Fast auto design and check are available to find the most suitable steel bar profiles. All section shapes and classes - including class 4 profiles (slender sections) - can be checked for utilization. When modeling steel bars with 3D steel shell components, an auto design finds the proper thickness of the shell elements.

The table summarizes the available steel design features by FEM-Design module.

Design element typeDesign feature1585653000367-149.png1585653005373-969.png1585653010914-897.png
1585652787092-597.png  Steel BarAuto design1585653017267-997.png1585653021432-508.png1585653024373-352.png
 Manual design1585653019098-174.png1585653023020-114.png1585653025839-878.png
1585652994519-156.png  Shell ModelAuto design  1585653027225-956.png
 Manual design  1585653029231-967.png

Table: Steel design features by FEM-Design module

Steel Bar

Global Auto (steel bar) design (Calculate > Design calculations > Auto design all structural elements) finds the most suitable cross-section (from the profile range set at Auto design > Parameters) for all steel bars (columns, beams and truss members) based on their buckling length, stiffeners, calculation parameters, internal forces and detailed utilization calculations. With Manual design you can run quick utilization check for given profiles by bar elements and/or design groups. You can also do quick Auto design by elements and design groups only instead of global design. Of course, any number of design cycles is executable, so the global Auto design can be combined with both previous and additional element-based Auto designs.

No.Global steel bar designElement-based steel designCombined steel design
11585653335569-348.png  Calculation parameters1585653395657-131.png  Global Analysis1585653406580-206.png  Calculation parameters
21585653342083-533.png  Design group1585653404253-498.png  Calculation parameters1585653345774-816.png  Design group
31585653356186-514.png 1585653414535-767.png  Auto design > Parameters1585653343851-773.png  Design group1585653366182-867.png 1585653420228-806.png  Auto design > Parameters
41585653390033-860.png  Global Auto design1585653357667-370.png 1585653416268-549.png  Auto design > Parameters1585653393231-466.png  Global Auto design
51585653373155-845.png  Documentation1585653359638-555.png 1585653452601-397.png  Auto design by elements1585653361783-576.png 1585653418161-343.png  Auto design > Parameters
6 1585653462586-867.png  Manual design by elements1585653364720-610.png 1585653430288-923.png  Auto design by elements
7 1585653470339-646.png  Apply design changes1585653464271-136.png  Manual design by elements
8 1585653385299-391.png  Global Check1585653471928-565.png  Apply design changes
9 1585653375446-115.png  Documentation1585653387844-184.png  Global Check
10  1585653379131-325.png  Documentation

Table: Recommended steps by design alternatives

Initial Calculation and Design Parameters

All bar design calculations needs internal forces from Analysis calculations applied for Load combinations or Load-groups, 1585653527641-768.png  Buckling length and initial design settings defined by 1585653534035-284.png  Design calculation parameters.

1585653539785-232.png

Figure: Design calculation parameters

The flexural buckling curves (EN1993-1-1: 6.3.1.2) can be specified for each steel bar in Calculation parameters dialog or the user can let the program to calculate it as in the previous versions by selecting “Auto” option.

The method for considering imperfections of bars has to be selected, there are three types:

  • Ignore 2nd order analysis: The internal forces comes from the 1st order results.
  • Consider 2nd order analysis, if available: The internal forces comes from the 2nd order results.
  • 2nd order internal forces + 1st order design: The internal forces comes from the 2nd order results, but the design calculation will be linear.

1585653625140-439.png

Figure: Setting calculation parameters

warning.pngFor steel bars with varying section the “Auto” option cannot display the automatically calculated curve, since it is determined during the design calculation.
warning.pngWhen the section of a steel bar is modified, buckling curve options of the calculation parameter is reset to “Auto”
warning.pngWhen buckling curve is calculated automatically, applied section is considered, if it exist.

Convergence criteria and the maximum number of iteration steps can be set for effective cross-section calculation of Class 4 steel bar section in Calculation parameters dialog.

light.pngIn some cases the iteration for effective cross-section fails because of the too strong convergence criteria. In this case reducing its factor or increasing the number of the iteration steps may solve the problem.
light.pngLateral torsional buckling can be calculated using the formulas to general case instead of using the simplified method.When the general method is used for lateral torsional buckling calculation, the position of the load needs to be specified as well. Calculation method of the kij interaction factors can be specified by selecting the design configuration option from the ribbon.

For lateral torsional buckling the program can separate to top flange and bottom flange stability loss. In the following picture the top flange and it’s corresponding force is red and the bottom is blue.

1585653897756-170.png

1585653864181-921.png

1585653874937-809.png

Beta factors for all 4 direction-stability loss method are separate from each other.

1585653911563-415.png

To copy buckling lengths from one bar to another use the Copy buckling length command and:

  • Select the types to copy
  • Select the source bar
  • Select the destination bar

1585653925026-645.png

1585653936189-224.png

Stiffeners can be added manually to steel bars at any time during design (e.g. before Auto design, or between Auto design and final Check). Stiffeners can be defined element by element, but they can be copied among bar elements. Stiffener definition tools are:

  • 1585653964846-534.png  creates given number of evenly distributed stiffeners on a defined length section,
  • 1585653970730-422.png  creates stiffeners by given distance on a defined length section (in case the multiple of the distance does not fit in the section, the program distributes stiffeners with equal parts at the ends),
  • 1585653976146-643.png  defines stiffeners one by one in given position,
  • 1585653981351-820.png  copies stiffeners of a selected bar to other bars with the same length.

You can increase the number of stiffeners in more steps, if you inactivate 1585653994855-683.png  (Do not delete the original).

1585653999999-142.png

Figure: Stiffeners

Auto Design

1585654027068-138.png

Global Auto design gives utilization results and suitable profiles for all steel bars of the current project.

1585654045991-869.png

Figure: Global Auto design and utilization result

light.png

The recommended profile names can be displayed on screen by showing the “Steel bar, applied quantity” object layer, or click 1585654110042-729.png  Design tool of the Auto design and the parameters together with utilization results are available in table format. Utilization as colored figure (color palette) can be displayed by selecting New result > Steel bar > Utilization.

warning.pngVariable cross-section steel bars can’t be designed, just checked.

Applied profiles are displayed in blue in the Utilization table, if they are assigned to the steel bars during design, otherwise black color represents the original/initial profiles.

1585654149668-849.png

Element-based Auto design finds the most suitable profile of steel columns, beams and bars for selected unique or grouped members only from a range of available profiles defined by 1585654169799-983.png  Parameters. The design utilization can be limited between 10% and 100% with Limit utilization.

1585654175373-259.png

Figure: Range of available profiles for design

To run element-based design for the load combinations or the maximum of load groups, select the required members and/or group with the Auto design command and click 1585654188559-688.png  Design tool. The quick process results recommended profiles and their utilization. Check the Display table box to have a look at the overall design results (see the figure before).

The upper table shows the design efficiency and the maximal utilization of the designed single members and groups based on the given design parameters. The bottom table displays the utilization details of the bar or the members of the group selected in the upper table.

 MeaningNote
1585654219128-709.pngSuitable profile is available 
1585654225863-981.pngSuitable profile is not availableModify the range of available profiles or steel materials
image-20200331133035-1.pngSuitable profile is available, but the utilization is over the Limit utilization 
GroupID of a single bar or a group name 
Design parametersThe defined range of available profiles 
Applied profileProfile currently assigned to the bar 
MaxMax. utilization of a single bar or the significant member of a group 
MinMax. utilization of the less significant group member 
BarID of a single bar or a group member 
RCSResistance of cross-section: the maximum utilization from all strength calculations

According to Eurocode 3: 6.2.3 - 6.2.10

FBUtilization for flexural bucklingAccording to Eurocode 3: 6.3.1
TFBUtilization for torsional-flexural bucklingAccording to Eurocode 3: 6.3.1
LTBUtilization for lateral torsional bucklingAccording to Eurocode 3: 6.3.2.4
SBUtilization for shear bucklingAccording to Eurocode 3: 1-5: 5
IA

Interaction (between normal force and bending)

According to Eurocode 3: 6.3.3

Table: The meaning of symbols, design parameters and utilization results

Quick redesign can be done inside the Utilization table:

  1. Select a bar or a design group in the upper table.
  2. Modify the range of available profiles for the select element under Parameters.
  3. Click Design.

Save /load default sections

1585654286704-109.png

For each section type (e.g. IPE, HEA, CHS, etc.) a set of sections can be saved/loaded as default.

This will only work with one type cross-section (e.g. only HEA, or only KKR) selected. Otherwise, with Save command, the user can save a set of arbitrary sections into a file, and use them later for another model by Load command.

Manual Design

1585654369126-597.pngWith Manual design quick utilization check can be done for given steel profile and for selected steel beam, column, bar or design group only. Just, choose the load type (load combination or load group) and a profile name from the drop-down lists and select a bar, bars or group, and program displays detailed utilization results in table format.
warning.pngThe meaning of the utilization components, the table content and features are the same as written before at Auto design. The program use the chosen profile for all selected bar elements.

1585654421650-656.png

Figure: Quick check by Manual design

Detailed Result

Utilization of steel bars can be displayed in the following cases:

  • After global Auto design, you can display utilization of all steel bars checked for the recommended profiles.
  • When running element-based Auto design, utilization can be displayed by designed elements.
  • After Manual design, element-based Check displays utilization for selected elements.
  • After global Check done for all bar elements having final cross-section.
No.Global Auto designElement-based Auto des.Element-based CheckGlobal Check
11585654467668-415.png Calculate > Design calculation > Auto design all structural elements1585654540697-926.png Auto design

1585654546499-492.png Auto design and/or

1585654532071-809.png  Manual design

1585654550973-239.png Auto design and/or

1585654533943-756.png  Manual design

2

1585654490458-637.png New result > Steel bar

1585654497465-658.png New result > Steel bar1585654527003-278.png  Check1585654521036-969.png Apply changes
3  1585654500812-499.png New result > Steel bar1585654471339-281.png  Calculate > Design calculation > Auto design all structural elements
4   

1585654508830-980.png New result > Steel bar

Table: Steps of displaying steel bar utilization by different design cases

1585654569187-921.pngUtilization displayed with New result appears for all designed bars. The utilization components for a bar/design group can be displayed with Detailed result.

Detailed result opens a new window in the current project after selecting a bar/group member, which displays:

  • Input data
    The figure displays the applied steel cross-section with its main calculation and material parameters.

    1585654590787-377.png
    Figure: Applied cross-section
     
  • Detailed calculation formulas
    Calculation details and final values are collected by checking types:
    • Shear resistance (Eurocode3: 1-1: 6.2.6, 6.2.8),
    • Torsional resistance (1-1: 6.2.7),
    • Shear stress (1-1: 6.2.6),
    • Normal stress (1-1: 6.2.1),
    • Normal capacity (1-1: 6.2.1),
    • Flexural buckling (1-1: 6.3.1),
    • Torsional-flexural buckling (1-1: 6.3.1),
    • Lateral-torsional buckling (1-1: 6.3.2.4),
    • Interaction between normal force and bending (1-1: 6.3.3.) and
    • Shear buckling (1-5: 5).

      The proper results are displayed in green, while the red result warnings you to repeat design with new bar properties. The content of the utilization checks depends on Display options. Not relevant checks can also be hidden.

      1585654617784-697.png
      Figure: Utilization checks and formulas
       
  • Summary graph
    Summary graph is displayed with legend by default. Numeric values can be inquired in the calculation sections (set by Design calculation parameters).

    1585654637081-726.png
    Figure: Utilization summary

1585654653485-447.png Tabmenu contains the following tools and settings:

  • Selection of element to display
    You can choose a unique or a design group member from the drop-down lists to display its detailed results mentioned before. Each row displays the ID and the maximum utilization of a member. In case of a design group, “Maximum” means each check is displayed for the significant member having the maximum utilization for that check.

    1585654758567-477.png
    Figure: Selection of a unique or a group member
  • Selection of design load
    Depending on steel design was done for load combinations or load groups, a load combination or the maximum or a significant component of load groups can be selected for detailed results. Each row displays the name of the load combination/load group component and its utilization effect. “Maximum” means each check is displayed for the significant load combination or component of load groups having the maximum utilization for that check.

    1585654775005-862.png
    Figure: Selection from design loads
  • 1585654862323-747.png Auto design
    Quick Auto design can be done for the currently displayed unique/group member. Its design parameters can be set/modified in the appearing dialog, and then clicking OK starts steel design that updates all detailed result figures and formulas.
  • 1585654855258-686.png Manual design
    Manual design can be launched directly for the currently displayed unique member /group.
  • 1585654845984-672.png Display options
    The content and the appearance of the detailed result can be set with Display options. You can show only the final equation without details of the different checks (Hide details).
    1585654839027-624.png
    Figure: Display options of Detailed result
  • Go to
    Navigate in the detailed result window by selecting the required design type in the drop-down list. It is useful when you are in zoomed view.

1585654880904-396.png Click Tools > Add view to document to place all figures, fomulas and summary table or specified details only into Documentation.

Fire design for steel bars

Fire design gives the opportunity to check and design steel bars for fire effects according to EN 1993-1-2.

Launch Steel design/ Steel bar, fire design . To start Fire design it needs some new input data of the bars, and a special load combination and/or load group must be defined.

  • A „+Fire” type load case has to be defined in the Load cases dialog.
    1585654903292-534.png
  • For maximum of load groups calculations, an accidental load group must be defined that contains the „+Fire” type load case.
    1585654913288-557.png
  • For maximum of load combinations calculations, accidental load combinations must be defined that contains the „+Fire” type load case.
    1585654926562-624.png
  • The effects (internal forces) are calculated from accidental load combinations, where fire is the accidental effect. Resistance of bar is calculated by using reduced yield strength and elasticity modulus for steel at the elevated temperature.

Fire design contains Calculation parameter, Check, Design group, Auto design and Manual design commands.

Calculation parameter

  Explanation of data in calculation parameters are in EN 1993-1-2:3, 4 and EN 1992-1-2:3.

„Deflection criterion is essential” option is available for Danish national annex only.

image-20200331125036-34.png

Check

It works in exactly the same way as in case of steel bar design.

Design group

It works in exactly the same way as in case of normal steel bar design, except that fire design parameter and fire design calculation parameter of two bars must match to be placed into the same design group.

Auto design

There are two design options:

  • Design for fire protection material
    The design parameter contains the fire protection material, which can be selected from a library (see later). Its minimal and maximal thickness and an increment value, which is used by the automatic design procedure to find the minimal necessary thickness of the protection material, can be given by the User
  • Calculate maximum temperature 
    The Temperature step for maximum temperature calculation can be defined by the User.

Limit utilization can also be set in the Steel bar - fire design parameter dialog

1585654983150-702.png

Manual design

Fire protection material (from a library, see later), its thickness, or the Maximum member temperature can be selected in Steel bar, fire protection dialog for Manual Design..

1585655000724-715.png

Fire protection material library

It is available by clicking on „Edit library…” item in the material list of fire protection parameter in Auto and  Manual design dialogs.

1585655010127-795.png

Results

Utilization results are available to display on the model and to list.

A new result “Max. of combinations/Bar, Combined utilization summary” is available, where the maximum utilization of steel bars for both normal and fire check is displayed

1585655021923-512.png

1585655030224-469.png

Shell Model

In FEM-Design, a steel bar can be modeled as a real 3D element defined from steel plates.

light.pngTo convert a bar element to 3D shells apply the Steel bar, shell model tool of the 1585655069838-323.png  Tabmenu.

Global Auto (Shell model) design (Calculate > Design calculations > Auto design all structural elements) finds the most suitable thickness (from a thickness range set at Auto design > Parameters) for all steel plates of the shell model based on internal forces, stability check and detailed utilization calculations. With Manual design you can run quick utilization check of given thickness values for selected shell models or their design groups. You can also do quick Auto design by shell elements and design groups only instead of global design. Of course, any number of design cycles is executable, so the global Auto design can be combined with both previous and additional element-based Auto designs.

No.Global steel bar designElement-based steel designCombined steel design
11585655110330-554.png  Structure > Steel bar,shell model1585655112103-544.png  Structure > Steel bar,shell model1585655114374-463.png  Structure > Steel bar,shell model
21585655129235-663.png  Design group1585655158010-179.png  Global Stability analysis1585655132593-110.png  Design group
31585655138550-962.png 1585655180397-125.png  Auto design > Parameters1585655130886-154.png  Design group1585655142069-589.png 1585655185013-286.png  Design Parameters
41585655155928-228.png  Global Auto design1585655140288-697.png 1585655181897-706.png  Auto design > Parameters1585655161783-439.png  Global Auto design
51585655169306-415.png  Documentation1585655143460-852.png 1585655192442-628.png  Auto design by elements1585655148998-886.png 1585655186607-680.png  Auto design > Parameters
6 1585655199189-297.png  Manual design by elements1585655146290-327.png 1585655194279-860.png  Auto design by elements
7 1585655206657-954.png  Apply design changes1585655200908-342.png  Manual design by elements
8 1585655159689-227.png  Global Check1585655208027-158.png  Apply design changes
9 1585655170704-910.png  Documentation1585655163454-965.png  Global Check
10  1585655173659-102.png  Documentation

Table: Recommended steps by design alternatives

warning.pngStability analysis is required to get utilization check of steel bar-shell models. Global Auto design automatically runs stability analysis for the entire structure.

Auto Design

1585655270335-250.png Global Auto design gives utilization results and suitable thickness for all steel plates of shell models.

1585655276057-309.png

Figure: Global Auto design and utilization result

light.png

The recommended thickness values can be displayed on screen by showing the “Steel bar, shell model, applied quantity” object layer, or click 1585655329187-466.png  Design tool of the Auto design and the thickness values together with utilization results are available in table format. Utilization as colored figure (color palette) can be displayed by selecting New result > Steel bar, shell model > Utilization.

Applied thickness values are displayed in blue in the Utilization table, if they are assigned to the steel shell parts during design, otherwise black color represents the original/initial thickness.

1585655357850-434.pngElement-based Auto design finds the most suitable thickness of steel plates for selected unique or grouped shell models only from a range of available thicknesses defined by 1585655373290-257.png Parameters.

1585655378001-337.png

Figure: Range of available thickness values for design

To run element-based design for the load combinations, select the required shell element and/or element group with the Auto design command and click 1585655391773-363.png  Design tool. The quick process results recommended thickness values and the utilization of the shell model elements. Check the Display table box to have a look at the overall design results (see before).

The upper table shows the design efficiency and the maximal utilization of the designed single element and groups based on the found thickness values. The bottom table displays the utilization details of the shell model element or the members of a group selected in the upper table.

 Meaning
1585655414208-719.pngSuitable thickness is available
1585655420588-215.png

Suitable thickness is not available

(Modify the range of available thicknesses or steel materials.)

GroupID of a single element or a group name
Design parametersThe defined range of available thicknesses
Applied thicknessesThickness currently assigned to the shells
MaxMax. utilization of a model element or the significant member of a group
MinMax. utilization of the less significant group member
BarID of the designed single bar or a group member
StressStress utilization
FBSUtilization for flexural buckling around the stiff axis
FBWUtilization for flexural buckling around the weak axis
TBUtilization for torsional buckling
LTBUtilization for lateral torsional buckling
LBUtilization for local buckling

Table: The meaning of symbols and utilization results

Quick redesign can be done inside the Utilization table:

  1. Select a bar or a design group in the upper table.
  2. Modify the range of available plate thicknesses for the select element under Parameters.
  3. Click Design.

Manual Design

1585655460640-282.pngWith Manual design quick utilization check can be done for custom (also different) thickness values of selected steel plates (or their groups). Just select steel plate(s) and set a thickness value in the appeared dialog. Run Check calculation to run and display utilization check for the modified plates according to their new thickness values.
warning.pngThe meaning of the utilization components, the table content and features are the same as written before at Auto design.

1585655503440-284.png

Figure: Quick check by Manual design

Detailed Result

Utilization of steel bar-shell models can be displayed in the following cases:

  • After global Auto design, you can display utilization of all steel shell models.
  • When running element-based Auto design, utilization can be displayed by designed elements.
  • After Manual design, element-based Check displays utilization for selected elements.
  • After global Check done for all bar-shell elements having final plate thicknesses.
No.Global Auto designElement-based Auto des.Element-based CheckGlobal Check
11585655544674-590.png  Calculate > Design calculation > Auto design all structural elements1585655610365-993.png  Auto design

1585655611866-505.png  Auto design and/or

1585655620960-324.png  Manual design

1585655613472-125.png  Auto design and/or

1585655622549-398.png  Manual design

2

1585655592310-385.png  New result > Steel bar, shell model

1585655594347-587.png  New result > Steel bar, shell model

1585655628046-475.png  Check1585655604500-868.png  Apply changes
3  

1585655596493-206.png  New result > Steel bar, shell model

1585655548438-395.png  Calculate > Design calculation > Auto design all structural elements
4   

1585655598308-419.png  New result > Steel bar, shell model

Table: Steps of displaying steel bar-shell model utilization by different design cases

1585655641962-654.pngUtilization displayed with New result appears for all designed bar-shell models. The utilization components for an element/design group can be displayed with Detailed result.

Detailed result opens two new windows in the current project after selecting a shell model or group member, which display:

  • Applied shell thicknesses (Detailed result window)
    A list displays the applied thicknesses by the steel plate components.
  • Detailed calculation formulas (Detailed result window)
    Calculation details and final values are collected by checking types: Stresses, Flexural buckling, stiff/weak direction, Torsional buckling, Lateral torsional buckling and Local buckling. The proper results are displayed in green, while the red result warnings you to repeat design with new thickness values. The content of the utilization checks depends on Display options and Buckling mode (see later). Not relevant checks can also be hidden.

    1585655677097-404.png

    Figure: Utilization checks and formulas
  • Summary graph (Detailed result window)
    Summary graph is displayed with legend by default.
    1585655698189-890.png
    Figure: Utilization summary
  • Buckling mode (Buckling mode window)
    Based on stability analysis, the calculated shapes of the bar-shell model can be displayed in 3D view. Just select the required shape from the Shape drop-down list of the navigator panel and the program automatically shows the deformed shape in the current display mode. Buckling mode can be also chosen for the selected shape that affects on the design check content of the Detailed result window. You can add numeric values to the deformed shape or run buckling animation.
    1585655719486-312.png
    Figure: Buckling shape

1585655744718-515.png  Tabmenu contains the following tools and settings for the Detailed result window:

  • Selection of element to display
    You can choose a unique or a design group member from the drop-down lists to display its detailed results mentioned before. Each row displays the ID and the maximum utilization of a member. In case of a design group, “Maximum” means the significant member having the maximum utilization.
  • Selection of design load
    A load combination can be selected for detailed results. Each row displays the name of the available load combination and its utilization effect. “Maximum” means the significant load combination.
  • 1585655784875-736.png Auto design
    Quick Auto design can be done for the currently displayed unique/group member. Set the thickness of the steel plate components, and then click OK to start design that updates all detailed result figures and tables.

  • 1585655808924-391.png Display options
    The content and the appearance of the detailed result can be set with Display options.

  • 1585655816765-192.png Go to
    Navigate in the Detailed result window by selecting the required design type in the drop-down list. It is useful when you are in zoomed view.

1585655826034-120.png Click Tools > Add view to document to place all calculation and check formulas into Documentation.

Created by Fredrik Lagerström on 2020/03/31 12:50
Copyright 2020 StruSoft AB
FEM-Design Wiki