Transcript First Progress Report.ppt

Structural Analysis of Bridge
Gusset Plates:
Steel vs. Composite
RPI Master’s Project
First Progress Report
Stephen Ganz – 6/5/2012
Problem Description
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The objective of this project is to compare the performance
differences in metallic and composite plates by performing structural
analyses on a Warren truss bridge
Material performance is based on stresses and deflections
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This will be accomplished by comparing results from a computer
generated model of a bridge based on federal and state regulations
Work Accomplished
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Developed overall bridge design
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Developed gusset plate detailed dimensions
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Calculated loads based on bridge model
– Dead Load
– Live load
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Constructed a working 2D FEA model of a Warren truss bridge
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Model development has shown that it is best to include the truss members
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Complete mesh study
Mesh Study
A mesh study was conducted to verify accuracy of the model
This was done by varying the mesh density of the plates until a
convergence of stress was achieved
Plate E
12000
10000
8000
Stress (psi)
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6000
4000
2000
0
0
200
400
600
Num ber of Elem ents
800
1000
1200
Model Development
Model Development
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Originally the bridge model was intended to only consist of gusset plates,
loads and constraints
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The intent of this approach was to minimize model complexity by replacing
the trusses with constraints (infinitely stiff)
Model Development (cont’d)
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However, after many trials and different modeling techniques it has been
determined that 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
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In summary, the following approaches were taken to develop the model:
1. Bridge model consisting of plates and constraints only
2. Analyze plates individually
3. Bridge model consisting of plates and trusses
c
a
Pinned End
g
e
d
b
W
5
i
i
f
W
5
k
j
h
W
5
W
5
l
W
5
Roller End
Bridge Model
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Functional bridge model deflection x100
Expected Outcomes
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Composite gusset plates may offer possible strength advantages over steel
The composites will most likely behave differently
Future Work
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Re-run the bridge model using composite material (Hexcel 8552 / IM7) in
several different ply layups
Compare stresses and deflections
Compare factors of safety based on Von Mises stress for steels and TsaiWu failure criterion for laminates