Ram Elements Shells FAQ
| Applies To | |||
| Product(s): | RAM Elements | ||
| Version(s): | 13.0 or later | ||
| Environment: | N/A | ||
| Area: | N/A | ||
| Subarea: | N/A | ||
| Original Author: | Bentley Technical Support Group | ||
How can I report the flexural area of steel required for shells in Ram Elements?
For shell elements that are primarily subject to out of plane bending, Ram Elements can provide output for the area of steel required in the two principal directions per ACI 318-05.
The shells must be concrete and the model must include design combos to take advantage of this feature fully. Mechanical cover for the shells should also be assigned in the Shells - Materials spreadsheet.
To see the output on screen first select the desired combo at the bottom and then use View - Stresses to see stress contours. In the list of stress options, pick As 1 or As 3 top or bottom.
To get a report of the same information use Output - Analysis - Analysis Results - and select the last option "Flexural reinforcement in shells", Be sure to select the desired combo or combos on the right and then OK.
Obviously having shells with local axes aligned to the direction of the reinforcement is critical for making this output useful.
Also note, this does not take into acount shear design nore the effects of axial tension or comression acting on the shells.
CanRamElementsbeusedtodesignamatfoundationonsoil?
Yes,oneofthekeystomodelingthematfoundationistodefinearegularmesh.Sincethenodesofthemeshneedtobesupportedbyverticalcompression-onlysprings,weneedthemattobemanuallymeshed.Usingaregularsizemeshwillhelpsothatthetributaryareaofeachnodeisfairlyconstantallowingyoutousethesamespringstiffness.
Theassignedspringstiffnessshouldbederivedfromthesoilsubgrademodulusandtheaverageshellarea.Note,thespringunitsareinforce/length,e.g.kip/in,meaninghowmanykipsofcompressionatthispointdoesittaketoyield1inchofdeflection.Tomakethespringscompression-only,justchecktheCompressiononly-TYbox(assumingYisvertical).
Inordertoinsurestabilitysomesoilfrictionresistanceoredgerestraintshouldalsobemodeled.Modelingtheself-weightofthefoundationmayalsoberequiredforstability(thiscanbemodeledusingtheGen-Selfweightoption).Ifselfweightisincludedaspartofthedeadload,alsomakesurethatthedeadloadisusedinallofthecombos. Becausethemodelincludescompression-onlysprings,iterativeanalysisisrequired.Itmaybethatthemodelisstableforcombinations,butnotforthelateralloadcasesalone,butthat'sOKsolongasthecombosallproducevalidresults.
Asamplefilecanbefoundhere.
Themethodaboveoutlineshowtogetsteelrequirementsfortheshells.Bearingstressresultscanbederivedfromthespringreactions.
Forsomethingalittlemoreautomated,consider RamConcept.
See Also
Structural Product TechNotes And FAQs
External Links
Bentley Technical Support KnowledgeBase
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