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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
• 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 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
• Total Load (W) is 576,636 lbs
• Trusses 101,721 lbs
• Sidewalk 43,500 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
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