12 masterbeam composite design

8/7/2019 12 MasterBeam Composite Design

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7 MasterBeam Composite Design 7 - 1

12 MasterBeam: Composite Beam Design

12.1 Getting Stared with MasterBeam Composite Design

MasterBeam Composite Beam Design is an interactive program for the design of composite beams with or without web openings to BS 5950.MasterBeam Composite Design is a very powerful and an extremely user friendlyprogram with a short learning curve.

12.1.1 Design Features Analysis and design of simply supported composite beams Primary beams Secondary beams Combined primary-secondary beams

Option for non-composite analysis and design Propped or un-propped design Natural frequency checks Notched supports Web openings, with or without stiffeners Factored beam loads automatically calculated from floor loading Additional point and distributed loads The steel section can be a rolled I-section, a rolled channel or a built-up symmetrical

or asymmetrical I-section

12.1.2 Operational Features Easy to use, very fast with powerful editing facilities Analysis and design checks are carried out automatically and instantaneously as

beam input data is changed. Store multiple beam designs in one file. Global definition of particular parameters, which apply to all design briefs in a file. In-built library of standard British sections and open libraries for other sections In-built and open libraries of metal deck profiles and shear connectors A full summary of the design data is displayed with clear warnings of non-compliance Whilst viewing the results, AutoChange facilities are provided which enable the

Engineer to rapidly select the most appropriate steel section. AutoDesign function to automatically select the lightest or smallest adequate section. Automatic transfer of data from one beam to another for rapid analysis and design of

similar beams In-built on-screen training Clear and concise output Engineer friendly

MasterBeam - Composite design


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12.2 Primary Program Interface Regions

The screen above shows four main areas as follows: The bar menu and tool bar. The detailed output and graphics area with its scroll bar. The design summary with the paragraph and section design output navigator spin

buttons. The editing area comprising the five data input tabs: Floor Information, Beam Section,

Additional Loads, Web Openings and Open Library.

Please note that the information in the detailed output and the design summary areaschange dynamically as the beam data is altered in the editing area.

12.2.1 The MasterBeam Tool Bar

Create new file using the current defaults Open file Save current file

Delete the current brief Copy the current brief to clipboard Add new brief form clipboard Add new brief based on current defaults Enter global editing mode (changes all briefs) Graphics always on top


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Next/Previous brief spin button

Un-propped during construction stage Propped during construction stage

Secondary beam Primary beam with one transverse beam Primary beam with two transverse beam General (User defined) beam Mixed primary secondary beam Apply transverse beams (Primary beams ON/OFF)

Use continuous metal deck profile

Apply additional point loadsApply additional uniformly distributed load

Apply circular web openingsApply rectangular web opening

Export / print graphics ON/OFFProject title and Job referencesPrint current brief Print all briefsExport current brief to WordExport all briefs to Word

The tool bar provides quick and easy access to some of the primary MasterBeam filemanagement, editing and printing/exporting functions.

12.2.2 The Detailed Design Output and Graphics Area


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GraphicsThe on screen graphics of the current design brief changes dynamically with anymodifications to the information in the editing area. The overall graphics scale, as wellas the point loads and partial UDL scales may altered using the spin buttons asindicated above. By clicking the Graphics always on top button in the tool bar the

graphics will remain visible as you scroll through the design output.

Detailed Design OutputThe design output is presented in a detailed and concise format. The various deignchecks are clearly divided into headed sections. The results are generally displayedover four columns, in the format;Column 1 Description of calculation, item or numerical value.Column 2 Design data or calculation.Column 3 Calculation result or permissible values.Column 4 Design check verdict, OK or Warning.

The design output includes; Summary of design data details of beam geometry, steel section, metal deck

profile, concrete slab, reinforcement, shear connectors, and applied loading. Section Properties Ultimate limit state beam shear, shear connection, axial resistance and moment

capacity design checks at critical locations along the beam. Transverse reinforcement Serviceability limit state deflection, steel stress and concrete stress design checks. Vibration Analysis natural frequency check Openings summary of location and size. Composite / Non-composite moments,

Vierendeel moment, axial force design check. Upper and lower web-flangeclassifications, with axial and shear force capacity checks. Dimensional checks.

12.2.3 Design Summary Area

The design summary area permits immediate evaluation of the fundamental designchecks. The unity ratios are dynamically updated with any alteration of information inthe editing area.By clicking on any of the items in the design summary area, the corresponding detaileddesign output is displayed. The paragraph and section navigator spin buttons alsoprovide useful tools for scrolling the detailed design output.


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Any unity ratiosexceeding 1.0 representa design failure and arehighlighted in red. Thebackground colour of the

design output andgraphics area alsochanges to Cyan, makingany design failureimmediately apparent.

12.2.4 The Editing Area

The Editing Area is divided into 6 tabs: Floor Information, Beam Section, AdditionalLoads, Web Openings, Open Library and Defaults.

Analysis and design is carried out automatically and instantaneously as any influentialinput data is changed.


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12.3 Floor Information

or using the Simplified Menu (PowerPad and PowerPad Plus)

12.3.1 Floor Information Input Areas

Beam GeometryMain Beam span (primary or secondary)b & c. Distance from main beam to parallel left and right handbeams.

For an edge beam either b or c is set to zero.

Construction stage support

The metal deck profile support condition at construction stage may bespecified as propped or unpropped. In the unpropped condition anultimate limate state at construction stage design check for shear andmoment capacity is applied.

Floor Area Loading

The general floor area loading in kN/m 2 is defined in threecategories.The concrete slab and the steel beam self-weights are calculatedand added automatically.The program automatically adds 0.2 kN/m 2 for Deck/Mesh and

0.5 kN/m2

for Construction Loading. These values may bechanged in the defaults tab.


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Transverse Beams

Defines the position and section sizeof transverse beams in a primarybeam design. The transverse beamsapply a concentrated load to theprimary beam bases on their lengthand supported floor width as definedin the beam geometry.The Overwrite Area function enables the user to redefined the transverse beam lengthsand supported floor widths for each beam.This funtionality is not included where only the simplified menu is available, and thedefintion is limited to the application of 1 and 2 No. equedistant transerve beams.

Option Buttons

Apply design check at construction stage when propped.Displays the defaults tab and the customised program defaultsare usedPrints the combination of load groups and load factors in thedesign outputPrints steel and concrete stress details in the serviceability limitstate design check.Use the simplified input menu only.

12.3.2 Composite Beam Types

The design of composite beams is categorised into the following types;

1. Secondary Beam

Represents the beam spanning between two primary beams. The direction of the metaldeck profile spans between primary beams. Therefore the in beam graphics the metaldeck is shown in section through the hollow rib profile. The number of shear studs isspecified per trough.


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2. Primary Beam

The primary beams represent the main structural beams. Primary beams may supporttransverse beams. The program automatically calculates the floor area supported byeach beam. The Overwrite Floor Area option enables you to specify your own data for special cases.The beam size for the transverse beams is required to enable the correct value of their self-weight to be included.

3. Mixed Primary-Secondary Beam

The mixed primary secondary option is used for instances where the metal deckprofile spans in different direction on either side on the beam.

In the above screen, please note:The floor width supported directly by the beam is 1.5 m = the distance to the righthand beamThe transverse beam floor length supported is 4.5 m = the distance to the left handbeam


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12.4 Beam Section

The Beam Section tab defines steel section, metal deck, reinforcement, shear connection, and concrete slab properties.

The steel section type UB, UC, RSJ, UBP, IPE, HE, HL, HD,HPX, IPN, W, ., and Channels.The section size. The section size list can be sorted byserial size or weight order using the Sort check box.The section grade. You can select and add new rolledsection types, section sizes and grades in the main openlibrary for steel sections.

3.16 The Steel Sections and Open LibraryThe metal deck profile condition: Continuous or Non-Continuous.The metal deck profile type including solid slab. You canadd other metal deck profiles in the Open Library tab.The metal deck profile thickness.The overall concrete slab depth (zero for steel beam only).The concrete grade (zero for non-composite).The area of steel mesh provided perpendicular to the span

of the beam.The percentage deck contribution you wish to consider (100% for full contribution, 0% for no-contribution).The wet density of the concrete 1850 for light weight, 2350for normal weight.The modular ratio. 15 for light weight, 10 for normal weightand 0 to allow the program to calculate a default valuebased on the concrete type (light or normal weight) and theratio of the long term and short term loads.The shear connectors type. You can add other shear connectors from the Open Library tab.

The shear connectors spacing. In secondary and mixedprimary-secondary beams this can be One per AlternateTrough, One per Trough, Two per Trough or Spaced @ thespecified centres singly or in pair. In primary beam, thespacing, singly or in pair, can be specified for each regionbetween supports and transverse beamsSpacing values are used in primary beams where the metaldeck profile troughs run parallel with the beam. Spacing_01


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refers to the portion between the left-hand support and the1 st transverse beam, Spacing_02 refers to the portionbetween the 1 st and the 2 nd transverse beams and so on.The last spacing you need to define is between the lasttransverse beam and right hand support. If a spacing is left

to a value of zero, then it defaults to the previous valueLeft and right hand width of concrete flange in compositesection b1 and b2.The current brief beam reference title.

Add new brief (composite beam design) to data file basedon current brief. Delete current brief. The sort spin buttonmoves the position of the current brief in the brief list.AutoDesign button as described below.

Increase the number of shear connectors by one.

The Ignore Deck Contribution in Primary Beams is providedbecause BS 5950 is unclear about the contribution.MasterBeam will ignore the contribution if the profile isdiscontinuous, otherwise the contribution will be assumed tobe the same as for a discontinuous profile with ribs runningperpendicular to the span of the beam.

Using the Auto design

The auto design function will attempt to rectify failures related to the beam section andtransverse shear. The failures are prioritised in the following order.

If any failure (with the exception of transverse shear) is detected, the auto designscans through the selected beam section list to find a section which satisfies thefailing design criteria.

If a transverse shear failure is detected the auto design scans the list of standardsteel mesh sizes to find a mesh which satisfies the failing criteria.


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12.5 Open Library

The open library area is used to add new definitions of metal deck profiles and shear connectors.

Metal Deck Profiles

Please note that the profile name is limited to 23 characters.Shear Connectors

The shear connector name is limited to 28 characters.

To enter an item in the open libraryEnter the data for the itemBe sure to use a new reference number for the item unless you wish to overwrite anexisting itemClick on

Other editing functionsDelete the currently selected items from the library.Reset the Standard Library to original MasterBeam values (MetalDeck Profiles No 1 to 14 and Shear Connectors No 1 to 7 Only),Reset the complete library, i.e. delete all user defined metal deckprofiles and shear connectors.

Feel free to investigate the various options provided in the open library, but please becareful not to remove or change properties for items which have been added by other users in your company.If you wish to use the MasterBeam Composite Design on a number of machines thenremember to enter the same items in the open library on all the machines where theprogram is being used. Alternatively you can copy the open library fileC:\msprowd\combeam1.ovr.


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12.6 Additional Loads

MasterBeam provides the facility to apply:1. Additional point load positions (X) and values including Dead, Live and Super

Imposed Dead; and2. Additional partially distributed load positions (X1/X2 refer to start/end) and values

including Dead, Live and Super Imposed Dead.

! Note: Dead loads are applied at the construction stage before the composite action.

Live and Super Imposed Dead loads are applied after the composite action. The Copy load from spin buttons enable you to copy loads data from

previous or subsequent rows (loads are copied symmetrically on the beam).

Other editing functionsDelete the currently active load.Delete all point or partial loading.Mirror copy the loading information from either the line above or below tothe current line.

The applied point and partial uniformly distributed loading are displayed in the beamgraphics. The individual graphical scale of either load may be altered using the spinbuttons provided, as described in section 12.2.2 Design Output and Graphics area.


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12.7 Web Openings

The Web Openings area is where you can define:1. Circular Openings;2. Rectangular Openings; and3. Notches at supports (special case of rectangular opening).

The distance to the opening is always defined from the left-hand support tothe centre of the opening in meters.The Top Edge distance is measured from the top of the steel beam to the topedge of the openingThe Stiffener Area is the area of one of the two stiffeners provided, one at thetop and the other at the bottom of the opening. The two stiffeners arepositioned so that their centres are at the specified edge distance from theedge of the opening.The default Edge distance from the centre of a stiffener to the edge of theopening is 12 mmDiameter of the circular wed opening.

Depth of rectangular web opening

Width of rectangular web opening

The program uses default values for the opening diameter, depth, width and the topedge distance. The default values are based on the beam depth and aim at positioningeach opening at the centre of the beam. To check the exact values used, use theSection Navigator spin button to view the openings data in the detailed output area.

A notch at the support is a rectangular opening with a distance from the support equal toor less than its width.

Stiffener sizes and arrangements are suggested in the detailed design output based onthe area of stiffener provided and for a compact section. Further guidance for the


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detailing of stiffeners is given in [2]. Extracts from this technical note [2] concerning thedetailing are given in Appendix A.

Other editing functions

Delete the currently active web opening.Delete all circular or rectangular web openings.Mirror copy the web opening information from either the line above or belowto the current line.

Option ButtonsUse a refined analysis methodRecommended check for web openings, whereTo = axial force arising from non-composite actionN1 = number of shear connectors from support to start of openingPd = design strength of the shear connectors

Ignore web opening dimensional checks, as outlined in [1].Show error report on web openings.

Please note that some design check options; such as Ignore dimensional checks inweb openings, must be used at the discretion of the Engineer and should definitely notbe used blindly.

MasterBeam Composite Beam Design performs the dimensional checks on webopenings as outlined in [1]. Additional guidance is provided by [2] which is principallybased on [1] but also draws on other publication by AISC and ASCE. Extracts from [2]on this subject are given in Appendix B.

Civil and Structural Computer Services would like to acknowledge the co-operation andcontribution of the WSP Group in Appendices A and B. We believe the technicalcontent of Appendices A and B provide good best practice guidance, however should beused at the discretion of the design engineer.

[1] Lawson, R.M., Design for Openings in the Webs of Composite Beams . SteelConstruction Institute, SCI Publication 068, 19812.

[2] Stuart Alexander, WSP Group, Strengthening of Web Openings in Steel Beams.

Technical Reference Manual 118, Rev 1, 2001.


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12.8 Customisation of Default Settings

This area can be accessed using the button on Floor Information Tab.

The user may customise; Load factors for dead, super imposed and live load groups, according to each of the

listed design checks. Construction load and deck self weight. Minimum natural frequency value Option to include loading defined in the additional loading tab in the calculation of

natural frequency. Span/deflection ratios. The load group associated with service and partition floor area loads specified in the

floor information tab.

Saving customised settings

Save the current customised settings to a Master Beam Default(MBD) file, using different file names for different default values.Choose the desired previously saved MBD file, and click Opento active the files default settings.Instantaneously resets to the original MasterBeam programdefaults.


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12.9 Globally Defined Input Values

As described in section 12.4 Beam Section, the user may save a number of designbriefs, i.e. separate beam designs, in one data file. The multiple design briefs mayperhaps be associated with a common floor area, floor level or an entire project.

MasterBeam provides the facility to globally modify particular parameters for all beamdesign briefs stored in a single data file.

To enter the global editing mode click on the button. Input parameters that can beglobally edited are highlighted in Cyan for text boxes and Red for option labels.

Upon modifying a global parameter the program then applies that change to all designbriefs in the data file. Once complete the global editing mode is deactivated. Analysisand design is automatically updated. The global editing button must be selected for each individual modification of a global parameter.

To exit the global editing without making any changes simply click again on thebutton to deactivate the mode.


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12.10 Printing and Exporting Results

Export / print graphics ON/OFFEdit Project title and Job referencesPrint current brief

Print all briefsExport current brief to WordExport all briefs to Word

Sample of Design output exported to PowerPad


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12.11 Appendix A Detailing The Stiffeners in Web Openings

Appendix A is an extract from the following reference.

Stuart Alexander, WSP Group, Strengthening of Web Openings in Steel Beams .Technical Reference Manual 118, Rev 1, 2001.

Civil and Structural Computer Services would like to acknowledge the co-operation andcontribution of the WSP Group. We believe the technical content of Appendix Aprovides good best practice guidance, however should be used at the discretion of thedesign engineer.

Strengthening is generally only needed for rectangular openings; it is usuallyprovided in the form of longitudinal stiffeners placed immediately above and belowthe opening on one or both sides of the web, see figure 1. Vertical stiffeners are notnormally required in rolled sections.

Figure 1. Web opening with stiffeners showing elements and dimensions

Stiffener section

The stiffeners must be sized to be compact, ie the ratio b/T s T 8.5 for grade 275 and 7.5for grade 355 steel.

Welding

Stiffeners must be welded continuously throughout their length. The capacity of the

weld from the mid-point to each end of the opening must be at least the yield strength of the stiffener section. Similarly, the capacity of the weld anchoring the extension beyondthe opening at each end must also be at least the yield strength of the stiffener section.

American publications recommend welding one side only for the length of theopening (ie the side away from the opening) and welding both sides of the extension.This gives convenient geometry in which the extension length is one quarter of thelength of the opening. This detail also locates the stiffeners as close to the openingas possible.


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However, it is likely that the joint will widen slightly. If this creates a corrosion risk,welds both sides may be preferable. Remember to leave enough height between thestiffener and the opening to get the weld in, say at least the weld size plus 4 mm.

Web strengthIn order to ensure that the stiffeners are anchored without overstressing the web, thelength of the extensions ls must satisfy ls U V3 Ar / 2 t.

Shear lag

This describes the phenomenon in which at the free end of the stiffener the stress closeto the web is very much higher than the stress at the outer edge. Clearly, the longer theextension the more the stress will be able to equalise at the critical section. Noguidance on this aspect is provided in any of the quoted publications. However, thetests reported by Lawson et al were carried out with stiffeners 80 x 10 mm extending150 mm beyond the opening, ie with a ratio ls/b = 1.9. Until further evidence isforthcoming, it is recommended that this limiting ratio is adopted.

Stiffeners on one or both sides?

The guidance is generally based on stiffeners being located in pairs symmetrically eachside of the web. However, the tests reported by Lawson et al were carried out withstiffeners on one side only with no adverse effects observed. The ratio of stiffener widthto beam half-flange width in the tests was

(b + 0.5 t) / 0.5 B = (80 + 4.8) / 104 = 0.81.

It is recommended that paired stiffeners are used if a single stiffener would exceed thisratio.

If the stiffeners are predominantly restoring the overall moment capacity (as describedabove), they should be symmetrical about the web.

Equal stiffeners top and bottom?

It is theoretically OK to have different stiffeners top and bottom, or even to omit onealtogether if the hole is very high or low. Nevertheless, some computer programs canonly handle equal stiffeners.


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12.12 Appendix B Dimensional Checks in Web Openings

Appendix B is an extract from the following reference.

Stuart Alexander, WSP Group, Strengthening of Web Openings in Steel Beams .Technical Reference Manual 118, Rev 1, 2001.

Civil and Structural Computer Services would like to acknowledge the co-operation andcontribution of the WSP Group. We believe the technical content of Appendix Bprovides good best practice guidance, however should be used at the discretion of thedesign engineer.

For rectangular openings, there are a number of geometric criteria which should bemet, as follows:

Unstiffened openings should generally have h o T 0.6 D and l o T 1.5 D (SCI 068).

Stiffened openings should generally have h o T 0.7 D and l o T 2.0 D (SCI 068; AISCand ASCE require h o T 0.7 D only).

Openings should have corner radii r not less than 2 t nor 16 mm (AISC and ASCE).

The depths of the upper and lower sections of web s b, s t, should not differ by morethan a factor of two (SCI 068; AISC and ASCE limits are s t U 0.15 D, s b U 0.15 D for non-composite beams or 0.12 D for composite beams).

The ratio v = l o / s t or l o / s b should not exceed 12 (AISC, ASCE).

No opening should be closer to a support than 2.0 D or 0.1 L, where L is the span(SCI 068, a notch can be used instead; AISC and ASCE limit is D).

Openings should not be less than 1.0 D apart (SCI 068, American practice is moreconservative). If openings are closer together, the combined vierendeel action mayoverload the post between them, see below; this work shows that the lower limit of 1.0 D applies only to openings not requiring stiffeners, and calculations should becarried out for other cases.

Point loads should not be applied at less than D from an opening (SCI 068; AISC andASCE give criteria for reducing this to 0.5 D in some cases, otherwise bearingstiffeners are required. If the point loads arise from secondary beams, fin plateconnections can be detailed to create the required stiffeners).

12 masterbeam composite design

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