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SCIA Engineer Fact Sheet

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Design of composite members according to EN 1994

The new release 15 of SCIAEngineer featuresa comprehensive solution formodelling, analysis and design of composite-beam floor systems. This newdevelopment meets the two principle demands that engineers put forwardwhenworkingwith composite structures:l the accurate structural analysis in a 3D FEMenvironment,l the code-based design of individual structural entities (ULS and SLS

checks).

Accurate FEM-based calculationTheComposite AnalysisModel (CAM) in SCIA Engineer analyses the entirestructure during stages of construction, service, and maintenance.Deformations and load effects obtained from different stages aresuperimposed, taking into account the presence or lack of composite actionand creep in the concrete slabs.

TheEN 1994-1-1 standard stipulateswhich partsof a composite slab can beconsidered to contribute to the strength and stiffnessof the composite beam.In SCIAEngineer 15, the effectivewidth of the composite beam is calculatedautomatically. This includes the automaticdetection of:

l span length;l distance to neighbouring elements in the 3D model (i.e., other beams,

openings),l distance to slab edges;TheComposite AnalysisModel calculates the exact orthotropicproperties ofcorrugated steel decks and composite slabs (corrugated steel deck &concrete topping). These orthotropic properties, as well as the augmentedcontribution of the steel beams (depending on the degree of compositeaction), are used in the FEMcalculations.

Internally, the calculation distinguishes between three FEMsubmodels (withdifferent stiffness of the composite slabs) – one for the construction stageand two for the final (composite) stage. The stage-based model evaluatesrheological effects (i.e., creep) by distinguishing between long and short-term load cases in the final (service) phase.

The functionality supports two possible ways of modelling of steel ribs in acomposite slab. The first one (a "standard composite action") overrules anyparasiticnormal forces thatmayarise fromeccentricitybetween the slab andbeam in the FEM model. This idealisation is suitable for majorityof compositefloors. The second one (an "advanced composite action") uses the actualcross-section propertiesand alignment of beams. Asa result, normal forceswill be generated in both beam and deckas a result of the actual eccentricityof the 1D member, also taking into account the degree of composite action).

The latter approach is useful if horizontal loads could lead to additionalbending of the composite beams.

No limitations are imposed on the structural system, span type, orarrangement of beams in the slab. Composite beams may be simplysupported, continuous, or cantilevers. Regardless if these are parallel orwith arbitrary orientation within a slab – composite beams will be analysedaccuratelywithout anyadditional user input.

Finally, a shear stud library, as well as steel decks libraries with commonprofiles from European and North American manufacturers are alsoprovided.

Code-base designThe design of composite beams is performed according to theEN 1994-1-1standard and includes the following features:

l Ultimate limit states (ULS) design checks for both the construction andcomposite stages;

l Positive and negative flexural capacity of the composite beams(evaluated asper EN 1994-1-1, Chapter 6);

l Contribution of concrete slabs to the resistance of steel beams in thefinal, composite stage (taken into account via calculated effectivewidth);

l Shear lag taken into account at multiple locations along the beam (ineffective-width calculations for the composite stage asper EN 1994-1-1,5.4.1.2);

l Section classification of the steel beam in the composite stage (as perEN 1993-1-1, 5.5.2);

l Shear connector capacity and effect of number and strength ofconnectorson the overall beam resistance (evaluated per EN 1994-1-1,6.6.4);

l Verification of longitudinal shear (asper EN 1994-1-1, 6.6.6.4);l Verification of crushing of concrete flange (as per EN 1992-1-1, 6.2.2

(6));l Shear capacity and shear buckling of composite beams (evaluated per

EN 1993-1-1, 6.2.8 based on the steel section);l Serviceability limit state (SLS) checks for the final (composite) stage.

Main advantages of the module for design ofcomposite membersl The multi-model approach of Composite Analysis Model allows for

parallel checks for construction and composite stages to be performedwithoutmodifications to themodel.

l The partial connection between composite slab and steel beams will betaken into account both during the FEM analysis and in the designchecks.

l Creep in concrete slabs is taken into account during the FEM analysis(using amodular ratio for the concrete Young'smodulus).

l Calculated resistances are based on a plastic distribution of stresses inthe section.

l Section classification takes into account the actual position of the neutralaxis in the composite cross-section.

l Support for both longitudinal and transverse alignment of the steelsheeting

l Additional checkscontrolminimal degree of shear connection, minimumarea of longitudinal reinforcement asper EN 1994-1-1 5.5.1(5), etc.

l National annexsupport.

l Detailing provisions, e.g., on the spacing and diameter of shearconnectors, are taken into account.

l All unity checks values may be plotted along the beams in the 3Dwindow, or listed in tables.

l Brief & summarycalculation outputs in table form.l A detailed calculation output with rendered formulas, intermediate

calculation steps, realisticdynamicdrawings of the composite system, ofthe derivation of plasticmoment resistance and location of plasticneutralaxis.

The composite functionality benefits from a number of already existingfunctionalities in SCIAEngineer:

l Limit state design based on partial safety factors in accordance with EN1990;

l Actions in accordance with EN 1991; combination of actions inaccordancewith EN 1990;

l Action effects calculated in an elastic global analysis (in the CompositeAnalysisModel environment).

Additional remarksl Negative flexural strength can only be evaluated for beams with full

composite action (asspecified in EN 1994-1-1).l Beamsof section classes1 and 2 are supported.