Determination of the Design Parameters for the Route 601 Bridge

118 Pages·2001·2.84 MB·English

Determination of the Design Parameters for the Route 601 Bridge:
A Bridge Containing the Strongwell 36 in. Hybrid Composite Double Web Beam

by

Christopher Joseph Waldron

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

Approvals

Thomas E. Cousins, Co-chair John J. Lesko, Co-chair

_________________________ _________________________
Committee Co-Chairman Committee Co-Chairman

Carin Roberts-Wollmann

_________________________
Committee Member

July 30, 2001
Blacksburg, VA

Keywords: Composite materials, fiber-reinforced polymer (FRP), hybrid composite beam,
pultruded structural beam, bridge design, shear deformation, bolted deck-to-girder connection
for composite beams
Determination of the Design Parameters for the Route 601 Bridge:
A Bridge Containing the Strongwell 36 in. Hybrid Composite Double Web Beam

Christopher Joseph Waldron

(ABSTRACT)

The Route 601 Bridge spans 39 ft over Dickey Creek in Sugar Grove, VA and
represents the first use of Strongwell’s 36 in. double web beam (DWB) as the main load
carrying members for a traffic bridge. The bridge was designed for AASHTO HS20-44 and
AASHTO alternate military loading with a targeted deflection limit of L/800. For the
preliminary design, conservative properties for the 36 in. DWB were assumed based on
experience at Virginia Tech with Strongwell’s 8 in. DWB used in the Tom’s Creek Bridge.
An elastic modulus (E) of 6,000 ksi and a shear stiffness (kGA) of 20,000 ksi-in2 were
assumed and used with Timoshenko deformable beam theory to characterize the beams and
determine the deflections.
This thesis details the experimental work conducted in conjunction with the design of
the Route 601 Bridge, which had two goals. First, a deck-to-girder connection was tested to
determine if a bolted connection could develop composite action between the girder and the
deck. This connection was shown to provide a significant amount of composite action when
used with the 8 in. DWB and a composite deck, but little or no composite action when used
with the 36 in. DWB and a glue-laminated timber deck. Second, eleven 36 in. DWB’s were
tested to determine their stiffness properties (EI and kGA) to insure that these properties were
above the values assumed in the preliminary design, and all the beams had stiffness properties
that were close to or above the assumed values. The eleven beams were also proof tested to a
moment equivalent to five times the service load moment to insure the safety of the Route 601
Bridge. One beam was tested to failure to determine the failure mode and residual stiffness of
the 36 in. DWB. Finally, based on these results eight beams were chosen for the Route 601
Bridge.
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Acknowledgements

The author would like to thank the following people for their contribution and support in the
work required for this thesis:

• Dr. Thomas E. Cousins, for serving as my advisor, mentor, and role model over the past
two years. It has been a great pleasure to work with Dr. Cousins on this project, and
without his guidance, this thesis would not have become a reality.

• Dr. John “Jack” Lesko, for serving as my co-advisor and providing the attention to
detail that this project needed. His expertise in the behavior of composite materials and
his views from the materials side to balance the engineers, views were crucial to the
completion of this thesis.

• Dr. Carin Roberts-Wollmann, for serving on my committee and providing me with
entertaining and educational stories while I was waiting to see Dr. Cousins.

• Michael Hayes, for all his expertise in the testing of composite beams and showing me
the ins and outs of the MegaDAC. Also, for helping me for countless hours in the lab
while testing and especially for helping to drill what seemed like thousands of holes in the
36 in. DWB for the beam/deck testing.

• Jolyn Senne, for teaching me how to use the SCXI-1000 data acquisition system and for
spending so much time helping solve my data acquisition problems when I was first
getting started.

• Edgar “Renteria” Restrepo, for helping gage and test the eleven 36 in. DWB’s for the
bridge. His many turns at the hand pump saved me from a sure visit to the chiropractor.

• Tim Schniepp , for countless hours (and countless drill bits) drilling holes in the 36 in.
DWB for the beam/deck testing. His mastery of hand pump used in stiffness testing and
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assistance strain gaging the eleven beams was instrumental in the completion of this
project.

• Brett Farmer and Dennis Huffman, for all their expertise and guidance on using the
equipment at the lab and for the non-stop country music at the lab, which finally started to
grow on me. Without their help in setting-up and tearing-down the many tests in the lab
and moving the 40 ft beams in and out the lab on a weekly basis this work could not have
been completed.

• Those involved in the Route 601 Project. Strongwell, Inc., for providing the innovative
beams used in this research and making the Route 601 Bridge a reality. VTRC, for
providing funding and oversight that this project needed. VDOT, for allowing us to build
a “plastic” bridge on their network of highways and providing the expertise in bridge
design and construction needed to complete the details of the bridge.

• CEE Dept. of Virginia Tech, for imparting all the knowledge of structural engineering I
could absorb in two years and providing me with a Via Fellowship while pursuing my
Master’s Degree. The academic and financial support of the department made this thesis
possible.

• Sally White, my future wife, for providing endless love and support and providing me
with the motivation I needed to finish this thesis. I look forward to spending the rest of
my life with her and I know that no matter where we go, or what we do, I can always
count on her love and support.

Finally, I would like to thank my parents and grandparents, for a lifetime of love and
support, both emotional and financial. They have always stood by me, no matter what I chose
to do, and without their unending love, I would not be where I am today.

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Table of Contents
List of Tables........................................................................................................................vvii

List of Figures.......................................................................................................................vvii

Chapter 1: Introduction and Literature Review...................................................................1
1.1 Introduction.......................................................................................................................1
1.2 The Route 601 Bridge.......................................................................................................2
1.3 The Strongwell 36 in. Double Web Beam (DWB)...........................................................3
1.4 Literature Review.............................................................................................................4
1.4.1 Current Status of U.S. Bridges...................................................................................4
1.4.2 Reasons for Using Composites..................................................................................5
1.4.3 Bridges Constructed with Composites as Primary Load Carrying Members............5
1.4.3.1 Pedestrian Bridges..............................................................................................5
1.4.3.2 Traffic Bridges....................................................................................................8
1.5 Objectives/Scope............................................................................................................11
1.6 Figures............................................................................................................................14

Chapter 2: Preliminary Design..............................................................................................18
2.1 Design according to AASHTO Methods........................................................................18
2.2 Design Check using Finite Difference Model................................................................20
2.3 Determination of Glulam Deck Thickness.....................................................................21
2.4 Tables and Figures..........................................................................................................22

Chapter 3: Experimental Procedures...................................................................................26
3.1 Deck-to Girder Connection Testing................................................................................26
3.1.1 Small-Scale Connection...........................................................................................26
3.1.2 Full Scale Connection..............................................................................................29
3.2 Beam Testing..................................................................................................................30
3.2.1 Stiffness Testing.......................................................................................................31
3.2.2 Proof Testing............................................................................................................32
3.2.3 Failure Test..............................................................................................................33
3.3 Figures............................................................................................................................35

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Chapter 4: Analysis Procedures............................................................................................44
4.1 Beam/Deck System Testing............................................................................................44
4.2 Beam Testing..................................................................................................................47
4.2.1 Beam Stiffness Properties........................................................................................48
4.2.2 Determination of EI and kGA..................................................................................50
4.2.2.1 The Direct Method for Determining EI and kGA.............................................50
4.2.2.2 Slope-Intercept Method for Determining EI and kGA....................................51
4.2.3 Determination of E for the 36 in. DWB...............................................................52
eff.
4.3 Figures............................................................................................................................53

Chapter 5: Effectiveness of Deck-to-Girder Connection....................................................54
5.1 Overview of Composite Action......................................................................................54
5.2 8 in. DWB with FRP Deck.............................................................................................55
5.2.1 Stiffness Testing of Various Connection Configurations........................................55
5.2.2 Failure of Beam/Deck System with a Connection Spacing of 1 ft..........................58
5.3 36 in. DWB with Glue-Laminated Timber Deck...........................................................59
5.4 Tables and Figures..........................................................................................................63

Chapter 6: Beam Testing Results and Discussion................................................................75
6.1 Stiffness Testing.............................................................................................................75
6.2 Proof Testing..................................................................................................................78
6.3 Failure Testing of Beam #13..........................................................................................79
6.4 Comparison of Test Results to Preliminary Design Parameters.....................................81
6.5 Tables and Figures..........................................................................................................83

Chapter 7: Conclusions and Recommendations..................................................................96
7.1 Conclusions.....................................................................................................................96
7.2 Recommendations...........................................................................................................98

References..............................................................................................................................100

Appendix A: E and kGA Results for Each Test of Each Beam........................................103

Appendix B: Maximum Strains and Deflections for Each Test of Each Beam...............106

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List of Tables
Table 2.1 – Preliminary Design Parameters.............................................................................22
Table 2.2 – Moments and Deflections......................................................................................22
Table 2.3 – Allowable Deck Spans...........................................................................................22

Table 5.1 – Small-Scale Connection I ...................................................................................63
eff.
Table 5.2 – Small-Scale Connection Neutral Axis Locations..................................................63
Table 5.3 – Small Connection Girder Compressive Strains.....................................................64
Table 5.4 – Full-Scale 4-pt. Testing I ...................................................................................64
eff.
Table 5.5 – Full-Scale 4-pt. Testing N.A. Locations and Girder Compressive Strains............64
Table 5.6 – Full-Scale 3-pt. Testing I ...................................................................................65
eff.

Table 6.1 – Properties of the eleven 36 in. DWB’s..................................................................83
Table 6.2 – Comparison of Methods for Determining E and kGA...........................................83
Table 6.3 – Properties of the eleven 36 in. DWB’s Compared to Design Values....................84
Table 6.4 – Service Load Strain for Each Beam and Safety Factor to Failure Strain..............84

List of Figures
Figure 1.1 – Old Route 601 Bridge...........................................................................................14
Figure 1.2 – New Route 601 Bridge Section............................................................................15
Figure 1.3 – New Route 601 Bridge Plan.................................................................................15
Figure 1.4 – The Strongwell 36 in. DWB.................................................................................16
Figure 1.5 – 4-Point Bending Set-up........................................................................................16
Figure 1.6 – Deck-to-Girder Connection..................................................................................17

Figure 2.1 – AASHTO HS20-44 Truck Loading and Spacing.................................................23
Figure 2.2 – AASHTO HS20-AML Loading and Spacing......................................................23
Figure 2.3 – Plan View of AASHTO HS20-44 Trucks on the Bridge.....................................24
Figure 2.4 – Girder Spacing Design Curves.............................................................................24
Figure 2.5 – HS20-44 Loads on Girder, Including Distribution (0.7) and Impact (1.3)..........25
Figure 2.6 – HS20-AML Loads on Girder, Including Distribution (0.7) and Impact (1.3)......25
Figure 2.7 – Deck Effective Clear Span and Overhang............................................................25
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Figure 3.1 – Strongwell’s 8 in. double web beam....................................................................35
Figure 3.2 – Composite Deck...................................................................................................35
Figure 3.3 – Small-Scale Connection.......................................................................................36
Figure 3.4 – Photo of Small-Scale Connection.........................................................................36
Figure 3.5 – Four-Point Set-Up for Small Scale Connection Testing......................................37
Figure 3.6 – Photo of Small-Scale Beam/Deck Set-Up............................................................37
Figure 3.7 – Gage Plan for 8 in. DWB Beam Testing..............................................................38
Figure 3.8 – Gage Plan for Small-Scale Connection Testing...................................................38
Figure 3.9 – Full-Scale Connection..........................................................................................39
Figure 3.10 – Photo of Full-Scale Deck-to-Girder Connection................................................39
Figure 3.11 – Full-Scale Connection Testing, Four-Point Set-Up and Gage Plan...................40
Figure 3.12 – Full Scale Connection Testing, Three-Point Set-Up and Gage Plan..................40
Figure 3.13 – Photo of Three-Point Full-Scale Connection Testing........................................41
Figure 3.14 – Connection Configurations for Full-Scale Testing............................................41
Figure 3.15 – Elastomeric Bearing Pads Used in Stiffness, Proof, and Failure Testing..........42
Figure 3.16 – Beam Stiffness and Proof Testing Set-Up and Gage Plan.................................42
Figure 3.17 – Beam Failure Testing Set-Up and Gage Plan.....................................................43

Figure 4.1 – Slope-Intercept Method for Determining EI and kGA.........................................53

Figure 5.1 –Load-Deflection Plots for 8 in. DWB Beam/Deck Testing...................................65
Figure 5.2 – Variation of the Effective Moment of Inertia with Connection Spacing.............66
Figure 5.3 – Determination of Neutral Axis for Small-Scale Connection at 1 ft Spacing.......66
Figure 5.4 – Determination of Neutral Axis for Small-Scale Connection at 2 ft Spacing.......67
Figure 5.5 – Determination of Neutral Axis for Small-Scale Connection at 3 ft Spacing.......67
Figure 5.6 – Determination of Neutral Axis for Small-Scale Connection at 4 ft Spacing.......68
Figure 5.7 – Determination of Neutral Axis for Small-Scale Connection at 6 ft Spacing.......68
Figure 5.8 – Determination of Neutral Axis for Small-Scale Connection at 12 ft Spacing.....69
Figure 5.9 – Determination of Neutral Axis for No Deck-to-Girder Connections...................69
Figure 5.10 – Determination of Neutral Axis for 8 in. DWB with No Deck...........................70
Figure 5.11 – Comparison of Strain Distributions for the Various Connection Spacings........70
viii
Figure 5.12 – Strain Across Deck to Investigate Shear Lag.....................................................71
Figure 5.13 – Pre- and Post-Failure Load-Deflection Plots for Small-Scale Connection........71
Figure 5.14 – Load-Deflection Plot for 36 in. DWB Beam/Deck 4-pt. Testing.......................72
Figure 5.15 – Determination of Neutral Axis for 36 in. DWB with No Deck.........................72
Figure 5.16 – Determination of N.A. for Three Full-Scale Connections Per Panel.................73
Figure 5.17 – Comparison of Strain Distributions for Full-Scale 4-pt. Testing.......................73
Figure 5.18 – Load-Deflection Plot for 36 in. DWB Beam/Deck 3-pt. Testing.......................74
Figure 5.19 – Elevation of Bridge Showing Deck-to-Girder Connection at Panel Joints........74

Figure 6.1 – Typical Load versus Deflection Plot....................................................................85
Figure 6.2 – Typical Variation of E and kGA with Load.........................................................85
∆
Figure 6.3 – Typical Variation of with Load................................................................86
PL3
Figure 6.4 – Determination of E and kGA Using Slope-Intercept Method for Beam #8.........86
Figure 6.5 – Determination of E and kGA Using Slope-Intercept Method for Beam #10.......87
Figure 6.6 – Load versus Deflection Plot for Beam #6 to First Audible Emission..................87
Figure 6.7 – Load versus Strain for Beam #6 to First Audible Emission.................................88
Figure 6.8 – Load versus Deflection Plot for Beam #13 to First Audible Emission................88
Figure 6.9 – Load versus Strain for Beam #13 to First Audible Emission...............................89
Figure 6.10 – Photo of Blistered Top Flange of Beam #5........................................................89
Figure 6.11 – Load versus Strain for Beam #5 to 50 kips (Before Growth of Blister)............90
Figure 6.12 – Load versus Strain for Gage T5 Showing Effect of Blister Growth..................90
Figure 6.13 – Load v. Deflection Plot of Beam #5 to 136 kips (First Audible Emission).......91
Figure 6.14 – Load versus Elastic Modulus for Beam #5 to 136 kips......................................91
Figure 6.15 – Photo of Initiation Point of Delamination from the Side...................................92
Figure 6.16 – Photo of Initiation Point of Delamination from the Top....................................92
Figure 6.17 – Lateral Shift of Top Flange................................................................................93
Figure 6.18 – Load versus Deflection Plot for Failure of Beam #13........................................93
Figure 6.19 – Load versus Strain for Failure of Beam #13......................................................94
Figure 6.20 –Load versus Deflection Relationship Before and After Failure..........................94
Figure 6.21 – Strain in Gages Near the Load Points................................................................95
Figure 6.22 – Plan of Bridge Showing Route 601 Beam Numbering......................................95
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Chapter 1: Introduction and Literature Review
1.1 Introduction
Since the birth of civilization, humans have used composite materials for tools and for
construction applications. The earliest of these materials were wood (a natural composite)
and straw reinforced clay, and today engineers are regularly using steel reinforced concrete.
It should be no surprise, then, that Fiber Reinforced Plastic (FRP) composites are beginning to
gain popularity as a construction material. One of the areas where FRP composites are slowly
beginning to be used is bridge construction.
Several factors contribute to the slow rate at which the bridge community is accepting
these materials. Composites have significantly higher initial costs than do conventional
building materials, such as steel, concrete, and timber but, many of composite’s proponents
believe that composites exhibit lower life-cycle costs than conventional materials due to their
increased durability and reduced need for maintenance. However, so few bridges have been
built using fiber-reinforced composites that little long-term, real-world test data exists to
substantiate this idea. Furthermore, since so few bridges have been built, the construction
community has little experience with these materials and this has the effect of increasing the
initial construction costs even higher. Connection design tends to be more complicated with
composites due to their sensitivity to stress concentrations and free-edge effects at holes.
Finally, even though composites typically have higher stiffness-to-weight ratios than
conventional materials, their absolute stiffness is typically much lower than steel making it
nearly impossible to utilize their full strength due to the deflection limits imposed on many
bridges.
Despite these drawbacks, composites are gaining acceptance due to their advantages
over conventional materials. Composites typically have higher stiffness-to-weight and
strength-to-weight ratios than conventional materials. This allows bridge engineers to
produce significantly lighter bridges than can be designed with any other material. These
lighter structures allow for easier construction in remote locations, increased live load
capacities on existing abutments, and smaller mechanisms in moveable span bridges. Also, it
is believed that composites have greater durability and require less maintenance than
conventional materials. Unlike steel, composites do not corrode and do not need to be painted
and composites resist crack growth better than either steel or concrete.
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