https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/190403/ram-frame-dynamic-mass-offsetI have a model in which the periods and effective mass modal participation is different for each of these dynamic load cases: 1. Modal Analysis ( Dynamic with No Ecc) 2. Dynamic with + Eccentricity (5%) 3. Dynamic with - Eccentricity (5%) Doesen-USTelligent Community 12https://communities.bentley.com/thread/567740?ContentTypeID=1Fri, 07 Feb 2020 01:05:13 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c75ea7ba-11b0-412a-b7cb-c8b44967d414Karthik Madhur<p>Got it, thank you!&nbsp;</p><div style="clear:both;"></div>https://communities.bentley.com/thread/567732?ContentTypeID=1Thu, 06 Feb 2020 23:16:56 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:d4f20387-34d4-4d77-9cf6-1f742d5bb85fSeth Guthrie<p>Check the Ram Frame manual (RamFrameAnalysis.pdf) for details on how eccentricity of mass is accounted for in a semi-rigid diaphragm&nbsp;dynamic analysis.&nbsp;</p><div style="clear:both;"></div>https://communities.bentley.com/thread/567726?ContentTypeID=1Thu, 06 Feb 2020 22:59:54 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:e617be27-b9af-487f-a79b-76099e117542Karthik Madhur<p>What about semi-rigid diaphragms ?</p><div style="clear:both;"></div>https://communities.bentley.com/thread/561389?ContentTypeID=1Thu, 26 Dec 2019 16:38:12 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:77c9fb66-c816-4dfe-a148-de5deae6f412Seth Guthrie<p>For a rigid diaphragm, dynamic analysis with eccentricity we shift the center of mass by the 5% or other user input eccentricity value.</p> <p>For the Equivalent Lateral Force procedure we shift the point that the load is applied. We don&#39;t automatically apply additional torsion for irregular structures with ELF. The user has to increase the eccentricity under Loads Masses when such is required by code. The wiki you cited is specifically about ELF.</p><div style="clear:both;"></div>