Determination of AASHTO Bridge Design Parameters through Field

179 Pages·2002·4.57 MB·English

by  Thomas E. Cousins

Determination of AASHTO Bridge Design Parameters through Field Evaluation of
the Rt. 601 Bridge: A Bridge Utilizing Strongwell 36 in. Fiber-Reinforced Polymer
Double Web Beams as the Main Load Carrying Members

By

Edgar Salom Restrepo

Thesis submitted to the Faculty of the
Virginia Polytechnic Institute and State University
In partial fulfillment of the requirements for the degree of

Master of Science
In
Civil Engineering

Thomas E. Cousins, Chair
John J. Lesko
Jose P. Gomez
Carin L. Roberts-Wollmann

December 3rd, 2002

Blacksburg, Virginia

Key Words: Composite materials, fiber-reinforced polymer (FRP), hybrid composite
beam, pultruded structural beam, wheel load distribution, dynamic load allowance,
deflection control, bridge design
Determination of AASHTO Bridge Design Parameters through Field Evaluation of
the Rt. 601 Bridge: A Bridge Utilizing Strongwell 36 in. Fiber Reinforced Polymer
Double Web Beams as the Main Load Carrying Members

Edgar Salom Restrepo

(ABSTRACT)

The Route 601 Bridge in Sugar Grove, Virginia spans 39 ft over Dickey Creek.
The Bridge is the first to use the Strongwell 36 in. fiber reinforced polymer (FRP) double
web beam (DWB) in its superstructure. Replacement of the old bridge began in June
2001, and construction of the new bridge was completed in October 2001. The bridge
was field tested in October 2001 and June 2002.
This thesis details the field evaluation of the Rt. 601 Bridge. Using mid span
deflection and strain data from the October 2001 and June 2002 field tests, the primary
goal of this research was to determine the following AASHTO bridge design parameters:
wheel load distribution factor g, dynamic load allowance IM, and maximum deflection.
The wheel load distribution factor was determined to be S/5, a dynamic load allowance
was determined to be 0.30, and the maximum deflection of the bridge was L/1500.
Deflection results were lower than the AASHTO L/800 limit. This discrepancy is
attributed to partial composite action of the deck-to-girder connections, bearing restraint
at the supports, and contribution of guardrail stiffness.
Secondary goals of this research were to quantify the effect of diaphragm removal
on girder distribution factor, determine torsion and axial effects of the FRP girders,
compare responses to multiple lane symmetrical loading to superimposed single lane
response, and compare the field test results to a finite element and a finite difference
model. It was found that diaphragm removal had a small effect on the wheel load
distribution factor. Torsional and axial effects were small. The bridge response to
multilane loading coincided with superimposed single lane truck passes, and curb-
stiffening effects in a finite difference model improved the accuracy of modeling the Rt.
601 Bridge behavior.
Acknowledgements

The author would like to thank the following people for their contribution and support in
this research:
• Dr. Thomas E. Cousins, for serving as my advisor throughout the course of this
research. Dr. Cousins was very instrumental in influencing my decision to
continue my education in structural engineering at Virginia Tech. Without his
guidance and patience in dealing with me throughout this research, this thesis
would not have been possible. It has been a tremendous experience to work for
Dr. Cousins, an individual who is committed to both his profession and family.

• Dr. John (Jack) Lesko, for serving on my committee and playing an integral part
in making this research possible. As the resident expert on composite materials,
his insights toward making suggestions and improvements on this research have
been valuable.

• Dr. Carin Roberts-Wollmann, for serving on my committee and helping me to
know the whereabouts of Dr. Cousins whenever he had vacated his office. Her
inspiration in the classroom as well influenced my decision to steer my emphasis
toward bridge engineering. And for her flexibility in allowing me to borrow her
students from time to time to accompany me to Sugar Gove.

• Jose Gomez, for serving on my committee and acting as the liason between
Virginia Tech and VDOT. Without his help, this project would have never
progressed.
• Christopher Waldron, for his guidance when I began on this project as an
assistant in laboratory experimentation, and helping to instrument the FRP girders
at the Strongwell plant. His enthusiasm on Monday mornings on providing expert
football analysis for Miami Dolphin victories will sorely be missed as well.
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• Michael Hayes, for his expertise on composite materials, MegaDac assistance,
providing assistance with the finite models, and for scheduling pickup basketball.
Tuesday and Thursday afternoons at War Memorial will sorely be missed as well.

• Matthew Harlan, for assisting me on both field tests and accompanying me on
all those journeys to Sugar Grove and back regardless of what the task called for.
Matthew’s help was invaluable to this research.

• Mike Brown and Bernie Kassner, for providing much needed assistance during
the June 2002 field test. Their help and cooperation was invaluable to this
research.

• Jim Fazio, for helping to instrument the FRP girders at the Strongwell Highlands
Plant. Our discussions on freshman statics classes brought back some fond
memories.

• Jason Cawrse, for accompanying me during trips to take pictures of construction.
And for our “wager”, which motivated me to finish before the 2003 new year.

• The Sugar Grove Diner, for providing quality food at a close proximity to the
Rt. 601 Bridge. Whether it was breakfast, lunch or dinner, the diner satisfied
appetites after a full day of work.

• Brett Farmer and Dennis Huffman, for allowing me lab space while I worked
on the MegaDac among other miscellaneous tasks when preparing for the field
tests.

• Strongwell Inc., VTRC, and VDOT, for their collective efforts and cooperation
among one another in making this project happen. Without their efforts in
providing materials, funding, and construction services, this research would never
have become a reality.
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• Virginia Tech Structural Engineering and Materials Program, both students
and faculty for their influence in helping me to make the most out of this
opportunity of pursuing an advanced degree. The lessons I’ve learned, both in
and outside of class from, will be invaluable as I begin the next stage of my life as
a young professional.

• Marty and Pamela Downs, for allowing me to stay put in Blacksburg at the most
critical time of this research. Their flexibility and hospitality is much appreciated.

I would like to thank my brothers, Frank, and Edward, for their emotional and
motivational support upon completing this research. They have always been there for
me when I needed advice.

And Finally, I would like to thanks my parents, Ana Maria and Jairo Restrepo, for
their emotional as well as financial support they have given me over my academic
career. Without their love, support, and encouragement, all of this would have never
been possible.
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Table of Contents
Table of Contents............................................................................................................... .vi
List ofTables .................................................................................................................... viii
List of Figures.................................................................................................................... ix
Chapter 1: Introduction...............................................................................................1
1.1 Introduction.........................................................................................................1
1.1.1 Design Standards........................................................................................2
1.1.2 Objectives...................................................................................................4
Chapter 2: Literature Review.....................................................................................6
2.1 Literature Review................................................................................................6
2.1.1 Field Test of Bridges using FRP as main load carrying members..............6
2.1.2 Tom’s Creek Bridge....................................................................................9
2.2 Route 601 Bridge..............................................................................................10
2.2.1 Rt. 601 Bridge Design Assumptions.........................................................11
2.3 AASHTO Design Guide Parameters................................................................14
2.3.1 Dynamic Load Allowance........................................................................14
2.3.2 Wheel Load Distribution Factor...............................................................16
2.3.3 Deflection Control....................................................................................19
2.4 Scope of Research.............................................................................................20
2.5 Figures...............................................................................................................22
Chapter 3: Experimental Procedures.......................................................................28
3.1 Bridge Instrumentation.....................................................................................28
3.1.1 Girder Strains............................................................................................28
3.1.2 Girder Deflections.....................................................................................30
3.1.3 Data Acquisition.......................................................................................31
3.2 Procedure of Field Testing................................................................................32
3.2.1 Truck Description.....................................................................................32
3.2.2 Truck Orientations....................................................................................33
3.2.3 Dynamic Testing.......................................................................................34
3.2.4 Investigation of Diaphragm effects...........................................................34
3.3 Tables................................................................................................................36
3.4 Figures...............................................................................................................38
Chapter 4: Discussion of AASHTO Parameter Results..........................................56
4.1 Wheel Load Distribution Factor, g...................................................................56
4.1.1 Procedure of Calculation of GDF.............................................................58
4.1.2 Wheel Load Distribution Results of October 2001 Test...........................58
4.1.3 Wheel Load Distribution Results June 2002 Test.....................................62
4.1.4 Comparison of Girder Distribution Results..............................................64
4.2 Dynamic Load Allowance................................................................................65
4.2.1 Procedure of Calculation of Dynamic Load Allowance...........................66
4.2.2 Dynamic Load Allowance Results October 2001 Test.............................67
4.2.3 Dynamic Load Allowance Results June 2002 Test..................................69
4.2.4 Comparison of Dynamic Load Allowance Results...................................69
4.3 Deflection Limits..............................................................................................70
4.4 Tables................................................................................................................74
4.5 Figures...............................................................................................................92
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Chapter 5: Secondary Results.................................................................................121
5.1 Effects of Diaphragms....................................................................................121
5.2 Axial and Torsional Effects............................................................................124
5.3 Symmetry Response........................................................................................125
5.4 Comparison to Theoretical Models.................................................................125
5.4.1 October 2001 Comparisons.....................................................................126
5.4.2 June 2002 Comparison............................................................................128
5.5 Bridge Redesign and Optimization.................................................................131
5.6 Tables..............................................................................................................133
5.7 Figures.............................................................................................................137
Chapter 6: Conclusions and Recommendations....................................................157
6.1 Conclusions.....................................................................................................157
6.2 Recommendations for future research............................................................159
References.......................................................................................................................161
Vita..................................................................................................................................164

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List of Tables
Table 2-1: AASHTO LRFD (1998) Dynamic Load Allowance......................................16
Table 2-2: AASHTO LRFD (1998) Girder distribution factors for glued laminated deck
supported by steel stringers.......................................................................................17
Table 3-1: October 2001 test sequence............................................................................36
Table 3-2: June 2002 test sequence..................................................................................37
Table 4-1: Girder distribution results based on strain data for the East interior lane passes
during October 2001 test...........................................................................................74
Table 4-2: Girder distribution results based on deflection data for the East interior lane
passes during October 2001 test...............................................................................74
Table 4-3: Girder distribution results based on strain data for the West interior lane passes
during October 2001 test...........................................................................................75
Table 4-4: Girder distribution results based on deflection data for the West interior lane
passes during October 2001 test...............................................................................75
Table 4-5: Girder distribution results for center lane pass based on strain data from
October 2001 test......................................................................................................76
Table 4-6: Girder distribution results for center lane pass based on deflection data from
October 2001 test......................................................................................................76
Table 4-7: Girder distribution results for multiple lane pass based on deflection and
strain data from October 2001 test............................................................................77
Table 4-8: Girder distribution results based on strain data for center lane passes during
June 2002 test............................................................................................................78
Table 4-9: Girder Distribution Results based on deflection data for Center Lane Passes
during June 2002 test................................................................................................79
Table 4-10: Girder distribution results based on strain data for East interior lane passes
during June 2002 test................................................................................................80
Table 4-11: Girder distribution results based on deflection data for East interior lane
passes during June 2002 test.....................................................................................81
Table 4-12: Girder distribution results based on strain data for West interior lane passes
during June 2002 test................................................................................................82
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Table 4-13: Girder distribution results based on deflection data for West interior lane
passes during June 2002 test.....................................................................................83
Table 4-14: Girder distribution results based on strain and deflection data for West and
East exterior lane passes during June 2002 test........................................................84
Table 4-15: Girder distribution results based on strain and deflection data for multiple
lane passes during June 2002 test.............................................................................85
Table 4-16: Summary of maximum girder distribution results from the fall 2001 and
summer 2002 field tests............................................................................................86
Table 4-17: Summary of maximum girder distribution results from the fall 2001 and
summer 2002 field tests............................................................................................87
Table 4-18: Sample calculation of dynamic load allowance............................................88
Table 4-19: Dynamic Load Allowance Summary. Results are based on maximum girder
strain..........................................................................................................................89
Table 4-20: Dynamic Load Allowance Summary. Results are based on maximum girder
deflections.................................................................................................................90
Table 4-21: Deflection Summary of October 2001 and June 2002 field tests.................91
Table 5-1: East interior pass comparison showing effect of diaphragm removal on girder
distribution factors based on averaged strain data..................................................133
Table 5-2: East interior pass comparison showing effect of diaphragm removal on girder
distribution factors based on averaged deflection data...........................................133
Table 5-3: East exterior pass comparison showing effect of diaphragm removal on girder
distribution factors based on averaged strain data..................................................134
Table 5-4: East exterior pass comparison showing effect of diaphragm removal on girder
distribution factors based on averaged deflection data...........................................134
Table 5-5: Superimposed vs. multiple lane results based on strain...............................135
Table 5-6: Superimposed vs. multiple lane results based on deflection........................136

ix
List of Figures
Figure 2-1:Old Route 601 Bridge Elevation.....................................................................22
Figure 2-2: Old Rt. 601 Bridge Superstructure.................................................................22
Figure 2-3: Timeline of Rt. 601 Bridge Project ..............................................................23
Figure 2-4: Strongwell 36 in. Double Web Beam. All dimensions in inches..................23
Figure 2-5: Rt. 601 Bridge Cross Section.........................................................................24
Figure 2-6: Rt. 601 Bridge Plan View.............................................................................24
Figure 2-7: Diaphragm Detail...........................................................................................25
Figure 2-8: Deck-to-Girder Connection Detail.................................................................25
Figure 2-9: AASHTO HS20-44 Truck Loading Dimensions..........................................26
Figure 2-10: Design Curves for Rt. 601 Bridge (from Waldron 2001)............................27
Figure 2-11: Summary of Properties of Individual 36 in . DWB.....................................27
Figure 3-1: Weatherproof Gage Components..................................................................38
Figure 3-2: Rt. 601 Bridge Instrumentation Plan.............................................................38
Figure 3-3: Elevation View of Girder 8 Strain Gage Instrumentation.............................39
Figure 3-4: Girder 8 Cross Section of Strain Gage Instrumentation...............................39
Figure 3-5: Elevation View of Girder 7 & 2 Strain Gage Instrumentation.....................40
Figure 3-6: Girder 7 & 2 Cross Section of Strain Gage Instrumentation ........................40
Figure 3-7: Elevation View of Girder 6, 4, & 3 Strain Gage Instrumentation................41
Figure 3-8: Girder 6, 4 & 3 Cross Section of Strain Gage Instrumentation.....................41
Figure 3-9: Elevation View of Girder 5 Strain Gage Instrumentation.............................42
Figure 3-10: Girder 5 Cross Section of Strain Gage Instrumentation..............................42
Figure 3-11: Elevation View of Girder 1 Strain Gage Instrumentation............................43
Figure 3-12: Girder 1 Cross Section of Strain Gage Instrumentation..............................43
Figure 3-13: Plot of ten point floating average to reduce excessive strain gage noise....44
Figure 3-14: Sample calculation of ten point floating average.........................................44
Figure 3-15: Deflectometer Top Plate Sized to Fit FRP flange........................................45
Figure 3-16: Deflectometer predeflected 0.5 in................................................................45
Figure 3-17: Instrumentation wired to data acquisition system in van............................46
Figure 3-18: Axle weights and dimensions for dump truck used for October 2001 single
lane test runs.............................................................................................................47
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