Solutions and settings for a correct export

4.2 – Sap2000 v20 - IFC

Material Structural Exchange Requirements

IfcMaterial Ok

IfcMaterialClassificationRelationship Ok

IfcMaterialList Ok

Table 4.4: Material

Measure Structural Exchange Requirements

IfcContextDependentUnit Ok

IfcConversionBasedUnit Ok

IfcDerivedUnit Ok

IfcDerivedUnitElement Ok

IfcSIUnit Ok

IfcUnitAssignment Ok

Table 4.5: Measure

Profile Property Structural Exchange Requirement

IfcGeneralProfileProperties No

IfcReinforcementBarProperties No

IfcRibPlateProfileProperties No

IfcSectionProperties No

IfcSectionReinforcementProperties No

IfcStructuralProfileProperties No

IfcStructuralSteelProfileProperties No Table 4.6: Profile Property

Profile Structural Exchange Requirements

IfcClosedProfileDef Ok

IfcOpenProfileDef Ok

IfcIShapeProfileDef Ok

IfcLShapeProfileDef Ok

IfcParametrizedProfileDef Ok

IfcRectangleProfileDef Ok

IfcRoundedRectangleProfileDef Ok

IfcTShapeProfileDef Ok

IfcTrapeziumProfileDef No

IfcUShapeProfileDef Ok

IfcZShapeProfileDef Ok

Table 4.7: Profile

4.2 – Sap2000 v20 - IFC

Property Structural Exchange Requirements

IfcComplexProperty Ok

IfcPropertyEnumeration No

IfcPropertyListValue No

IfcPropertyReferenceValue No

IfcPropertySingleValue Ok

IfcPropertyTableValue No

IfcSimpleProperty Ok

Table 4.8: Property

Representation Structural Exchange Requirements

IfcGeometricRepresentationContext Ok

IfcGeometricRepresentationSubContext Ok

IfcMaterialDefinitionRepresentation Ok

IfcShapeAspect No

IfcShapeRepresentation Ok

IfcShapeModel Ok

IfcStyleModel Ok

Table 4.9: Representation

Structural Load Exchange Requirements

IfcBoundaryCondition No

IfcBoundaryEdgeCondition No

IfcBoundaryFaceCondition No

IfcBoundaryNodeCondition No

IfcStructuralConnectionCondition No

IfcStructuralLoad No

IfcStructuralLoadLinearForce No

IfcStructuralLoadPlanarForce No

IfcStructuralLoadSingleDisplacement No

IfcStructuralLoadSingleDisplacementDistortion No

IfcStructuralLoadSingleForce No

IfcStructuralLoadSingleForceWarping No

IfcStructuralLoadStatic No

IfcStructuralLoadTemperature No

Table 4.10: Structural Load

Giving a careful look to these results table, furnished by buildingSMART, it is clear

for structural analysis; moreover, this problem is not about the knowledge of software users but it is an interoperability limitation.

Indeed, structural exchange requirements completely not satisfied for constraints, material property, profile property and, especially, structural load. This table represent an important step in this research about interoperability: IFC file format is not able to guarantee a cleaned and linear workflow with structural analysis software because of its same informative definition.

Problems related to analytical models, their materials and profiles can be only par-tially solved, for the only thing to do it is waiting for new export types of IFC files to reach a perfect level of communication. Possible adjustments and improvements can be taken only in the structural analysis software.

Although the problems in this case are many and appear unsolvable, it was decided to persist on this way and try to find an approximate solution to perform an analy-sis. This decision was taken because this interoperability path represents an important chance in the spread of BIM in the international view: allowing a total free exchange of data is the starting point to persuade all companies, even the most settled in the traditional methodology of working, to approach this new workflow for all the design aspects. Moreover, engineers have to understand that they can do without any licenses, only following this way they can avoid becoming software-house slaves.

Summarized problems and limitations of this workflow, it was found a solution mak-ing some adjustments on model elements in the software for structural analysis. It will be illustrated the main points in this chapter dedicated to interoperability, then they will be accurately described in the next chapter where structural analysis will be performed.

Figure 4.6: Assign frame local axes rotation

4.2 – Sap2000 v20 - IFC

The first point to solve was the rotation about their local axes of beam elements; as seen in the previous section, these elements result rotated of 90 degrees. To obtain a model with all the elements rotated it was necessary to assign beam frames an angle of rotation, respect their same axes, of 0 degrees (image 4.6). It is necessary opening the window to assign frame local axes and then selecting beam elements to give a new local rotation; it was necessary to apply this operation many times: once for horizontal beams parallel to X global axis, once for horizontal beams parallel to Y global axis, twice for oblique beams that compose the transversal bracing systems, twice for oblique beams that compose the inferior bracing system.

Then, the second critical point analysed, before starting the structural analysis, is that steel beams of the imported model result not connected between them as amply said before. To obtain a analytical model with all the elements correctly connected be-tween them, it was decided to define a new frame section.

Figure 4.7: Properties creation for frames

A new fictitious rectangular section was defined with dimension of 10 mm for depth/height (image 4.9) and a new material with a null value of weight per unit volume (in this way future values of stresses will not be altered) and an elevated value of the modulus of elasticity, E and consequently of the shear modulus, G (image 4.9); in this way a “connection” was created using frame elements, which could be called rigid link between beams.

It does not affect the structural analysis, but rather it allows this last one. This solu-tion was adopted after noticed that the funcsolu-tion contained in sap2000 for rigid links comported problems to the structural model, once that the analysis was performed (trend of stresses did not correspond to the right trend expected).

Figure 4.8: Input data for rigid frames section

Figure 4.9: Material properties of rigid links

software to obtain a model ready to run structural analysis. More information will be given in the section dedicated to SAP2000 of the next chapter, making some consid-erations about solutions given. As said before, an important fact, that also after this

4.2 – Sap2000 v20 - IFC

little research comes to eye, is that it was not possible to make operations and modi-fies in Tekla Structures: it is not possible to make important and efficient adjustments in the BIM model authoring software, an important interoperability limitation for the workflow.

Final results will be shown only to give an overall idea of what the author have tried to describe with words and that will be elaborated on in the next chapter.

Figure 4.10: Analytical model with adjustments

Figure 4.11: Analytical model with correct local axes