bridge combinations en 1990
TRANSCRIPT
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Bridge DesignBridge Combinations EN 1990
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Chapter 1
Disclaimer 4
Introduction 6
Bridge Combinations 7
Step1: Activate protection 7New projects: 8
Older projects: 9
Step2: Create Load groups 11
Loadgroup: 14
Load case: 15
Step3: Assign Loadcasesto theLoadgroups 15
Step 4: Createa CodeCombination 16
Example: 19
Step5: Decomposed EN combinations 20
Generation rules for Building 21
Generation rules for Roadbridges 23
Generation rules for Footbridges 26
Generation rules for Railway bridges 27
Step6: NA Setupdialog 29
Combinationsetup 30
Combinationrulesfor Buildings: 31
Combinationrules for Roadbridges: 32
gr1bnottobe combinedwithother non-traffic loads 32
Snow or wind load not to be combined with gr2 32
Snow or wind load not to be combined with gr3 32
Snow or wind load not to be combined with gr4 33
Snow not to be combined with gr1a and gr1b 33
Windloadsnottobe combined with Thermal loads 33
Snow loadsandwind loads not to be combined withconstr. activity 33
Combinationrulesfor Footbridges: 34
Qfvk not to be combined with other non-traffic loads 34
Wind loadsnot to be combinedwith Ther malloads 34
Snow loads not to be combined with gr1and gr2 34
Snow loads and wind loadsnot to be combined withconstr. activity 35
Combination rules for Railway bridges: 35
Snow loadsnot to be taken into account 35
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Windaction not to be combined with gr13 or gr23 36
Windaction not to be combined with gr16, gr17, gr26, gr27 36
Snow loadsandwind loadsnot to be combinedwith constr.activity 36
Psifactors 36Loadcombination factors 39
Other features 44
Leading variable action 44
(STR/GEO) alternative 45
Equation 6.10: 45
Equation 6.10a & 6.10b 45
Equation 6.10a "modified" & 6.10b 45
Construction stages 46
Example 50
Step1: ActivateProtection 50
Step2:CreateLoad groups 50
Step3:Assign Load casesto the Load groups 51
Step 4: Createa CodeCombination 53
Step 5: Decomposed EN combinations 59
Step6: NA Setup dialog 63
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Chapter 1
Disclaimer
Allinformation in this document is subject to modification without prior notice. No part or this manual may be reproduced,
stored in a database or retrieval system or published, inany form or in any way, electronically, mechanically, by print, photo
print, microfilmor anyother means withoutprior written permission from the publisher. NemetschekScia isnot responsible
for anydirect or indirect damagebecause of imperfectionsin the documentation and/or thesoftware.
© Copyright 2012 NemetschekScia. All rights reserved.
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Chapter 1
Introduction
The purposeof thisdocument isto introduce andexplain, how the combinationsfor bridges, described in EN 1990 and EN
1991-2, are implemented within SciaEngineer. Thisdocumentalso containsa smalltutorial example, whichdetails how the
user can define bridge combinationscorrectlytogether withthe standard buildingcombinations.
Special rules for bridge combinationsare definedbyEN 1990 Amendment A1,whichbringsAnnexe A2.
In this Annex A2, three main types of bridge combinations are defined. Combinations for Road bridges, Footbridges and
Railbridges. Special typesof loadingfor each particular type are alsodefined together withitsѱandgvalues. For each struc-
ture type a list of rules on how to combine these typesof loading in thecombination itself isalsoprovided.
The basic idea of new combinations is, that in addition user defines in his combinationso called Structure parameter, which
willbe the main parameter, for distinguishing which types of loads, ѱ andgvaluesand finally rules, are to be applied. After-
wardsuser can insertall suitable loadcases to hiscombination. When generatingenvelope combinations, a sub levelof com-
bination, called Decomposed EN combinations, is introduced. These decomposed EN combinations are generated with
respect to the activatedrules.
The bridge functionality is protected by a new protection code, therefore a new item is implemented in the Functionality
folder in the Project datadialog.
In general, the user may proceed in several steps, when defining new bridge (or even building) combination. Do not take
thisas an exact order incombination definition. User mayalso start with adjustingparameters in NA Setup dialog and then
proceeddifferently. Takethis asa proposal, whichwill be used asan example in this document.
Step 1: ActivateProtection
Step 2: Create Loadgroups
Step 3: AssignLoadcasesto theLoadgroups
Step 4: Createa CodeCombination
step 5: Decomposed EN combinations
Step 6: Adjust (if needed)ѱ values,gvaluesand combination rules inNA Setup dialog
The user should have a good understanding of Eurocodes in general, especially the application of the EN 1990 and EN
1991-2.
Accompanyingthisdocument, the reader willfind two files for the example:
Footbridgeexample_initial.esa (onlystructure)
Footbridgeexample_final.esa (structure with loading and combinations)
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BridgeCombinations
Bridge Combinations
Step 1: Activate protection
The bridge combinations functionality is protected by a new commercial module and appropriate technical module, there-fore new item Bridge design is added in the Functionality folder in the Project data dialog. If checked, then the user may
check also two new items in the right window. By activating the Load combinations check box in the project, a new para-
meter called Structure, will be expanded withother itemsfor bridges. It canbe set for Load groups, Combination andalso in
the Construction stages Setupdialog.
If the functionality isoff, theStructuresetting willautomatically be set to Buildingand allbridge itemswill not be visible to the
user. If thefunctionalityis off,no bridge combinationscan be defined.
Itmay happen,that the usertries to open project, whichisalready containing some loadgroupsor combinationsor even con-
struction stages which have the Structure parameter set to any bridge type, with Scia Engineer without proper license. In
this casewarning dialog below will be displayed.
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Chapter 2
Similar usecasemay happen,when the user deactivatesthecheckLoad combinations in theFunctionalityfolder in the Pro-
ject data dialog.
If theuser confirmsone of thetwo dialogs above, then a fewthingsshould be kept inmind:
New projects:
Content of a the Structure combo box in the Load groupdialog will be reduced onlyto Building and will be always disabled
(nonew load groups with bridgestructureare allowedto be created).
Content of a the Structure combo box inCombinations dialogs will be reduced only toBuilding and will be always disabled
(no new combinationswith bridge Structure are allowed to be created).
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Content of a the Structure combo box in the Construction stages dialog(also in the variable loads imputing dialog), will be
reduced only to Buildingand will be always disabled.
Older p rojects:
Anypreviously created Load groups, which were set to some bridge Structure type, will remain untouched, until they are
edited. If edited, the Structure parameter willbe automaticallyset to Building and parameter Load type to Category A (first
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Chapter 2
item inthe combo).
Anypreviously created Combinations, which were set to some bridgeStructure type, will remain untouched, untilthey are
edited. If edited, the Structure parameter will be automatically set to Building. All non-suitable variable load cases will be
removed from the combination.
The Structure parameter in the Construction stages Setup dialog will be directly changed to Building and all variable load
casesinpreviously created Construction stageswillbe removed from these stages.
The user will also not be able to calculate projects with these bridge combinationswithout a proper license. If the licensewill
not be found, a warning will be displayed whencalculation isstarted. After confirmation of this warning dialog thecalculation
will be terminated. It will alsonot be possible to explode such combinationsinto envelopesor linear combinations.
On theother hand, all parameters connectedto thebridges willstillbe visible inThe NASetup dialog, both for new and old
projects:
l NASetup manager – Combination setup
l NASetup manager - Psi factorsѱ
l NA Setup manager - Load combination factorsγ
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BridgeCombinations
Step 2: Create Load groups
For further generation of bridge combinationsit is neccessary to distinguishvariable load groupscontaining loadsfor build-
ings from variable load groups containing loadsfor bridges. When a Load groupis setto Variable, new parameter Structure
will be displayed. In the comboboxit ispossible to selectfrom four options:
l Building(default standard, asit isimplementednow)
l Roadbridge(for list of actionsseeEN 1990;2002 AnnexA2,table A2.1)
l Footbridge (for list of actionsseeEN 1990;2002 AnnexA2,table A2.2)
l Railway bridge (for list of actionssee EN 1990;2002 AnnexA2,table A2.3)
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Chapter 2
The Structure parameter will be disabled, whenthe functionality Bridgecombinationsis not activatedin the Project data dia-
log. It isset to Buildingby default.
Accordingto the selection in thiscombobox, the content of Load typecombobox isadjusted.
Content of a Load type comboboxwith the Structure parameter set to Buildings:
Content of a Load type combo box with theStructureparameter set to Road Bridges:
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Content of a Load type comboboxwiththe Structureparameter set to Footbridges:
Content of a Load type comboboxwiththe Structureparameter set to Railwaybridges:
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Chapter 2
There isno mapping table betweenthe itemsfrom this combobox. If for example the Structure parameter is set to Building
andthe Loadtype is set to Cat H andafterwards theStructure parameter is changed, the first value of the selected option
will be selected in theLoadtype combo.
Whenever a certain load case willbe assigned to a certain combination, aditional restrictionsare implemented both for load
group and load case in the Load group and the Load case dialogs. Let's imagine that we have a LC4 assigned to a LG4,
whichStructure isset to Roadbridges. A combination CO1 for Roadbridgesis alreadycreated andLC4 isassigned in the
combination.
Load group:
The Structure parameter for LG4 will becamedisabled andwill not be possible to change. On the other hand, Loadtype will
stillbe possibleto change.
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BridgeCombinations
Load case:
For LC4 it will still be possible to change the Load group parameter to something else, but the user may select only load
groupswith the same Structure parameter or independentvariable loadgroups for accidental and seismic loads. By press-
ingthe threedots edit button, theLoadgroup dialog will be displayed, butwithfiltered content.
These restrictions become active right after assigning a certain load case into the combination. If the load case is not
assigned yet, theuser mayfreelychange the load group.
Step 3: Assign Load cases to the Load groups
Inthisstep, theuser assigns his load casesin the loadgroups, whichwere defined inpreviousstep. The only change, incom-
parison to the use of older versionsof Scia Engineer, is the restriction with load group change,after assigning aload case
into the combination. Thishas been describedalso in the previousstep.
The user opens theLoadcases dialog andfrom the comboboxLoad groupchoosesan appropriate load group.
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Chapter 2
Step 4: Create a Code Combination
Combinationsfor buildingsare distinguished from combinationsfor bridgestoo. The reason for this is the usageof correct γ
and Ψ factors, whichare different andwill be definedin another system requirement. There isalso a new comboboxnamed
Structure, whereuser maychoosefrom four possibilities: Buildings, Roadbridges, Footbridges,and Railway bridges.
Thiscombo isvisibleonly for marked typesof combinations, shown on picture below. Else it ishidden.
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Chapter 2
The right window withlist of load casesisfiltered according to the Structure selected in thecombo. Thiswindow shows:
l Permanent loadcases
l Permanent prestressload cases
l Loadcases connectedto Accidental and Seismic loadgroups(onlyfor Accidental or Seismic combinations)
l Load cases,whichare assigned to a certainvariableloadgroup, withthe same Structure type defined
If a Building combinationfor example iscreated, and then it isswitched for example to Footbridgecombination, thecontent
of the right window isrefreshed and also thecontent of the combination is checked. If any non-compatible variable load isfound, it isautomaticallyremoved from the content of thecombination.
During this switch a warning message is displayed together with the changed content on the background. the user may
accept thechangeor cancel it.
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BridgeCombinations
The same warning is displayed when switching to/from Accidental and Seismic combinations. Load cases which are
assignedto Accidental loadgroups,are possible to input into the code combinationonly when typeof the combinationis set
to Accidental1 or Accidental 2 combination. Practically the same way behavesload casesassigned to Seismic load groups,
whichare possible to inputonly intoSeismic code combination. In allother cases, accidental and seismicload cases are not
displayed in theList of load caseswindow.Alsowhensuch load casesare alreadyinputed in thecontentof combination and
after thatthe type ischanged, theyare removed from the combination.
Example:
Type of the com bina tion List of loa dcas es
Envelope, Linear All
EN-Code non-Accidental 1,2 and non-Seismic All exceptA ccidental and Seismic
EN-Code Accidental 1,2 All except Seismic
EN-Code Seismic All except Accidental
The previous warning dialog is also displayed whenswitching combinationtype from non-code to a code combination. The
Structure parameter isset to Buildingas the defaultoption.
The Structure parameter isalso visible in the main Combinations dialog, where it has only informative character. Here it is
disabled andis not possible to changeit. Thereforethe list of the loadcases isalways valid. The Structure parameter is vis-
ible againonly for theCodecombinationshere. Else it ishidden.
Parameter Typeis alsoalwaysdisabled andit isnot possible to changeit.
Thisrestrictionsare implemented to ensure the correct input for the combinations.
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Chapter 2
Step 5: Decomposed EN combinations
For further generation of envelope combinationsit isnecessary to extractso-called Decomposed EN combinationsfrom the
userdefined"mother" Codecombination. These new combinationsare theresultcombinationsafter applyingboth fixed ele-
mentaryrules andoptional combination setup rules, on a originalcombination. These Decomposed EN combinationswillbe
then usedfor generating envelope combinations.
There is Decomposed EN combination action button shown for all buildings, road bridge, footbridge and railway bridge
Code combinations in the main Combinations dialog. It is hidden for all other combinations. By pressing red marked three
dotseditbutton the user may accessa dialog, wherethese combinations are stored together with thedocumented decom-
positionprocess itself.
Bypressing mentionededit button a new dialog isdisplayed. Here the precise processof decomposed EN combinationscan
be viewed andchecked. Finalcombinations canbe foundon the bottom of the dialog, as in each step rule isapplied on the
combinationsfrom theprevious step. Bydefault, all checkare active andneed to be taken into the consideration. If the user
deactivatesthe check itself in the setup, it means, that the rule should be skipped. This will be recognized in the dialog by
showing the warning message under such rule.
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There isalsoa button for exporting all thedataintothe txt file. If used,the user isasked for a path and a filename. Bydefault,
thepathto theuser folder willbe set. After confirmation, txt fileis saved and directly opened ina notepad.
In general, thereare threelevelsof filtering redundantcombinations.
l First filtering isapplied on the levelof decomposed combinations, whereallduplicatedcombinationsare removed
at eachdecomposition level.
l Second level isdone duringgenerating envelope combinations
l Final levelis executed on the levelof linear explosion.
Decomposed EN combinationstakesinto account special rulesgiven byEN 1990Annex A2andEN 1991-2. Not every vari-
able load shouldbe combinedwithall others. For each Structure,a set of appropriate rules isdefined to enableproper gen-
erationof envelope combinations.
Generation rules for Building
CodeEN 1990 A1table A1.1 specifies these possible variable loads:
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Chapter 2
Accordingto the codeEN1991-1-1, it isnot necessaryto combineevery variable loadwith therest. Exact rulesare given sep-
aratelyalsofor buildings. Bydefault, all these rules are enabled, to followstandardEC-EN. However user isable to override
theserules in national annex setup by certain checkboxes. If the certain rule will be unchecked, than the combinations will
ignore the recommendation from EC-EN andwill skip this rule.
In fact, there isonly one rule to be applied for buildings:
Thiscan be interpreted indifferent wordslike:
Category H loading should not be combined withsnow or wind.
Here isthe table, whichshows,how to combine variableloads:
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Asyoucanseefor example, Cat H should be combined with everythingbut Snow and Wind.
Table above shows only Standard EN load groups. Also other additional NA load groups
are correctly taken into accountin the combination rules.
Generation rules for Road bridges
CodeEN 1990 A2table A2.1 specifies these possible variable loads:
Traffic loads(Loadmodels) for road bridges should be, according to thecode EN 1991-2, sorted to severalso called Group
of loads. These groupsof loadsshould be combined with other variable loadsbutnot withother groupof loads fromtraffic.
They are mutuallyexclusive.
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Chapter 2
Problematic groupof loadsgr1a– see example, how it maybe used inthe combination
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If theuser will create multiple load groups withTS, UDL or Pedestrianloadsfor gr1a, it will always be consideredtogether in
thecombination!!Thismeansthat allloadcases from these load groups together will be consideredeither leading or accom-
panying.
Here isthe list of Roadbridgesrulesand a table, whichshows,how to combine variable loads:
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Chapter 2
Asyoucanseefor example, group of loads gr1a should be combined with Wind, Thermal forces Tk and Construction loads
Qc only.
Concentrated load Qfvk
is also mentioned in the EN 1990, but for road bridges no exact group of loads is defined for this
load. It isup to theuser, where heputsit. Probably load groupgr3-pedestrian isthe mostsuitableone.
Generation rules for FootbridgesCodeEN 1990 A2table A2.2 specifies these possiblevariableloads:
Infactgr1equalstoqfk
In fact gr2equalsQserv
+theQfwk
, wherehorizontalforcesshouldnot be considered
Here isthe listof rules for Footbridgesanda table, whichshows, how to combine variable loads:
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BridgeCombinations
Asyou canseefor example, the Group of loadsgr1 shouldbe combined with wind forcesFWk
, Thermal actionsTk andCon-
struction loadsQc only.
Generation rules for Railway bridges
The EN 1990 specifies two different typesof trafficactions whichcan be used. Individual Componentsof traffic Actionsand
Main traffic actions(groupof loads). Sincethe majority of combinationsare done through groupof loads,onlythis option issupported.
CodeEN 1990 A2table A2.3 specifies these possible variable loads:
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Chapter 2
Here isthe listof rules for Railway bridgesand a table, whichshows,how to combine variable loads:
Asyou canseefor example,group of loadsgr13 shouldbe combinedwith Aerodynamics, Gml,ThermalactionsTk andCon-
struction loadsQc only.
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Step 6: NA Setup dialog
Allcombination rules together withѱ values andgvalues may be accessed in the NA Setup dialog. They are different for
buildings and for all three types of bridges. The user mayaccessthem bypressing editbutton for EN 1990 inthe manager of
Nationalannexesdialog.
Bypressing this button theSetup dialog isopened andfrom theveryfirst lookit isobvious, that thewhole structurehasbeen
changed.
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Chapter 2
Combination setup
Accordingto the codes EN 1990 Annex2 and EN 1991-2, it is not necessary to combine every variable load with the rest.
Exactrules are givenseparately for all kindsof bridgesand alsofor buildings. Bydefault, allthese rules are enabled, to follow
standard EC-EN. However user will be able to usethe rules innational annexsetup bycertaincheckboxes. If the certainrule
will be unchecked, thanthe combinationswillignore therecommendation from EC-EN andwill notconsider this rule.
Combination setup rules bothfor bridgesand for buildingsare listed here.
Bysetting focuson a certainrule, the description field will be displayedin thedialog to provide moredetailed info on a selec-
ted value. In this field, threestrings (Reference, Description andApplication) are displayed.
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Combination rules for Buildings:
The followingrulesfor Combination setup for Buildingsare given:
CategoryH loading notto becombinedwith snow or wind
l Reference: EN 1991-1-1: 3.3.2 (1)
l Description: On roofs, imposed loads, andsnow loadsor wind actionsshould not be appliedtogether sim-
ultaneously.
l Application:Generation rule usedincombinations for buildings.
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Combination rules for Road bridges:
The followingrulesfor Combination setup for Roadbridgesare given:
gr1b not to be combined with other non-traffic loads
l Reference: EN 1990: AnnexA2A2.2.2 (2)
l Description:LoadModel2 (or associatedgroup of loadsgr1b) andtheconcentrated load Qfwk
(see 5.3.2.2 inEN
1991-2) on footways need notbe combinedwithany other variable nontraffic action.
l Application: Generation ruleusedincombinationsfor roadbridges.
Snow or wind load not to be combined with gr2
l Reference: EN 1990: AnnexA2A2.2.2 (3)
l Description:Neither snow loadsnor wind actionsneed be combined withbraking andacceleration forcesor the
centrifugal forcesor the associated groupof loadsgr2.
l Application: Generation ruleusedincombinationsfor roadbridges.
Snow or wind load not to be combined with gr3
l Reference: EN 1990: AnnexA2A2.2.2 (3)
l
Description:Neither snow loadsnor wind actionsneed be combined withloadson footways andcycle tracks or with
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theassociatedgroup of loadsgr3
l Application: Generation ruleused incombinationsfor roadbridges.
Snow or wind load not to be combined with gr4
l Reference: EN 1990: AnnexA2A2.2.2 (3)
l Description: Neither snow loadsnor wind actionsneed be combinedwith crowdloading (LoadModel4) or the asso-
ciatedgroup of loadsgr4.
l Application: Generation ruleused incombinationsfor roadbridges.
Snow not to be combined with gr1a and gr1b
l Reference: EN 1990: AnnexA2A2.2.2 (4)
l Description: Snow loadsneed not be combinedwithLoad Models 1 and2 or withthe associatedgroupsof loads
gr1aandgr1bunlessotherwisespecified for particular geographicalareas.
l Application: Generation ruleused incombinationsfor roadbridges.
Wind loads not to be combined with Thermal loads
l Reference: EN 1990: AnnexA2A2.2.2 (6)
l Description: Wind actions andthermalactionsneednot be taken into account simultaneouslyunless otherwise spe-
cified for local climatic conditions.
l Application: Generation ruleused incombinationsfor roadbridges.
Snow loads and wind loads not to be combined with constr. activity
l Reference: EN 1990: AnnexA2A2.2.1 (10)
l Description: Snow loadsand wind actionsneednot be consideredsimultaneously withloadsarising from con-struction activityQca (i.e.loadsdue to working personnel).
l Application: Generation ruleused incombinationsfor roadbridges.
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Chapter 2
Combination rules for Footbridges:
The followingrulesfor Combination setup for Footbridgesare given:
Qfvk
not to be combined with other non-traffic loads
l Reference: EN 1990: AnnexA2A2.2.3 (1)
l Description:The concentrated load Qfwk need not be combinedwithany other variableactionsthatare notdueto
traffic.
l Application:Generation rule usedin combinations for footbridges.
Wind loads not to be combined with Thermal loads
l Reference: EN 1990: AnnexA2A2.2.3 (2)
l Description:Wind actionsandthermalactionsneednot be taken into account simultaneouslyunless otherwise spe-
cifiedfor local climatic conditions.
l Application:Generation rule usedin combinations for footbridges.
Snow loads not to be combined with gr1 and gr2
l Reference: EN 1990: AnnexA2A2.2.3 (3)
l
Description:Snow loadsneed notbe combinedwithgroupsof loadsgr1 andgr2 for footbridgesunless otherwise
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specified for particular geographicalareasand certain typesof footbridges.
l Application:Generation rule usedincombinations for footbridges.
Snow loads and wind loads not to be combined with constr. activity
l Reference: EN 1990: AnnexA2A2.2.1 (10
l Description: Snow loadsand wind actionsneednot be consideredsimultaneously withloadsarising from con-
struction activityQca (i.e.loadsdue to working personnel).
l Application:Generation rule usedincombinations for footbridges.
Combination rules for Railway bridges:
The followingrulesfor Combination setup for Railway bridgesare given:
Snow loads not to be taken into account
l Reference: EN 1990: AnnexA2A2.2.4 (1)
l Description: Snow loadsneed not be taken into account inanycombination for persistentdesign situationsnor for
anytransientdesign situationafter thecompletion of the bridge unless otherwise specified for particular geo-
graphicalareasand certain typesof railwaybridges.
l Application:Generation rule usedincombinations for railwaybridges.
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Wind action not to be combined with gr13 or gr23
l Reference: EN 1990: AnnexA2A2.2.4 (3)
l Description: Windaction need not be combined with groups of loads gr 13 or gr 23.
l Application:Generation rule usedin combinations for railwaybridges.
Wind action not to be combined with gr16, gr17, gr26, gr27
l Reference: EN 1990: AnnexA2A2.2.4 (3)
l Description: Windaction need not be combined with groups of loads gr 16, gr 17, gr 26, gr 27.
l Application:Generation rule usedin combinations for railwaybridges.
Snow loads and wind loads not to be combined with constr. activity
l Reference: EN 1990: AnnexA2A2.2.1 (10)
l Description:Snow loadsandwind actionsneednot be consideredsimultaneously withloadsarising from con-
struction activityQca (i.e.loadsdue to working personnel).
l Application:Generation rule usedin combinations for railwaybridges.
Psi factors
Groupsfor Psi factorsΨ bothfor bridgesand buildingsare implemented here.
Psi factorsare code recommendedvalues and user may edit themby using theappropriate editbutton. By pressing it,new
dialog appears and here the user may adjust the values. The dialog name correspondsto the appropriate typeused. (for
example Psifactors for buildings)
Psi factorsΨ0, Ψ1 and, Ψ2 for buildings are given byEN1990A1, TableA1.1.
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BridgeCombinations
Table above shows only Standard EN load groups. Also other additional NA load groups
are correctly shown inappropriate nationalannexes.
Psi factorsΨ0, Ψ1 and, Ψ2 for road bridgesare given byEN1990 A2, TableA2.1.
Psi factorsΨ0, Ψ1 and, Ψ2 for footbridges aregiven byEN1990 A2, TableA2.2.
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Chapter 2
Psi factorsΨ0, Ψ1 and, Ψ2 for railwaybridges are given byEN1990A2, TableA2.3.
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BridgeCombinations
Load combination factors
Groupsfor Load combination factorsγ bothfor bridgesand buildingsare implemented here.
Loadcombination factorsγ values will be editable directly in the setup.
Asyoucansee from the picture above, by setting focuson an item, the description field isdisplayed at the bottom of the dia-
logto providemore detailed info on a selected value. In this field, threestringsare displayed:
l Reference - providesreferenceto theEN Code
l Description - provides explanation on thevalue
l Application - providesplace, wherethevalue isused
Loadcombination factorsfor buildings from EN 1990 A1,TablesA1.2 (B,C)
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Chapter 2
Load combination factorsfor Roadbridgesfrom EN 1990 A2,TablesA2.4 (B,C)
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BridgeCombinations
Loadcombination factorsfor Footbridges from EN 1990 A2,TablesA2.4 (B,C)
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Chapter 2
Load combination factorsfor Railway bridgesfrom EN 1990 A2,TablesA2.4 (B,C)
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BridgeCombinations
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Chapter 3
Other features
Leading variable action
There isa sub-group, which shows which variable load case isleading for each generatedenvelope combination. Thisinfoisvisible in thecombination dialog, whenthe Content of combination filter isactive.
Thischange willbe noticeablein Content of combination onlyfor such EN Code combinations, which define a leading vari-
able action. These are in fact the red marked combinationson the followingpicture.
The sub-group Leading variable action is displayed together with the appropriate leading variable load case only for such
generatedenvelopecombinations, whichreallycontainsome leading variable action. The load case isdisplayed withoutany
coefficient in this sub-group. If thereis no leading variableaction in the generated envelope combination,no sub groupis
shown.
In caseof Roadbridges, whenall sub-groupsof Group of loadsgr1a are defined,there maybe also morethanone leadingvariable action.
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Other features
(STR/GEO) alternative
The EN 1990 code specifies three possibilities how to define Combinations of actions for persistent or transient design situ-
ations:
Equation 6.10:
Equation 6.10a & 6.10b
Equation 6.10a "modified" & 6.10b
Note1 of Table A1.2(B) specifies, that the choice between 6.10, or 6.10aand6.10b will be in the National annex. In caseof
6.10a and6.10b, the National annexmayin addition modify6.10ato include permanentactionsonly. If applied, thenthe for-
mula would look likethis:
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Chapter 3
The user cannow selectthis 6.10a "modified"& 6.10bequation in the samecombobox, next to alreadyimplemented equa-
tions6.10and equation 6.10a & 6.10b inNA setup dialog. Seethe picture below.
By choosing this Equation, envelope combinations generated from a Code combination 6.10a "modified" will contain only
permanentunfavorable and permanent favorable load cases. No variable, accidental, seismic or prestress load casesare
taken into accountwith this 6.10a "modified" part of equation. Envelope combinationscoming from 6.10b will be the same as
for previousoption from the combobox.
Construction stages
AutomaticallygeneratedCode combinations from the Constructionstagesare createdwith respect to the latest bridgecom-
bination developmentand also envelope combinations should respect rulesand appropriatesettings.
Adjustedimplementation of a Structureparametertogether with the filter for variableload cases in constructionstages envir-
onment should do thetrick.
There isone major switch in the Construction stagessetup, where the user decides which Structure parameter will be used
for allConstructionstages. Building will be setas a defaultvalue, but theuser maystill choose alsooneof thethreebridge
items.
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Other features
When the user creates some construction stages, there will also be parameter Structure displayed right below the Type
parameter. It will not be possible to change it. Also the Type of generated combinations isdisabled if any load group in theproject hasits Structure parameter different thanBuildings.
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Chapter 3
Two comboboxesare implemented inthe dialog below. Combo boxStructure isread from thesetup andis always disabled.
Combo box Type isenabled.The Structurecombo box isnot shownfor Type set to Code independent.
List of variable load cases, inright window, isalways filteredoutaccording to the Structure parameter setin the setup.
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Other features
If the user selects possibility"All", then allgenerated code combinations will havethe Structure parameter set accordingto
the setup.Generated code independent combinationswillnot have the Structure parameter.
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Chapter 4
Example
In this simple example the way how to define and adjust a combination for a Footbridge is illustrated. The functionality is
demonstratedon a simple beam structure, where ineach load case only point force loading will be defined. It showshow to
define load groups, combinationsand also how to handlerules in the NA Setup dialog.
In this example the same steps,as in the previous chapters, are used.
To follow this example, please open the project Footbridge example_initial.esa, which contains a predefined one beam
structureand supports.
Step 1: Activate Protection
In the very first step, the user needs to activate functionality for bridge combinations. This can be done through the folder
Functionalityin the Project datadialog, bychecking theBridgedesign iteminthe left window andthenalsochecking the item
Load combinationsin the right window.
Please note, thatalso functionalityfor Prestressing isactivated, to enableinputof load casesused for prestress loading.
The ruling check box for the bridge combinations functionality is the one which is called
Load combinations. If only the Bridgedesign item in the left window ischecked, it will stillnot
be possible to changetheStructure parameter to oneof thebridge types.
Step 2: Create Load groups
In this step load groupsare created for the Footbridge Structure. Load groupscan be added using theLoad group dialog.The followingloadgroups for permanent, variable, accidental, seismic andprestressloadingwillbe defined:
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Example
Name Load Structure Load type
perm Permanent - -
gr1 Variable Footbridge gr1
Q fvk V ari ab le Fo otb rid ge Q fvk
gr2 Variable Footbridge gr2
Tk Variable Footbridge Tk
Fwk Variable Footbridge Fwk
Q snk V ari ab le Fo otb rid ge Q sn k
Qc Variable Footbridge Qc
Acc Accidental - -
Seis Seismic - -
Prst Permanent - -
Whenever a certain load caseisassigned to a certaincombination, aditionalrestrictionsare
implementedfor load group in Load groups dialog. The Structure parameter will became
disabled anditwill not be possible to change it.On the other hand, the Load type will stillbe
possible to be changed. If the load case is not assigned yet, the user may freely change
loadgroup.
Step 3: Assign Load cases to the Load groups
In this steploadcasesare created for eachload group.Thiscanbe done ina standard wayin theLoadcasesdialog.
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Chapter 4
Name Action type Loadgroup Loadtype
perm Permanent perm Standard
gr1 Variable gr1 Static
Qfvk Variable Qfvk Static
gr2 Variable gr2 Static
Tk Variable Tk Static
Fwk Variable Fwk Static
Qsnk Variable Qsnk Static
Qc Variable Qc Static
Acc Accidental Acc Static
Seis Seismic Seis Static
Prst Permanent Prst Prestress
After definition of all load cases, loading isdefined. In this example, aswe already mentioned at the very beginning, we will
defineonly1KNpoint load inthe middleof thebeam, for everyload case.
Theonlydifference isprestressing load case Prst, wherewe willdefine line load, shown on the picture below, withthe intens-
ityof -0,2Kn/m.
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Example
Whenever a certain load caseisassigned to a certaincombination, aditionalrestrictionsare
implementedfor load case in Load cases dialog. It will still be possible to change the Load
group parameter to something else, but the user may select only load groups with the
sameStructure parameter or independentvariable loadgroupsfor accidental and seismic
loads. By pressing the three dots edit button, the Loadgroups dialogis displayed, but with
filteredcontent. If a load caseisnot assigned yet, the user mayfreelychange load group.
Step 4: Create a Code Combination
After definitionof allload casescombination canbe created. Thiscanbe done through standard Combinationsdialog.User
presses button New inmain Combinationsdialog:
The edit dialog isopenedand bydefault theTypeof thecombination isset to Envelope -ultimate. The structure parameter isnot displayed andtherefore all load casesare visiblein the right window.
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Chapter 4
Setthe type of the combination to EN-ULS (STR/GEO) Set B. The Structure parameter is displayedand bydefault it is set
to Building. Due to this, only permanentload casesare displayed in the right window.
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Example
If theStructure parameter is changed to Footbridge,almost all the predefined load casesappear in the right window.Only
the loadcases fromAccidental and Seismic load groupsare missing. The reasonis that thosemay be inputted only in Acci-
dental1,2or Seismictypesof combinations.
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Chapter 4
Change the Type of the combination to EN-Accidental 1. Notice that now also load case Accis displayedin the window for
possible input.Addall load casesin the combination.
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Example
Change thetype backto EN-ULS(STR/GEO) Set B.A warning that content may be changedis displayed. This isdueto the
fact thataccidental load casesmay be included in thecombination, which isnot correct.Confirm the warning dialog.
If we take a lookat the content of the combination we can find out, that load caseAcc for accidental loadingwas removed
from bothleft andr ight windows. Rename the combination andconfirmthedialog.
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Chapter 4
After the confirmation,we haveSet B combinationcreated in the mainCombinationsdialog.
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Example
Both the Typeand theStructure comboboxesare disabledin this dialog. Thisis to avoidan
incorrect input for thecombination. Both can be changed byediting the combination.
Step 5: Decomposed EN combinations
At thisstep, in fact, everything isdone and envelope combinations are generatedfrom our Code combination. The user may
seeall generated envelope combinations in the main Combinations dialog, by changing filter to "Contents of combination".
In our example thereare 80 generated envelope combinations.
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Chapter 4
A complete info on the decomposed combinations may be found in Decomposed EN combinations dialog, which can be
opened by pressing red marked action button. Here the user may further investigate what happened to the original
"mother" code combinationsand how the rules were applied in theprocess.
Bypressing this action button, thedialog Decomposed EN combinationsis opened:
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Example
Here the user besidesreference and nationalannex is ableto see other infoon the selectedcombination, such asname ,
description, type, structure andoriginal content before the rules were applied. The most important thing in this dialog is, that
allapplicable rules are alsodisplayed. Rulesare split into two main groups:
Fixed elementary rules
these are the rules, whichare alwaysapplied andcannot be changed.
Optional combination rules
theseare rules, whichmay beadjusted in NA setup bychecking/uncheckingappropriate item. There is always a
reference to a EN Codearticle and also status of thecheck box inthe NA setup. If the rule isused, it hasa sign of
greencheck.If therules isnotused, than ithas a redcross sign.
Under each rule, theremaybe a split of original so-called "mother" combination to severaldecomposed combinations. Let's
take a look at the first fixed rule, which specifies, that only one group of traffic loads should be in combination. Since load
cases gr1, Qfwkand gr2are connectedto theload groups,with thesame nameand thesame typeof loads, whichare given
byEN astraffic groups, theyshould notbe combined together. In this stepthe original combination issplit into three decom-
posed combinations called Set B;1, Set B;2 and Set B;3. Each of these combinations contains only load cases from one
traffic load group.
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Chapter 4
Next examine another rule, which is the first from the group of Optionalcombination rules. It specifies thatQfwk should not
be combined with other non-traffic loading. Since this is the second rule which is used, the decomposed combinations,
obtained inthe previous step(Set B;1, Set B;2 andSet B;3) areused.
It can be seen that decomposed combinationsSet B;1 andSet B;3did notchange. It may be seen also in the name of these
combinations. They are exactly the sameas in the previous step. On the other hand thecombination Set B;2 was split into
Set B;2;1and Set B;2;1.
The same procedure can be followed for theother rules. The combinationsused for generation of envelopecombinations
are alwaysshownin the verylast step of the decomposition process(under the last applied rule).
In addition, theExport button can be used to save all information from this Decomposed EN combinationsdialog ina txt file.
Each Structure (Building, Roadbridge,Footbridge, Railway bridge) hasits own setof rules
whichcanbe applied. This isbased onEN 1990 A1& A2.
The first rule applied on the original combination is applied on its original content. Any other rule is applied on the decom-
posed EN combinations, which were generated in previous step. Combinations used for generation of envelope com-
binationsare always shown inthe last step of decomposition process (under last applied rule).
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Example
Step 6: NA Setup dialog
In this step we will show only the change in decomposed EN combinations which concerns deactivating some rules. In the
NA Setup dialog we will deactivate allrulesfor footbridges(see picture below). Changesin Psi andGammavalueswill cause
onlydifferent coefficients, which will be used by load cases in the generated envelope combinations and if not zero, it does
not influence the number of generatedenvelopecombinations.
If take a lookat the generated envelope combinations in main combinations dialog,by changing filter to "Contents of com-
bination" we can see, that80 generatedenvelopecombinationswere reduced to 48 envelope combinations.
In Decomposed EN combinations dialog we can see, that only one fixed rule is being applied. These three combinations
coming from thisrule, are used for generating envelopecombinations instead of the originalCode combination. There isa
note under eachrulewiththe redcross,that this rule isnotusedin decomposition.
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Chapter 4