Aashto Beams Design

8/12/2019 Aashto Beams Design

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FourSpan PS Concrete

Beam AASHTO Type III

Simple Spans InputAsBuilt Model Only

September,2011


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DETAILEDEXAMPLE

FOURSPANPSCONCRETEBEAMAASHTOTYPEIIISIMPLESPANSINPUT

ONLYFOR

AS

BUILT

MODEL

PageNo.

CoverSheet 1

TableofContents 2

BridgeInformation 36

MaterialPropertiesInput 712

BeamShape 1314

Parapet 15

Impactand

Factors

16

17

SuperstructureDefinition(usingtheDiaphragmWizard) 1831

G1Input 3250

LinkingGirders 5153

G2Input(copyingpropertiesfromG1andmodifying) 5463

BridgeAlternative(usingtheSuperstructureWizard) 6468

RatingBridgeandReviewtheOutput(atbothbridgeandmemberlevel) 6987

MathCADcalculations

88

90

SuperstructureBridgePlans(plan,elevation,beamanddeckdetails) 9197


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BRIDGEINFORMATION


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BRIDGEINFORMATION

To create a new bridge right click on the folder where you want to save the bridge and choose New New Bridge.New window will appear, fill the data as shown below. See bridge plans for bridge information.

Template: Template bridges serve as templates to help develop other bridges.

Bridge Completely Defined: Check the box if the specified bridge is completely defined within the Virtis/Opis

Create new

bridge

Input bridge type

and plan number

Federal

ID


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BRIDGEINFORMATIONEnter fields as shown:

The data to input traffic values can usually be found in the road plans for new bridges. For existing bridges, trafficinformation can be found in VDOT traffic report or bridge RNS/PONTIS.

OK button: Saves the bridge description in this window and its tabs to memory and closes the window.

Apply but ton: Saves the bridge description in this window and its tabs to memory and keeps the window open.

Virtis/Opis computes this value as theTruck PCT * ADT * Directional PCT.

Click to acceptand close


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BRIDGEINFORMATION

Click to save

Click to save


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BEAMSHAPE4 ksi concrete for deck:

Copy from Library button: Opens the Library - Materials - Concrete window, allowing you to copy a set of concretematerial properties from the library to this window.

Double click to

open

Click to use datafrom library

Click toaccept


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BEAMSHAPE

5 ksi concrete for PS Concrete beams:

Click to accept

and close

Double click to

open



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BEAMSHAPE

Click toaccept

Change nameto A5


Change to 5and push tab

Select Yes

Ec will be recalculatedbased on 5 ksiconcrete

Select YesInput 4 andpush tab

Initial modulus of


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BEAMSHAPEGrade 60 ksi reinforcing steel:

Double click to

open


Cli k t


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BEAMSHAPE

Prestress strand:


Double click to

open

Click to use data


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BEAMSHAPE

Click toaccept



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BEAMSHAPEI-beam section:

Double click to

open

Click once to

expand

Click once to

expand


Select narrowflange


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BEAMSHAPE


Strand patterncan be modifiedusing this tab


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PARAPETParapet:

Since there are 11 beams in the superstructure, parapet unit weight inputted as zero in this screen. Parapet load willbe applied only to 3 exterior girders in later steps.

Click to accept

Parapet load only appliesto 3 exterior girders. In thiswindow, parapet input asweightless.

Input parapet

name

I t t

Input parapetgeometry

Double click to

open


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IMPACTANDFACTORSImpact/Dynamic Load Allowance:

Factors:


AASHTO

LRFD Default

Double click toopen


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IMPACTANDFACTORS


Click toaccept


You can open to review the factorsfor different materials. Nomodification is needed.


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SUPERSTRUCTUREDEFINITIONSuperstructure Definition:

A girder system defines a set of girders within a cross section, including each girders relationship to the others.

In this example, all spans are identical, so one simple span was defined and assigned for Spans 1 to 4.

For PS Concrete Bridges, some of the lengths are defined based on CL to CL of bearings (full model) and some of thelengths are defined based on end to end of the PS beams (beam model). For further clarification, following is theinstruction from Virtis Manual:

Double click to

open



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SUPERSTRUCTUREDEFINITION


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Factor override:Allows you to override the System Defaults library factors with a set of factors that have beenentered for this bridge only. Factor overrides will remain when files are imported into future versions of Virtis. Unless

CL to CL ofbearings

Simplespan

OverrideLRFR factors


Click to applythe changes

Do not check (forillustration only)


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Add Default Load Case Descript ions button: Adds four default load cases to the load case description table asshown above. The default load cases include dead load (DC) acting on non-composite section, dead load (DC) actingon long term composite section, dead load (DW) acting on long term composite section and stay-in-place forms actingon non-composite section. These default load cases can be edited and modified as desired.

Framing Plan Detail:

Double click to

open


Click to usedefault loads


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Clockwise

skew, positive

Input skew

Input girder

spacing

Click to apply

the changes


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See MathCAD

calculations on page 90


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Click to apply

the changes

Click to applythe changesClick to add

new line orduplicate a line


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SUPERSTRUCTUREDEFINITIONCompute button: Opens the Compute Lane Positions window, which presents the computed values in the laneposition table based on information that you have entered using the other tabs of the Structure Typical Sectionwindow.

Apply button will populate the computed values for Lane Position.

Click toapply

This exampledoes not havewearingsurface



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SUPERSTRUCTUREDEFINITIONNote: It is strongly recommended that the bridge data be saved at this point.

To access the Structure Typical Section view , your structure typical section must be highlighted in the BridgeWorkspace tree. Once structure typical section is highlighted, schematic view can be accessed by selecting ViewSchematic. This option is also available in toolbar under Bridge Menu or by right clicking on Structure TypicalSection.

Click on ViewSchematic

Highlight StructureTypical Section

Click here toclose thescreen

O S S CO C S O S S S


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SUPERSTRUCTUREDEFINITIONTo access the Framing Plan view , your framing plan detail must be highlighted in the Bridge Workspace tree. Onceframing plan detail is highlighted, schematic view can be accessed by selecting View Schematic. This option is alsoavailable in toolbar under Bridge Menu or by right clicking on Framing Plan Detail.

Click on ViewSchematic

Highlight FramingPlan Detail

Click here toclose thescreen

FOUR SPAN PS CONCRETE BEAM AASHTO TYPE III SIMPLE SPANS INPUT


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SUPERSTRUCTUREDEFINITIONStress Limits:

Double click to

open

Select Class A5 forPS Beams

Programcalculates stresslimits

Click to accept

and close



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SUPERSTRUCTUREDEFINITIONPrestress Properties:

Double click to

open

Select P/S strand




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SUPERSTRUCTUREDEFINITIONShear Reinforcement:

Double click to

open


FOURSPAN PS CONCRETE BEAM AASHTO TYPE III SIMPLE SPANS INPUT


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G1INPUTMembers:

Existing: Check the box next to the name of the member alternative that represents the existing member. The

Double click to

open

Click to accept

and close

FOURSPAN PS CONCRETE BEAM AASHTO TYPE III SIMPLE SPANS INPUT


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FOUR SPANPSCONCRETEBEAMAASHTOTYPEIIISIMPLESPANSINPUT

G1INPUTMember Loads:

Double click to

open

Select DC1 to add

additional deckweight at overhang Click to add

load



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G1INPUT

Select DC2 to addparapet weight

Click to addload

Input parapet load(1/3 of parapet weight,see MathCAD calcs.)

Click to applythe load

Select SIP Formsto add SIP weight

Click to addload



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G1INPUT

Load for G2 to G11: Repeat the same steps and input DC1, DC2 and SIP Form loads for all other beams. SeeMathCAD calculations for interior and exterior loads. Self-weight for deck and PS concrete beams will be calculatedby program. Concrete diaphragm weight was input previously in framing plan.

Note: It is strongly recommended that the bridge data be saved at this point.

Supports:

Input SIP Form weight(see MathCAD calcs.)


Double click to

open



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G1INPUT

Support Type: Select the support types as either pinned, roller, fixed, free, or other. Check marks will automaticallyappear in the appropriate boxes for translation and rotation constraints to correspond with the selected support type.

Support Type for G2 to G11: Repeat the same step and input support type for all other beams.

Member Alternatives: Note that the following steps provide input for G1. Later, Member Alternative contents will becopied to G2 and G4 and modified. The remaining girders will be linked to either G1, G2 or G4.


Double click to

open



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G1INPUT

Material Type: Select the material type. Virtis/Opis currently limits floorbeam and stringer definitions to steel beams.

Girder Type: Select the girder type. The girder types available are dependent upon the selected material type.

Default rating method: Select the default rating method to be used for the member alternative.


For PS beam, only optionis schedule based


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G


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G1INPUT

Live Load Distribution:


Virtis does not have the beam

information to generate Live Load

Distribution at this stage. Skip this

item for now.


G1 INPUT


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G1INPUTShrinkage/Time:

Double click to

open



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G1 INPUT


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G1INPUT


End of thebeam to CLbearings

SeeMathCADcalculations

Click to add aline


Beamlength (end

to end)


G1 INPUT


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G1INPUT

Strand Layout:


Double click to

open

Virtis computesfor intentionallyroughened


G1 INPUT


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G1INPUT

By clicking on each

location, selectstrands at mid-spanbased on PSconcrete beam

Strands pattern at

mid-span

Verify total

Length from endof the beam toharp point


G1INPUT


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Note: Since G2 (interior girder) is not inputted yet, Virtis cannot generate deck profile for G1 at this point. Deck profilefor G1 will be generated in next steps, after inputting G2.

By clicking on eachlocation, selectharped strands at endof the beam based onPS concrete beam

Select left end toinput harpedstrand location



G1INPUT


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Haunch Profile:

Double click to

open

Click to add aline


G1INPUT


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Shear Reinforcement Ranges:


Double click to

open


G1INPUT


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The ranges of Shear Reinforcement must be defined in this tab over the entire the length of the PS Concrete Beam.

At this point beam information for G1 is completed and Virtis will be able to generate Standard Live Load DistributionFactors.

Input stirrupslocation



G1INPUT


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Live Load Distribution:

Double click to

open


G1INPUT


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Note: Standard Distribution Factors for LFR were created. However, since G2 (interior girder) is not input yet, Virtiscannot generate LRFD Live Load Distribution Factors for G1 at this point. LRFD Live Load Distribution Factors for G1will be generated after inputting G2.




LINKINGGIRDERS


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Link with: Select the member to which this member is to be linked. If two members are linked, they share the samedefinition and any revisions to one member affect the other member. If the applied loads acting on the two membersare different (due to different tributary width, different arrangements of parapets, medians, sidewalk, the railings, and

different lane positions), then they should not be linked with one another. If you do not want to link this member withany other member, select None. This input field is available for girder system only.

G11 is identical to G1 so it can be linked to G1 as shown below:

Double click to

open


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LINKINGGIRDERS


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Repeat same steps to link G9 and G10 to G2.

G5, G6, G7 and G8 are identical to G4 so they can be linked to G4 (see linking G3 to G2 instruction).



G11 is linked to G1

G3, G9 and G10 linked to G2

G5, G6, G7 and G8 linked to G4


G2INPUTCopy Properties:


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Copy Properties:

Since most girder detail and properties are similar between interior and exterior girders of this bridge, you can copy

properties of one girder to another as shown below:

Right click on G1 and choose Copy.


G2INPUT


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Right click on Member Alternative for G2 and paste. You will notice that a copy of G1 is placed under G2 MemberAlternative. Double click to open it.

After copying and pasting exterior beam to interior, the following items need to be updated in interior beam:

- Live Load Distribution Factors (Standard and LRFD)- Deck Profile- Haunch Profile- Beam details and strand layout (if interior and exterior beams are different) In this case, they are identical.


Rename MemberAlternative to G2

Double click to

open


G2INPUT


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Click tore-compute



G2INPUT


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Click here to reviewdeflection, moment andshear distribution factors

Click to accept

Virtis generatesLive LoadDistribution Factors


G2INPUT


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Double click to

open

Click tocompute

deck thicknessid d


G2INPUT


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If there is an error,manually input

effective width

For simple span, inputtingdeck reinforcement is notnecessary


Double click to

open

Click to accept

and close


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G2INPUT


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Click here to reviewdeflection, moment andshear distribution factors


Virtis generates

Live LoadDistribution Factors


G2INPUTAt this point G2 is input and Virtis can generate Deck Profile for G1:


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At this point, G2 is input and Virtis can generate Deck Profile for G1:

Double click to

open

Click tocompute


G2INPUT


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Next step Copy G2 to G4 (similar to copying G1 to G2). When you copy a beam, the following items may need to beupdated:

- Live Load Distribution Factors (Standard and LRFD)- Deck Profile- Haunch Profile- Beam details and strand layout (if interior and exterior beams are different)

In this example, since G2 and G4 are identical, no update is needed.


deck thicknessconsidered non-structural

If there is an error, manuallyinput effective width based onbridge typical section

For simple span, inputtingdeck reinforcement is notnecessary



BRIDGEALTERNATIVEA bridge can have several unique bridge alternatives. Each bridge alternative must include the entire bridge but canconsist of different layout of superstructures The number of spans the span lengths and the pier locations are


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consist of different layout of superstructures. The number of spans, the span lengths, and the pier locations aredefined within the bridge alternative (and its accompanying windows). Entering different alternatives can be usefulwhen comparing various alternatives for a preliminary study.

The Description tab of bridge Alternative window allows you to describe the orientation of the bridge alternativereference line with respect to the bridge global reference point. You can generate the bridge alternative using theSuperstructure wizard or manually enter the require information. This data is more for information purpose than forcalculations. In this example, Superstructure wizard was used as shown below:

Double click to

open

Click here


BRIDGEALTERNATIVE


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Input number

of spans

Click to

generate

Click to

finish

Verify correct

superstructure

definition is selected

Click to

generate


BRIDGEALTERNATIVE


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Bridge alternative for 4 simplespans (spans are identical)


Right click on Bridge

Alternatives and select

Expand Branch


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BRIDGEALTERNATIVETo export the XML file to hard drive or server, click on file\export.


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RATINGBRIDGEANDREVIEWTHEOUTPUTRating the bridge, reviewing the results and output:

Click on View analysis setting to select vehicles for ratings


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Click on View analysis setting to select vehicles for ratings.

Set the Rating

Method to LRFR

VA Semi is similar to VA Type 3S2 andVA Single is similar to VA Type 3


RATINGBRIDGEANDREVIEWTHEOUTPUT


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Select the following trucks for simple span bridge rating. Since span lengths are less than 200, Legal Lane Load isnot required for rating.


RATINGBRIDGEANDREVIEWTHEOUTPUTClick on


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Click on

Advanced

Make sure permit loads are

set with unlimited crossing

mixed with traffic



RATINGBRIDGEANDREVIEWTHEOUTPUTTo review the reactions and specification checks, make sure all items are checked in output menu.


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Click on Analyze button to start the analysis to rate individual girders in Bridge Workspace:

Select to analyze

all girders



RATINGBRIDGEANDREVIEWTHEOUTPUTAnalysis can be done from the top for the whole structures as shown above or from the member folder for eachindividual girder as shown below. Simply select and click Analyze button to start.


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g p y y

Select for one

girder rating


RATINGBRIDGEANDREVIEWTHEOUTPUTTo review the result, select the girder and click on View analysis report icon.


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Step 1: Select

one girder

Step 2: Click to

review results


RATINGBRIDGEANDREVIEWTHEOUTPUTRate entire bridge in Bridge Explorer:


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Select the bridge in Bridge Explorer and click Rate.

Click to

close model

Step 2: Clickon the bridgein explorer

Step 1: Select Bridge

Explorer

Step 3: Click

on Rate




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Click to acceptand run

Click toclose


RATINGBRIDGEANDREVIEWTHEOUTPUTWhen using this method to rate the entire bridge, a screenshot for the lowest ratings will show on the screen


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Reviewing Output in Virtis. To review the output, calculations and specification checks, open the bridge and run allgirders or one individual girder as shown in the previous steps. In this example G1 is analyzed.




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To review the reactions and specification checks, make sure all items are checked in output menu.



RATINGBRIDGEANDREVIEWTHEOUTPUTClick on Analyze button to start the analysis.


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RATINGBRIDGEANDREVIEWTHEOUTPUTTo review analysis charts, select girder and click on view analysis charts icon.


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Click on view analysis

charts to see moment,

shear and deflection


RATINGBRIDGEANDREVIEWTHEOUTPUTTo review specification check, select girder and click on view spec check icon. Click on Specification Referencecolumn header to sort the column.


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Click on View Spec

Check to see

calculation details

Click to

select

Click on each column

to sort the results


RATINGBRIDGEANDREVIEWTHEOUTPUTScroll down to 5.7.3.2 Flexural Resistance to review moment capacity.


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Click toselect

Shows if item

passed or

failed




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RATINGBRIDGEANDREVIEWTHEOUTPUTRating factor for Flexure (scroll down to 6.4.2.1 concrete flexure general load rating equation)


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Click to

select


RATINGBRIDGEANDREVIEWTHEOUTPUTRating factor for PS Tensile Stress:


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Click to

select


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RATINGBRIDGEANDREVIEWTHEOUTPUTRating factor for Shear: Scroll down to 6.4.2.1 concrete shear general load rating equation.


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Click to

select

Subject: Calculations for Bridge Load Rating Using Virtis

Structure ID: 21953State Bridge No: 131-2551

S D fi i i (A B il S 1 2 3 4)


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Superstructure Definition (As-Built Spans 1, 2, 3 or 4):

Framing Plan:

Skew DMS 10 21, 15,( ) 10.354 deg=:=

Structure Typical Section:

Spacing

Bay1to10

5ft 8in+ 5.667 ft=:=

Overhang 2ft:=

Member Alternatives:

kips 1000lb:=

Beam Details:

n

28500kips

in2

4074.28kips

in2

6.995=:= Use 7

Member Loads:

SIP Form Weight:

wSIP 20 lb

ft2

:=

WSIP_Ext wSIP

SpacingBay1to10

2 0.057

kips

ft=:= On G1 & G11

WSIP_Int wSIPSpacingBay1to10 0.113 kipsft

=:= On G2 to G10

Additional deck overhang weight:


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Diaphragm Weight (Intermediate):


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5'-8"

3'-9"

1'-212"

Adiaphragm 13.4417ft2

:=

tdiaphragm 8in:=

Wdiaph Adiaphragmtdiaphragm c 1.34 kips=:=

Diaphragm Weight (End) :

5'-8"

3'-9"

1'-9"

Adiaphragm 9.908ft2

:=


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VDOT VERSION 6.2


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VDOT VERSION 6.2


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VDOT VERSION 6.2


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VDOT VERSION 6.2


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VDOT VERSION 6.2


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Aashto Beams Design

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Transcript of Aashto Beams Design