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2 ##Available in: 3D Structure, 3D Frame##
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7 IFC (Industry Foundation Classes) is an open, neutral data exchange format. It is optimized for physical model sharing among design disciplines. The IFC format is ISO-certified, and it is developed and maintained by buildingSMART (formerly the International Alliance for Interoperability).
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10 Through IFC, FEM-Design can use 3D geometrical representation of construction elements defined by architectural and structural modelers as input for analysis models and calculation.
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13 Within IFC, a so-called “Model View Definition” (MVD) gives recommendation for which data and elements the IFC model should include depending on the collaboration (model-exchange) purpose. For analysis software such as FEM-Design, the model view definitions that provide the most important physical model input are: IFC2x3 Coordination View (the most widely implemented view), IFC4 Reference View and IFC4 Design Transfer View.
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16 [[image:IFC logo.png||height="150" width="150"]]
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20 For more information about officially available IFC Model View Definitions, see [[the buildingSMART website>>url:https://technical.buildingsmart.org/standards/ifc/mvd/mvd-database/]].
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25 Contents:
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31
32 == IFC Import ==
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35 FEM-Design can read IFC models and create native and editable FEM-Design analytical model elements from the following types of structural building elements: IfcColumn, IfcBeam, IfcMember, IfcSlab, IfcWall, IfcPlate and IfcRoof. Other IFC types of IFC Building Elements (for example IfcStair, IfcFooting, IfcCurtainWall, IfcPile), or IFC Distribution Elements (MEP equipment), or IFC Furnishing Elements can be displayed as reference elements only in the model space.
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38 The most important steps to get a correct, usable structural analytical model from the IFC input are:
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40 1. **Loading IFC file** by applying conversion and mapping settings. As a result, FEM-Design creates editable analytical model members that are not properly connected to each other. The analytical model  is not continuous. The non-recognized and non-structural elements can be displayed as reference elements in the model space.
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43 [[image:ifc01.png||height="383" width="1300"]]
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46 1. Creating continuous and task-appropriate analytical model with numerous checking and automatic adjustment tools (**Subsequent model adjustments**). Using unrecognized, non-convertible elements as reference elements, create analytical members to replace them by using the FEM-Design STRUCTURE tools.
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49 [[image:ifc02.png||height="377" width="1300"]]
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52 === Loading IFC File ===
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54 When loading an IFC file (with //File menu// //>// //Open//) a dialog pops up with the following conversion and general options:
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56 [[image:1617892971106-423.png]]
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58 * //Bar analytical axis position//: select one option to set the axis position of the new FEM-Design Beam and Column analytical members generated from IfcBeams, IfcColumns and IfcMembers.
59 ** //Center of solid// sets the position of the axis to the center of the recognized cross-section of the IFC physical body.
60 ** //Local coordinate system, centric// sets the position to the axis as described (if available) for the IFC element and without considering eccentricity.
61 ** //Local coordinate system, eccentric// sets the position to the axis as described (if available) for the IFC element and with considering eccentricity.
62 * //Shell analytical plane position//: select one option to set the plane position of the new FEM-Design Plate and Wall analytical members generated from IfcSlab, IfcWall, IfcPlate and IfcRoof.
63 ** //Center of solid// sets the position of the plane to the center of the recognized IFC physical body.
64 ** //Local coordinate system, centric// sets the position to the plane as described (if available) for the IFC element and without considering eccentricity.
65 ** //Local coordinate system, eccentric// sets the position to the plane as described (if available) for the IFC element and with considering eccentricity.
66 * //Filter for load bearing elements (if available) //option converts only the structural elements (IfcBeam, IfcColumn, IfcMember, IfcSlab, IfcWall, IfcPlate and IfcRoof) that are classified as load-bearing elements in the IFC file (by applying the standard "LoadBearing" IFC boolean-type property with "True" value in the IFC exporter software).
67 * //Import original geometry as solid //generates solids from the body of structural elements besides their automatic analytical member generation, and places them on "Imported solids" //Drawing layer //as reference. This option also provides a visual opportunity to check the success of the analytical member conversion, by coloring the solids:
68 ** (% style="color:#27ae60" %)Green (%%)represents physical elements converted to analytical members without any problem.
69 ** (% style="color:#f39c12" %)Orange (%%)represents physical elements converted to analytical members but with some issues (for example the physical body is too complex to convert,or cross-section cannot be identified).
70 ** (% style="color:#e74c3c" %)Red (%%)represents physical elements not converted to analytical members.
71 * //Import as reference solid //generates solids from the body of non-structural IFC element types that are not supported for conversion, and places them on "Imported solids" //Drawing layer //as reference. The solid of these elements will be (% style="color:#3498db" %)blue(%%).
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73 [[image:1617891507891-781.png]]
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77 * In the import process, it is not possible to filter "only for elements relevant to analysis" (although analysis elements are only derived from IfcBeam, IfcColumn, IfcMember, IfcSlab, IfcWall, IfcPlate and IfcRoof), so if you request an IFC model from your partner, ask them to save only the load-bearing elements or the reference objects for load and support definition. This avoids unnecessary conversion elements and reduces the size of the model to be processed.
78 * The sloping IfcWall and IfcColumn elements come in as Slab or Beam elements (because there are no sloping Wall and Column tools in FEM-Design). However, in the latter case, "sloping reinforced concrete columns" modeled as Beams can also act as Columns in the design thanks to the //__[[Calculate as a Column>>doc:New features.FEM-Design 20 New Features.RC Design.WebHome||anchor="Design beam as column"]]__// design option.
79 * A curved IfcWall element is also read as multiple straight Walls thanks to an automatic segmentation procedure.
80 * IfcRoof has no LoadBearing property in IFC2x3-version files, so in that case the active "//Filter for load bearing elements//" option does not import them.
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84 The automatic conversion can be controlled by mapping the materials and cross-sections of physical IFC elements to proper FEM-Design data. Although the conversion process try to recognize valid cross-sections, the "Section" mapping can override them. If the cross-section is not recognizable and there is no mapping the cross-section of the default element is used (with a warning message).
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87 [[image:1605175742584-469.png]]
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90 === Subsequent Model Adjustments ===
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93 ==== Type Modification ====
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95 The result of the conversion analysis element type depends on the type of IFC element to be converted:
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98 |=(% style="width: 286px;" %)IFC Type|=(% style="width: 283px;" %)FEM-Design Analytical Member
99 |(% style="width:286px" %)IfcColumn|(% style="width:283px" %)Column
100 |(% style="width:286px" %)IfcBeam / IfcMember|(% style="width:283px" %)Beam
101 |(% style="width:286px" %)IfcSlab / IfcPlate / IfcRoof|(% style="width:283px" %)Plate
102 |(% style="width:286px" %)IfcWall|(% style="width:283px" %)Wall
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105 The IFC output type in modeling software is most often tool- or classification-driven. Thus, it may happen (typically in architectural practice) that, for example, a structural element that would be considered as a wall in a structural analysis was modeled with a column creator tool in a modeler and was exported as an IfcColumn. This is converted to a //Column //analytical member by the FEM-Design automatic converter. To solve this "modelling" issue, we can change the analysis and so the FEM-Design structural object type (here //Column//) with the CONVERT tool of the target element (here one of the wall commands). The following figure shows an example of its use.
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107 [[image:Manual convertion.png||height="569" width="700"]]
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112 The converted object keeps as much properties of the original one as possible; all other properties are derived from //Default settings// of the target object's tool. An examples: if the original object is a Wall, the converted Column gets its material from the Wall's material, its cross-section is set according to the Wall’s width and thickness, its length is equal to Wall’s height, but its analysis and design data, its //Stiffness //values and its //End conditions// are set according to //Default settings //of the applied //Column //command.
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115 The following table shows all the conversion possibilities of the structural elements:
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118 [[image:1617892860247-104.png]]
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122 Multiple //Beams //or //Columns //can be converted into a single common //Profiled panel, //if the selected elements are connected to each other and their common geometry and position allows.
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126 ==== Analytical Member Correction ====
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129 When converting physical elements, due to inaccurate physical modeling and differences between physical and analytical models, members with incorrect or distorted geometry can be created from the point of view of analysis and design.
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132 These cases can be checked and resolved easily and quickly with the [[CORRECT MODEL>>doc:Manuals.User Manual.Model check.Correct Model Tool.WebHome]] command (//Tools //menu). The image shows examples of solutions to the following major and common problems:
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134 1. There may be overlaps between the created members
135 1. Solid element operations (SEO) performed in physical modelers can cause small redundant elements and holes in 2D analytical members too.
136 1. Small parts unnecessary for analysis may remain around the openings.
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141 [[image:correct model.png||height="700" width="1244"]]
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143 ==== ====
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145 ==== Analytical Model Adjustment ====
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148 The physical body geometries stored in IFC and their automatic conversion based on their parameters (lengths, heights, mid-planes etc.) do not give a continuous analytical model. As a post-process of the IFC import, we should connect the analysis members correctly by applying position and geometry modification rules (like axial or planar stretch, cutback and parallel offset). The [[ADJUST ANALYTICAL MODEL>>doc:Manuals.User Manual.Model check.Adjust Analytical model.WebHome]] command provides tools to resolve such modelling issues.
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155 Adjustments can be made between structural elements (for example "fit //Beams //to a //Plate //(plane)") or to the structural grid defined by //Storeys //and //Axes//. A //Storey //can be used as an infinite horizontal adjuster plane, while an //Axis //can be used as an infinite vertical adjuster plane.
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161 //Storeys //and //Axes //can be easily and quickly allocated to analytical members generated from an IFC model. Just select (even faster with multi-selection) horizontal elements (//Plates //and //Beams//) for the //Storeys//, or //Beams //and //Plate/Wall //edges for the //Axes//. In case of //Storey //definition, if more objects are selected and their position is closer than a given //Tolerance, Storey //will be generated at the bottom-most object’s level.
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165 [[image:storey adjustment.png||height="700" width="1244"]]
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168 ==== Continuity Check ====
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170 The correctness, so the continuity, of the model can be checked by the following:
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172 * Run a quick finite element mesh generation without any error (PREPARE), or
173 * run a quick analysis for the self-weight (Dead load) after support definition, and check displacement with deformed shape.
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176 [[image:results.png||height="400" width="1094"]]
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180 **Parent topic**: [[BIM Integration>>doc:BIM Integration.WebHome]]
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182 **Check also:**
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184 * [[Correct model tool>>doc:Manuals.User Manual.Model check.Correct Model Tool.WebHome]]
185 * [[Adjust analytical model>>doc:Manuals.User Manual.Model check.Adjust Analytical model.WebHome]]
186 * [[Objects conversion>>doc:New features.FEM-Design 20 New Features.Input.WebHome||anchor="Objects conversion"]]
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