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RPI Master

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Structural Analysis of Bridge Gusset Plates: Steel vs. Composite RPI Master s Project Second Progress Report Stephen Ganz 6/5/2012 Problem Description The ... – PowerPoint PPT presentation

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Title: RPI Master


1
Structural Analysis of Bridge Gusset
Plates Steel vs. Composite
  • RPI Masters Project
  • Second Progress Report
  • Stephen Ganz 6/5/2012

2
Problem Description
  • The objective of this project is to compare the
    performance differences in metallic and composite
    plates by performing structural analyses on the
    vertical section of a Warren truss bridge
  • Material performance is based on stresses and
    deflections
  • The materials chosen are A36 Carbon Steel and
    HexPly 8552 IM7 prepreg composite
  • This will be accomplished by comparing results
    from computer generated Finite Element Analyses.
  • Requirements for the bridge is based on federal
    and state regulations

3
Steps to Completion
  • Develop Bridge Model
  • Develop Gusset Plate Detail Dimensions
  • Calculated loads based on bridge model
  • Dead Load
  • Live load
  • Constructed a working 2D FEA model of a Warren
    truss bridge
  • Perform a Mesh Study
  • Determine Best Evaluation Method to Analyze
    Composite Plates
  • Run Analyses Compare Results based on FS and
    Deflections

4
Bridge and Plate Details
  • As previously mentioned, the vertical section is
    a Warren Truss with verticals. Its length was
    arbitrarily chosen, but its height and width are
    based on state and federal requirements
  • Gusset plates were selected to be 2 inches thick

5
Loads
  • Loads were based on the overall dimensions of the
    bridge model as well as state and federal
    requirements for vehicles. This included weights
    of the trusses, sidewalks, snow, vehicles and
    road deck.
  • Total Load (W) is 576,636 lbs
  • Total Dead Load 297,201 lbs
  • Trusses 101,721 lbs
  • Sidewalk 43,500 lbs
  • Roadway 205,200 lbs
  • Floor and Roof Joists 98,759 lbs
  • Total Live Load 279,435 lbs
  • Vehicles 188,235 lbs
  • Snow 182,400 lbs

6
Model Development
  • The best way to produce accurate results is to
    include the truss members
  • By using a coarse mesh for the trusses their
    presence comes at very little computing cost
  • Tie constraints bond the the trusses to the
    plates to simulate a weld

Loads were applied as surface tractions (psi) at
the 5 locations shown
7
Mesh Study Failure Method
  • Mesh studies were carried for both steel and
    composite models
  • This was done by varying the mesh density of the
    plates until a convergence of stress or TSAI-WU
    criteria was observed
  • Developing an accurate way of calculating Factors
    of Safety for the composites (CFAILURE)

8
CFAILURE
  • This field output request has been selected as
    the tool to provide the necessary results from
    FEA to base composite failure on
  • CFAILURE is a built in feature in Abaqus that can
    allow the user to view results based on Maximum
    Stress Theory, Maximum Strain Theory, Tsai-Hill
    and Tsai-Wu criterion
  • Factors of safety are calculated as 1/TSAIW for
    each layer
  • Defining the failure stresses in Abaqus (Edit
    Material -gt Suboptions -gt Fail Stress)

9
FEA Results
  • A36 Steel Model
  • Composite Models

0 90S
0 45 90S
Shown here are the maximum values for stress in
the A36 Steel Model and maximum TSAIW values in
the composite models Factors of Safety for Steel
are based on Von Mises stress Factors of Safety
for Composite model are based on TSAIW values
0 15 30 45 60 75 90S
10
Deflections Illustrated x100
  • Composite Models
  • A36 Steel Model

0 90S
0 45 90S
The best performing composite model deformed
nearly twice as much as A36 steel.
0 15 30 45 60 75 90S
11
Factors of Safety
The table below lists the factors of safety based
on failure for all the FEA models. The factors of
safety are based on peak stresses or maximum
TSAIW values for that particular model Steel
displayed the highest factor of safety,
outperforming the best composite by approximately
30.
Table 4 Factors of Safety Table 4 Factors of Safety Table 4 Factors of Safety Table 4 Factors of Safety Table 4 Factors of Safety
Steel Model Steel Model Von-Mises Stress Max allowable FS
A36 Carbon Steel 12668 58000 4.58

Composite Models Composite Models TSAIW Max allowable FS
HexPly 0 90S 0.296 1 3.38
HexPly 0 45 90S 0.286 1 3.50
HexPly 0 15 30 45 60 75 90S 0.400 1 2.50
12
Deflections Illustrated x100
The best performing composite model deformed
nearly twice as much as A36 steel.
Table 5 Deflections Table 5 Deflections Table 5 Deflections Table 5 Deflections Table 5 Deflections
Steel Model Steel Model U magnitude U1 U2
A36 Carbon Steel 0.454 0.180 -0.447

Composite Models Composite Models
HexPly 0 90S 0.890 0.329 -0.879
HexPly 0 45 90S 0.833 0.331 -0.816
HexPly 0 15 30 45 60 75 90S 0.944 0.377 -0.921
Lowest over steel 183 183 183
13
Outcomes
  • The A36 Carbon Steel Gusset plates outperformed
    those made from HexPly 8552 IM7 composite
    material based on failure margin and deflections
  • This is primarily due to ther orthotropic nature
    of composites
  • HexPly 8552 IM7 is much stronger than steel when
    loaded longitudinally, but it is only about half
    as strong as A36 in the transverse directions.
  • Composites do have desirable qualities, but they
    are not suited for this application in which a
    plate is loaded in up to 6 different directions.

14
References
  1. State of Connecticut Department of
    Transportation. Bridge Design Manual.
    Newington, CT 2003.
  2. Kinlan, Jeff. Structural Comparison of a
    Composite and Steel Truss Bridge. Rensselaer
    Polytechnic Institute, Hartford, CT, April, 2012.
    http//www.ewp.rpi.edu/hartford/ernesto/SPR/Kinl
    an-FinalReport.pdf
  3. Abaqus/CAE 6.9EF-1. Abaqus User Manual.
    Dassault Systèmes, Providence, RI, 2009.
  4. Budynas, Richard G. and Nisbett, J. Keith.
    Shigleys Mechanical Engineering Design 9th
    Edition. McGraw-Hill, New York, NY, 2011. 
  5. Abaqus Technology Brief TB-09-BRIDGE-1. Failure
    Analysis of Minneapolis I-35W Bridge Gusset
    Plates, Revised December, 2009.
  6. Gibson, Ronald F. Principles of Composite
    Material Mechanics Second Edition. Boca Raton,
    FL Taylor and Francis Group, 2007.
  7. Najjar, Walid S., DeOrtentiis, Frank. Gusset
    Plates in Railroad Truss Bridges Finite Element
    Analysis and Comparison with Whitmore Testing.
    Briarcliff Manor, New York, 2010.

15
References
  • Beer, Johnston. Vector Mechanics for Engineers
    Statics and Dynamics 7th Edition. New York, NY.
    McGraw-Hill, 2004.
  • Kulicki, J.M. Bridge Engineering Handbook. Boca
    Raton CRC Press, 2000.
  • Meyers, M. M. Safety and Reliability of Bridge
    Structures. CRC Press, 2009.
  • Portland Cement Association. Unit Weights, 2012.
    http//www.cement.org/tech/faq_unit_weights.asp
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