steel-ec3 (1)

8/13/2019 steel-ec3 (1)

1/89

Program STEEL EC3 2013 Dlubal Software GmbH

Add-on Module

STEEL EC3Ultimate Limit State, Serviceability,

Fire Resistance, and Stability Analyses

According to Eurocode 3

ProgramDescription

VersionAugust 2013

All rights, including those of translations, are reserved.

No portion of this book may be reproduced mechanically, electronically, orby any other means, including photocopying without written permission ofder DLUBAL-SOFTWARE GMBH.

Dlubal Software GmbH

Am Zellweg 2 D-93464 Tiefenbach

Tel.: +49 9673 9203-0

Fax: +49 9673 9203-51E-Mail: [email protected]: www.dlubal.com
http://www.dlubal.com/http://www.dlubal.com/http://www.dlubal.com/

8/13/2019 steel-ec3 (1)

2/89

8/13/2019 steel-ec3 (1)

3/89

8/13/2019 steel-ec3 (1)

4/89

1 Introduction

4 Program STEEL EC3 2013 Dlubal Software GmbH

1. Introduction1.1

Add-on Module STEEL EC3

The European Standard Eurocode 3 (EN 1993-1-1:2005) describes design, analysis, and con-struction of steel structures in the member states of the European Union. With the RSTAB add-on module STEEL EC3, DLUBAL SOFTWARE provides a powerful tool for designing steel structures.Country-specific regulations are taken into account by National Annexes (NA). In addition tothe parameters included in the program, you can define your own limit values or create newNational Annexes.

STEEL EC3 can carry out all typical ultimate limit state designs as well as stability and defor-mation analyses. The program is able to take into account various actions for the ultimate limitstate design. Furthermore, you can choose between the interaction formulas given in the code.An important part of the analysis in STEEL EC3 is the categorization of the cross-sections into

the Classes 1 through 4. In this way, you can check the limitation of the design capacity and ofthe rotational capacity due to local buckling for cross-section parts. Moreover, STEEL EC3 de-termines the c/t-ratios of the cross-section elements subjected to compression and classifiesthe cross-sections completely automatically.

For the stability analysis, you can specify for each member or set of members whether flexuralbuckling occurs in y- and/or z-direction. Furthermore, you can define additional lateral supportsin order to represent the model close to reality. In addition, the stabilizing effect of purlins andsheeting can be taken into account by rotational restraints and shear panels. STEEL EC3 deter-mines the slendernesses and elastic critical buckling loads from the boundary conditions. Theelastic critical moment for lateral torsional buckling required for the lateral torsional bucklinganalysis can be determined automatically or specified manually. In addition to this, it is possibleto take into account the load application point of transverse loads, which is affecting the tor-sional resistance considerably.

STEEL EC3 can also perform the fire resistance design according to EN 1993-1-2. The steelstructure is designed on the bearing capacity level according to the simplified calculationmethod. As fire protection, you can select encasements with different physical properties.

For structures with extremely slender cross-sections, the serviceability limit state represents animportant design. The load cases, load combinations, and result combinations can be assignedto different design situations. The limit deformations are preset by the National Annexes andcan be adjusted, if necessary. In addition, you can specify reference lengths and precambersthat are considered accordingly in the design.

STEEL EC3 also allows you to design structural components made of stainless steel according

to EN 1993-1-4.If required, you can optimize cross-sections in the model, and then export the modified cross-sections to RSTAB. Using the design cases, you can design separate structural components incomplex structures or analyze variants.

STEEL EC3 is integrated as an add-on module in RSTAB. Thus, the design relevant input data isalready preset when you start the module. After the design, you can use the graphical RSTABuser interface to evaluate the results. Finally, you can document the design process in theglobal printout report, from determination of internal forces to design.

We hope you will enjoy working with STEEL EC3.

Your DLUBALTeam

8/13/2019 steel-ec3 (1)

5/89

8/13/2019 steel-ec3 (1)

6/89

1 Introduction


1.3 Using the ManualTopics like installation, graphical user interface, results evaluation, and printout are describedin detail in the manual of the main program RSTAB. The present manual focuses on typical fea-

tures of the STEEL EC3 add-on module.

The descriptions in this manual follow the sequence and structure of the module's input andresults windows. In the text, the described buttonsare given in square brackets, for example[View mode]. At the same time, they are pictured on the left. Expressionsappearing in dialogboxes, windows, and menus are set in italicsto clarify the explanations.

At the end of the manual, you find the index. However, if you still cannot not find what youare looking for, please check our websitewww.dlubal.comwhere you can go through our FAQpages by selecting particular criteria.

1.4 Open the Add-on Module STEEL EC3RSTAB provides the following options to start the add-on module STEEL EC3.

Menu

To start the program from the RSTAB menu bar, select

Add-on ModulesDesign - SteelSTEEL EC3.

Figure 1.1: Menu:Add-on ModulesDesign - SteelSTEEL EC3
http://www.dlubal.com/http://www.dlubal.com/http://www.dlubal.com/http://www.dlubal.com/

8/13/2019 steel-ec3 (1)

7/89

1 Introduction

7Program STEEL EC3 2013 Dlubal Software GmbH

Navigator

As an alternative, you can start the add-on module in the Datanavigator by clicking

Add-on ModulesSTEEL EC3.

Figure 1.2: Data navigator:Add-on ModulesSTEEL EC3

Panel

If results from STEEL EC3 are already available in the RSTAB model, you can also open the de-sign module in the panel:

Set the relevant STEEL EC3 design case in the load case list of the RSTAB toolbar. Then, click the[Show Results] button to graphically display the design criterion on the members.

When the results display is activated, the panel is available, too. Now you can click [STEEL EC3]in the panel to open the module.

Figure 1.3: Panel button [STEEL EC3]

8/13/2019 steel-ec3 (1)

8/89

2 Input Data


2. Input DataWhen you have started the add-on module, a new window opens. In this window, a Navigator

is displayed on the left, managing the windows that can be currently selected. The drop-downlist above the navigator contains the design cases (see chapter7.1, page69).

The design relevant data is defined in several input windows. When you open STEEL EC3 forthe first time, the following parameters are imported automatically:

Members and sets of members Load cases, load combinations, result combinations, and super combinations Materials Cross-sections Effective lengths Internal forces (in background, if calculated)

To select a window, click the corresponding entry in the navigator. To set the previous or nextinput window, use the buttons shown on the left. You can also use the function keys to selectthe next [F2] or previous [F3] window.

To save the results, click [OK]. Thus, you exit STEEL EC3 and return to the main program. To exitthe module without saving the new data, click [Cancel].

2.1 General DataIn the 1.1 General Datawindow, you select the members, sets of members, and actions thatyou want to design. The tabs are managing the load cases, load combinations, result combina-tions, and super combinations for the different designs.

Figure 2.1: Window 1.1 General Data

8/13/2019 steel-ec3 (1)

9/89

8/13/2019 steel-ec3 (1)

10/89

8/13/2019 steel-ec3 (1)

11/89

2 Input Data


This classification controls the partial safety factors M0, M1, and M2that are included in the de-termination of the resistances Rdfor the cross-section and stability analyses (seeFigure 2.10,page13).

To change the design situation, use the list at the end of the input field which you can open by

clicking the drop-down arrow [].

Figure 2.6: Assigning a design situation

For a multiple selection, press [Ctrl] and click the corresponding entries. Thus, you can changeseveral entries at once.

The design of an enveloping max/min result combination is performed faster than the designof all contained load cases and load combinations. However, the analysis of a result combina-tion has also disadvantages: First, the influence of the contained actions is difficult to discern.Second, for the determination of the elastic critical moment for lateral-torsional buckling Mcr,the envelope of the moment distributions is analyzed, from which the most unfavorable dis-tribution (max or min) is taken. However, this distribution only rarely reflects the moment dis-tribution in the individual load combinations. Thus, in the case of a RC design, more unfavora-ble values for Mcr, are to be expected, leading to higher ratios.

Result combinations should be selected for design only for dynamic combinations. For "usual"combinations, load combinations are recommended, because here the actual moment distri-butions are taken for the determination of Mcr.

2.1.2 Serviceability

Figure 2.7: Window 1.1 General Data, tabServiceability Limit State

Existing Load Cases and Combinations

This section lists all load cases, load combinations, result combinations, and super combina-tions created in RSTAB.

Result

combination

8/13/2019 steel-ec3 (1)

12/89

2 Input Data


Selected for Design

Load cases, load combinations, and result combinations can be added or removed as de-scribed in chapter 2.1.1.

You can assign different deflection limit values to the individual load cases, load combina-tions, and result combinations. You can select from the following design situations:

Characteristic Frequent Quasi-permanent

To modify the design situation, use the list, which you access at the end of the input field byclicking [] (seeFigure 2.7).

The limit values of the deformations are defined in the National Annex. To adjust these valuesaccording to the design situation, click [Nat. Annex]. The National Annex Settingsdialog boxappears (seeFigure 2.10,page13).

The 1.9 Serviceability Datawindow manages the reference lengths governing for the defor-mation check (see chapter2.9,page32).

2.1.3 Fire Resistance

Figure 2.8: Window 1.1 General Data, tabFire Resistance

Existing Load Cases and Combinations

This section lists all load cases, load combinations, result combinations, and super combina-tions created in RSTAB.

Selected for Design

Load cases, load combinations, and result combinations can be added or removed, as de-scribed in chapter 2.1.1. In this dialog section, you can select the actions that have beendetermined according to EN 1991-1-2[2].

8/13/2019 steel-ec3 (1)

13/89

2 Input Data


2.1.4 National Annex (NA)In the upper-right list of the 1.1 General Datawindow, you can select the National Annexwhose parameters you want to apply to the design and the limit values of the deformation.

Figure 2.9: Selecting a National Annex

To check and, if necessary, adjust the preset parameters, click [Edit] (see the following figure).

To create a user-defined National Annex, click [New].

In addition to that, you can use the [Nat. Annex] button in all input windows to open theNational Annex Settingsdialog box consisting of two tabs.

Base

Figure 2.10: Dialog box National Annex Settings - BS, tab Base

8/13/2019 steel-ec3 (1)

14/89

2 Input Data


In the dialog box sections, you can check the Partial Factors, the Serviceability Limits (Deflec-tions), as well as the Parameters for Lateral-Torsional Bucklingand adjust them, if necessary.

In the dialog box section General Method Acc. to 6.3.4, you can specify whether you want toperform the stability analysis always in accordance with[1] clause 6.3.4. The option Enablealso for non I-sectionsallows you to use the method also for other cross-sections.

In addition, you can perform a stability analysis using the European lateral-torsional bucklingcurveaccording to NAUMES[8].In his dissertation, NAUMES[9] expanded the "General methodfor buckling and lateral torsional buckling of structural components" according to[1] clause6.3.4 for additional transverse bending and torsion. This expanded methodis now available fordesigning unsymmetrical cross-sections as well as tapered members and sets of members withbiaxial bending (torsion is currently not considered in STEEL EC3).

According to[1] clause 6.3.4 (4), the reduction factor opis to be calculated either

a) as minimum value of the values for buckling according to 6.3.1 or LTfor lateral-torsionalbuckling according to 6.3.2 by means of the slenderness ratio op, or

b) as a value that is interpolated between

andLT

see also[1] Equation (6.66).Since the method acc. to NAUMESis based on the standardized European lateral-torsional buck-ling curve taking into account the modified imperfection factor *, the interaction betweenlocal buckling and lateral-torsional buckling according to[1] equation (6.66) can be omitted.

Figure 2.11: Calculation run for the method according to NAUMES

In the first step, the calculation is carried out separately for the principal and the secondaryload-bearing plane. In this step, the moment factor qmZaccording toFigure 2.12 is determined.

In the second step, the design criterion nRis determined.

Finally, the design is performed by summing up the design ratios for the principal and the

secondary load-bearing plane and compared to the design criterion nR.

8/13/2019 steel-ec3 (1)

15/89

2 Input Data


Figure 2.12: Determination of the moment factor qMz

The buttons in the National Annex Settingsdialog box have the following functions:

Table 2.2: Buttons in the dialog National Annex Settings

Button Function

Resets the original settings of the program

Imports user-defined default settings

Saves modified settings as default

Deletes a user-defined National Annex

8/13/2019 steel-ec3 (1)

16/89

2 Input Data


Stainless Steel

STEEL EC3 also allows for the design of structural components made of stainless steel accord-ing to EN 1993-1-4[4].

In the second tab of the National Annex Settingsdialog box, you find the relevant Partial Factorsand Parameters for Stability Design.

Figure 2.13: Dialog box National Annex Settings - BS, tab Stainless Steel (EN 1993-1-4)

8/13/2019 steel-ec3 (1)

17/89

2 Input Data


2.2 MaterialsThe window is subdivided into two parts. The upper part lists all materials created in RSTAB.The Material Propertiessection shows the properties of the current material, that is, the table

row currently selected in the upper section.

Figure 2.14: Window 1.2 Materials

Materials that will not be used in the design are dimmed. Materials that are not allowed arehighlighted in red. Modified materials are displayed in blue.

The material properties required for the determination of internal forces are described in chap-ter 4.2 of the RSTAB manual (Main Properties). The material properties required for design arestored in the global material library. These values are preset (Additional Properties).

To adjust the units and decimal places of material properties and stresses, select from themodel's menu Settings Units and Decimal Places (see chapter7.3,page73).

Material Description

The materials defined in RSTAB are already preset, but you can always modify them: To selectthe field, click the material in column A. Then click [] or press function key [F7] to open thematerial list.

Figure 2.15: List of materials

8/13/2019 steel-ec3 (1)

18/89

2 Input Data


According to the design concept of the Standard[1],you can select only materials of theSteel category.

When you have imported a material, the design relevant Material Propertiesare updated.

If you change the material description manually and the entry is stored in the material library,STEEL EC3 will import the material properties, too.

In principal, it is not possible to edit the material properties in the add-on module STEEL EC3.

Material Library

Numerous materials are already available in the library. To open the corresponding dialog box,select

EditMaterial Library

or click the button shown on the left.

Figure 2.16: Dialog box Material Library

In the Filter section, Steelis preset as material category. Select the material quality that youwant to use for the design in the Material to Selectlist. You can check the corresponding prop-erties in the dialog section below.

Click [OK] or press [] to transfer the selected material to window 1.2 of the module STEEL EC3.

Chapter 4.2 in the RSTAB manual describes in detail how materials can be filtered, added, orrearranged.

You can also select material categories like Cast Ironor Stainless Steel. Please check, however,whether these materials are allowed by the design concept of the Standard[1].

8/13/2019 steel-ec3 (1)

19/89

2 Input Data


2.3 Cross-SectionsThis window manages the cross-sections used for design. In addition, the module windowallows you to specify optimization parameters.

Figure 2.17: Window 1.3 Cross-Sections

Cross-Section Description

The cross-sections defined in RSTAB are preset together with the assigned material numbers.

To modify a cross-section, click the entry in column B selecting this field. Click [Cross-sectionLibrary] or [...] in the field or press function key [F7] to open the cross-section table of the cur-rent input field (see the following figure).

In this dialog box, you can select a different cross-section or a different cross-section table. Toselect a different cross-section category, click [Back to cross-section library] to access the gen-eral cross-section library.

Chapter 4.3 of the RSTAB manual describes how cross-sections can be selected from the library.

8/13/2019 steel-ec3 (1)

20/89

2 Input Data


Figure 2.18: IS cross-sections in the cross-section library

The new cross-section description can be entered in the input field directly. If the data basecontains an entry, STEEL EC3 imports these cross-section parameters, too.

A modified cross-section will be highlighted in blue.

If cross-sections specified in STEEL EC3 are different from the ones used in RSTAB, both cross-sections are displayed in the graphic on the right. The designs will be performed with the in-ternal forces from RSTAB for the cross-section selected in STEEL EC3.

Cross-Section Type for Classification

The cross-section type used for the classification is displayed. The cross-sections listed in[1]Table 5.2 can be designed plastically or elastically depending on the Class. Cross-sections thatare not covered by this table are classified as General. These cross-sections can only be de-signed elastically (Class 3 or 4).

Max. Design Ratio

This table column is displayed only after the calculation. It is a decision support for the optimi-

zation. By means of the displayed design ratio and colored relation scales, you can see whichcross-sections are little utilized and thus oversized, or overloaded and thus undersized.

Optimize

You can optimize every cross-section from the library: For the RSTAB internal forces, the pro-gram searches the cross-section that comes as close as possible to a user-defined maximumutilization ratio. You can define the maximum ratio in the Othertab of the Detailsdialog box,(seeFigure 3.8,page49).

To optimize a cross-section, open the drop-down list in column D or E and select the desiredentry: From Current Row or, if available, From favorites'Description'. Recommendations for thecross-section optimization can be found in chapter7.2 on page71.

8/13/2019 steel-ec3 (1)

21/89

8/13/2019 steel-ec3 (1)

22/89

2 Input Data


The buttons below the graphic have the following functions:

Table 2.3: Buttons of cross-section graphic

Click [Details] to call up detailed information on stress points (distances to center of gravity,statical moments of area, normalized warping constants etc.) and c/t-parts.

Figure 2.20: Dialog box Stress Points of HE B 260

Button Function

Displays or hides the stress points

Displays or hides the c/t-parts

Displays or hides the numbering of stress points or c/t-parts

Displays or hides the details of the stress points or c/t-parts (seeFigure 2.20)

Displays or hides the dimensions of the cross-section

Displays or hides the principal axes of the cross-section

Resets the full view of the cross-section graphic

8/13/2019 steel-ec3 (1)

23/89

2 Input Data


2.4 Lateral Intermediate SupportsIn window 1.4, you can define lateral intermediate supports for members. STEEL EC3 alwaysassumes this kind of support as perpendicular to the minor z-axis of the cross-section (seeFig-ure 2.19). Thus, you can influence the members' effective lengths which are important for thestability analyses for flexural buckling and lateral-torsional buckling.

Figure 2.21: Window 1.4 Lateral Intermediate Supports

In the upper part of the window, you can assign up to nine lateral supports to each member.TheSettingssection shows the input as column overview for the member selected above.

To define the intermediate supports of a member, select the LateralSupportscheck box incolumn A. To graphically select the member and to activate its row, click []. By selecting thecheck box, the other columns become available for entering the parameters.

In column B, you can select the SupportTypefrom the list. The fork support is preset. Further-more, you can place the intermediate supports also at the lower or upper flange. The User-definedoption allows you to individually specify the support parameters (support in the direc-

tion of the member axis y, restraint about longitudinal member axis x, eccentricity of support)in the Settingssection.

In column D, you specify the number of the intermediate support. Depending on the specifica-tion, one or more of the following Lateral Intermediate Supportscolumns for the definition ofthe x-locations are available.

If the Relatively (0 1)check box is selected, the support points can be defined by relative in-put. The positions of the intermediate supports are determined from the member length andthe relative distances from the member start. If the Relatively (0 ... 1)check box is cleared, youcan define the distances manually in the upper table.

In case of cantilevers, avoid intermediate supports, because such supports divide the member

into segments. For cantilevered beams, this would results in segments that are fork supportedon one side and thus statically underdetermined (fork support on one end only, respectively).

8/13/2019 steel-ec3 (1)

24/89

2 Input Data


2.5 Effective Lengths - MembersThe window is subdivided into two parts. The table in the upper part provides summarized in-formation about the factors for the lengths of buckling and lateral-torsional buckling as well as

the equivalent member lengths of the members to be designed. The effective lengths definedin RSTAB are preset. In the Settingssection, you can see further information on the memberwhose row is selected in the upper section.

Click [] to select a member graphically and to show its row.

You can make changes in the table as well as in the Settingstree.

Figure 2.22: Window 1.5 Effective Lengths - Members

The effective lengths for buckling about the minor z-axis are aligned automatically with theentries of the 1.4 Lateral Intermediate Supportswindow. If lateral intermediate supports are di-viding the member into member segments of different lengths, the program displays no valuein the table columns G, K, and L of window 1.5.

The effective lengths can be entered manually in the table and in the Settingstree, or defined

graphically in the work window after clicking [...]. This button is enabled when you click in theinput field (see figure above).

The Settingstree manages the following parameters:

Cross-Section Member Length Buckling Possiblefor the member (cf. columns B, E, and H) Buckling about Axis y Possible (cf. columns C and D) Buckling about Axis z Possible(cf. columns F and G) Lateral-Torsional Buckling Possible(cf. columns I through K)

In this table, you can specify for the currently selected member whether to carry out a buckling

or a lateral-torsional buckling analysis. In addition to this, you can adjust the Buckling LengthCoefficientand the Warping Length Coefficientfor the respective lengths. When a coefficient ismodified, the equivalent member length is adjusted automatically, and vice versa.

8/13/2019 steel-ec3 (1)

25/89

2 Input Data


You can also define the buckling length of a member in a dialog box. To open it, click thebutton shown on the left. It is located on the right below the upper table of the window.

Figure 2.23: Dialog box Select Buckling Length Coefficient

For each direction, you can define the buckling length according to one of the four Euler buck-ling modes or as User-defined. If a RSBUCK case calculated according to the eigenvalue analysisis already available, you can also define a Buckling Shapeto determine the factor.

Buckling Possible

A stability analysis for flexural buckling and lateral-torsional buckling requires that memberscan resist compressive forces. Therefore, members for which such resistance is not possiblebecause of the member type (for example tension members, elastic foundations, rigid cou-plings) are excluded from design in the first place. The corresponding rows appear dimmedand a note is displayed in the Commentcolumn.

The Buckling Possiblecheck boxes in table row A and in the Settingstree offer you a control op-tion for the stability analyses: They determine whether the analyses should or should not beperformed for a member.

Buckling about Axis y or Axis zWith the check boxes in the Possibletable columns, you decide whether a member is suscepti-ble to buckling about the y-axis and/or z-axis. These axes represent the local member axes,where the y-axis is the major and the z-axis the minor member axis. The buckling length coef-ficients kcr,y and kcr,zfor buckling around the major or the minor axis can be selected freely.

You can check the position of the member axes in the cross-section graphic in the 1.3 Cross-Sectionswindow (seeFigure 2.17,page19). To access the RSTAB work window, click [Viewmode]. In the work window, you can display the local member axes by using the member'scontext menu or the Displaynavigator.

8/13/2019 steel-ec3 (1)

26/89

2 Input Data


Axis definition for kzand kw

Figure 2.24: Selecting the member axis systems in the Displaynavigator of RSTAB

If buckling is possible about one or even both member axes, you can enter the buckling lengthcoefficients as well as the buckling lengths in the columns C and D as well as F and G. Thesame is possible in the Settingstree.

To graphically specify the buckling lengths in the work window, click [...]. This button becomesavailable when you click in an Lcrinput field (seeFigure 2.22).

When you specify the buckling length coefficient kcr, the program determines the effectivelength Lcrby multiplying the member length Lby the buckling length coefficient. The inputfields kcrand Lcrare interactive.

Lateral-Torsional Buckling Possible

Table column H shows you for which members the program performs an analysis of lateral-torsional buckling.

Buckling Length Coefficient kz

To determine Mcrby the eigenvalue calculation method, a member model with four degreesof freedom is created in the program background. The following definitions of kzand kw(seepage27)are possible to represent the degrees of freedom on the supports of such a model:

kz = 1.0 fork support on both beam ends

kz = 0.7le restrained on the left and fork support on the right

kz = 0.7ri restrained on the right and fork support on the left

kz = 0.5 restraint on both girder ends

kz = 2.0le restrained on the left and free member end on the rightkz = 2.0ri restrained on the right and free member end on the left

A fork support with kz =1.0 results in a support with a fixation in direction of the y-axis and arestraint to the torsion about the x-axis (longitudinal axis) of the member. In case a restraint isused, the torsion of the cross-section about the z-axis is prevented, too. The abbreviations leand rirefer to the left and right side. The description lealways refers to the support conditionsat the member start.

As the definitions for kzand kwalways refer to member start and member end, particular atten-tion must be paid when intermediate supports are taken into account: These supports dividethe member into individual segments for the calculation. For cantilevered beams, segmentswith fork supports on one side would therefore result that are statically underdetermined (fork

support respectively on one end only).

8/13/2019 steel-ec3 (1)

27/89

2 Input Data


Buckling Length Coefficient kw

With the warping length coefficient kw,you define the supports fourth degree of freedom,which is also included in the determination of the elastic critical moment for lateral torsionalbuckling Mcr. You must define whether the cross-section can be warped freely (support is free

to warp) or a warping restraint is set.

The definition follows the one of the buckling length coefficient kz(see above) but now it is arestraint that describes the prevention of warping. By default, STEEL EC3 applies the memberlength for the length of lateral-torsional buckling. When you have a structural component con-sisting of several members between the supports, it may be reasonable to define the lengthfor lateral-torsional buckling manually. You can use the select function [...] for such a definition.

kw= 1.0 support free to warp on both beam ends

kw= 0.7le restrained on the left and fork support on the right

kw= 0.7ri restrained on the right and fork support on the left

kw= 0.5 warping restraint on both beam ends

kw= 2.0le restrained on the left and free member end on the rightkw= 2.0ri restrained on the right and free member end on the left

Since the internal member model requires only four degrees of freedom, a definition of theremaining degrees of freedom (displacement in x- and z-direction) is unnecessary.

Below the Settingstable, you find the Set input for members No.check box.If selected, the set-tings entered afterwards will be applied to the selected or to Allmembers. Members can beselected by typing the member number or by selecting them graphically using the [] button.This option is useful when you want to assign the same boundary conditions to several mem-bers. Please note that already defined settings cannot be changed subsequently with thisfunction.

It may happen that the length for lateral-torsional buckling Lwor the torsional buckling length

LTdiffer from the member length or the effective length. In these cases, it is possible to definethe lengths Lwand LTin the columns K and L manually.

Comment

In the last table column, you can enter you own comments for each member to describe, forexample, the selected equivalent member lengths.

8/13/2019 steel-ec3 (1)

28/89

2 Input Data


2.6 Effective Lengths - Sets of MembersThis window appears only if you selected at least one set of members for design in the1.1 General Datawindow (seeFigure 3.2, page44)and selected the Equivalent Member Method

for sets of members in the dialog box Details. With these settings, however, the windows 1.7and 1.8 will not be displayed. In this case, you can define the lateral intermediate supports bydivision points in window 1.4.

Figure 2.25: Window 1.6 Effective Lengths - Sets of Members

This window's concept is similar to the one of the previous 1.5 Effective Lengths - Memberswin-dow. In this window, you can enter the effective lengths for the buckling about the two princi-pal axes of the set of members as described in chapter2.5.

8/13/2019 steel-ec3 (1)

29/89

2 Input Data


2.7 Nodal Supports - Sets of MembersThis window is displayed only if you have selected at least one set of members for the designin the 1.1 General Data window.

In STEEL EC3, the stability analysis for sets of members is performed usually according to[1],clause 6.3.4. If, however, the Equivalent Member Methodis selected in the Details dialog box(seeFigure 3.2,page44), window 1.7 will not be displayed. In that case, you can define thelateral intermediate supports by using division points in window 1.4.

Figure 2.26: Window 1.7 Nodal Supports Set of Members

According to[1],clause 6.3.4 (1), only monosymmetrical cross-sections that are loaded exclu-sively in their principal plane may be designed. For this analysis method, it is necessary toknow the amplification factor cr,opof the entire set of members. To determine this factor, aplanar framework is created with four degrees of freedom for each node, which you have todefine in window 1.7. This window refers to the current set of members (selected in the add-onmodules navigator on the left).

The orientation of the axes in the set of members is important for the definition of nodal sup-ports. The program checks the position of the nodes and internally defines, according toFig-ure 2.27 throughFigure 2.30, the axes of the nodal supports for window 1.7.

Figure 2.27: Auxiliary coordinate system for nodal supports straight set of members

If all members of a set of members are lying in a straight line as shown inFigure 2.27, the localcoordinate system of the first member in the set of members corresponds to the equivalentcoordinate system of the entire set of members.

8/13/2019 steel-ec3 (1)

30/89

2 Input Data


Figure 2.28: Auxiliary coordinate system for nodal supports set of members in vertical plane

If members of a set of members are not lying in a straight line, they must at least lie in the sameplane. InFigure 2.28,they are lying in a vertical plane. In this case, the X-axis is horizontal and

oriented in direction of the plane. The Y-axis is horizontal as well and defined perpendicular tothe X-axis. The Z-axis is oriented perpendicularly downwards.

Figure 2.29: Auxiliary coordinate system for nodal supports set of members in horizontal plane

If the members of a buckled set of members are lying in a horizontal plane, the X-axis is de-fined parallel to the X-axis of the global coordinate system. Thus, the Y-axis is oriented in theopposite direction to the global Z-axis and the Z-axis is directed parallel to the global Y-axis.

Figure 2.30: Auxiliary coordinate system for nodal supports set of members in inclined plane

Figure 2.30 shows the general case of a buckled set of members: The members are not lying inone straight line but in an inclined plane. The definition of the X-axis arises out of the intersec-tion line of the inclined plane with the horizontal plane. Thus, the Y-axis is defined perpendic-ular to the axis X and directed perpendicular to the inclined plane. The Z-axis is defined per-pendicular to the X- and Y-axis.

8/13/2019 steel-ec3 (1)

31/89

2 Input Data


2.8 Member End Releases - Sets of MembersThis window is displayed only if you have selected at least one set of members for the designin the 1.1 General Datawindow . Here, you can define releases for members and sets of mem-

bers that, due to structural reasons, do not transfer the locked degrees of freedom specified inwindow 1.7 as internal forces. This window refers to the current set of members (selected inthe add-on modules navigator on the left).

Window 1.8 is not be displayed, if the Equivalent Member Methodis selected in the dialog boxDetails(seeFigure 3.2, page44)for the sets of members.

Figure 2.31: Window 1.8 Member Releases Set of Members

In table column B, you define the Member Sideto which the release should be assigned. Youcan also connect the releases to both member sides.

In the columns C through F, you can define releases or spring constants to align the set ofmembers model with the support conditions in window 1.7.

8/13/2019 steel-ec3 (1)

32/89

2 Input Data


2.9 Serviceability DataThis input window controls several settings for the serviceability limit state design. It is onlyavailable if you have set the according entries in the Serviceability Limit Statetab of window 1.1(see chapter2.1.2,page11).

Figure 2.32: Window 1.9 Serviceability Data

In column A, you decide whether you want to apply the deformation to single members, listsof members, or sets of members.

In table column B, you enter the numbers of the members or sets of members that you want todesign. You can also click [] to select them graphically in the RSTAB work window. Then, theReference Lengthappears in column D automatically. This column presets the lengths of themembers, sets of members, or member lists. If required, you can adjust these values after se-lecting the Manuallycheck box in column C.

In table column E, you define the governing Directionfor the deformation analysis. You canselect the directions of the local member axes y and z (or u and v for unsymmetrical cross-

sections).

In column F, you can consider aprecamberwc.

The Beam Typeis of crucial importance for the correct application of limit deformations. In col-umn G, you can specify whether there is a beam or a cantilever and which end should have nosupport.

The settings in the Serviceabilitytab of the Detailsdialog box decide whether the deformationsare related to the undeformed initial structure or to the shifted ends of members or sets ofmembers (seeFigure 3.3,page46).

8/13/2019 steel-ec3 (1)

33/89

2 Input Data


2.10 Specifications for Fire Resistance DesignThe final input window manages the different fire resistance parameters. It is only available ifyou have set relevant entries in the Fire Resistancetab of window 1.1 (see chapter2.1.3,page12).

Figure 2.33: Window 1.10 Fire Protection Members

Table column A contains the members that are taken into account for fire resistance design.Click [] to graphically select the members in the RSTAB work window.

In column B, you define the number of cross-section sides that are exposed to fire.Fire Exposurehas an effect on the determination of the section factors according to[2] window4.2 and window 4.3.

In case an encasement for fire resistance is used, you can select the Protection Typein column D.You can choose between a spray (contour) encasement that follows the geometry of the cross-section (for example intumescent coating) and a hollow encasements of the cross section. Then,you specify the corresponding parameters in table columns E through H.

The general parameters for the fire resistance design are managed in the Fire Resistancetab ofthe Detailsdialog box (seeFigure 3.4,page47).

8/13/2019 steel-ec3 (1)

34/89

2 Input Data


2.11 Parameters - MembersThis window allows you to enter specifications for beams that laterally supported by sheetingor purlins (see[3] clauses 10.1 and 10.3).

The upper section lists the members intended for design together with the parameters thatare relevant for the lateral-torsional buckling design. These parameters interact with the speci-fications in the section Settings for Member No.below.

To the right of the Settingstable, you can see information or options in the form of graphicsfacilitating the definition of boundary conditions. The display is controlled by the currentlyselected parameters.

Figure 2.34: Window 1.11 Parameters - Members

Below the Settingstable, you find the Set inputs for members No.check box.If selected, the set-tings entered afterwards will be applied to the selected or to Allmembers. Members can be se-lected by typing the member number or by selecting them graphically using the [] button.This option is useful when you want to assign the same boundary conditions to several mem-bers.

In the Commentcolumn, you can enter user-defined comments for each member to describe,for example, a member's parameters relevant for lateral-torsional buckling.

Cross-Section

In this column, the cross-section description is displayed. In the case of a tapered member, thedescription of the cross-section start and end is displayed.

8/13/2019 steel-ec3 (1)

35/89

2 Input Data


Shear Panel

To enter the shear panel parameters, select the check box in column A or in the Settingstable.

The type of shear panel can be selected from the list.

Figure 2.35: Selection of shear panel type

Trapezoidal sheeting

The application of a continuous lateral support is described in 1993-1-1[1] Annex BB.2.1 andEN 1993-1-3[3] clause 10.1.5.1.

To determine the shear panel stiffness of a trapezoidal sheeting (corrugated sheet), the follow-ing specifications are required (seeFigure 2.35):

Shear panel length lS Beam spacing a Position of trapezoidal sheeting on section Trapezoidal sheeting description Fastening arrangement

Theshear panel lengthand the beam spacingcan be entered manually or selected graphical-ly after clicking [...]. This button becomes available when you click in one of the two inputfields. Then, you can select the two snap points in the RSTAB work window that define theshear panel or the beam spacing.

The trapezoidal sheetings Position on sectioncan be taken into account in different ways byusing the list shown on the left. The selected point of torsion Dis marked in the cross-sectiongraphic, even in case of user-defined input. Here, the distance dis related to the centroid; thesign results from the z-axis of the cross-section.

To access the corrugated sheet library, click the [...] button that becomes available after youclick in the Trapezoidal sheeting descriptioninput field (seeFigure 2.38,page37). The RSTABcross-section library appears (seeFigure 2.36), where you can select the trapezoidal sheet bydouble-clicking it or clicking [OK]. Thus, the shear panel coefficient K1and K2(according to theapproval certificate) is automatically entered in the Settingstable. The basic width bof thetrapezoidal sheeting has no influence on these coefficients.

The Fastening arrangementof the trapezoidal section influences the shear stiffness that thesheeting provides to the beam. If the trapezoidal sheeting is fastened only in every second rib,the shear stiffness to be applied is reduced by a factor of 5.

8/13/2019 steel-ec3 (1)

36/89

2 Input Data


Figure 2.36: Cross-section library Rolled Cross-Sections - Corrugated Sheets

Bracing

Figure 2.37: Shear panel type Bracing

To determine the provided shear panel stiffness, the following specifications are required:

Shear panel length lS Beam spacing a Position of the bracing on section Post spacing b Number of bracings Section of diagonals Section of posts

The Shear panel length, the Beam spacing, and the Post spacingcan be entered manually orselected graphically after clicking [...]. This button becomes available when you click in one of

these input fields. Then, you can select the two points defining the shear panel or the spacingin the RSTAB work window.

8/13/2019 steel-ec3 (1)

37/89

2 Input Data


The bracingsposition on sectioncan be considered in different ways by using the list shownon the left. The selected point of torsion Dis marked in the cross-section graphic, even in caseof manual input. Here, the distance dis related to the centroid; the sign results from the z-axisof the cross-section.

The easiest way to specify the cross-sectional area of the diagonals and posts is to select theSection Descriptionfor the RSTAB library. To access the library, click [...] at the end of the inputfield. Then, the CS-Areais imported automatically. It is also possible to enter this value directly.

Trapezoidal sheeting and bracing

Figure 2.38: Shear panel type Trapezoidal sheeting and bracing

To determine the provided shear panel stiffness due to trapezoidal sheeting and bracing, thefollowing specifications are required:

Shear panel length lS Beam spacing a Position of shear panel on section Trapezoidal sheeting description Fastening arrangement Post spacing b Number of bracings Section of diagonals Section of posts

This way of defining the shear panel combines the parameters of the aforementioned optionsTrapezoidal sheetingand Bracing.

Define Sprov

Figure 2.39: Defining S-prov

The value of the provided Shear panel stiffnessSprovcan also be entered directly. In addition tothis, you have to specify the shear panels Position on section.

8/13/2019 steel-ec3 (1)

38/89

2 Input Data


Rotational restraint

To enter the rotational restraint parameters, select the check box in column B or in the Settingstable.

The type of rotational restraint can be selected in the list or by clicking the graphics to the rightof the Settings.

Figure 2.40: Selection of the type of rotational restraint

Continuous rotational restraint

To determine the stiffness components from a trapezoidal sheeting and the connection de-formation, you need the following specifications (seeFigure 2.40):

Material and description of the trapezoidal sheet Method of determining CD,A Beam spacing s Continuous beam effect

To access the corrugated sheet library, click the button [...] that becomes available when youclick in the input field Component description. The RSTAB cross-section library appears whereyou can select a corrugated sheet by double-clicking it or clicking [OK]. The section parametersSheeting thickness t, Position of sheeting, effective Second moment of area Isfor the downwardloading direction, Distance of ribs bR(corrugation width), and Width of the flange bTare import-ed automatically.

In case of continuous rotational restraint, you have also to consider the deformation of the con-nection. You can specify the rotational spring stiffness C100in the entry Method of determiningCD,Aor determined by the program according to[3] Table 10.3. Use the [] button for automat-ic calculation. To access the button [...], click in the input field of the row C100. Use this button toopen a dialog box where you can select the appropriate coefficient (see the following figure).Click [OK] to assign this value to all load cases and load combinations that you want to design.

A dialog box opens where you can specify the appropriate coefficient.

8/13/2019 steel-ec3 (1)

39/89

2 Input Data


Figure 2.41: Dialog box Import Coefficient C100from Table 10, EN 1 993-1-3

After you confirm the specification by clicking [OK], this values is assigned to all load cases and

load combinations selected for the design. To assign by load case, open the dialog box ImportCoefficient via the C100input fields of the individual load cases and load combinations, click [OK].

The Beam spacingcan also be specified manually or graphically after clicking [...]. To do this,click two nodes in the RSTAB work window that define the distance between the beams.

The Continuous beam effecthas an impact on the coefficient kof the rotational restraint CD,C,which you can define in the list of this row (End panel: k = 2, Internal panel: k = 4).

8/13/2019 steel-ec3 (1)

40/89

2 Input Data


Discrete rotational restraint

Figure 2.42: Type of rotational restraint Discrete rotational restraint

To determine the stiffness component from isolated columns (for example purlins), the follow-ing specifications are required:

Material and description of the cross-section Spacing of purlins e Beam spacing s Continuous beam effect

You can select theMaterialand Cross-section descriptionin the RSTAB library, which you canaccess by clicking [...]. To do this, select the relevant input field by clicking it.

The Spacing of the purlins and the Beam spacingcan be entered manually or graphically after

clicking [...]. To do this, select two nodes defining the spacing of the purlins or beams by click-ing them in the RSTAB work window.

The Continuous beam effecthas an impact on the coefficient kof the rotational restraint CD,C,which you can define in the list of this row (End panel: k = 2, Internal panel: k = 4).

Cross-Sectional Area

Figure 2.43: Defining cross-sectional area for tension design

According to[1] clause 6.2.3, holes for fasteners must be taken into account in the tension de-sign. The Net Cross-Sectional Area Anetcan be defined separately for the Startand Endof themember fasteners are usually located at these two x-locations the. The gross cross-sectionalareaAis shown for control purposes.

8/13/2019 steel-ec3 (1)

41/89

2 Input Data


2.12 Parameters - Sets of MembersThis window is displayed only if you have selected at least one set of members for the designin window 1.1 General Data.

Figure 2.44: Window 1.12 Parameters - Sets of Members

This window's concept is similar to the one of the previous window 1.11 Parameters - Members.In this window, you can define the parameters of shear panels and rotational restraints foreach set of members as described in chapter2.11.

8/13/2019 steel-ec3 (1)

42/89

3 Calculation


3. Calculation3.1

Detail Settings

Before you start the [Calculation], it is recommended to check the design details. You can openthe according dialog box in all windows of the add-on module by clicking [Details].

The Detailsdialog box contains the following tabs:

Ultimate Limit State Stability Serviceability Fire Resistance Other

3.1.1 Ultimate Limit State

Figure 3.1: Dialog box Details, tab Ultimate Limit State

8/13/2019 steel-ec3 (1)

43/89

3 Calculation


Classification of Cross-Sections

If stresses from compression and bending occur together in the cross-section, you can deter-mine the stress-deformation ratio in two ways (the factor is required for the determinationof the appropriate c/t-ratio according to[1] table 5.2):

Fixed NEd, increase MEdto reach fydOnly the flexural stress component is increased to reach the yield strength.

Increase NEdand MEduniformlyThe flexural stress components from axial force and bending are increased uniformlyuntil the yield strength fydis reached.

The check box For limit c/t of Class 3, increase material factor acc. to 5.5.2 (9)can be accessed ifthe stability analysis has been deactivated in the tab Stability. This is based on the specificationsfor classification in[1] clause 5.5.2 (10). If the stability analysis is deactivated, you can treatcross-sections classified as Class 4 like cross-sections of Class 3 by increasing the factor .

If select the check box Use SHAPE-THIN for Classification of all supported cross-section types, theeffective cross-section properties of Class 4 sections will be calculated according to the meth-

od used in SHAPE-THIN. If cross-sections are classified as 'general' (that is, belong neither to arolled nor a parameterized cross-section table), the classification will generally be performedwith SHAPE-THIN. These cross-sections can be designed only elastically as Class 3 or Class 4cross-sections.

Options

Cross-sections that are assigned to Class 1 or 2 are designed plastically in STEEL EC3. If you donot want to perform a plastic design, you can activate the Elastic Designfor these cross-sectionclasses, too.

Stability Analyses with Second-Order Internal Forces

If the stability analyses are performed not with the equivalent member method according to[1] clause 6.3 but with second order internal forces, you can use this check box to specify if touse the partial safety factor M1(instead of M0) for the cross-section design.

The partial safety factor M1is relevant for the determination of resistance in case of instability(structural component check). The safety factor can be checked and, if necessary, modified inthe dialog box National Annex Settings(seeFigure 2.10, page13).

Cross-Section Check for M+N

With the check box Use linear interaction acc. to 6.2.1(7), you controlif to use a linear addition ofthe utilization ratios for the moments and axial forces according to Eq. (6.2) or Eq. (6.44) as con-servative approximation for the resistance verification of the cross-section.

8/13/2019 steel-ec3 (1)

44/89

3 Calculation


3.1.2 Stability

Figure 3.2: Dialog box Details, tab Stability

Stability Analysis

The Usecheck box controls whether to run, in addition to the cross-section checks, a stabilityanalysis. If you clear the check box, the input windows 1.4 through 1.8 will not be displayed.

If the check box is selected, you can define the axes relevant for the determination of Flexuralbuckling. In addition to that, you can include Effects from 2nd order theoryaccording to[1]clause 5.2.2(4) by an increase factor for bending moments that can be defined manually. Thuswhen you design, for example, a frame whose governing buckling mode is represented by lat-eral displacement, you can determine the internal forces according to linear static analysis and

increase them with the appropriate factors. If you increase the bending moment, this does notaffect the flexural-buckling analysis according to[1] clause 6.3.1, which is performed by usingthe axial forces.

Determination of Elastic Critical Moment for LTB

By default, STEEL EC3 determines the ideal critical moment for lateral-torsional bucklingAuto-matically by Eigenvalue Method. For the calculation, the program uses a finite model to deter-mine Mcr, taking into account the following items:

Dimensions of gross cross-section Load type and position of load application point Effective distribution of moments

Lateral restraints (by support conditions) Effective boundary conditions

8/13/2019 steel-ec3 (1)

45/89

3 Calculation


Mcruser-defined

The degrees of freedom can be controlled by the factors kzand kw(see chapter2.5,page26).

The elastic critical moment is determined Automatically bycomparison of moment coursesandassignment of coefficient C1. To view the load courses and moment distributions, open thecorresponding dialog box by clicking [Info]. The coefficients C2and C3are determined auto-

matically by the eigenvalue method, if required.

If you select the Manual definition in Table 1.5option, the name of column J changes to Mcr,thus allowing you to enter the elastic critical moment for LTB manually.

If transverse loads are available, it is important to define where these forces are acting on thecross-section: Depending on the Load applicationpoint, transverse loads can be stabilizing ordestabilizing, and thus can decisively influence the elastic critical moment.

Model Type According to Table B.3

According to[1],Table B.3, the equivalent uniform moment factor for structural componentswith buckling in the form of lateral deflection should be taken as Cmy= 0.9 or Cmz= 0.9, respec-tively. The two check boxes are cleared by default. If you select the check boxes, the program

determines the factors Cmyand Cmzaccording to the criteria given in Table B.3.

Limit Load for Special Cases

To design non-symmetrical cross-sections for intended axial compression according to[1]6.3.1, you can neglect small momentsabout the major and the minor axis using the settingsdefined in this dialog section.

In the same way, according to[1] 6.3.2, you can switch off small compression forcesfor the purecheck of bending by defining a limit ratio for N to Npl.

For the design of Unsymmetric Cross-Sections, Tapered Members or Sets of Membersaccording to

[1] 6.3.4, only uniaxial bending in the principal plane and/or compression is allowed. To neglect

a minor moment about the minor axis, you can define a limit for the moment ratio Mz,Ed/Mpl,z,Rd.

Intended torsionis not clearly specified in EN 1993-1-1. If a torsional stress is available that doesnot exceed the shear stress ratio of 5 % preset by default, it is not considered in the stability de-sign. In this case, the output shows results for flexural buckling and lateral-torsional buckling.

If one of the limits in this dialog section is exceeded, a note appears in the results window. Nostability analysis is carried out. However, the cross-section checks are run independently. Theselimit settings are not part of EN 1993-1-1 or any National Annex. Changing the limits is in theresponsibility of the program user.

Stability Analysis Method of Sets of Members

The stability behavior of sets of members can be analyzed according to two methods.

According to 6.3.1 6.3.3(Equivalent Member Method), it is possible to treat sets of membersas one single member. To do this, the factors kzand kwhave to be defined in the window1.6 Effective Lengths - Sets of Members. They are used to determine the support conditions , uy,x, z, and . If you apply these settings, however, the windows 1.7 and 1.8 will not be dis-played. Please note that the factors kzand kware identical for each section or member of theset of members. In general, the equivalent member method should be used only for straightsets of members.

With the presetting 6.3.4 (General Method), the program performs a general analysis accordingto[1] clause 6.3.4, based on the coefficientcr. In window 1.7, you define the support condi-tions for each set of members individually. The factors kzand kwfrom window 1.5 are not used.

8/13/2019 steel-ec3 (1)

46/89

3 Calculation


3.1.3 Serviceability

Figure 3.3: Dialog box Details, tab Serviceability

Deformation Relative to

The option fields control whether the maximum deformations are related to the shifted endsof members or sets of members (connection line between start and end nodes of the de-formed system) or to the undeformed initial system. As a rule, the deformations are to bechecked relative to the displacements in the entire structural system.

In the National Annex Settingsdialog box, you can check and, if necessary, adjust the limitdeformations (seeFigure 2.10, page13).

Limitation of Web BreathingIn the serviceability limit state design of steel bridges, the plate slenderness ratio is to be re-stricted to avoid excessive rippling and breathing of plates as well as a reduction of stiffnessesdue to plate buckling. The check box Design as steel bridge structure according to EN 1993-2, 7.4controls whether the breathing (repeated out-of-plane deformation) is to be analyzed, whichcan result in fatigue at or adjacent to the web-to-flange connections. You have to selectwhether you design a Road bridgeor a Railway bridge.

In the design, it is necessary to limit the slenderness of stiffened and unstiffened plates.

8/13/2019 steel-ec3 (1)

47/89

3 Calculation


3.1.4 Fire ResistanceThis tab manages the detail settings for the fire resistance check.

Figure 3.4: Dialog box Details, tab Fire Resistance

In addition to the Required time of fire resistanceand the Time interval of analysisfor the deter-mination of the temperature change, you have to define the governing Temperature Curve forDetermination of Temperature of Gases. You can select one of the three following curves:

Figure 3.5: Standard temperature-time curve

8/13/2019 steel-ec3 (1)

48/89

3 Calculation


Figure 3.6: External fire curve

Figure 3.7: Hydrocarbon curve

The Factors for determination of net heat flux are preset in accordance with EN 1991-1-2 andEN 1993-1-2, but you can adjust them to the given conditions.

If you select the Define final temperature manuallycheck box, you can define the temperatureain window 1.9 individually.

8/13/2019 steel-ec3 (1)

49/89

3 Calculation


3.1.5 Other

Figure 3.8: Dialog box Details, tab Other

Cross-Section Optimization

The optimization is targeted to the maximum design ratio of 100 %. If necessary, you can spec-ify a different limit value in this input field.

Check of Member Slendernesses

In the two input fields, you can specify the limit values limitin order to define member slender-nesses. You can enter specifications separately for members with pure tension forces andmembers with bending and compression.

The limit values are compared to the real member slendernesses in window 3.3. This windowis available after the calculation (see chapter4.8, page58 ) if the corresponding check box isselected in the Display Result Tablesdialog box section.

Design of Welds

To carry out designs of welds in the analysis, select this check box. The program performs thetypical designs according to EN 1993-1-8. After the calculation, you can find the results underthe cross-section designs.

Display Result Tables

In this dialog section, you can select the results table including parts list that you want to be

displayed. The tables are described in chapter4 Results.

The 3.3 Member Slendernesseswindow is inactive by default.

8/13/2019 steel-ec3 (1)

50/89

8/13/2019 steel-ec3 (1)

51/89

4 Results


4. ResultsWindow 2.1 Design by Load Caseis displayed immediately after the calculation.

Figure 4.1: Results window with designs and intermediate values

The designs are shown in the results windows 2.1 through 2.5, sorted by different criteria.

The windows 3.1 and 3.2 list the governing internal forces. Window 3.3 informs you about themember slendernesses. The last two results windows, 4.1 and 4.2 show parts sorted by mem-ber and set of members.

Every window can be selected by clicking the according entry in the navigator. To set the pre-vious or next input window, use the buttons shown on the left. You can also use the functionkeys to select the next [F2] or previous [F3] window.

To save the results, click [OK]. Thus you exit STEEL EC3 and return to the main program.

Chapter4 Resultsdescribes the different results windows one by one. Evaluating and checkingresults is described in chapter5 Results Evaluation, page61ff.

8/13/2019 steel-ec3 (1)

52/89

4 Results


4.1 Design by Load CaseThe upper part of the window provides a summery, sorted by load cases, load combinations,and result combinations of the governing designs. Furthermore, the list is divided in ultimate

limit state, serviceability, fire resistance, and stability designs.

The lower part gives detailed information on the cross-section properties, analyzed internalforces, and design parameters for the load case selected above.

Figure 4.2: Window 2.1 Design by Load Case

Description

This column shows the descriptions of the load cases, load combinations, and result combina-tions used for the designs.

Member No.

This column shows the number of the member that bears the maximum stress ratio of thedesigned loading.

Location x

This column shows the respective x-location where the member's maximum stress ratio occurs.For the table output, the program uses the following member locationsx:

Start and end node Division points according to possibly defined member division (see RSTAB table 1.6) Member division according to specification for member results (RSTAB dialog box

Calculation Parameters, tab Global Calculation Parameters)

Extreme values of internal forcesDesign

Columns D and E display the design conditions according to EN 1993-1-1.

The length of the colored scale represents the respective utilization ratio.

8/13/2019 steel-ec3 (1)

53/89

4 Results


Design According to Formula

This column lists the code's equations by which the designs have been performed.

DS

The final column provides information on the respective check-relevant design situation(DS):PTorACfor the ultimate state or one of three design situations for serviceability (CH, FR, QP)according to the specifications in the 1.1 General Datawindow (seeFigure 2.7,page11).

4.2 Design by Cross-Section

Figure 4.3: Window 2.2 Design by Cross-Section

This window lists the maximum ratios of all members and actions selected for design, sortedby cross-section. The results are sorted by cross-section design, stability analysis, serviceabilitylimit state design, and fire resistance design.

If there is a tapered member, both cross-section descriptions are displayed in the table row

next to the section number.

8/13/2019 steel-ec3 (1)

54/89

8/13/2019 steel-ec3 (1)

55/89

4 Results


4.4 Design by Member

Figure 4.5: Window 2.4 Design by Member

This results window presents the maximum utilization ratios for the individual designs sortedby member number. The columns are described in detail in chapter4.1 on page52.

4.5 Design by x-Location

Figure 4.6: Window 2.5Design by x-Location

8/13/2019 steel-ec3 (1)

56/89

4 Results


This results window lists the maxima for each member at the locationsxresulting from thedivision points in RSTAB:

Start and end node Division points according to possibly defined member division (see RSTAB table 1.6) Member division according to specification for member results (RSTAB dialog box

Calculation Parameters, tab Global Calculation Parameters)

Extreme values of internal forces

4.6 Governing Internal Forces by Member

Figure 4.7: Window 3.1Governing Internal Forces by Member

For each member, this window displays the governing internal forces, that is, those internalforces that result in the maximum utilization in each design.

Location x

At this x location of the member, the respective maximum design ratio occurs.

Loading

This column displays the number of the load case, the load combination, or result combinationwhose internal forces result in the maximum stress ratio.

Forces / Moments

For each member, this column displays the axial and shear forces as well as the torsional andbending moments producing maximum ratios in the respective cross-section designs, stabilityanalyses, serviceability limit state designs, and fire resistance designs.

Design According to Formula

The final column provides information on the types of checks and the equations by which thechecks according to[1], [2], or[4] have been performed.

8/13/2019 steel-ec3 (1)

57/89

4 Results


4.7 Governing Internal Forces by Set of Members

Figure 4.8: Window 3.2Governing Internal Forces by Set of Members

This window shows the internal forces that result in the maximum ratios of the design for each

set of members.

8/13/2019 steel-ec3 (1)

58/89

4 Results


4.8 Member Slendernesses

Figure 4.9: Window 3.3Member Slendernesses

This results window appears only if you select the respective check box in the Othertab of the

Detailsdialog box (seeFigure 3.8, page49).The table lists the effective slendernesses of the designed members for both directions of theprincipal axes. They were determined depending on the type of load. At the end of the list, youfind a comparison with the limit values that have been defined in the Detailsdialog box, tabOther(seeFigure 3.8,page49).

Members of the member "Tension" or "Cable" type are not included in this window.

This table is displayed only for information. No stability analysis of slendernesses is intended.

8/13/2019 steel-ec3 (1)

59/89

4 Results


4.9 Parts List by MemberFinally, STEEL EC3 provides a summary of all cross-sections included in the design case.

Figure 4.10: Window 4.1Parts List by Member

By default, this list contains only the designed members. If you need a parts list for all membersof the model, select the corresponding option in Othertab of the Detailsdialog box (seeFigure3.8,page49).

Part No.

The program automatically assigns item numbers to similar members.

Cross-Section Description

The column lists the cross-section numbers and descriptions.

Number of Members

The column shows how many similar members are used for each part.

Length

This column displays the respective length of an individual member.

Total Length

This column shows the product determined from the two previous columns.

Surface Area

For each part, the program indicates the surface area related to the total length. The surfacearea is determined from the Surface Areaof the cross-sections that can be seen in windows 1.3and 2.1 through 2.5 in the cross-section information (seeFigure 2.19,page21).

8/13/2019 steel-ec3 (1)

60/89

4 Results


Volume

The volume of a part is determined from the cross-sectional area and the total length.

Unit Weight

The Unit Weight of the cross-section is relative to the length of one meter. For tapered cross-sections, the program averages both cross-section masses.

Weight

The values of this column are determined from the respective product of the entries in columnC and G.

Total Weight

The final column indicates the total mass of each part.

Sum

At the bottom of the list, you find a sum of the values in the columns B, D, E, F, and I. The lastdata field of the column Total Weightgives information about the total amount of steel re-quired.

4.10 Parts List by Set of Members

Figure 4.11: Window 4.2Parts List by Set of Members

The last results window is displayed if you have selected at least one set of members for de-sign. The window summarizes an entire structural group (for example a horizontal beam) in aparts list.

Details on the various columns can be found in the previous chapter. If there are differentcross-sections in a set of members, the program averages the surface area, the volume, andcross-section weight.

8/13/2019 steel-ec3 (1)

61/89

5 Results Evaluation


5. Results EvaluationYou can evaluate the design results in different ways. The buttons below the first window part

can help you to evaluate the results.

Figure 5.1: Buttons for results evaluation

The buttons have the following functions:

Button Description Function

Ultimate Limit State DesignsShows or hides the results of the ultimate limit statedesign

Serviceability Limit StateDesigns

Shows or hides the results of the serviceability limitstate design

Fire Protection DesignsShows or hides the results of the fire protectiondesign

Show Color Bars

Shows or hides the colored relation scales in

the results windows

Show Rows with Ratio > 1Displays only the rows where the ratio is greaterthan 1, and thus the design is failed

Result DiagramsOpens the window Result Diagram on Memberchapter5.2,page64

Excel ExportExports the table to MS Excel / OpenOfficechapter7.4.3,page75

Member SelectionAllows you to graphically select a member todisplay its results in the table

View Mode

Jumps to the RSTAB work window to change the

view

Table 5.1: Buttons in results windows 2.1 through 2.5

8/13/2019 steel-ec3 (1)

62/89



When evaluating the fire resistance design, you can check the steel temperature developmentgraphically: To open the Fire Curvesdiagram shown inFigure 3.5 toFigure 3.7 on page47ff.,click the button shown on the left (below the cross-section graphic in the results window).

5.1 Results in the RSTAB ModelTo evaluate the design results, you can also use the RSTAB work window.

RSTAB background graphic and view mode

The RSTAB work window in the background is useful for finding the position of a particularmember in the model: The member selected in the STEEL EC3 results window is highlighted inthe selection color in the background graphic. Furthermore, an arrow indicates the member'sx-location that is displayed in the selected window row.

Figure 5.2: Indication of the member and the current Location xin the RSTAB model

If you cannot improve the display by moving the STEEL EC3 module window, click [Jump toGraphic] to activate the View Mode: Thus, you hide the module window so that you can modifythe display in the RSTAB user interface. In the view mode, you can use the functions of theViewmenu, for example zooming, moving, or rotating the display. The pointer remains visible.

Click [Back] to return to the add-on module STEEL EC3.

RSTAB work window

You can also graphically check the design ratios in the RSTAB model: Click [Graphics] to exitthe design module. In the RSTAB work window, the design ratios are now displayed like theinternal forces of a load case.

In the Resultsnavigator, you can specify which design ratios of the service and ultimate limitstate or fire resistance design you want to display graphically.

To turn the display of design results on or off, use the [Show Results] button known from thedisplay of internal forces in RSTAB. To display the result values, click the [Show Values] toolbar

button to the right.

The RSTAB tables are of no relevance for the evaluation of design results.

8/13/2019 steel-ec3 (1)

63/89

8/13/2019 steel-ec3 (1)

64/89



5.2 Result DiagramsYou can also graphically evaluate a member's result distributions in the result diagram.

To do this, select the member (or set of members) in the STEEL EC3 results window by clickingin the table row of the member. Then, open the Result Diagram on Memberdialog box by click-ing the button shown on the left. The button is located below the upper results table (seeFig-ure 5.1,page61).

To display the result diagrams, select the command from the RSTAB menu

Results Result Diagrams for Selected Members

or use the button in the RSTAB toolbar shown on the left.

A window opens, graphically showing the distribution of the maximum design values on themember or set of members.

Figure 5.5: Dialog box Result Diagram on Member

Use the list in the toolbar above to choose the relevant STEEL EC3 design case.

The Result Diagram on Memberdialog boxis described in the RSTAB manual, chapter 9.5.

8/13/2019 steel-ec3 (1)

65/89



5.3 Filter for ResultsThe STEEL EC3 results windows allow you to sort the results by various criteria. In addition, youcan use the filter options for graphical evaluation of the results as described in chapter 9.7 of

the RSTAB manual.

You can use the Visibilityoption also for STEEL EC3 (see RSTAB manual, chapter 9.7.1) to filterthe members in order to evaluate them.

Filtering designs

The design ratios can easily be used as filter criteria in the RSTAB work window, which you canaccess by clicking [Graphics]. To apply this filter function, the panel must be displayed. If it isnot shown, select

ViewControl Panel (Color Scale, Factors, Filter)

or use the toolbar button shown on the left.

The panel is described in the RSTAB manual, chapter 3.4.6. The filter settings for the resultsmust be defined in the first panel tab (Color spectrum). Since this register is not available forthe two-colored results display, you have to use the Displaynavigator and set the displayoptions Colored With/Without Diagramor Cross-Sectionsfirst.

Figure 5.6: Filtering design ratios with adjusted color spectrum

As the figure above shows, the color spectrum can be set in such a way that only ratios higherthan 0.50 are shown in a color range between blue and red.

If you select the Display Hidden Result Diagramoption in the Displaynavigator (ResultsMem-bers), you can display all design ratio diagrams that are not covered by the color spectrum.Those diagrams are represented by dotted lines.

8/13/2019 steel-ec3 (1)

66/89

8/13/2019 steel-ec3 (1)

67/89

6 Printout


6. Printout6.1

Printout Report

Similar to RSTAB, the program generates a printout report for the STEEL EC3 results, to whichyou can add graphics and descriptions. The selection in the printout report determines whatdata from the design module will be include in the printout.

The printout report is described in the RSTAB manual. In particular, chapter 10.1.3.5 SelectingData of Add-on Modulesdescribes how to select input and output data from add-on modulesfor the printout report.

For complex structural systems with many design cases, it is recommended to split the data in-to several printout reports, thus allowing for a clearly-arranged printout.

6.2 STEEL EC3 Graphic PrintoutIn RSTAB, you can add every picture that is displayed in the work window to the printout re-port or send it directly to a printer. In this way, you can prepare the design ratios displayed onthe RSTAB model for the printout, too.

The printing of graphics is described in the RSTAB manual, chapter 10.2.

Designs on the RSTAB model

To print the currently displayed graphic of the design ratios, click

FilePrint Graphic

or use the toolbar button shown on the left.

Figure 6.1: Button Print Graphicin RSTAB toolbar

Result Diagrams

You can also transfer the Result Diagram on Memberto the report by using the [Print] button orprint it directly.

Figure 6.2: Button Print Graphicin the dialog boxResult Diagram on Member

The Graphic Printoutdialog box appears (see the following page).

8/13/2019 steel-ec3 (1)

68/89

6 Printout


Figure 6.3: Dialog box Graphic Printout, tab General

This dialog box is described in the RSTAB manual, chapter 10.2. The RSTAB manual alsodescribes the Optionsand Color Spectrumtab.

You can move a graphic anywhere within the printout report by using the drag-and-dropfunction.

To adjust a graphic subsequently in the printout report, right-click the relevant entry in thenavigator of the printout report. The Propertiesoption in the context menu opens theGraphic Printout dialog box, offering various options for adjustment.

Figure 6.4: Dialog box Graphic Printout, tab Options

8/13/2019 steel-ec3 (1)

69/89

7 General Functions


7. General FunctionsThis chapter describes useful menu functions as well as export options for the designs.

7.1 Design CasesDesign cases allow you to group members for the design: In this way, you can combine groupsof structural components or analyze members with particular design specifications (for exam-ple changed materials, partial safety factors, optimization).

It is no problem to analyze the same member or set of members in different design cases.

To calculate a STEEL EC3 design case, you can also use the load case list in the RSTAB toolbar.

Create New Design Case

To create a new design case, use the STEEL EC3 menu and click

FileNew Case.

The following dialog box appears:

Figure 7.1: Dialog box New STEEL EC3 Case

In this dialog box, enter a No.(one that is still available) for the new design case. The corre-sponding Descriptionwill make the selection in the load case list easier.

Click [OK] to open the STEEL EC3 window 1.1 General Datawhere you can enter the designdata.

Rename Design Case

To change the description of a design case, use the STEEL EC3 menu and click

FileRename Case.


Figure 7.2: Dialog box Rename STEEL EC3 Case

In this dialog box, you can specify a different Descriptionas well as a different No.for thedesign case.

8/13/2019 steel-ec3 (1)

70/89

7 General Functions


Copy Design Case

To copy the input data of the current design case, select from the STEEL EC3 menu

FileCopy Case.


Figure 7.3: Dialog box Copy STEEL EC3 Case

Define the No.and, if necessary, a Descriptionfor the new case.

Delete a Design Case

To delete design cases, select from the STEEL EC3 menu

FileDelete Case.


Figure 7.4: Dialog box Delete Case

The design case can be selected in the list Available Cases. To delete the selected case,click [OK].

8/13/2019 steel-ec3 (1)

71/89

7 General Functions


7.2 Cross-Section OptimizationThe design module offers you the option to optimize overloaded or little utilized cross-sections.To do this, select in column D or E of the relevant cross-sections in the 1.3 Cross-Sectionswin-

dow whether to determine the cross-section From the current rowor the user-defined Favorites(seeFigure 2.17,page19). You can also start the cross-section optimization in the results win-dows by using the context menu.

Figure 7.5: Context menu for cross-section optimization

During the optimization process, the module determines the cross-section that fulfills the anal-ysis requirements in the most optimal way, that is, comes as close as possible to the maximumallowable stress ratio specified in the Detailsdialog box (seeFigure 3.8, page49). The requiredcross-section properties are determined with the internal forces from RSTAB. If another cross-section proves to be more favorable, this cross-section is used for the design. Then, the graphicin window 1.3 shows two cross-sections: the original cross-section from RSTAB and the opti-mized one (seeFigure 7.7).

For a parameterized cross-section, the following dialog box appears after you select 'Yes' fromthe drop-down list.

Figure 7.6: Dialog box Welded Cross-Sections - I symmetric : Optimize

By selecting the check boxes in the Optimizecolumn, you decide which parameter(s) you wantto modify. This enables the Minimumand Maximumcolumns, where you can specify the upper

and lower limits of the parameter. The Incrementcolumn determines the interval in which thesize of the parameter varies during the optimization process.

8/13/2019 steel-ec3 (1)

72/89

7 General Functions


If you want to Keep current side proportions, select the corresponding check box. In addition,you must select at least two parameters for optimization.

Cross-sections built up from rolled cross-sections cannot be optimized.

Please note that the internal forces are not automatically recalculated with the changed cross-sections during the optimization: It is up to you to decide which cross-sections should betransferred to RSTAB for recalculation. As a result of optimized cross-sections, internal forcesmay vary significantly because of the changed stiffnesses in the structural system. Therefore, itis recommended to recalculate the internal forces of the modified cross-section data after thefirst optimization, and then to optimize the cross-sections once again.

You can export the modified cross-sections to RSTAB: Go to the 1.3 Cross-Sectionswindow, andthen click

EditExport All Cross-Sections to RSTAB.

Alternatively, you can use the context menu in window 1.3 to export optimized cross-sectionsto RSTAB.

Figure 7.7: Context menu in window 1.3 Cross-Sections

Before the modified cross-sections are transferred to RSTAB, a security query appears as towhether the results of RSTAB should be deleted.

Figure 7.8: Query before transfer of modified cross-sections to RSTAB

8/13/2019 steel-ec3 (1)

73/89

8/13/2019 steel-ec3 (1)

74/89

7 General Functions


7.4 Data Transfer7.4.1 Export Material to RSTABIf you have adjusted the materials in STEEL EC3 for design, you can export the modified mate-rials to RSTAB in a similar way as you export cross-sections: Open the 1.2 Materialswindow,and then click

EditExport All Materials to RSTAB.

You can also export the modified materials to

Documents

steel-ec3 (1)