Page Comparison

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[SAP2000|sap2000:home] provides various ways ofto model modelingthe [composite behavior|kb:Composite behavior] of a beam-and-slab assembly in SAP2000. For your reference and study, we have attached Attached are four SAP2000 models thatwhich demonstrate showthese different waysapproaches. forThe modelinggeometric compositeand actionmaterial for girder-and-slab assembly. The model description properties of the model used for the comparison isare as follows:

* The Slab width = 2.0 m
* Slab thickness = 0.2 m
* GirderTotal totalgirder height = 1.2 m
* Top and bottom flangesflange width = 1.0 m
* Top and bottom flange thickness = 0.1 m
* Web thickness = 0.1 m
* TheApplied applied load at midmidspan span is= 100 kN
* ModulesModulus of elasticity, E = 33000000 kN/m2m ^2^
* Span length L = 20 m,
* Boundary condition: fixed at both ends

The deflectionmidspan atdeflections mid-spanare is calculated for the naked girder and composite girder asas follows:

* Naked girder, Δ = 0.0018m
and
* Composite girder, Δ = 0.00083m
respectively.

h1. Model overview
Overview
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{center-text}Figure 1 - Model overview{center-text}


h1. Various Approaches to composite-behavior Modelingmodeling
Composite
Behavior\\

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{center-text}Figure 2 - Modeling composite behavior {center-text}


h1. Fixed-beam model
Beams
ModelThe eight Theapproaches modelto containsmodeling containscomposite 8behavior, beamsdescribed thatabove, are fixedapplied atusing theireight bothdifferent endsbeam andmodels thewhich compositeare behaviorfixed isat modeledeither usingend. theResults 8are approachessummarized outlinedas infollows:
the figure above.
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|| Beam Designation || Behavior || Midspan Deflection \\
\[mm\] || Comments ||
| Theoretical Beam | composite \\ | 0.8181 | Theoretical deflection is based on the {math}\frac{PL^3}{192EI}{math} formulaPL^3 / 192EI formulation. Please note that the SAP2000 calculatedcalculations deflectionsproduce areslightly slightlygreater highervalues because shear thedeformation programis considersconsidered shearin deformationsdeflection. |
| Beam 1 \\
(top beam) \\
\\ | nocomposite \\ | 1.7938 | The deck-slab center line of deck slab coincides with the thesection neutral axis of the  section. HenceTherefore, the contribution of deck -slab contribution to thesection flexural stiffness  of the section will be negligible. andFurther, thebecause there deflectionis atno mid-span for  this modelcomposite action, midspan deflection should be close to thethat deflectionof  fora naked girder (i.e. no  composite action). | |
| Beam 2 \\ | composite \\ | 0.8313 | In this model, theslab shell elements representing the slab are drawn at the girder CGcenter of the girdergravity (COG), and then offset vertically, above the girder, to model the  composite action. The shells are offset such that the soffit of the slab soffit is at the top oflocated above the girder top flange. |
| Beam 3 \\ | composite \\ | 0.8313 | In this model, the girder and the slab are drawn at their respective center-lines. centerlines and then the The corresponding joints of the girder and the slab joints are then connected together through body constraints. This is another way to  model the composite action. |
| Beam 4 \\ | composite \\ | 0.8313 | In this model the concept of, composite action is modeled using frame insertion points is used to model the  composite action. |
| Beam 5 \\ | noncompostite \\ | 1.7938 | Equal constrainconstraints isare used to model noncompositenon-composite behavior. \\ |
| Beam 6 \\ | noncomposite \\ | 1.7938 | LinkLinks isare used to model noncompositenon-composite behavior. \\ |
| Beam 7 \\ | partially composite \\ | 1.0302 | LinkLinks isare used to model partially -composite behavior. \\ |
| Beam 8 \\
(bottom beam) \\ | composite \\ | 0.8313 | LinkLinks isare used to model composite behavior. \\ |

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In
Composite viewaction of the foregoing, you can use a beam-slab assembly may be modeled using either area offsets, body constraints, frame insertion points, or [links|kb:Link].
to
model
composite action of the beam-and-slab assembly.

h1. Simply-supported Supportedbeam Beamsmodel
Model
The Theeight modelapproaches containsto contains 8 beams thatcomposite-behavior modeling, described above, are simplyapplied supportedusing ateight theirdifferent bothsimply-supported endsbeam andmodels. theResults compositeare behaviorsummarized isas modeledfollows:
using the 8 approaches outlined in the figure above.


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|| Beam Designation || Behavior || Midspan Deflection \\
\[mm\] || Comments ||
| Theoretical Beam | composite \\ | 3.2725 | Theoretical deflection is based on the {math}\frac{PL^3}{48EI}{math} formulaPL^3 / 48EI formulation. Please note that the SAP2000 calculatedcalculations deflectionsproduce areslightly slightlygreater highervalues because theshear deformation programis considersconsidered shearin deformationsdeflection. |
| Beam 1 \\
(top beam) \\
\\ | nocomposite \\ | 7.1752 | The deck-slab center line of deck slab coincides with the thesection neutral axis of the  section. HenceTherefore, the contribution of deck -slab contribution to thesection flexural stiffness  of the section will be negligible. andFurther, thebecause there deflectionis atno mid-span for  this model composite action, midspan deflection should be close to thethat deflectionof a for naked girder (i.e. no  composite action). | |
| Beam 2 \\ | composite \\ | 3.2624 \\ | In this model, theslab shell elements representing the slab are drawn at the girder CGcenter of the girdergravity (COG), and then offset vertically, above the girder, to model the  composite action. The shells are offset such that the soffit of the slab soffit is atlocated the topabove of the girder top flange. |
| Beam 3 \\ | composite \\ | 3.2624 \\ | In this model, the girder and the slab are drawn at their respective center-lines. centerlines and then the corresponding joints of theThe corresponding girder and the slab joints are then connected together through body constraints. This is another way to  model the composite action. |
| Beam 4 \\ | composite \\ | 3.2624 \\ | In this model, composite action theis conceptmodeled ofusing frame insertion points is used to model the  composite action. |
| Beam 5 \\ | noncompostite \\ | 7.1752 \\ | Equal constrainconstraints isare used to model noncompositenon-composite behavior. \\ |
| Beam 6 \\ | noncomposite \\ | 7.1752 \\ | LinkLinks isare used to model noncompositenon-composite behavior. \\ |
| Beam 7 \\ | partially composite \\ | 3.5036 \\ | LinkLinks isare used to model partially -composite behavior. \\ |
| Beam 8 \\
(bottom beam) \\ | composite \\ | 3.2624 \\ | LinkLinks isare used to model composite behavior. \\ |


h1. Attachments

* [Modeling composite behavior in SAP2000.zip |^Modeling_composite_behavior_in_SAP2000.zip] -(zipped SDB file)
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The zippedfile fileabove contains the following files:
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** SAP2000 V12.0.0 file for with 8 fixed beams for which the composite behavior is modeled using different approachesdemonstrating composite-behavior modeling for eight fixed beams.
** SAP2000 V12.0.0 file for with 8 simply supported beams for which the composite behavior is modeled using different approachesdemonstrating composite-behavior modeling for eight simply-supported beams.
** Sketches which illustratingillustrate the modeling of composite, noncompositenon-composite, and partially -composite behavior in SAP2000 (PDF file)..


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*Note:*

The "Modeling composite behavior in SAP2000.zip" attachment file can be directly emailed to directly answer support questions.
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