequency of the structure. Started by running a self-weight only analysis and adding Y supports at all of my nodesen-USTelligent Community 12https://communities.bentley.com/thread/612413?ContentTypeID=1Fri, 02 Oct 2020 16:19:45 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:429d51f2-b204-4457-9130-b9946d41ed1eSeth Guthrie<p>It helps to tell us what application you are using. In this model, with Ram Elements version 16.02.00.88 I get some instability warnings in analysis.&nbsp;</p> <p style="padding-left:30px;">[Information] Active degrees of freedom 6 (Tx Ty Tz Rx Ry Rz)<br />[Warning] Local instability at or near Node Node 118<br />[Warning] Local instability at or near Node Node 119<br />[Warning] Local instability at or near Node Node 120<br />[Warning] Local instability at or near Node Node 118<br />[Warning] Local instability at or near Node Node 119<br />[Warning] Local instability at or near Node Node 120<br />[Error] Error during analysis</p> <p>This is due to having hinged members connected to pinned supports. That leaves the node(s) free to rotate. Ether don&#39;t hinge the beams (and fix one end against rotation), or make the supports rotationally fixed to avoid the problem.&nbsp;</p> <p><img alt=" " src="/resized-image/__size/600x400/__key/communityserver-discussions-components-files/5932/instabilityopt1.png" /></p> <p>See also:&nbsp;<a href="/products/ram-staad/w/structural_analysis_and_design__wiki/3038/ram-instability-in-finite-element-analysis-tn">https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/3038/ram-instability-in-finite-element-analysis-tn</a>&nbsp;</p><div style="clear:both;"></div>https://communities.bentley.com/thread/612271?ContentTypeID=1Thu, 01 Oct 2020 21:25:46 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:0f31b7d6-c730-4355-ac5e-b3e08377f131Nulukkizdin<p>See attached.<a href="https://communities.bentley.com/cfs-file/__key/communityserver-discussions-components-files/5932/FF-Vibration-Test.zip">communities.bentley.com/.../FF-Vibration-Test.zip</a></p><div style="clear:both;"></div>https://communities.bentley.com/thread/612270?ContentTypeID=1Thu, 01 Oct 2020 21:08:40 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:805b8001-373a-4f8c-b04c-2686219e7736Sye<p>Please upload the .std file.</p><div style="clear:both;"></div>