Design and Rating 1 3D Analysis with AASHTOWare Bridge Design and - - PowerPoint PPT Presentation

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Design and Rating 1 3D Analysis with AASHTOWare Bridge Design and - - PowerPoint PPT Presentation

Dec 20, 2023 135 likes •688 views

3D Analysis with AASHTOWare Bridge Design and Rating 1 3D Analysis with AASHTOWare Bridge Design and Rating Heres what youll learn in this presentation: 1. Review of finite element modeling basics 2. Review of generated model 3.

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SLIDE 1

3D Analysis with AASHTOWare Bridge Design and Rating

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SLIDE 2

3D Analysis with AASHTOWare Bridge Design and Rating

Here’s what you’ll learn in this presentation:

1. Review of finite element modeling basics 2. Review of generated model 3. Review of the user-interface for steel multi-girder superstructure 4. Review of how the analysis is performed 5. Review of available output 6. Comparison of results for four models with different mesh sizes

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3D Analysis with AASHTOWare Bridge Design and Rating

Here’s what you’ll learn in this presentation:

1. Review of finite element modeling basics 2. Review of generated model 3. Review of the user-interface for steel multi-girder superstructure 4. Review of how the analysis is performed 5. Review of available output 6. Comparison of results for four models with different mesh sizes

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Review of Finite Element Modeling Basics

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Beam elements:

  • Are used for concrete beams, steel girder flanges, and

diaphragms

  • Have six degrees of freedom (DOFs) at each node
  • Generally recognize only single curvature bending
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Shell elements:

  • Are used for the steel girder web and the deck
  • Have four nodes with six DOFs at each node

Review of Finite Element Modeling Basics

Girder Web (Shell Element) (Typ.)

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Deck-to-beam connection:

  • Master-slave constraint – used for 3D curved girder systems
  • Rigid link connection – used for 3D straight girder systems
  • Connects center of gravity of deck to girder top flange

Review of Finite Element Modeling Basics

Deck-to-beam Connection (Typ.)

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Modeling of reinforced concrete sections in 3D:

  • Beam elements used for reinforced concrete beam
  • Shell elements used for deck/top flange
  • Rigid links used for connection (straight girder)

Review of Finite Element Modeling Basics

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Modeling of prestressed concrete sections in 3D:

  • Beam elements used for prestressed concrete beam
  • Shell elements used for deck
  • Rigid links used for connection (straight girder)

Review of Finite Element Modeling Basics

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Modeling of steel beam with concrete deck in 3D:

  • Beam elements used for steel girder flanges
  • Shell elements used for deck and steel girder web
  • Rigid links used for connection (if straight girder)

Review of Finite Element Modeling Basics

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Dead loads:

  • Stage 1 – non-composite dead loads
  • Stage 2 – composite dead loads
  • Distributed loads are converted to nodal forces
  • Discretization of model must be sufficient to ensure series
  • f nodal loads accurately represents distributed load

Review of Finite Element Modeling Basics

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Live loads:

  • Stage 3 – live loads
  • Applied to influence surface
  • Location of vehicle selected to produce maximum of

desired effect

Review of Finite Element Modeling Basics

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Support conditions:

  • Free bearings – permit translation in all directions
  • Guided bearings – permit translation in only one direction,

usually either longitudinal or transverse

  • Fixed bearings – do not permit translation in any direction

For each of these three support conditions, rotation can be provided

  • r limited in many different combinations

Review of Finite Element Modeling Basics

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SLIDE 13

3D Analysis with AASHTOWare Bridge Design and Rating

Here’s what you’ll learn in this presentation:

1. Review of finite element modeling basics 2. Review of generated model 3. Review of the user-interface for steel multi-girder superstructure 4. Review of how the analysis is performed 5. Review of available output 6. Comparison of results for four models with different mesh sizes

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Definition of elements for curved structures:

  • Curvature is represented by straight elements with

small kinks at node points

  • Elements are not curved

Review of the Generated Model

Actual Curve Elements in the model

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Non-skewed model:

  • Deck and beam are divided into elements
  • The software allows user to adjust number of shell

elements and target aspect ratio for shell elements

Review of the Generated Model

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Skewed model:

  • Nodes are defined along the skew

Review of the Generated Model

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Nodes:

  • Numbers each node of generated model
  • Defines X, Y, and Z coordinates for each node

Review of the Generated Model

The tables on this and the following slides define the model generated based on data entered by the user

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Master Slave Node Pairs:

  • Used to define connection between girder and deck for steel

curved girders

  • Master node is in deck
  • Slave node is along girder top flange
  • One-to-one correlation between master node and slave node

Review of the Generated Model

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Beam Elements:

  • Numbers each beam element in the generated model
  • Defines start node and end node
  • Also defines reference node

Review of the Generated Model

  • Sta. Ahead
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Shell Elements:

  • Numbers each shell element in generated model
  • Defines Node1 through Node4 for each shell element

Review of the Generated Model

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Supports:

  • Identifies all support nodes
  • Defines the following in X, Y, Z directions
  • Translation state (fixed or free)
  • Translation spring constant (kip/in)
  • Rotation state (fixed or free)
  • Rotation spring constant (in-kip/Deg)

Review of the Generated Model

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Inclined Supports:

  • Defines constraint type – translational or rotational
  • Defines X, Y, and Z components of a 10’ line oriented in

the direction of constraint (i.e., oriented perpendicular to the direction of allowable movement)

Review of the Generated Model

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Inclined Supports:

  • Constraints specified in local coordinate system at support
  • User defines orientation of local coordinate system as either:
  • Parallel to tangent of member reference line at support
  • Parallel to specified chord angle from the tangent

Review of the Generated Model

S u p p

  • r

t L i n e x z Member Reference Line Plan View Alignment chord 35° to left of tangent

  • 35°

Member is allowed to move along this local x axis Tangent X Z Global Local 1 ' P e r p . L i n e

  • X

+Z

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Member Releases:

  • Generated to model hinges and pinned diaphragm connections
  • Provides the following in X, Y, Z directions
  • Translation release (false or true)
  • Rotation release (false or true)

Review of the Generated Model

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Load Case:

  • Each load is identified by load case and load ID
  • Loads are applied at nodes
  • Provides the following in X, Y, Z directions
  • Force (kips)
  • Moment (kip-ft)

Review of the Generated Model

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SLIDE 26

3D Analysis with AASHTOWare Bridge Design and Rating

Here’s what you’ll learn in this presentation:

1. Review of finite element modeling basics 2. Review of generated model 3. Review of the user-interface for steel multi-girder superstructure 4. Review of how the analysis is performed 5. Review of available output 6. Comparison of results for four models with different mesh sizes

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Superstructure Definitions:

  • Provides tree structure
  • Includes each Member and each

Member Alternative

  • Provides navigational tool to

access each window

Review of the User-Interface for Steel Multi-Girder Superstructure

The following slides highlight data that is specific to 3D finite element models

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Girder System Superstructure Definition – Definition Tab

Review of the User-Interface for Steel Multi-Girder Superstructure

Define Horizontal Curvature Along Reference Line Right Left

  • Sta. Ahead
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Girder System Superstructure Definition – Definition Tab

Review of the User-Interface for Steel Multi-Girder Superstructure

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Review of the User-Interface for Steel Multi-Girder Superstructure

Girder System Superstructure Definition – Analysis Tab

Define refined

  • vs. speed

Define Longitudinal Loading and Transverse Loading

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Review of the User-Interface for Steel Multi-Girder Superstructure

Define Bearing Alignments (Tangent or Chord with Chord Angle) Enter Distance from Reference Line to Leftmost Girder Summary of Girder Radii

Structure Framing Plan Details – Layout Tab

Applies Bearing Alignment Properties to All Members

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Diaphragm Definition

Review of the User-Interface for Steel Multi-Girder Superstructure

Provide all required diaphragm information

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Structure Framing Plan Details – Diaphragms Tab

Review of the User-Interface for Steel Multi-Girder Superstructure

For a 3D analysis, this load is used only if it is entered, and if it is not entered, the software will determine the dead load based on the Diaphragm Definition

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Diaphragm Loading Selection

Review of the User-Interface for Steel Multi-Girder Superstructure

Select diaphragms for influence surface loading in the 3D analysis

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SLIDE 35

3D Analysis with AASHTOWare Bridge Design and Rating

Here’s what you’ll learn in this presentation:

1. Review of finite element modeling basics 2. Review of generated model 3. Review of the user-interface for steel multi-girder superstructure 4. Review of how the analysis is performed 5. Review of available output 6. Comparison of results for four models with different mesh sizes

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Analysis Settings

Review of How the Analysis is Performed

Select 3D FEM (for Design Review or Rating) or 3D FEM- Vehicle Path (for Rating only)

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Analysis Settings – Output Tab

Review of How the Analysis is Performed

Select AASHTO Engine Reports

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SLIDE 38

3D Analysis with AASHTOWare Bridge Design and Rating

Here’s what you’ll learn in this presentation:

1. Review of finite element modeling basics 2. Review of generated model 3. Review of the user-interface for steel multi-girder superstructure 4. Review of how the analysis is performed 5. Review of available output 6. Comparison of results for four models with different mesh sizes

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List of major sections of output

  • Model Actions report provides moments and shears
  • Model, FE Model Graphics, Transverse Loader Patterns available

Review of Available Output

Select for list of major sections of output

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Review of Available Output

Model Viewer:

  • Model can be viewed graphically
  • Model Viewer permits view from many different vantages
  • Ability to select what portions of model are viewed
  • Ability to view influence surfaces
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Review of Available Output

User-interface tabular reports:

  • Output can be viewed in tabular reports
  • This example presents dead load analysis results

Select for tabular results for dead load effects, live load effects, and ratings

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Review of Available Output

User-interface tabular reports:

  • This example presents live load analysis results
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Review of Available Output

User-interface tabular reports:

  • This example presents load rating results
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Review of Available Output

User-interface graphs:

  • Output can also be viewed as graphs
  • This example presents dead load and live load moments

Select for graphical results for dead load and live load effects

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Review of Available Output

Specification checks:

  • Stages 1, 2, and 3 spec checks can be selected at each node
  • Available for selected method (LFR/LFD or LRFR/LRFD)
  • Detailed calculations available for each spec check

Select for specification checks for plate

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SLIDE 46

3D Analysis with AASHTOWare Bridge Design and Rating

Here’s what you’ll learn in this presentation:

1. Review of finite element modeling basics 2. Review of generated model 3. Review of the user-interface for steel multi-girder superstructure 4. Review of how the analysis is performed 5. Review of available output 6. Comparison of results for four models with different mesh sizes

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Compare Results for Four Models with Different Mesh Sizes

Simple beam model example:

  • Consider a 72-ft long simple-span beam
  • Beam depth = 6 feet
  • Concentrated load = 10 kips at midspan

𝐍 =

𝐐𝐌 𝟓 = (𝟐𝟏 𝐥𝐣𝐪𝐭)(𝟖𝟑 𝐠𝐮) 𝟓

= 180 kip-ft

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Simple beam model example:

  • Model 1 – one shell element in the depth
  • Resulting Moment = 110 kip-ft

Compare Results for Four Models with Different Mesh Sizes

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Simple beam model example:

  • Model 2 – two shell elements in the depth
  • Resulting Moment = 144 kip-ft

Compare Results for Four Models with Different Mesh Sizes

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Simple beam model example:

  • Model 3 – four shell elements in the depth
  • Resulting Moment = 170 kip-ft

Compare Results for Four Models with Different Mesh Sizes

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Simple beam model example:

  • Model 4 – eight shell elements in the depth
  • Resulting Moment = 177 kip-ft

Compare Results for Four Models with Different Mesh Sizes

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Simple beam model example:

Analytical solution = 180.0 kip-ft at midspan Conclusion: More shell elements along the depth of the beam results in more accurate results.

Compare Results for Four Models with Different Mesh Sizes

110.238 144.159 169.544 177.13 100 110 120 130 140 150 160 170 180 190 2 4 6 8 10

Middle point moment (kip-ft) Number of shell elements along the depth of the beam

Middle Point Moment (kip-ft)

Analytical solution is 180.0 kip-ft

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Simple beam model example:

Analytical solution = 0.0 kip-ft at support Same conclusion: More shell elements along the depth of the beam results in more accurate results.

Compare Results for Four Models with Different Mesh Sizes

10.018 6.385 3.477 1.78

  • 1

1 3 5 7 9 11 2 4 6 8 10

Support point moment (kip-ft)

Number of shell elements along the depth of the beam

Support Point Moment (kip-ft)

Analytical solution is 0.0 kip-ft

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SLIDE 54

3D Analysis with AASHTOWare Bridge Design and Rating

Here’s what you’ve learned in this presentation :

1. Review of finite element modeling basics 2. Review of generated model 3. Review of the user-interface for steel multi-girder superstructure 4. Review of how the analysis is performed 5. Review of available output 6. Comparison of results for four models with different mesh sizes

54