Etabs - Composite Floor Frame Design Manual

Computers and Structures, Inc.Berkeley, California, USA

Version 8January 2002

ETABS

Integrated Building Design Software

Composite Floor Frame Design Manual

Copyright Computers and Structures, Inc., 1978-2002.The CSI Logo is a trademark of Computers and Structures, Inc.

ETABS is a trademark of Computers and Structures, Inc.Windows is a registered trademark of Microsoft Corporation.

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Copyright

The computer program ETABS and all associated documentation are proprietary andcopyrighted products. Worldwide rights of ownership rest with Computers andStructures, Inc. Unlicensed use of the program or reproduction of the documentation inany form, without prior written authorization from Computers and Structures, Inc., isexplicitly prohibited.

Further information and copies of this documentation may be obtained from:

Computers and Structures, Inc.1995 University Avenue

Berkeley, California 94704 USA

Phone: (510) 845-2177FAX: (510) 845-4096

e-mail: [email protected] (for general questions)e-mail: [email protected] (for technical support questions)

web: www.csiberkeley.com

DISCLAIMER

CONSIDERABLE TIME, EFFORT AND EXPENSE HAVE GONE INTO THEDEVELOPMENT AND DOCUMENTATION OF ETABS. THE PROGRAM HASBEEN THOROUGHLY TESTED AND USED. IN USING THE PROGRAM,HOWEVER, THE USER ACCEPTS AND UNDERSTANDS THAT NO WARRANTYIS EXPRESSED OR IMPLIED BY THE DEVELOPERS OR THE DISTRIBUTORSON THE ACCURACY OR THE RELIABILITY OF THE PROGRAM.

THIS PROGRAM IS A VERY PRACTICAL TOOL FOR THE DESIGN/CHECK OFSTEEL STRUCTURES. HOWEVER, THE USER MUST THOROUGHLY READ THEMANUAL AND CLEARLY RECOGNIZE THE ASPECTS OF COMPOSITE DESIGNTHAT THE PROGRAM ALGORITHMS DO NOT ADDRESS.

THE USER MUST EXPLICITLY UNDERSTAND THE ASSUMPTIONS OF THEPROGRAM AND MUST INDEPENDENTLY VERIFY THE RESULTS.

iCOMPUTERS AND STRUCTURES, INC., BERKELEY, CALIFORNIA DECEMBER 2001COMPOSITE BEAM DESIGN

Contents

General Composite Beam Design Information

1 General Design InformationDesign Codes 1-1Units 1-1Beams Designed as Composite Beams 1-1

Material Property Requirements for Com-posite Beams 1-2

Other Requirements for CompositeBeams 1-2

Frame Elements Designed by Default asComposite Beams 1-3

Overwriting the Frame Design Procedurefor a Composite Beam 1-3

How the Program Optimizes Design Groups 1-5Using Price to Select Optimum Beam

Sections 1-6Design Load Combinations 1-8Analysis Sections and Design Sections 1-8Output Stations 1-10

2 Composite Beam Design ProcessDesign Process for a New Building 2-1Check Process for an Existing Building 2-4

3 Interactive Composite Beam DesignMember Identification 3-1Section Information 3-2Acceptable Sections List 3-3ReDefine 3-4

Composite Beam Design Manual

ii

Temporary 3-5Show Details 3-5

4 Output Data Plotted Directly on the ModelOverview 4-1Labels Displayed on the Model 4-2Design Data 4-3Stress Ratios 4-4Deflection Ratios 4-5

5 Input DataGeneral 5-1Using the Print Composite Beam Design

Tables Form 5-1Material Properties Input Data 5-2Section Properties Input Data 5-3Deck Properties Input Data 5-4Design Preferences Input Data 5-6Beam Overwrites Input Data 5-8

6 Output DataOverview 6-1Using the Print Composite Beam Design

Tables Form 6-1Summary of Composite Beam Output 6-2

7 Composite Beam PropertiesBeam Properties 7-1Metal Deck and Slab Properties 7-3Shear Stud Properties 7-5Cover Plates 7-5

8 Effective Width of Concrete SlabLocation Where Effective Slab Width is

Checked 8-1Multiple Deck Types or Directions Along the

Beam Length 8-2Effect of Diagonal Beams on Effective Slab

Width 8-6

Contents

iii

Effect of Openings on Effective SlabWidth 8-8

Effective Slab Width and TransformedSection Properties 8-9

9 Beam Unbraced LengthOverview 9-1Determination of the Braced Points of a

Beam 9-2User-Defined Unbraced Length of a Beam

Overview 9-3User-Specified Uniform and Point

Bracing 9-4Design Check Locations 9-7

10 Design Load CombinationsOverview 10-1Special Live Load Patterning for

Cantilever Back Spans 10-2Special Live Load Patterning for

Continuous Spans 10-4

11 Beam Deflection and CamberDeflection 11-1Camber 11-4

12 Beam VibrationOverview 12-1Vibration Frequency 12-1Murray's Minimum Damping Requirement 12-4

Initial Displacement Amplitude 12-4Effective Number of Beams Resisting

Heel Drop Impact 12-6References 12-7

13 Distribution of Shear Studs on a CompositeBeamOverview 13-1Composite Beam Segments 13-1


iv

Physical End of the Beam Top Flange 13-2Distribution of Shear Studs Within a

Composite Beam Segment 13-5How the Program Distributes Shear Studs

on a Beam 13-5Equations Used When the Program

Works from Left to Right 13-8Equations Used When the Program

Works from Right to Left 13-9Minimum and Maximum Number of

Shear Studs in a Composite BeamSegment 13-11

A Note About Multiple Design LoadCombinations 13-11

14 The Number of Shear Studs that Fit in aComposite Beam SegmentGeneral 14-1Solid Slab or Deck Ribs Oriented Parallel to

Beam Span 14-2Deck Ribs Oriented Perpendicular to Beam

Span 14-6Different Deck Type or Orientation on Beam

Sides 14-8

15 User-Defined Shear Stud PatternsSpecifying a User-Defined Shear Connector

Pattern 15-1Uniformly Spaced Shear Studs Over the

Length of the Beam 15-2Additional Shear Studs in Specified Sections

of Beam 15-4Defining Additional Beam Sections 15-4Example of a User-Defined Shear Stud

Pattern 15-8How the Program Checks a Beam with User-

Defined Shear Studs 15-9

Contents

v

Composite Beam Design Specific to AISC-ASD89

16 General and NotationIntroduction to the AISC-ASD89 Series of

Technical Notes 16-1Notation 16-2

17 PreferencesGeneral 17-1Using the Preferences Form 17-1Preferences 17-2Factors Tab 17-3Beam Tab 17-3Deflection Tab 17-4Vibration Tab 17-5Price Tab 17-6

18 OverwritesGeneral 18-1Using the Composite Beam Overwrites

Form 18-2Overwrites 18-3Beam Tab 18-4Bracing (C) Tab and Bracing Tab 18-6Deck Tab 18-9Shear Studs Tab 18-10Deflection Tab 18-13Vibration Tab 18-14Miscellaneous Tab 18-14EQ Factor 18-15

19 Width-to-Thickness ChecksOverview 19-1Limiting Width-to-Thickness Ratios for

Flanges 19-2Compact Section Limits for Flanges 19-2Noncompact Section Limits for

Flanges 19-2


vi

Limiting Width-to-Thickness Ratiosfor Webs 19-3Compact Section Limits for Webs 19-3Noncompact Section Limits for Webs 19-3

Limiting Width-to-Thickness Ratios forCover Plates 19-4Compact Section Limits for Cover

Plates 19-5Noncompact Section Limits for Cover

Plates 19-5

20 Transformed Section Moment of InertiaBackground 20-2Properties of Steel Beam (Plus Cover

Plate) Alone 20-4Properties of the Composite Section

General Calculation Method 20-7Equivalent Hand Calculation Method to

Calculate the Distance ye 20-10Background Equations 20-11

Hand Calculation Process for ye 20-17Equivalent Hand Calculation Method to

Calculate the Composite Properties 20-18

21 Elastic Stresses with Partial CompositeConnectionEffective Moment of Inertia for Partial

Composite Connection 21-1Effective Section Modulus Referred

to the Extreme Tension Fiber 21-2Location of the ENA for Partial

Composite Connection 21-3Steel Section Stresses for Partial

Composite Connection 21-5Concrete Slab Stresses for Partial

Composite Connection 21-6

22 Allowable Bending StressesGeneral 22-1

Contents

vii

Allowable Bending Stress for Steel BeamAlone 22-2

Allowable Bending Stresses for PositiveBending in the Composite Beam 22-6

23 Bending Stress ChecksBending Stress Checks Without

Composite Action 23-1Positive Moment in a Composite Beam 23-2Important Notes Regarding Unshored

Composite Beams 23-5Steel Stress Checks 23-5Concrete Stress Checks 23-6

24 Beam Shear ChecksShear Stress Check 24-1

Typical Case 24-1Slender Web 24-2

Copes 24-3Shear Rupture Check 24-4Limitations of Shear Check 24-7

25 Shear StudsOverview 25-1Shear Stud Connectors 25-1

Reduction Factor when Metal Deck isPerpendicular to Beam 25-2

Reduction Factor when Metal Deck isParallel to Beam 25-3

Horizontal Shear for Full CompositeConnection 25-4

Number of Shear Studs 25-5Between the Output Station with

Maximum Moment and thePoint of Zero Moment 25-6

Between Other Output Stations andPoints of Zero Moment 25-6


viii

26 Calculation of the Number of Shear StudsBasic Equations 26-1Shear Stud Distribution Example 1 26-4Shear Stud Distribution Example 2 26-8Shear Stud Distribution Example 3 26-13

Detailed Calculations 26-15

27 Input DataBeam Overwrites Input Data 27-1

28 Output DetailsShort Form Output Details 28-1

Composite Beam Design Specific to AISC-LRFD93

29 General and NotationAISC-LRFD93 Design Methodology 29-1Notation 29-7

30 PreferencesGeneral 30-1Using the Preferences Form 30-1Preferences 30-2Factors Tab 30-3Beam Tab 30-4Deflection Tab 30-5Vibration Tab 30-5Price Tab 30-6

31 OverwritesGeneral 31-1Using the Composite Beam Overwrites

Form 31-2Resetting Composite Beam

Overwrites to Default Values 31-3Overwrites 31-3Beam Tab 31-4Brace (C) Tab and Bracing Tab 31-6

Contents

ix

Deck Tab 31-9Shear Studs Tab 31-10Deflection Tab 31-12Vibration Tab 31-13Miscellaneous Tab 31-14

32 Design Load CombinationsStrength Check for Construction Loads 32-1Strength Check for Final Loads 32-2Deflection Check for Final Loads 32-2Reference 32-3

33 Compact and Noncompact RequirementsOverview 33-1Limiting Width-to-Thickness Ratios for

Flanges 33-2Compact Section Limits for Flanges 33-2Noncompact Section Limits for

Flanges 33-2Limiting Width-to-Thickness Ratios for

Webs 33-3Compact Section Limits for Webs 33-3Noncompact Section Limits for Webs 33-4

Limiting Width-to-Thickness Ratios forCover Plates 33-5Compact Section Limits for Cover

Plates 33-5Noncompact Section Limits for Cover

Plates 33-6

34 Composite Plastic Moment Capacity forPositive BendingOverview 34-1Location of the Plastic Neutral Axis 34-2

PNA in the Concrete Slab Abovethe Steel Beam 34-5

PNA within the Beam Top Flange 34-8PNA within the Beam Top Fillet 34-9PNA within the Beam Web 34-10


x

PNA within the Beam Bottom Fillet 34-11PNA within the Beam Bottom Flange 34-12PNA within the Cover Plate 34-13Calculating the PNA Location 34-15

Plastic Moment Capacity for PositiveBending 34-16

35 Composite Section Elastic MomentCapacityPositive Moment Capacity with an Elastic Stress

Distribution 35-1

36 Moment Capacity for Steel Section AloneOverview 36-1Steel Beam Properties 36-1Moment Capacity for a Doubly Symmetric Beam

or a Channel Section 36-2Lateral Unbraced Length Checks 36-3Yielding Criteria in AISC-LRFD93 Section

F1.1 36-5Lateral Torsional Buckling Criteria in

AISC-LRFD93 Section F1.2a 36-5AISC-LFRD Appendix F1(b) Equation

A-F1-3 46-5Moment Capacity for a Singly Symmetric

Beam with a Compact Web 36-7AISC-LFRD93 Equation A-F1-1 for

WLB 36-8AISC-FLRD93 Equation A-F1-1 for

FLB 36-8AISC-FLRD93 Equation A-F1-3 for

FLB 36-9AISC-FLRD93 Equation A-F1-1 for

LTB 36-9AISC-FLRD93 Equation A-F1-2 for

LTB 36-10Moment Capacity for a Singly Symmetric

Beam with a Noncompact Web 36-11

Contents

xi

AISC-LFRD93 Equation A-F1-3 forWLB 36-12

37 Partial Composite Connection with a Plas-tic Stress DistributionEstimating the Required Percent Composite

Connection 37-1Calculating MPFconc 37-2Location of PNA 37-3

Determining the Effective Portion ofthe Concrete Slab 37-4

Moment Capacity of a Partially CompositeBeam with a Plastic StressDistribution 37-6

38 Bending and Deflection ChecksBending Check Locations 38-1Bending Check 38-1Deflection Check 38-2

39 Shear ConnectorsShear Stud Connectors 39-1Horizontal Shear for Full Composite

Connection 39-1Number of Shear Connectors 39-2

Between Maximum Moment andPoint of Zero Moment 39-2

Between Point Load and Point ofZero Moment 39-3

40 Beam Shear CapacityShear Capacity 40-1Checking the Beam Shear 40-2Limitations of Beam Shear Check 40-2

41 Input DataBeam Overwrites Input 41-1


xii

42 Output DetailsShort Form Output Details 42-1Long Form Output Details 42-8

Design Codes Technical Note 1 - 1

COMPUTERS AND STRUCTURES, INC., BERKELEY, CALIFORNIA DECEMBER 2001COMPOSITE BEAM DESIGN

Technical Note 1General Design Information

This Technical Note presents some basic information and concepts that areuseful when performing composite beam design using this program.

Design CodesThe design code is set using the Options menu > Preferences > Compos-ite Beam Design command. You can choose to design for any one designcode in any one design run. You cannot design some beams for one code andothers for a different code in the same design run. You can however performdifferent design runs using different design codes without rerunning theanalysis.

UnitsFor composite beam design in this program, any set of consistent units can beused for input. Typically, design codes are based on one specific set of units.The documentation in the Composite Beam Design series of Technical Notes ispresented in kip-inch-seconds units unless otherwise noted.

Again, any system of units can be used to define and design a building in theprogram. You can change the system of units at any time using the pull-downmenu on the Status Bar or pull-down menu on individual forms where avail-able.

Note:You can use any set of units in composite beam design and you can change the units "onthe fly."

Beams Designed as Composite BeamsSection Requirements for Composite BeamsOnly I-shaped and channel-shaped beams can be designed as compositebeams. The I-shaped and channel-shaped beams can be selected from the

General Design Information Composite Beam Design

Technical Note 1 - 2 Beams Designed as Composite Beams

built-in program section database, or they can be user defined. The user-defined sections can be specified using the Define menu > Frame Sectionscommand and clicking either the Add I/Wide Flange or the Add Channel op-tion.

Note that beam sections that are defined in Section Designer are alwaystreated as general sections. Thus, if you define an I-type or channel-typesection in Section Designer, the program will consider it as a general section,not an I-shaped or channel-shaped section, and will not allow it to be de-signed as a composite beam.

Note:Beam sections defined in the section designer utility cannot be designed as compositebeams.

Material Property Requirement for Composite BeamsIf a beam is to be designed as a composite beam, the Type of Design associ-ated with the Material Property Data assigned to the beam must be Steel. Usethe Define menu > Material Properties > Modify/Show Materials com-mand to check your beams.

Other Requirements for Composite BeamsThe line type associated with the line object that represents a compositebeam must be "Beam." In other words, the beam element must lie in a hori-zontal plane. Right click on a line object to bring up the Line Information formto check the Line Type.

For composite beams, the beam local 2-axis must be vertical. The Local axis 2Angle is displayed on the Assignments tab of the Line Information form.

Note:The line object representing a composite beam should span from support to support.Composite beams should not be modeled using multiple, adjacent line objects betweensupports for a single composite beam.

The line object representing a composite beam should span from support tosupport. In the case of a cantilever beam overhang, the line object shouldspan from the overhang support to the end of the beam. The cantilever beamback span should be modeled using a separate line object. If you do notmodel cantilever beams in this way, the analysis results for moments and

Composite Beam Design General Design Information

Beams Designed as Composite Beams Technical Note 1 - 3

shears will still be correct but the design performed by the Composite BeamDesign processor probably will not be correct.

Frame Elements Designed by Default as Composite BeamsThe program will design certain frame elements using the design proceduresdocumented in these Technical Notes by default. Those elements must meetthe following restrictions:

The beam must meet the section requirements described in the subsectionentitled "Section Requirements for Composite Beams" in this TechnicalNote.

The beam must meet the material property requirement described in thesubsection entitled "Material Property Requirement for Composite Beams"in this Technical Note.

The beam must meet the two other requirements described in the subsec-tion entitled "Other Requirements for Composite Beams" in this TechnicalNote.

At least one side of the beam must support deck that is specified as aDeck section (not a Slab or Wall section). The deck section can be filled,unfilled or a solid slab. When the deck is unfilled, the beam will still gothrough the Composite Beam Design postprocessor and will simply be de-signed as a noncomposite beam.

The beam must not frame continuously into a column or a brace. Bothends of the beam must be pinned for major axis bending (bending aboutthe local 3-axis).

Overwriting the Frame Design Procedure for a Composite BeamThe three procedures possible for steel beam design are:

Composite beam design

Steel frame design

No design

By default, steel sections are designed using either the composite beam de-sign procedure or the steel frame design procedure. All steel sections that


Technical Note 1 - 4 Beams Designed as Composite Beams

meet the requirements described in the previous subsection entitled "FrameElements Designed by Default as Composite Beams" are by default designedusing the composite beam design procedures. All other steel frame elementsare by default designed using the steel frame design procedures.

Change the default design procedure used for a beam(s) by selecting thebeam(s) and clicking Design menu > Overwrite Frame Design Proce-dure. This change is only successful if the design procedure assigned to anelement is valid for that element. For example, if you select two steel beams,one an I-section and the other a tube section, and attempt to change the de-sign procedure to Composite Beam Design, the change will be executed forthe I-section, but not for the tube section because it is not a valid section forthe composite beam design procedure. A section is valid for the compositebeam design procedure if it meets the requirements specified in the subsec-tions entitled "Section Requirements for Composite Beams," "Material Prop-erty Requirement for Composite Beams" and "Other Requirements for Com-posite Beams" earlier in this Technical Note.

Note that the procedures documented for composite beam design allow fordesigning a beam noncompositely. One of the overwrites available for com-posite beam design is to specify that selected beams are either designed ascomposite, noncomposite but still with a minimum number of shear studsspecified, or noncomposite with no shear studs. These overwrites do not af-fect the design procedure. Changing the overwrite to one of the noncompositedesigns does not change the design procedure from Composite Beam Designto Steel Frame Design. The noncomposite design in this case is still performedfrom within the Composite Beam Design postprocessor.

Using the composite beam design procedure, out-of-plane bending is not con-sidered and slender sections are not designed. This is different from the SteelFrame Design postprocessor. Thus, the design results obtained for certainbeams may be different, depending on the design procedure used.

Finally, note that you can specify that the composite beam design proceduresare to be used for a beam even if that beam does not support any deck, or forthat matter, even if no slab is specified. In these cases, the beam will be de-signed as a noncomposite beam by the Composite Beam Design postproces-sor.


How the Program Optimizes Design Groups Technical Note 1 - 5

How the Program Optimizes Design GroupsThis section describes the process the program uses to select the optimumsection for a design group. In this description, note the distinction betweenthe term section, which refers to a beam section in an auto select sectionlist, and the term beam, which refers to a specific element in the designgroup.

When considering design groups, the program first discards any beam in thedesign group that is not assigned an auto select section list.

Next, the program looks at the auto select section list assigned to each beamin the design group and creates a new list that contains the sections that arecommon to all of the auto select section lists in the design group. The pro-gram sorts this new common section list in ascending order, from smallestsection to largest section based on section weight (area).

Note:When designing with design groups, the program attempts to quickly eliminate inade-quate beams.

The program then finds the beam with the largest positive design moment inthe design group, or the "pseudo-critical beam." The program then checks thedesign of the pseudo-critical beam for all sections in the common section list.Any sections in the common section list that are not adequate for the pseudo-critical beam are discarded from the common section list, making the listshorter. This new list is the shorter common section list. The shorter commonsection list is still in ascending order based on section weight (area).

Now the program checks all beams in the design group for the first section(smallest by weight [area]) in the shorter common section list. If the optimi-zation is being performed on the basis of beam weight and the section is ade-quate for all beams in the design group, the optimum section has been iden-tified. If the section is not adequate for a beam, the next higher section in theshorter common section list is tried until a section is found that is adequatefor all beams in the design group.

If the optimization is based on price instead of weight, the program finds thefirst section in the shorter common section list (i.e., the one with the lowestweight) that is adequate for all beams. Next it calculates the cost of this first


Technical Note 1 - 6 Using Price to Select Optimum Beam Sections

adequate section and then determines the theoretical heaviest section thatcould still have a cost equal to the adequate section by dividing the total priceof the beam with the adequate section (steel plus camber plus shear connec-tors) by the unit price of the steel. This assumes that when the cost of thesteel section alone is equal to or greater than the total cost of the adequatesection, the section could not have a total cost less than the adequate sec-tion. The program then checks any other sections in the shorter common sec-tion list that have a weight less than or equal to the calculated maximumweight. If any of the other sections are also adequate, a cost is calculated forthem. Finally, the section with the lowest associated cost is selected as theoptimum section for the design group.

Regardless of whether the optimization is based on weight or cost, if all sec-tions in the shorter common section list are tried and none of them are ade-quate for all of the beams in the design group, the program proceeds to de-sign each beam in the design group individually based on its own auto sectionlist and ignores the rest of the design group. If for a particular beam none ofthe sections in the auto select section list are adequate, the program displaysresults for the section in the auto select list with the smallest controlling ratioin a red font. Note that the controlling ratio may be based on stress or deflec-tion.

Note:By default, the program selects the optimum composite beam size based on weight, notprice.

Using Price to Select Optimum Beam SectionsBy default, when auto select section lists are assigned to beams, the programcompares alternate acceptable composite beam designs based on the weightof the steel beam (not including the cover plate, if it exists) to determine theoptimum section. The beam with the least weight is considered the optimumsection. The choice of optimum section does not consider the number of shearconnectors required or if beam camber is required.


Using Price to Select Optimum Beam Sections Technical Note 1 - 7

You can request that the program use price to determine the optimum sectionby clicking the Options menu > Preferences > Composite Beam Designcommand, selecting the Price tab and setting the "Optimize for Price" item toYes. If you request a price analysis, the program compares alternate accept-able beam designs based on their price and selects the one with the least costas the optimum section.

For the cost comparison, specify costs for steel, shear studs and beam cam-ber. The steel cost is specified as a part of the steel material property usingthe Define menu > Material Properties command. The shear stud andbeam camber costs are specified in the composite beam preferences.

The costs for steel and cambering are specified on a unit weight of the beambasis; for example, a cost per pound of the beam. The shear connector cost isspecified on a cost per connector. By assigning different prices for steel, shear

Important Note about Optimizing Beams by Weight and Price

When a beam is optimized by weight, the program internally optimizes thebeam based on area of steel (excluding the cover plate, if it exists). Thus,the weight density specified for the steel is irrelevant in such a case.

When a beam is optimized by price, the program determines the price as-sociated with the steel by multiplying the volume of the beam (includingthe cover plate, if it exists) by the weight density of the beam by the priceper unit weight specified in the material properties for the steel. The priceassociated with camber is determined by multiplying the volume of thebeam (including the cover plate, if it exists) by the weight density of thebeam by the specified price per unit weight for camber defined in the com-posite beam preferences. The price for shear connectors is determined bymultiplying the total number of shear connectors by the price per connec-tor specified in the composite beam preferences. The total price for thebeam is determined by summing the prices for the steel, camber andshear connectors. Thus, when a beam is optimized by price, the weightdensity for the steel is important and must be correctly specified for theprice to be correctly calculated.

Note that the volume of the beam is calculated by multiplying the area ofthe steel beam (plus the area of the cover plate, if used) by the length ofthe beam from center-of-support to center-of-support


Technical Note 1 - 8 Design Load Combinations

connectors and camber, you can influence the choice of optimum section. Thecost of the cover plate is not included in the comparison (but it would be thesame for all beam sections if it were included).

See the previous "Important Note about Optimizing Beams by Weight andPrice" for additional information.

Design Load CombinationsUsing the Composite Beam Design postprocessor, three separate types ofload combinations are considered. They are:

Construction load strength design load combinations

Final condition strength design load combinations

Final condition deflection design load combinations

You can specify as many load combinations as you want for each of thesetypes. In addition, the program creates special live load patterns for cantile-ver beams. See Composite Beam Design Technical Note 20 Design Load Com-binations for additional information on design load combinations for the Com-posite Beam Design postprocessor.

Analysis Sections and Design SectionsAnalysis sections are those section properties used to analyze the modelwhen you click the Analyze menu > Run Analysis command. The designsection is whatever section has most currently been designed and thus desig-nated the current design section.

Tip:It is important to understand the difference between analysis sections and design sec-tions.

It is possible for the last used analysis section and the current design sectionto be different. For example, you may have run your analysis using a W18X35beam and then found in the design that a W16X31 beam worked. In thatcase, the last used analysis section is the W18X35 and the current designsection is the W16X31. Before you complete the design process, verify thatthe last used analysis section and the current design section are the same.


Analysis Sections and Design Sections Technical Note 1 - 9

The Design menu > Composite Beam Design > Verify Analysis vs De-sign Section command is useful for this task.

The program keeps track of the analysis section and the design sectionseparately. Note the following about analysis and design sections:

Assigning a beam a frame section property using the Assign menu >Frame/Line > Frame Section command assigns the section as both theanalysis section and the design section.

Running an analysis using the Analyze menu > Run Analysis command(or its associated toolbar button) always sets the analysis section to bethe same as the current design section.

Assigning an auto select list to a frame section using the Assign menu >Frame/Line > Frame Section command initially sets the design sectionto be the beam with the median weight in the auto select list.

Unlocking a model deletes the design results, but it does not delete orchange the design section.

Using the Design menu > Composite Beam Design > Select DesignCombo command to change a design load combination deletes the designresults, but it does not delete or change the design section.

Using the Define menu > Load Combinations command to change adesign load combination deletes the design results, but it does not deleteor change the design section.

Using the Options menu > Preferences > Composite Beam Designcommand to change any of the composite beam design preferences de-letes the design results, but it does not delete or change the design sec-tion.

Deleting the static nonlinear analysis results also deletes the design re-sults for any load combination that includes static nonlinear forces. Typi-cally, static nonlinear analysis and design results are deleted when one ofthe following actions is taken:

9 Use the Define menu > Frame Nonlinear Hinge Properties com-mand to redefine existing or define new hinges.


Technical Note 1 - 10 Output Stations

9 Use the Define menu > Static Nonlinear/Pushover Cases com-mand to redefine existing or define new static nonlinear load cases.

9 Use the Assign menu > Frame/Line > Frame Nonlinear Hingescommand to add or delete hinges.

Again, note that these actions delete only results for load combinations thatinclude static nonlinear forces.

Output StationsFrame output stations are designated locations along a frame element. Theyare used as locations to report output forces and to perform design, and asplotting points used for graphic display of force diagrams. When force dia-grams are plotted, exact forces are plotted at each output station and thenthose points are connected by straight lines. Output stations occur at user-specified locations and at point load locations along a beam. Designate theoutput stations for a frame element using the Assign menu.

Note:

Access the display of frame element output stations using the View menu.

For composite beam design, the program checks the moments, shears anddeflections at each output station along the beam. No checks are made at anypoints along the beam that are not output stations.

Design Process for a New Building Technical Note 2 - 1


Technical Note 2Composite Beam Design Process

This Technical Notes describes a basic composite beam design process usingthis program. Although the exact steps you follow may vary, the basic designprocess should be similar to that described herein. Separate processes aredescribed for design of a new building and check of an existing building. OtherTechnical Notes in the Composite Beam Design General series provide addi-tional information.

Design Process for a New BuildingThe following sequence describes a typical composite beam design process fora new building. Note that although the sequence of steps you follow mayvary, the basic process probably will be essentially the same.

1. Use the Options menu > Preferences > Composite Beam Designcommand to choose the composite beam design code and to review othercomposite beam design preferences and revise them if necessary. Notethat default values are provided for all composite beam design prefer-ences, so it is unnecessary to define any preferences unless you want tochange some of the default values. See AISC-ASD89 Composite Beam De-sign Technical Note 17 Preferences and AISC-LRFD93 Composite BeamDesign Technical Note 30 Preferences for more information about prefer-ences.

2. Create the building model, as described in Volumes 1 and 2.

3. Run the building analysis using the Analyze menu > Run Analysiscommand.

4. Assign composite beam overwrites, if needed, using the Design menu >Composite Beam Design > View/Revise Overwrites command. Notethat you must select beams before using this command. Also note thatdefault values are provided for all composite beam design overwrites so itis unnecessary to define overwrites unless you want to change some of

Composite Beam Design Process Composite Beam Design

Technical Note 2 - 2 Design Process for a New Building

the default values. Note that the overwrites can be assigned before or af-ter the analysis is run. See AISC-ASD89 Composite Beam Design Techni-cal Note 18 Overwrites and See AISC-LRFD93 Composite Beam DesignTechnical Note 31 Overwrites.

5. Designate design groups, if desired, using the Design menu > Compos-ite Beam Design > Select Design Group command. Note that youmust have already created some groups by selecting objects and clickingthe Assign menu > Group Names command.

6. To use design load combinations other than the defaults created by theprogram for composite beam design, click the Design menu > Compos-ite Beam Design > Select Design Combo command. Note that youmust have already created your own design combos by clicking the De-fine menu > Load Combinations command.

Note that for composite beam design, you specify separate design loadcombinations for construction loading, final loading considering strength,and final loading considering deflection. Design load combinations for eachof these three conditions are specified using the Design menu > Com-posite Beam Design > Select Design Combo command. See Compos-ite Beam Design Technical Note 10 Design Load Combinations.

7. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to run the composite beam design.

8. Review the composite beam design results by doing one of the following:

a. Click the Design menu > Composite Beam Design > Display De-sign Info command to display design input and output information onthe model. See Composite Beam Design Technical Note 4 Data PlottedDirectly on the Model.

b. Right click on a beam while the design results are displayed on it toenter the interactive design mode and interactively design the beam.Note that while you are in this mode, you can also view diagrams(load, moment, shear and deflection) and view design details on thescreen. See Composite Beam Design Technical Note 3 InteractiveComposite Beam Design for more information.

Composite Beam Design Composite Beam Design Process

Design Process for a New Building Technical Note 2 - 3

If design results are not currently displayed (and the design has beenrun), click the Design menu > Composite Beam Design > Inter-active Composite Beam Design command and then right click abeam to enter the interactive design mode for that beam.

c. Use the File menu > Print Tables > Composite Beam Designcommand to print composite beam design data. If you select beamsbefore using this command, data is printed only for the selectedbeams. See AISC-ASD89 Composite Beam Design Technical Note 27Input Data, AISC-LRFD93 Composite Beam Design Technical Note 41Input Data, AISC-ASD89 Composite Beam Design Technical Note 28Output Details, and AISC-LRFD93 Composite Beam Design TechnicalNote 42 Output Details for more information.

d. Use the Design menu > Composite Beam Design > Verify allMembers Passed command to verify that no members are over-stressed or otherwise unacceptable.

9. Use the Design menu > Composite Beam Design > Change DesignSection command to change the beam design section properties for se-lected beams.

10. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to rerun the composite beam designwith the new section properties. Review the results using the proceduresdescribed in Step 8.

11. Rerun the building analysis using the Analyze menu > Run Analysiscommand. Note that the beam section properties used for the analysis arethe last specified design section properties.

12. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to rerun the composite beam designwith the new analysis results and new section properties. Review the re-sults using the procedures described in Step 8.

13. Again use the Design menu > Composite Beam Design > ChangeDesign Section command to change the beam design section propertiesfor selected beams, if necessary.


Technical Note 2 - 4 Check Process for an Existing Building

14. Repeat Steps 11, 12 and 13 as many times as necessary.

Note:Composite beam design in the program is an iterative process. Typically, the analysisand design will be rerun multiple times to complete a design.

15. Select all beams and click the Design menu > Composite Beam Design> Make Auto Select Section Null command. This removes any auto se-lect section list assignments from the selected beams.

16. Rerun the building analysis using the Analyze menu > Run Analysiscommand. Note that the beam section properties used for the analysis arethe last specified design section properties.

17. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to rerun the composite beam designwith the new section properties. Review the results using the proceduresdescribed above.

18. Click the Design menu > Composite Beam Design > Verify Analysisvs Design Section command to verify that all of the final design sectionsare the same as the last used analysis sections.

19. Use the File menu > Print Tables > Composite Beam Design com-mand to print selected composite beam design results if desired. SeeAISC-ASD89 Composite Beam Design Technical Note 28 Output Detailsand AISC-LRFD93 Composite Beam Design Technical Note 42 Output De-tails

It is important to note that design is an iterative process. The sections used inthe original analysis are not typically the same as those obtained at the endof the design process. Always run the building analysis using the final beamsection sizes and then run a design check using the forces obtained from thatanalysis. Use the Design menu > Composite Beam Design > VerifyAnalysis vs Design Section command to verify that the design sections arethe same as the analysis sections.

Check Process for an Existing BuildingThe following sequence is a typical composite beam check process for an ex-isting building. In general, the check process is easier than the design process

Composite Beam Design Composite Beam Design Process

Check Process for an Existing Building Technical Note 2 - 5

for a new building because iteration is not required. Note that although thesequence of steps you follow may vary, the basic process probably will be es-sentially the same.

Tip:You can define your own shear stud patterns on the Shear Studs tab in the compositebeam overwrites. This allows you to model existing structures with composite floor fram-ing.

1. Use the Options menu > Preferences > Composite Beam Designcommand to choose the composite beam design code and to review othercomposite beam design preferences and revise them if necessary. Notethat default values are provided for all composite beam design prefer-ences so it is unnecessary to define preferences unless you want tochange some of the default preference values. See AISC-ASD89 Compos-ite Beam Design Technical Note 17 Preferences and AISC-LRFD93 Com-posite Beam Design Technical Note 30 Preferences for more informationabout preferences.

2. Create the building model, as explained in Volumes 1 and 2.

3. Run the building analysis using the Analyze menu > Run Analysiscommand.

4. Assign composite beam overwrites, including the user-defined shear studpatterns, using the Design menu > Composite Beam Design >View/Revise Overwrites command. Note that you must select beamsfirst before using this command. See AISC-ASD89 Composite Beam De-sign Technical Note 18 Overwrites and See AISC-LRFD93 Composite BeamDesign Technical Note 31 Overwrites.

5. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to run the composite beam design.

6. Review the composite beam design results by doing do one of the follow-ing:

a. Click the Design menu > Composite Beam Design > Display De-sign Info command to display design input and output information onthe model. See Composite Beam Design Technical Note 4 Data PlottedDirectly on the Model.


Technical Note 2 - 6 Check Process for an Existing Building

b. Right click on a beam while the design results are displayed on it toenter the interactive design and review mode and review the beam de-sign. Note that while you are in this mode you can also view diagrams(load, moment, shear and deflection) and view design details on thescreen. See Composite Beam Design Technical Note 3 InteractiveComposite Beam Design for more information.

If design results are not currently displayed (and the design has beenrun), click the Design menu > Composite Beam Design > Inter-active Composite Beam Design command and then right click abeam to enter the interactive design mode for that beam.

c. Use the File menu > Print Tables > Composite Beam Designcommand to print composite beam design data. If you select beamsbefore using this command, data is printed only for the selectedbeams.

d. Use the Design menu > Composite Beam Design > Verify allMembers Passed command to verify that no members are over-stressed or otherwise unacceptable. See AISC-ASD89 Composite BeamDesign Technical Note 27 Input Data, AISC-LRFD93 Composite BeamDesign Technical Note 41 Input Data, AISC-ASD89 Composite BeamDesign Technical Note 28 Output Details, and AISC-LRFD93 CompositeBeam Design Technical Note 42 Output Details for more information.

Member Identification Technical Note 3 - 1


Technical Note 3Interactive Composite Beam Design

Interactive composite beam design is a powerful feature that allows the userto review the design results for any composite beam and interactively revisethe design assumptions and immediately review the revised results.

Note that a design must have been run for the interactive design mode to beavailable.

To enter the interactive design mode and interactively design the beam, rightclick on a beam while the design results are displayed in the active window. Ifdesign results are not displayed (and the design has been run), click the De-sign menu > Composite Beam Design > Interactive Composite BeamDesign command and then right click a beam.

The following sections describe the features that are included in the Interac-tive Composite Beam Design and Review form.

Member IdentificationStory IDThis is the story level ID associated with the composite beam.

Beam LabelThis is the label associated with the composite beam.

Design GroupThis list box displays the name of the design group that the beam is assignedto if that design group was considered in the design of the beam. If the beamis part of a design group but the design group was not considered in the de-sign, N/A is displayed. If the beam is not assigned to any design group,"NONE" is displayed.

If a beam is redesigned as a result of a change made in the Interactive Com-posite Beam Design and Review form, the design group is ignored and onlythe single beam is considered. Thus, as soon as you design a beam in the

Interactive Composite Beam Design Composite Beam Design

Technical Note 3 - 2 Section Information

Interactive Composite Beam Design and Review form, the Design Group boxeither displays N/A or None.

You cannot directly edit the contents of this list box.

Section InformationAuto Select ListThis drop-down box displays the name of the auto select section list assignedto the beam. If no auto select list has been assigned to the beam, NONE isdisplayed. You can change this item to another auto select list or to NONEwhile in the form and the design results will be updated immediately. If youchange this item to NONE, the design is performed for the Current De-sign/Next Analysis section property.

OptimalIf an auto select section list is assigned to the beam, this list box displays theoptimal section as determined by beam weight or price, depending on whathas been specified in the composite beam preferences. If no auto select list isassigned to the beam, N/A is displayed for this item.


Last AnalysisThis list box displays the name of the section that was used for this beam inthe last analysis. Thus, the beam forces are based on a beam of this sectionproperty. For the final design iteration, the Current Design/Next Analysis sec-tion property and the Last Analysis section property should be the same.


Current Design/Next AnalysisThis list box displays the name of the current design section property. If thebeam is assigned an auto select list, the section displayed in this form initiallydefaults to the optimal section.

Tip:The section property displayed for the Current Design/Next Analysis item is used by theprogram as the section property for the next analysis run.

Composite Beam Design Interactive Composite Beam Design

Acceptable Sections List Technical Note 3 - 3

If no auto select list has been assigned to the beam, the beam design is per-formed for the section property specified in this edit box.

It is important to note that subsequent analyses use the section propertyspecified in this list box for the next analysis section for the beam. Thus, theforces and moments obtained in the next analysis are based on this beamsize.

The Current Design/Next Analysis section property can be changed by clickingthe Sections button that is described later in this Technical Note.

Important note: Changes made to the Current Design/Next Analysis sectionproperty are permanently saved (until you revise them again) if you click theOK button to exit the Interactive Composite Beam Design and Review form. Ifyou exit the form by clicking the Cancel button, these changes are consid-ered temporary and are not permanently saved.

Acceptable Sections ListThe Acceptable Sections List includes the following information for each beamsection that is acceptable for all considered design load combinations.

Section name

Steel yield stress, Fy

Connector layout

Camber

Ratio

Tip:A single beam displayed in a red font in the Acceptable Sections List means that none ofthe sections considered were acceptable.

Typically, the ratio displayed is the largest ratio obtained considering thestress ratios for positive moment, negative moment and shear for both con-struction loads and final loads, as well as the stud ratio(s), deflection ratios,and if they are specified to be considered when determining if a beam sectionis acceptable, the vibration ratios.


Technical Note 3 - 4 ReDefine

If the beam is assigned an auto select list, many beam sections may be listedin the Acceptable Sections List. If necessary, use the scroll bar to scrollthrough the acceptable sections. The optimal section is initially highlighted inthe list.

If the beam is not assigned an auto select list, only one beam section will belisted in the Acceptable Sections List. It is the same section as specified in theCurrent Design/Next Analysis edit box.

At least one beam will always be shown in the Acceptable Sections List, evenif none of the beams considered are acceptable. When no beams are accept-able, the program displays the section with the smallest maximum ratio in ared font. Thus, a single beam displayed in a red font in the Acceptable Sec-tions List means that none of the sections considered were acceptable.

ReDefineSections ButtonUse the Sections button to change the Current Design/Next Analysis sectionproperty. This button can designate a new section property whether the sec-tion property is or is not displayed in the Acceptable Sections List.

When you click on the Sections button, the Select Sections form appears.Assign any frame section property to the beam by clicking on the desiredproperty and clicking OK. Note that if an auto select list is assigned to thebeam, using the Sections button sets the auto select list assignment toNONE.

Overwrites ButtonClick the overwrites button to access and make revisions to the compositebeam overwrites and then immediately see the new design results. Modifyingsome overwrites in this mode and exiting both the Composite Beam Over-writes form and the Interactive Composite Beam Design and Review form byclicking their respective OK buttons permanently saves changes made to theoverwrites.

Exiting the Composite Beam Overwrites form by clicking the OK button tem-porarily saves changes. Subsequently exiting the Interactive Composite BeamDesign and Review form by clicking the Cancel button cancels the changesmade. Permanent saving of the overwrites does not occur until the OK but-


Temporary Technical Note 3 - 5

tons in both the Composite Beam Overwrites form and the Interactive Com-posite Beam Design and Review form have been clicked.

TemporaryCombos ButtonClick this button to access and make temporary revisions to the design loadcombinations considered for the beam. This is useful for reviewing the resultsfor one particular load combination, for example. You can temporarily changethe considered design load combinations to be just the one you are interestedin and review the results.

The changes made to the considered design load combinations using thecombos button are temporary. They are not saved when you exit the Interac-tive Composite Beam Design and Review form, whether you click OK or Can-cel to exit it.

Show DetailsDiagrams ButtonClicking the Diagrams button displays a form with the following four types ofdiagrams for the beam.

Applied loads

Shear

Moment

Deflection

The diagrams are plotted for specific design load combinations specified in theform by the user.

Details ButtonClicking the Details button displays design details for the beam. The infor-mation displayed is similar to the short form output that can be printed usingthe File menu > Print Tables > Composite Beam Design command. TheTechnical Notes describe short form output.


Technical Note 3 - 6 Show Details

Note:Stud Details Information is available using the Details button, but is not included in theshort form output printed using File Menu > Print Tables> Composite Beam Design.

Stud details information is one item included in the interactive design detailsthat is not included in the short form output details (and thus not described inAISC-ASD89 Composite Beam Design Technical Note 28 Output Details orAISC-LRFD93 Composite Beam Design Technical Note 42 Output Details). Thisinformation is provided in a table with six columns on the Stud Details tab.The definitions of the column headings in this table are given in the followingbullet items.

Location: This is either Max Moment or Point Load. If it is Max Moment,the information on the associated row applies to the maximum momentlocation for the specified design load combination. If it is Point Load, theinformation on the associated row applies to the point load location for thespecified design load combination.

Distance: The distance of the Max Moment or Point Load location meas-ured from the center of the support at the left end (I-end) of the beam.

Combo: The final strength design load combination considered for the as-sociated row of the table.

L1 left: The dimension L1 left associated with the specified location. See"How the Program Distributes Shear Studs on a Beam" in CompositeBeam Design Technical Note 13 Distribution of Shear Studs on a Beam formore information.

Recall that L1 left is the distance from an output station to an adjacent pointof zero moment or physical end of the beam top flange, or physical end ofthe concrete slab, measured toward the left end (I-end) of the beam.

L1 right: The dimension L1 right associated with the specified location. See"How the Program Distributes Shear Studs on a Beam" in CompositeBeam Design Technical Note 13 Distribution of Shear Studs on a Beam formore information.

Recall that L1 right is the distance from an output station to an adjacentpoint of zero moment or physical end of the beam top flange, or physical


Show Details Technical Note 3 - 7

end of the concrete slab, measured toward the right end (J-end) of thebeam

Studs: The number of shear studs required between the specified locationand adjacent points of zero moment, the end of the concrete slab, or theend of the beam top flange.

The Stud Details table reports information at each maximum moment locationand each point load location (if any) for each final strength design load com-bination.

The Stud Detail information allows you to report your shear studs in compos-ite beam segments that are different from the default composite beam seg-ments used by the program. See "Composite Beam Segments" in CompositeBeam Design Technical Note 13 Distribution of Shear Studs on a Beam for adefinition of composite beam segments. It is very important that you un-derstand how the program defines composite beam segments, be-cause in the composite beam output, the program reports the re-quired number of shear studs in each composite beam segment. See"How the Program Distributes Shear Studs on a Beam" in Composite BeamDesign Technical Note 13 Distribution of Shear Studs on a Beam for discus-sion of how the program distributes shear studs along a beam.

Overview Technical Note 4 - 1


Technical Note 4Data Plotted Directly on the Model

This Technical Note describes the input and output data that can be plotteddirectly on the model.

OverviewUse the Design menu > Composite Beam Design > Display Design Infocommand to display on-screen output plotted directly on the model. If de-sired, the screen graphics can then be printed using the File menu > PrintGraphics command.

The on-screen display data is organized into four data groups, as follows.

Labels

Design Data

Stress Ratios

Deflection Ratios

Each of these data groups is described in more detail later in this TechnicalNote. It is important to note that items from different data groups cannot bedisplayed simultaneously.

Tip:The colors related to the beam ratios can be modified by clicking the Options menu >Colors > Output command.

When design information is displayed directly on the model, the frame ele-ments are displayed in a color that indicates the value of their controlling ra-tio. (Note that this controlling ratio may be a stress ratio or a deflection ra-tio.) The colors associated with various ranges of ratios are specified in theSteel Ratios area of the Assign Output Colors form, which is accessed usingthe Options menu > Colors > Output command.

Data Plotted Directly on the Model Composite Beam Design

Technical Note 4 - 2 Labels Displayed on the Model

Labels Displayed on the ModelBeam labels and associated beam design group labels can be displayed on themodel. A beam label is the label that is assigned to the line object that repre-sents the composite beam.

Tip:Long labels may not display or print properly (fully).If a beam has been assigned to a group that has been designated as a com-posite beam design group, the group name for the beam will be displayedwhen requested. If a beam is not part of a composite beam design group, nogroup name will be displayed for that beam. Note that you can assign beamdesign groups by clicking the Design menu > Composite Beam Design >Select Design Group command.

As shown in Figure 1, beam labels (B7, B8, etc.) are plotted above or to theleft of the beam, and beam design groups (Group01, Group07, etc.) are dis-played below or to the right of the beam.

Figure 1: Example of Beam and Design Group Labels

Floor Plan

B7

B8Group01

B9Group01

B24

Gro

up07B2

3G

roup

08

Composite Beam Design Data Plotted Directly on the Model

Design Data Technical Note 4 - 3

Tip:The design data and ratios output that is plotted directly on the model is also available intext form in the short and long form printed output, which are described in AISC-ASD89Composite Beam Design Technical Note 28 Output Details and AISC-LRFD93 Compos-ite Beam Design Technical Note 42 Output Details.

Design DataThe following design data can be displayed on the model:

Beam section (e.g., W18X35)

Beam yield stress, Fy

Shear stud layout

Beam camber

Beam end reactions

One or more of these items can be displayed at the same time. Figure 2shows an example where all five of these items are displayed. The beam sec-tion size (e.g., W18X35) is apparent and needs no further explanation.

The beam yield stress is displayed just after the beam section size.

The shear stud layout pattern is displayed in parenthesis just after the beamyield stress. The number of equally spaced shear studs is reported for eachcomposite beam segment. See Composite Beam Segments in CompositeBeam Design Technical Note 13 Distribution of Shear Studs on a CompositeBeam for more information on composite beam segments.

Important note: It is very important that you fully understand the conceptof composite beam segments. This is necessary to properly interpret the out-put results for shear studs.

The beam camber is displayed below or to the right of the beam. All otherdata is displayed above or to the left of the beam.

The end reactions are displayed at each end of the beam. They are displayedbelow or to the right of the beam. The end reactions displayed are the maxi-mum end reactions obtained from all design load combinations. Note that the


Technical Note 4 - 4 Stress Ratios

left end reaction and the right end reaction displayed may be from two differ-ent design load combinations.

Note that cover plate information is not displayed on the model. This infor-mation is available in the printed output (short form or long form; see AISC-ASD89 Composite Beam Design Technical Note 28 Output Details and AISC-LRFD93Composite Beam Design Technical Note 42 Output Details) and in the overwrites.

Tip:The length of the composite beam segments associated with the shear stud layout isdocumented in the short and long form printed output, which are described in AISC-ASD89 Composite Beam Design Technical Note 28 Output Details and AISC-LRFD93Composite Beam Design Technical Note 42 Output Details.

Stress RatiosThe following design data can be displayed on the model:

Construction load bending and shear ratios

Final load bending and shear ratios

Floor Plan

W16X26 Fy=36.00 (14)

W18X35 Fy=36 (22)

W24

X55

Fy=5

0 (1

6,16

)C

=0.7

5

W24

X55

Fy=5

0 (1

6,16

)C=

1.00

W18X35 Fy=36 (48)C=1.25

16.2 16.2

20.7 20.7

25.2 25.2

23.7

23.7

18.4

18.4 Right reaction

Shear stud layout inparenthesis

Camber

Beam section

Left reaction

Yield stress

Figure 2: Example of Design Data that Can be Displayed on the Model

Composite Beam Design Data Plotted Directly on the Model

Deflection Ratios

You can display the construction load ratios, the final load ratios, or both.Bending ratios are always displayed above or to the left of the beam. Shearratios are always displayed below or to the right of the beam.

When both construction and final stress ratios are displayed, the constructionload ratios are displayed first, followed by the final load ratios. See Figure 3for an example.

Deflection RatiosWhen the Deflection Ratios option is chosen, the program plots one or both ofthe following two ratios.

The maximum live load deflection ratio (live load deflection divided by al-lowable live load deflection) for deflection loads.

The maximum total load deflection ratio (total load deflection divided byallowable total load deflection) for deflection loads.

When both ratio are plotted, the live load deflection ratio is plotted first, fol-lowed by the tot l load deflection ratio, as shown in Figure 4.

Floor Plan

0.678, 0.9610.121, 0.245

0.882, 0.9780.134, 0.222

0.765, 0.9940.179, 0.311

0.46

7, 0

.968

0.13

5, 0

.224

0.56

1, 0

.983

0.21

3, 0

.293 Construction

load bendingratio

Final loadbending ratio

Constructionload shearratio

Final loadshear ratio

0.678, 0.9610.121, 0.245

Legend

Figure 3: Example of Stress Ratios That Are Displayed on the ModelsaTechnical Note 4 - 5


Technical Note 4 - 6 Deflection Ratios

Floor Plan

0.521, 0.426

0.612, 0.433

0.445, 0.409

0.41

9, 0

.326

0.39

2, 0

.372

Live loaddeflection ratio

Total loaddeflection ratio

0.521, 0.426

Legend

Figure 4: Example of Deflection Ratios That AreDisplayed on the Model

General Technical Note 5 - 1


Technical Note 5Input Data

GeneralThis Technical Note describes the composite beam input data that can beprinted to a printer or to a text file when you click the File menu > PrintTables > Composite Beam Design command. You can print any combina-tion of five data categories.

Using the Print Composite Beam Design Tables FormTo print composite beam design input data directly to a printer, use the Filemenu > Print Tables > Composite Beam Design command and click thecheck box on the Print Composite Beam Design Tables form next to the de-sired type(s) of input data. Click the OK button to send the print to yourprinter. Click the Cancel button rather than the OK button to cancel theprint.

Use the File menu > Print Setup command and the Setup>> button tochange printers, if necessary.

To print composite beam design input data to a file, use the File menu >Print Tables > Composite Beam Design command and click the Print toFile check box on the Print Composite Beam Design Tables form. Click theFilename>> button to change the path or filename. Use the appropriate fileextension for the desired format (e.g., .txt, .xls, .doc). Click the OK buttonson the Open File for Printing Tables form and the Print Composite Beam De-sign Tables form to complete the request.

Note:The File menu > Display Input/Output Text Files command is useful for displaying out-put that is printed to a text file.

The Append check box allows you to add data to an existing file. The path andfilename of the current file is displayed in the box near the bottom of the Print

Input Data Composite Beam Design

Technical Note 5 - 2 Material Properties Input Data

Composite Beam Design Tables form. Data will be added to this file. Or usethe Filename>> button to locate another file, and when the Open File forPrinting Tables caution box appears, click Yes to replace the existing file.

If you select a specific composite beam(s) before using the File menu >Print Tables > Composite Beam Design command, the Selection Onlycheck box will be checked. The print will be for the selected beam(s) only. Ifyou uncheck the Selection Only check box, the print will be for all compositebeams.

Material Properties Input DataThe Material Properties input data item prints the concrete and steel materialproperties assigned to all frame sections that are the current design sectionfor a selected composite beam. If no objects are selected, it prints the con-crete and steel material properties assigned to all frame sections that are thecurrent design section for any composite beam.

The material properties printed in this output are those that are used in thecomposite beam design. For example, mass per unit volume is not used in thecomposite beam design so it is not printed in these tables. Table 1 lists thecolumn headings in the material property tables and provides a brief descrip-tion of what is in the columns.

Table 1 Material Properties Input DataCOLUMN HEADING DESCRIPTIONConcrete Material PropertiesMaterial Label Label (name) of the concrete material property.Modulus of Elasticity Modulus of elasticity, Ec, of the concrete material. Note that this

is the modulus of elasticity used for deflection calculations, butnot necessarily for stress calculations. See "Effective SlabWidth and Transformed Section Properties" in Compos-ite Beam Design Technical Note 8 Effective Width of theConcrete Slab for more information.

Unit Weight Weight per unit volume of the concrete.Concrete f'c Compressive strength of the concrete.

Composite Beam Design Input Data

Section Properties Input Data Technical Note 5 - 3

Table 1 Material Properties Input DataCOLUMN HEADING DESCRIPTIONSteel Material PropertiesMaterial Label Label (name) of the steel material property.Modulus of Elasticity Modulus of elasticity, Es, of the steel material.Unit Weight Weight per unit volume of the steel.Steel Fy Yield stress of the steel.Steel Fu Minimum tensile strength of the steel.Steel Price Price per unit weight (e.g., $/pound) of the steel.

Section Properties Input DataThe section properties input data is provided in two tables, labeled FrameSection Property Data (Table 1) and Frame Section Property Data (Table 2).This data is provided in two tables because it would not all fit onto one line ina single table. Table 2 herein lists the column headings in the section propertytables and provides a brief description of what is in the columns.

Table 2 Section Properties Input DataCOLUMN HEADING DESCRIPTIONFrame Section Property Data (Table 1)Section Label Label (name) of the steel frame section.Material Label Label (name) of the steel material property that is assigned to

the steel frame section.bf Top Width of beam top flange.tf Top Thickness of beam top flange.d Depth Depth of beam measured from the top of the beam top flange to

the bottom of the beam bottom flange.tw Web Thick Thickness of beam web.bf Bottom Width of beam bottom flange.tf Bottom Thickness of beam bottom flange.


Technical Note 5 - 4 Deck Properties Input Data

Table 2 Section Properties Input DataCOLUMN HEADING DESCRIPTIONFrame Section Property Data (Table 2)Section Label Label (name) of the steel frame section.Material Label Label (name) of the steel material property that is assigned to

the steel frame section.k In a rolled beam section, the distance from the outside face of

the flange to the web toe of the fillet.I33 Major Moment of inertia about the local 3-axis of the beam section.S33 Major Section modulus about the local 3-axis of the beam section. If

the section moduli for the top and bottom of the beam are dif-ferent, the minimum value is printed.

Z33 Major Plastic modulus about the local 3-axis of the beam section. Ifthe plastic moduli for the top and bottom of the beam are differ-ent, the minimum value is printed.

Deck Properties Input DataThe deck properties input data is provided in three tables, labeled Deck Sec-tion Property Data (Geometry), Deck Section Property Data (Material Proper-ties), and Deck Section Property Data (Shear Studs). Table 3 lists the columnheadings in the deck property tables and provides a brief description of whatis in the columns.

Table 3 Deck Properties Input DataCOLUMN HEADING DESCRIPTION

Deck Section Property Data (Geometry)Section Label Label (name) of the deck section.Solid Slab This item is Yes if the deck section represents a solid slab with

no metal deck. Otherwise it is No.Slab Cover The depth of the concrete slab above the metal deck, tc. If the

deck section represents a solid slab with no metal deck, this isthe thickness of the solid slab.

Deck Depth The height of the metal deck ribs, hr. This item is specified asN/A if the deck section represents a solid slab.


Deck Properties Input Data Technical Note 5 - 5

Table 3 Deck Properties Input DataCOLUMN HEADING DESCRIPTIONRib Width The average width of the metal deck ribs, wr. This item is speci-

fied as N/A if the deck section represents a solid slab.Rib Spacing The center-to-center spacing of the metal deck ribs, Sr. This

item is specified as N/A if the deck section represents a solidslab.

Deck Section Property Data (Material Properties)Section Label Label (name) of the deck section.Deck Type This item is either Filled, Unfilled or Solid. Filled means that the

deck section is a metal deck filled with concrete. Unfilled meansit is a bare metal deck. Solid means it is a solid slab with nometal deck.

Slab Material This is the concrete material property associated with the con-crete slab defined by the deck section. If the Deck type is Un-filled, this item is specified as N/A.

Deck Material This is the steel material property associated with the metaldeck. This item is only specified when the Deck Type is Un-filled. If the Deck type is not Unfilled, this item is specified asN/A.

Deck Shear Thickness This is the shear thickness of the metal deck. This item is onlyspecified when the Deck Type is Unfilled. It is used for calcu-lating the shear (in-plane, membrane) stiffness of the deck. Ifthe Deck type is not Unfilled, this item is specified as N/A.

Deck Unit Weight This is the weight per unit area of the metal deck, wd. See"Metal Deck and Slab Properties" in Composite BeamDesign Technical Note 7 Composite Beam Properties formore information.

Deck Section Property Data (Shear Studs)Section Label Label (name) of the deck section.Stud Diameter Diameter of the shear studs associated with the deck section,

ds.Stud Height Height after welding of the shear studs associated with the deck

section, Hs.

Stud Fu Minimum specified tensile strength of the shear studs associ-ated with the deck section, Fu.


Technical Note 5 - 6 Design Preferences Input Data

Design Preferences Input DataThe output for the composite beam design preferences is provided in a seriesof tables. The tables correspond to the tabs in the Preferences form. You canclick the Options menu > Preferences > Composite Beam Design com-mand to access the composite beam preferences.

Note:The composite beam preferences are described in AISC-ASD89 Composite Beam De-sign Technical Note 17 Preferences and AISC-LRFD93 Composite Beam Design Tech-nical Note 30 Preferences.

Recall that the composite beam preferences apply to all beams designed us-ing the Composite Beam Design postprocessor. A few of the preference itemscan be overwritten on a beam-by-beam basis in the composite beam over-writes. Those preferences items that can be overwritten are mentioned in thisdocumentation. You can select one or more beams and then click the Designmenu > Composite Beam Design > View/Revise Overwrites commandto access the composite beam overwrites.

The preference input data is provided in tabular format. Table lists the columnheadings in the preference table and provides a brief description of what is inthe columns.

Table 4 Preferences Input DataCOLUMN HEADING DESCRIPTIONFactorsThe input data related to factors is described in AISC-ASD89 Composite Beam DesignTechnical Note 17 Preferences and AISC-LRFD93 Composite Beam Design TechnicalNote 30 Preferences.

Beam PropertiesShored Floor This item is Yes if the composite beam preferences designate

that the composite beams are to be shored. Otherwise, it is No.Note that this item can be modified on a beam-by-beam basisin the composite beam overwrites.


Design Preferences Input Data Technical Note 5 - 7

Table 4 Preferences Input DataCOLUMN HEADING DESCRIPTIONMiddle Range Length in the middle of the beam over which the program

checks the effective width on each side of the beam, expressedas a percentage of the total beam length. See "Location WhereEffective Slab Width is Checked" in Composite Beam DesignTechnical Note 8 Effective Width of the Concrete Slab for moreinformation.

Pattern LL Factor Factor applied to live load for special pattern live load check forcantilever back spans and continuous spans. See "Special LiveLoad Patterning for Cantilever Back Spans" and "Special LiveLoad Patterning for Continuous Spans" in Composite BeamDesign Technical Note 10 Design Load Combinations for moreinformation.

Deflection and CamberNote:Deflection and camber are described in Composite Beam Design TechnicalNote 11 Beam Deflection and Camber.

Live Load Limit Live load deflection limitation. The term L represents the lengthof the beam. Note that this item can be modified on a beam-by-beam basis in the composite beam overwrites.

Total Load Limit Total load deflection limitation. The term L represents the lengthof the beam. Note that this item can be modified on a beam-by-beam basis in the composite beam overwrites.

Camber DL Percent Percentage of dead load (not including superimposed deadload) on which the program camber calculations are based.See "Camber" in Composite Beam Design Technical Note 11Beam Deflection and Camber for more information.

VibrationNote:Vibration is described in Composite Beam Design Technical Note 12 BeamVibration.

Percent Live Load Percentage of live load plus reduced live load considered (inaddition to full dead load) when computing weight supported bythe beam for use in calculating the first natural frequency of thebeam.


Technical Note 5 - 8 Beam Overwrites Input Data

Table 4 Preferences Input DataCOLUMN HEADING DESCRIPTIONConsider Frequency If this item is Yes, the specified minimum acceptable frequency

is considered when selecting the optimum beam section froman auto select section list. If this item is No, frequency is notconsidered when selecting the optimum beam section.

Minimum Frequency The minimum acceptable first natural frequency for a floorbeam. This item is used when the Consider Frequency item isset to Yes.

Murray Damping If this item is Yes, the Murray's minimum damping requirementis considered when selecting the optimum beam section froman auto select section list. If this item is No, Murray's minimumdamping requirement is not considered when selecting the op-timum beam section. See "Murray's Minimum DampingRequirement" in Composite Beam Design Technical Note 12Beam Vibration for more information.

Inherent Damping Percentage critical damping that is inherent in the floor system.This item is used when the Murray Damping item is set to Yes.

PriceConsider Price If this item is Yes, the section price rather than steel weight is

considered when selecting the optimum beam section from anauto select section list. If this item is No, section price is notconsidered when selecting the optimum beam section. Thesection price is based on specified prices for steel, shear studs,and camber.

Stud Price Installed price for a single shear stud.Camber Price Camber price per unit weight of steel beam (including cover

plate, if it exists).

Beam Overwrites Input DataBeam Overwrites Input Data is described in AISC-ASD89 Composite BeamDesign Technical Note 18 Overwrites and AISC-LRFD93 Composite Beam De-sign Technical Note 31 Overwrites.

Overview Technical Note 6 - 1


Technical Note 6Output Details

OverviewThis Technical Note describes the composite beam output summary that canbe printed to a printer or to a text file. Additionally, both short form and longform of the output details can be printed. See AISC-ASD89 Composite BeamDesign Technical Note 28 Output Details and AISC-LRFD93 Composite BeamDesign Technical Note 42 Output Details for more information about theshort- and long-form outputs.

Using the Print Composite Beam Design Tables FormTo print composite beam design output data directly to a printer, use the Filemenu > Print Tables > Composite Beam Design command and click theSummary check box on the Print Composite Beam Design Tables form. Alsoselect the form, or detail, of the print by selecting None, Short Form, or LongForm. Click the OK button to send the print to your printer. Click the Cancelbutton rather than the OK button to cancel the print. Use the File menu >Print Setup command and the Setup>> button to change printers, if neces-sary.

Note:A design must be run before output data can be generated.

To print summary output data to a file, use the File menu > Print Tables >Composite Beam Design command and click the Print to File check box onthe Print Composite Beam Design Tables form. Click the Filename>> buttonto change the path or filename. Use the appropriate file extension for the de-sired format (e.g., .txt, .xls, .doc). Click the OK buttons on the Open File forPrinting Tables form and the Print Composite Beam Design Tables form tocomplete the request.

Output Details Composite Beam Design

Technical Note 6 - 2 Summary of Composite Beam Output

Note:The File menu > Display Input/Output Text Files command is useful for displaying out-put that is printed to a text file.

The Append check box allows you to add data to an existing file. The path andfilename of the current file is displayed in the box near the bottom of the PrintComposite Beam Design Tables form. Data will be added to this file. Or usethe Filename button to locate another file, and when the Open File for Print-ing Tables caution box appears, click Yes to replace the existing file.

If you select a specific composite beam(s) before using the File menu >Print Tables > Composite Beam Design command, the Selection Onlycheck box will be checked. The print will be for the selected beam(s) only. Ifyou uncheck the Selection Only check box, the print will be for all compositebeams.

Summary of Composite Beam OutputThe summary of composite beam output prints a concise summary of thecomposite beam results in a tabular form. One row of the output table is de-voted to each composite beam.

If you have selected some composite beams before printing the summarydata, only summary data for the selected beams is printed. If you have notselected any composite beams before printing the summary data, summarydata for all composite beams is printed.

Table 1 lists the column headings in the Summary of Composite Beam Outputtable and provides a brief description of what is in the columns.

Table 1 Composite Beam Output TableCOLUMN HEADING DESCRIPTIONStory Level Story level associated with the beam.Beam Label Label associated with the line object that represents the beam.

A typical beam label example is "B23." Do not confuse this withthe Section Label, which may be identified as "W18X35."

Section Name The current design section for the beam.Beam Fy Yield stress of the beam, Fy.

Composite Beam Design Output Details

Summary of Composite Beam Output Technical Note 6 - 3

Table 1 Composite Beam Output TableCOLUMN HEADING DESCRIPTIONStud Diameter Diameter of shear studs, ds.Stud Layout Number of studs in each composite beam segment separated

by commas. They are listed starting with the composite beamsegment at the I-end of the beam and working toward the J-endof the beam.

Beam Shored This item is Yes if the beam is shored and No if it is unshored.Beam Camber The camber for the beam. This item may be calculated by the

program, or it may be user-specified.

Beam Properties Technical Note 7 - 1


Technical Note 7Composite Beam Properties

This Technical Note provides an overview of composite beam properties.Items described include beam properties, metal deck and concrete slab prop-erties, shear connector properties, user-defined shear connector patterns,cover plate properties, effective slab width and beam unbraced length.

The many properties associated with composite beams are defined using vari-ous menus in the program. The steel beam itself is defined using the Definemenu > Frame Sections command. The cover plate, if it exists, is defined inthe composite beam overwrites for the beam. The metal deck, concrete slaband shear connectors are defined together as part of the Deck section prop-erties using the Define menu > Wall/Slab/Deck Sections command.Other items related to the beam properties are specified in the compositebeam preferences or overwrites.

Beam PropertiesFigure 1 shows a typical composite beam for reference. The beam shown is arolled beam section from the built-in section database.

Tip:The Composite Beam Design postprocessor only designs beams that are I-shaped sec-tions and channel sections.

Basic steel beam properties are defined using the Define menu > FrameSections command. Use this command to define the basic geometry of thesteel section, except for the cover plate, if it exists. Define the cover plate onthe Beam tab in the composite beam overwrites. When defining a beam, amaterial property that includes the yield stress for that beam is also assigned.That yield stress is assumed to apply to the beam and the cover plate unlessit is revised in the beam overwrites. The steel Material Property also includesthe price or cost-per-unit-weight that is assigned to the beam.

Composite Beam Properties Composite Beam Design

Technical Note 7 - 2 Beam Properties

The beam section for a composite beam can be any I-shaped section, or achannel. The I-shaped section can be defined by selecting a W, M, S or HPshape from the built-in program steel section database, or by defining yourown I-shaped section using the Define menu > Frame Sections commandand selecting the Add I/Wide Flange option from the drop-down list on theDefine Frame Properties form. It is not necessary that the top and bottomflanges have the same dimensions in user-defined I-shaped sections used ascomposite beams. A channel section used as a composite beam can also be asection taken from the built-in program steel section database or user-defined, using the Define menu > Frame Sections command and selectingthe Add Channel option from the drop-down list on the Define Frame Proper-ties form.

Note:See the section entitled Cover Plates later in this Technical Note for more information.

Figure 1: Illustration of Composite Beam

bcp

h rt c

dt cp

Concrete slab

Metal deck

Shear stud

Steel beam

Cover plate

wr

Sr

Hs

Composite Beam Design Composite Beam Properties

Metal Deck and Slab Properties Technical Note 7 - 3

Beam sections defined using Section Designer are considered as general sec-tions, not I-shaped or channel-shaped sections (even if they really are I-shaped or channel-shaped), and cannot be designed using the CompositeBeam Design postprocessor.

If you define a beam section by selecting it from the built-in section database,the program assumes that it is a rolled section and applies the design equa-tions accordingly. If you create your own user-defined section, the programassumes it is a welded section and revises the design equations as necessary.The program does not check or design any of the welding for these weldedbeams.

Metal Deck and Slab PropertiesBasic metal deck and concrete slab properties are defined using the Definemenu > Wall/Slab/Deck Sections command. This command specifies thegeometry and the associated material properties of the metal deck, concreteslab and shear connectors.

Tip:A beam designed using the Composite Beam Design postprocessor can only have com-posite behavior if it supports a deck section (not a slab or wall section).Important note: You must specify the concrete slab over metal deck as adeck section property (not a slab section property) if you want the beam tohave composite behavior. If you specify the slab using a slab section propertyinstead of a deck section property, the Composite Beam Design postprocessordesigns the beams supporting that slab as noncomposite beams.

Using the Define menu > Wall\Slab\Deck Sections command, select adeck-type section and click the Modify/Show>> button to bring up the DeckSection form. This box allows you to specify that

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Etabs - Composite Floor Frame Design Manual