ANSYS and GT STRUDL Models

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25 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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Evaluation of the Sandwich Plate System
in Bridge Decks Using a Plate Approach


Devin Harris


Michigan Tech

Chris Carroll


Virginia Tech

A Comparison Between

ANSYS and GT STRUDL Models

Project Overview

POLYURETHANE CORE
STEEL FACEPLATES
POLYURETHANE CORE
STEEL FACEPLATES
SPS Introduction

Design Approach

Element Validation

ANSYS Models

GT STRUDL Models

Comparison

SPS for Civil Structures

Introduction to SPS


Developed by Intelligent Engineering


Maritime industry


Bridge Application (deck)

Pre
-
fab Panels

Disadvantages


Cost


Limited application


No design provisions

Advantages


Lightweight


Rapid installation


New/rehab

Prefabricated Decks/Bridges


Fabricated panel


limited girder configuration


Wide girder spacing


Larger
cantilevers


Fast erection

Structured Panel Deck

Slip-Critical Bolt
Welded
Connection
Cold-Formed
Angle
Built-up or
Wide Flange
Section
Polymer Core
(Unexposed)
Steel Face Plates
Panel Edge Plate
(Cold-Formed Angle)
Half
-
Scale Bridge (VT Laboratory)


Span ≈ 40 ft; width ≈ 14.75 ft


Deck ≈ 1 in. (3.2
-
19.1
-
3.2)


8 SPS panels


Transversely welded/bolted


Bolted to girders (composite)


2 girder construction

4'-10"
5'-1"
4'-10"
Top Flange Plate
PL 0.625 x 6 x 480
Bottom Flange Plate
PL 1 x 6.4 x 480
Diaphragm Angles
2 x 2 x 0.31
Top and Bottom
Sandwich Plate
PL 0.125 x 60 x 177.2
Girder Web
PL 0.25 x 21.4 x 480
Elastomer Core
0.75 x 60 x 177.2
Bent Angle
PL 0.19 x 7.9 x 177.2
Shenley Bridge (St. Martin, QC)


Completed
-

November 2003


7 days of total construction


Span ≈ 74 ft; width ≈ 23 ft


Deck ≈ 2 in. (6.4
-
38
-
6.4)


10 SPS panels


Transversely welded/bolted


Bolted to girders (composite)


3 girder construction

LAY PANELS

ERECT GIRDERS

& BRACING

Sequence of SPS Construction

BOLT
PANELS TO
BEAMS &
TOGETHER

WELD
DECK
SEAM

COAT DECK

ERECT BARRIERS

Sequence of SPS Construction

LAY ASPHALT

Prefabricated Decks/Bridges


Simple plate


many girder configuration


Small girder spacing


Short cantilevers


Girders attached to deck in factory


Very fast erection

Simple Plate Deck

Welded
Connection
Wide Flange
Section
Polymer Core
(Unexposed)
Steel Face Plates
Cedar Creek Bridge (Wise County, TX)


2
-
Lane rural road


SPS Deck (integral girders)


Span = 3@50 ft


Width = 30 ft


Deck ≈ 1
-
5/8 in.


5/16”
-
1”
-
5/16”

Fabrication Process

Current Bridge Projects

New Bridge IBRC


Cedar Creek


Texas


June ‘08

Research Objective


To develop a
simple

design procedure for
SPS decks for bridge applications

SPS Deck Design Approach

AASHTO Deck Design


Design Methods


Linear Elastic (Equivalent Strip)


Inelastic (Yield
-
Line)


Empirical (R/C only)


Orthotropic Plate


Limit States


Serviceability


Strength


Fatigue

SPS Approach (Layered Plate)


Variable loads and B.C.s


Assume deflection controls


Plastic hinges

Strip Width (S)
Equivalent Strip
Equivalent Strip on Rigid Girders
Slab-Girder Bridge
Slab Section Cut-out
Arbitrary Loading
Deck Continuity
Cut-out
Plate Representation of Bridge Deck
Edge BCs
Simplified
Edge BCs
Simplified
Arbitrary Loading
Slab-Girder Bridge
Slab Section Cut-out
Arbitrary Loading
Deck Continuity
Cut-out
Plate Representation of Bridge Deck
Edge BCs
Simplified
Edge BCs
Simplified
Arbitrary Loading
Simple Support
Fixed Support
Traffic Direction
SPS Plate Representation

Analysis Options


Classical Plate Approach


Navier


Levy


Energy (Ritz)


Finite Element Approach


Shell


Solid


Grid (line elements)

Approach primarily
dependent on B.C.s

FE Model Approach


Shell Model


Advantages


Ideal for thin elements


Computationally efficient


Membrane/bending effects


Single thru thickness
element


Solid Model


Advantages


Realistic geometry
representation


Element connectivity




Disadvantages


Element compatibility


Element connectivity


Stacking limitations*





Disadvantages


Can be overly stiff


User error (more likely)


Complicated mesh
refinement

Material Properties

Face Plates
(Steel)

Core
(Polyurethane)

Composite Section

Young’s
Modulus

(
E
-
ksi
)

29,878

109

Poisson’s
Ratio (
n
)

0.287

0.36

Flexural
Rigidity
(
D
)

N/A





3 3
3
2
2
2 2
2
2
3
1
1
c c
c
p
t p c
c
p
t t
t
t
D E E
n
n
 
 
   
 
 
 
 
   
 
   
   
 
 
 


 




3 3
3
2 2
2 2
2
2
3
1 1
c c
c
p p p
c c
eq
t
p c
t t
t
E t
E
D
n
n
n
n n
 
 
   
 
 
 
 
   
 
   
 
 
   
 
 
 
 
 


2
3
12 1
t eq
equiv
total
D
E
t
n


*
D
t

= flexural rigidity for layered plate (equivalent to EI for a beam)

*
Ventsel, E., and Krauthammer, T. (2001).
Thin plates and shells:theory,
analysis, and applications
, Marcel Dekker, New York, NY.

a
b
q
Fixed Edge
Element Validation (Generic)

Givens:


Boundary Conditions: Fully Restrained


Material Properties: E=29,000 ksi;
n
=0.25


Dimensions: thickness=6” (constant); a=b=L [L/t … 1
-
200]


Load: q = 0.01 ksi (uniform)


ANSYS


Shell 63 (4
-
node)


Shell

91/93

(8
-
node)


Solid 45 (8
-
node)


Solid 95, Solid

191

(20
-
node)


GT STRUDL


BPR (4
-
node plate)


SBHQ6 (4
-
node shell)


IPLS (8
-
node solid)


IPQS (20
-
node solid)

4
0.00126
classical
q L
w
D
 

Midpanel

Deflection (
w
max
)

0
.
95
1
.
00
1
.
05
1
.
10
1
.
15
1
.
20
1
.
25
1.30
1
.
35
1
.
40
1
.
45
1
.
50
1
10
100
Span/thickness ratio (L/t)
SHELL
63
SHELL
91
/
93
SOLID
45
SOLID
95
/
191
IPLS
IPQS
BPR
SBHQ6
Convergence Comparison of ANSYS and STRUDL
Elements
(Square Fixed Plate with Uniform Load )
w
midspan
(FE) /w
midspan
(classical)
Shell
91
/
93
Shell
63
IPQS
Solid
95
/
191
Solid
45
IPLS
BPR
SBHQ
6
GT STRUDL Models

Element Types

BPR

SBHQ6

IPLS

IPQS

GT STRUDL Models

Mesh Verification

IPLS Element Validation
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1
10
100
1000
L/t Ratio
d
FEA
/
d
CLASSICAL
IPLS 6x6x6
IPLS 3x3x3
IPLS 2x2x2
IPLS 1x1x1
IPLS 2x2x1
GT STRUDL Models

Two Dimensional Example

60 in.

60 in.

IPLQ

(2D equivalent of IPLS)

Linear Shape Function

IPQQ

(2D equivalent of IPQS)

Quadratic Shape Function

A shape function is
the relationship of
displacements within
an element.

GT STRUDL Models

Two Dimensional Example

60 in.

60 in.

One Layer

GT STRUDL Models

Two Dimensional Example

60 in.

60 in.

Two Layers

GT STRUDL Models

Two Dimensional Example

60 in.

60 in.

Three Layers

GT STRUDL Models

Two Dimensional Example

60 in.

60 in.

Four Layers

GT STRUDL Models

Two Dimensional Example

120 in.

120 in.

GT STRUDL Models

2D Element Comparison Example
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
0
5
10
15
20
25
Number of Longitudinal Divisions
d
FEA
/
d
Classical
IPLQ 1 Layer
IPLQ 2 Layers
IPLQ 3 Layers
IPLQ 4 Layers
Two Dimensional Example

2D Element Comparison Example
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
0
5
10
15
20
25
Number of Longitudinal Divisions
d
FEA
/
d
Classical
IPLQ 1 Layer
IPLQ 2 Layers
IPLQ 3 Layers
IPLQ 4 Layers
IPQQ 1 Layer
IPQQ 2 Layers
GT STRUDL Models

Aspect Ratios (IPLS vs. IPQS)

Small Aspect Ratios

Large Aspect Ratios

SPS Models


Case I


Simple Support on all edges


Cold
-
formed angles


assume minimal rotational
restraint

Girder Line
Girder Line
Panel Length
Girder
Spacing
Simple Support
Fixed Support
SPS Models


Case II


Simple supports perpendicular to girders


Fixed supports along girders


Rotation restrained by girders & cold
-
formed angles

Girder Line
Girder Line
Panel Length
Girder
Spacing
Simple Support
Fixed Support
SPS Models


Case III


Full restraint on all edges


Rotation restrained by girders & cold
-
formed angles

Girder
Spacing
Panel Length
Girder Line
Girder Line
Simple Support
Fixed Support
GT STRUDL Models

Boundary Conditions/Symmetry

Full Model:

345,600 Elements

406,567 Joints

1,229,844 DOF

Reduced Model:

86,400 Elements

102,487 Joints

307,461 DOF

GT STRUDL Models


Simple


Simple


Simple


Fixed


Fixed


Fixed


2” Thick Plate


1” Thick Plate


Symmetry

Model Construction

GT STRUDL Models

Model Construction

GT STRUDL Models

Model Construction

½”

½”

GT STRUDL Models


Stiffness Analysis


GTSES


GTHCS

Model Construction

DPM
-
w
-
selfbrn, The module 'SPWNDX' may not be branched to recursively

The GTHCS solver partitions the global
stiffness matrix into hyper
-
column blocks of
size V
BS
, and stores these blocks on the
computer hard drive, with only two of these
blocks residing in the virtual memory at a time
reducing the required amount of virtual
memory space.

0
.
95
1
.
00
1
.
05
1
.
10
1
.
15
1
.
20
1
.
25
1.30
1
.
35
1
.
40
1
.
45
1
.
50
1
10
100
Span/thickness ratio (L/t)
SHELL
63
SHELL
91
/
93
SOLID
45
SOLID
95
/
191
IPLS
IPQS
BPR
SBHQ6
Convergence Comparison of ANSYS and STRUDL
Elements
(Square Fixed Plate with Uniform Load )
w
midspan
(FE) /w
midspan
(classical)
Shell
91
/
93
Shell
63
IPQS
Solid
95
/
191
Solid
45
IPLS
BPR
SBHQ
6
Summary of Element Validity


ANSYS Solids


Converged with single thru thickness element


ANSYS Shells


Minimal mesh refinement required for convergence


STRUDL Plate/Shells


Converged but no multiple layer capabilities


STRUDL Solids


Converged with sufficient thru thickness refinement

All Elements are capable of Modeling thin plates, but consideration must be
given to mesh density. Especially, thru thickness density for solid elements

Suggested Improvements


Layered element for composite materials


Redraw Issues in GT Menu


Contour plots without mesh


Undo Button in GT Menu

Model Validation


SPS Panel

Full Scale SPS Panel

Model Validation


SPS Panel

10'-0"
9'-9"
10'-0"
9'-9"
5'-11"
2'-1"
2'-1"

SPS Plate (0.25” plates; 1.5” core)


Support by W27 x 84 beams


Loaded to 77.8 k with concrete filled tires (assumed 10” x 20”)

Experimental vs. Shell Model Predictions

ANSYS

CASE I (SS)

CASE II (Fixed @ Beams)

CASE III (Fixed)

0
10
20
30
40
50
60
70
80
90
-
0
.
6
-
0
.
5
-
0
.
4
-
0
.
3
-
0
.
2
-
0
.
1
0
.
0
Applied Load (kip)
Deflection (in.)
Measured
SS Plate (Case I)
Fixed @ Beams (Case II)
Fully Fixed (Case III)
Load vs. Mid
-
panel Deflection
-
Full
-
Scale Panel (
ANSYS)
Case III
Case II
Case I
Experimental vs. Shell Model Predictions

ANSYS

Experimental vs. Solid Model Predictions

ANSYS

0
10
20
30
40
50
60
70
80
90
-
0
.
6
-
0
.
5
-
0
.
4
-
0
.
3
-
0
.
2
-
0
.
1
0
.
0
Applied Load (kip)
Deflection (in.)
Measured
SS Plate (Case I)
Fixed @ Beams (Case II)
Fully Fixed (Case III)
Load vs. Mid
-
panel Deflection
-
Full
-
Scale Panel (
ANSYS)
Case III
Case II
Case I
Experimental vs. Solid Model Predictions

GT STRUDL

Experimental vs. Solid Model Predictions

GT STRUDL

0
10
20
30
40
50
60
70
80
90
-
0
.
8
-
0
.
7
-
0
.
6
-
0.5
-
0
.
4
-
0
.
3
-
0
.
2
-
0
.
1
0
.
0
Applied Load (kip)
Deflection (in.)
Measured
SS Plate (Case I)
Fixed @ Beams (Case II)
Fully Fixed (Case III)
Load vs. Mid
-
panel Deflection
-
Full
-
Scale Panel (
GT STRUDL)
Case III
Case II
Case I
Model Validation


SPS Bridge

Half
-
Scale SPS Bridge

Model Validation


SPS Bridge


SPS Plate (0.125” plates; 0.75” core)


Support by Built
-
up Girders (depth ~ 23”)


Loaded ~ 24 k with bearing pad (9” x 14”)

9
3,6,8
GIRDER "B"
GIRDER "A"
XX
= STRAIN GAGES
X
= DISPLACEMENT TRANSDUCERS (WIRE POT OR DIAL GAGE)
= STRAIN GAGES LOCATED ON OPPOSITE FACE
"G"
"G"
ELEVATION "G-G"
4,5
1
3
4
6
1,2
2
6
3
4
5
6
5
2
40 ft
4.84 ft
5.09 ft
4.84 ft
1
7
1
2
3
9
7
8
5 ft
5
7
4
7
Panel 1
Panel 2
Panel 3
Panel 4
Panel 5
Panel 6
Panel 7
Panel 8
Experimental vs. Shell Model Predictions

ANSYS

CASE I (SS)

CASE II (Fixed @ Beams)

CASE III (Fixed)

Experimental vs. Shell Model Predictions

ANSYS

0
5
10
15
20
25
30
-
0
.
7
-
0
.
6
-
0
.
5
-
0
.
4
-
0
.
3
-
0
.
2
-
0
.
1
0
Load (kip)
Midspan Deflection (in.)
Measured
SS Plate (Case I)
Fixed @ Beams (Case II)
Fully Fixed (Case III)
Case II
Case I
Load vs. Mid
-
panel Deflection
-
Half
-
Scale Bridge (
ANSYS)
Case III
Experimental vs. Solid Model Predictions

ANSYS

0
5
10
15
20
25
30
-
0
.
7
-
0
.
6
-
0
.
5
-
0
.
4
-
0
.
3
-
0
.
2
-
0
.
1
0
Load (kip)
Midspan Deflection (in.)
Measured
SS Plate (Case I)
Fixed @ Beams (Case II)
Fully Fixed (Case III)
Case II
Case I
Load vs. Mid
-
panel Deflection
-
Half
-
Scale Bridge (
ANSYS)
Case III
Experimental vs. Solid Model Predictions

GT STRUDL

Experimental vs. Solid Model Predictions

GT STRUDL

0
5
10
15
20
25
30
-
0
.
8
-
0.7
-
0
.
6
-
0
.
5
-
0
.
4
-
0.3
-
0
.
2
-
0
.
1
0
Load (kip)
Midspan Deflection (in.)
Measured
SS Plate (Case I)
Fixed @ Beams (Case II)
Fully Fixed (Case III)
Case II
Case I
Load vs. Mid
-
panel Deflection
-
Half
-
Scale Bridge (
GT STRUDL)
Case III
Comparison of ANSYS and GT STRUDL
Models

0
0
.
25
0
.
5
0
.
75
SPS Panel
SPS Bridge
Maximum SPS Panel Deflections @ Peak Load
Measured vs. FEA
Measured
GT STRUDL Solid
ANSYS Shell
ANSYS Solid
Conclusions


SPS deck behavior can be modeled as plate
with variable boundary conditions


Solid and shell elements are applicable


Attention to mesh refinement critical to solid
elements


Higher order elements significantly increase # DOFs


Layered elements ideal for efficiency


GT STRUDL and ANSYS yield similar results,
but not identical


Future investigation of differences in solid/shell
boundary conditions

Acknowledgements


Virginia Department of Transportation


Intelligent Engineering (
www.ie
-
sps.com
)


GT STRUDL Users’ Group


Virginia Tech