bridge combinations en 1990

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Bridge DesignBridge Combinations EN 1990



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 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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BridgeCombinations

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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BridgeCombinations

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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BridgeCombinations

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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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BridgeCombinations

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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BridgeCombinations

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


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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BridgeCombinations

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.


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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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BridgeCombinations

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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BridgeCombinations

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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Chapter 2

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 Description:Neither snow loadsnor wind actionsneed be combined withbraking andacceleration forcesor the

centrifugal forcesor the associated groupof loadsgr2.

l Application: Generation ruleusedincombinationsfor roadbridges.



l

Description:Neither snow loadsnor wind actionsneed be combined withloadson footways andcycle tracks or with

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BridgeCombinations

theassociatedgroup of loadsgr3

l Application: Generation ruleused incombinationsfor roadbridges.



l Description: Neither snow loadsnor wind actionsneed be combinedwith crowdloading (LoadModel4) or the asso-

ciatedgroup of loadsgr4.


Snow not to be combined with gr1a and gr1b


l Description: Snow loadsneed not be combinedwithLoad Models 1 and2 or withthe associatedgroupsof loads

gr1aandgr1bunlessotherwisespecified for particular geographicalareas.


Wind loads not to be combined with Thermal loads


l Description: Wind actions andthermalactionsneednot be taken into account simultaneouslyunless otherwise spe-

cified for local climatic conditions.


Snow loads and wind loads not to be combined with constr. activity


l Description: Snow loadsand wind actionsneednot be consideredsimultaneously withloadsarising from con-struction activityQca (i.e.loadsdue to working personnel).


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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 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 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

Description:Snow loadsneed notbe combinedwithgroupsof loadsgr1 andgr2 for footbridgesunless otherwise

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BridgeCombinations

specified for particular geographicalareasand certain typesof footbridges.

l Application:Generation rule usedincombinations for footbridges.


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 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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Chapter 2

Wind action not to be combined with gr13 or gr23


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 Description: Windaction need not be combined with groups of loads gr 16, gr 17, gr 26, gr 27.




l Description:Snow loadsandwind actionsneednot be consideredsimultaneously withloadsarising from con-

struction activityQca (i.e.loadsdue to working personnel).


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

bridge combinations en 1990

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