FIELD TESTING AND NUMERICAL MODELING OF A HYBRID COMPOSITE

BEAM BRIDGE IN VIRGINIA

Devin K. Harris, Ph.D. Amir Gheitasi, Ph.D. John M. Civitillo

Assistant Professor Postdoctoral Research Associate Nuclear Engineer

Department of Civil and

Environmental Engineering

Department of Civil and

Environmental Engineering

Norfolk Naval Shipyard

University of Virginia University of Virginia

Charlottesville, VA 22904 Charlottesville, VA 22904 Portsmouth, VA 23709 U.S.A. U.S.A. U.S.A.

dharris@virginia.edu agheitasi@virginia.edu jmc4vr@virginia.edu

KEYWORDS: Hybrid Composite Beam (HCB), Live Load Testing, In-service Bridge Performance,

Wireless Instrumentation, Structural Health Monitoring.

ABSTRACT

A relatively new technology, Hybrid Composite Beams (HCB), are being deployed in bridges throughout

North America as an alternative to traditional materials. A HCB is comprised of a glass-fiber reinforced

polymer (FRP) box shell containing a tied parabolic concrete arch. In a girder-type bridge superstructure,

these beams can support a conventional reinforced concrete deck, while the inclined stirrups provide shear

integrity and enforce composite action between the HCBs and the concrete deck. The HCB system offers

an efficient use of materials, ease of construction, and resistance to corrosion, making the system ideal for

sustainable bridge design.

This research study focuses on evaluating the in-service performance of a new HCB bridge in Virginia.

In the corresponding evaluation program, the bridge was tested under live-load conditions and monitored

using a suite of sensors. Results from the experimental program were used to better understand the bridge

behavior including how the loads are transmitted, both at the system and element levels. Moreover, the

test results provided validity to the rational design approach employed for this system, but also highlighted

some of the key non-composite system behavior that warrant further consideration in future design. In

addition to the testing program, a detailed finite element model was generated to support the experimental

data and provide additional insight into the system behavior characteristics.

INTRODUCTION

In recent years, the challenges related to the transportation infrastructure network in the United States

have become an area of national focus. Transportation agencies are dealing with an aging infrastructure

that is documented to be in a poor condition state, but are also faced with limited resources available to

address the challenges (ASCE 2013; FHWA 2013). Within the bridge community, it is common

knowledge that the solution to these challenges will not come from a single source, but rather a strategic

mix of innovative solutions that include sustainable and adaptable designs, durable materials, and non-

invasive or accelerated construction (Carbonell Munoz et al. 2014; Fuhrman et al. 2014; Grace et al. 2013;

Harris et al. 2015; Harris et al. 2008; Russell 2013). For widespread adoption, however, the solution needs

to be cost effective and accepted by the practicing community, features which have hampered many of

these previous innovations.

The hybrid composite beam (HCB) system is a recent innovation that has the potential to address many

of the challenges and is also gaining acceptance in the bridge community. When incorporated in a

traditional beam bridge design, individual HCBs serve as the primary superstructure members or girders

and can be made composite with a traditional reinforced concrete deck. Each HCB, as illustrated in Fig.1,

consists of a glass fiber reinforced polymer (FRP) box shell that encases a passively tied concrete arch

(Hillman 2003). The tie reinforcement is unstressed prestressing strand (passive) that is integrated into the

FRP shell during fabrication, while the arch is typically made of self-consolidating concrete. With this

design, the concrete arch resists the internal compression forces due to self-weight and additional

construction loads, while the steel is intended to tie the arch together and carry internal tensile forces

imposed by the live loads. The primary shear resistance is provided by the combination of a monolithic

concrete fin that extends from the arch along the span and distributed reinforcing bars oriented at 45° from

vertical and anchored within the arch. The shear reinforcement also provides the composite connection

between the HCBs and a conventionally reinforced concrete deck.

Fig. 1 Components of hybrid composite beam.

The anticipated benefits of this system are derived from the efficient use of materials, lightweight design,

corrosion resistance, and use in accelerated construction projects to minimize the disruption to traffic flow,

when compared to conventional bridge designs. Although there has been a great deal of recent interest in

the application of this technology, the complex behaviors of the system and its response under standard

in-situ loading scenarios are still not completely understood and require further evaluation. For the bridge

community to accept the HCB system as a viable solution, there is a critical need to understand in-service

behavior of the system and confirm the assumptions that are being made in the current design

methodology.

BACKGROUND AND RESEARCH SIGNIFICANCE

The first investigation of hybrid composite girders was sponsored by the Transportation Research Board

as part of the Innovations Deserving Exploratory Analysis (IDEA) program. A companion experimental

study was conducted in Colorado, on a single prototype beam and a complete railroad bridge structure

(Hillman 2003; Hillman 2008). Results of these early tests validated the predictable structural behavior of

the HCB for its intended purpose in a bridge structure. In 2010, a large-scale project was described (Snape

and Lindyberg 2009) to construct an eight-span HCB bridge with the total length of 165 m (540 ft) in

Maine. Prior to construction, a single beam was tested for service and fatigue loads as well as the ultimate

capacity and failure mode. Results from this study demonstrated that the tested beam behaved as predicted,

although it was stiffer in the test due to the FRP wings, which is being neglected in design calculations

(Hillman 2012). The HCB technology was also used to construct three bridges in Missouri. Along with

the construction of these bridges, the Missouri Department of Transportation supported an exploratory

program, including live-load testing and finite element modeling to evaluate the in-service behavior of the

constructed HBC bridge superstructures (Myers et al. 2014). The results of this work suggested that the

HCB does not exhibit traditional flexural beam behavior, as the relative movements between the internal

components affect the flexural behavior of the girders.

In Virginia, the first HCB bridge superstructure was constructed in 2013 as a replacement to a

conventional concrete bridge, by the means of reusing the existing abutments and substructure. Virginia

Department of Transportation funded a multi-phase research project spearheaded by Virginia Polytechnic

Institute and State University (Virginia Tech) and the University of Virginia (UVa). Virginia Tech was

tasked with the investigation of the HCB system in a laboratory setting, and their study focused on the

element-level behavior, evaluation of flexural design methodology, reduced full-scale system-level

response, and load path generated between the concrete arch and FRP shell, at various phases throughout

the construction of the system and a variety of loading scenarios (Ahsan 2012; Nosdall 2013). The results

obtained from this experimental study also demonstrated that the concrete arch does not act compositely

with the rest of the HCB system. Also noted was the importance of including the FRP wings and the

concrete fin in the design and analysis of the HCB system, since they both contribute to the flexural

resistance. The companion study at UVa focused on evaluating the system behavior of the HCB under in-

service conditions, which is the focus of this paper.

METHOD OF STUDY

The purpose of this study was to use traditional live-load testing strategies and finite element modeling to

characterize the in-service structural behavior of the HCB system used on a skewed bridge superstructure

constructed in Virginia. To establish a mechanism for monitoring the in-service behavior, a suite of

external and internally embedded sensors were deployed on the structure at strategic locations. The

behavior characteristics of interest included the flexural lateral load distribution behavior, the element

load sharing behavior, and the dynamic load amplification of this specific HCB bridge system. To validate

the the design assumptions with respect to live load performance and dynamic response of this structure,

results obtained from the experimental investigation were compared to provisions with the AASHTO

provisions (AASHTO 2002; AASHTO 2012). In addition to the experimental investigation, a detailed

numerical study was also performed on the tested structure to support and complement the experimental

results, while providing additional insight into the system-level behavior characteristics.

SELECTED STRUCTURE

The selected structure was a short span HCB bridge constructed on Route 205 in Colonial Beach, Virginia.

For this bridge, the construction took place in series of phases including off-site fabrication of the HCBs,

shipping and concrete filling, as well as side-by-side installment and placement of the deck system

(Civitillo 2014; Harris and Civitillo 2014). As illustrated in Fig. 2a, the replaced structure consisted of

eight HCBs spanning 13.5 meters (44 ft) over a small creek and supporting a 19 cm (7.5 in) deep

conventionally reinforced cast-in-place concrete deck. The HCB girders used in this bridge were 53 cm

(21 in) deep by 61 cm (24 in) wide and consisted of a fiberglass box, which comprises the outer shell and

lid, reinforced with a shallow tied concrete arch. The HCB girders were spaced approximately at 1.2 m (4

ft) center-to-center, yielding a 9.9 m (32.5 ft) transverse width that allowed for two lanes of traffic with

0.9 m (3 ft) shoulders (see Fig. 2b). The bridge was constructed on parallel existing abutments with a 45°

skew, where the HCB girders were made integral with the backwall by encasing the end sections of the

beams in a concrete diaphragm. Section properties of the HCB girders at different locations along the

length are also illustrated in Fig. 2c. The material properties of the various components were not tested as

a part of this study, but Table 1 provides a summary of the material characteristics used in the design of

the investigated HCB girders.

Fig. 2 Selected structure and instrumentation: (a) plan view (b) section (c) HCB’s geometric configurations.

Table 1 Design material properties of the tested structure

Deck Shear

Reinf.

HCB

Conc. Reinf. Arch Strands FRP Shell Polyiso Foam

E (GPa) 26.4 29 29 30.4 27.5 E11: 21.4 E22: 18.5 E11: 8.4 E33: 3.2 E33: 3.2

ν 0.18 0.3 0.3 0.18 0.3 ν12: 0.3 ν 21: 0.26 ν12: 0.33 ν13: 0.33 ν23: 0.31

f'c (MPa) 31 - - 41.4 - - - - - -

fy (MPa) - 415 415 - - - - - - -

fu (MPa) - - - - 1860 - - - - -

EXPERIMENTAL INVESTIGATION

Instrumentation

Figs. 2a and 2b illustrate the implemented instrumentation plan for this structure, which was developed to

satisfy the testing program requirements and establish a mechanism for monitoring the in-service behavior

of the system. The program required a variety of sensors with multiple data acquisition systems with

different functionalities. The first system utilized a series of data-loggers and was based on the use of

internally mounted vibrating wire gauges (VWGs) in conjunction with a Campbell Scientific Inc. (CSI)

data acquisition system (DAQ) that were installed throughout the fabrication and construction phases of

the girders and bridge deck. A series of non-corrosive 3D printed frames, made of acrylonitrile butadiene

styrene, were used to position the gauges at the desired depths within the voided conduits such that the

VWGs were aligned longitudinally with the beam, as depicted in Fig.3. A total of 48 VWG locations were

selected and these VWGs were installed in three of the eight girders (G5, G7, and G8) so as to minimize

the interference with the construction of the girders. In addition, nine gauges were longitudinally affixed

to the deck reinforcement mat (at 100 cm/4 in depth) at companion locations to the mid-span and quarter-

span locations of the three selected girders. Table 3 illustrates and describes the location of the gauges

within the HCB cross-section. The resulting system of gauges was expected to provide a comprehensive

measure of the overall internal system behavior including location of the neutral axis and level of

composite action that exists between the deck and girders.

(a) (b) (c) (d)

Fig. 3 Internal VWG placement: (a) tension level (b) concrete arch (c) in concrete fin (d) concrete deck

Table 2 VWG instrumentation location matrix

Location G5 G7 G8

East 1/8 L - - R, CT, CB

East 1/4 L D, CT, CB, S D, CT, CB, S D, CT, CB, S

1/2 L D, CT, CB, S D, CT, CB, S D, CT, CB, S

West 1/4 L D, CT, CB, S D, CT, CB, S D, CT, CB, S

West 1/8 L R, CT, CB - R, CT, CB

D: Deck; CT: upper arch; CB: lower arch; S: tension strand; R: rosette within fin

The second data acquisition system utilized a rapidly deployable wireless system by Bridge Diagnostics

Inc. (BDI). Externally mounted strain gauges were placed on the bottom flange and web of each girder on

all of the girders at midspan as well as East quarter-span (Fig. 4a). Two additional external BDI strain

gauges were placed on the parapet at mid-span of the structure to investigate the level of stiffening

provided by the barriers to the system. These gauges were used to create an external strain profile that

could be aligned with the internal strain profiles and contribute to the evaluation of the load sharing

behavior of the individual HCB elements. On the day of the test, the BDI wire leads were connected to

the wireless nodes (4 gauges per node) that relayed to a central base station (Fig. 6b). The lead wires from

the internally mounted VWGs were also connected to the appropriate CSI data-logger for periodic

measurements (Fig. 4c). In addition to the instrumentation on the bridge, a BDI product called an

Autoclicker was attached to the wheel well of the load test truck to track the longitudinal position of the

truck as it crossed the bridge (Fig. 4d)

(a) (b) (c) (d)

Fig. 4 External BDI installation and final test preparation: (a) gauge alignment (b) BDI wireless nodes (c)

CSI data-loggers setup (d) truck autoclicker

Live-Load Testing

The load test was performed by driving load vehicles East to West across the bridge at predetermined

transverse positions (see Fig. 5a). These vehicles were standard VDOT tandem-axle dump trucks (Fig.

5b), which were loaded with gravel and used for the quasi-static tests and the dynamic tests. During quasi-

static testing, the truck driver was guided at a crawl speed (< 8 kmph or 5 mph) to ensure that the

passenger’s side wheel path aligned with the designated transverse locations (Fig. 5c). Each transverse

run was performed a total of three times, always pausing on the third run for 60 seconds at a pre-designated

longitudinal location close to the mid-span of the girder nearest the driver’s side wheel path. The pause

during the third run allowed the VWGs to collect a true static measurement in the loaded configuration.

During the static load testing, the data was captured at 25 Hz for the BDI system and 100 Hz for the CSI

system. In addition to the quasi-static testing, a series of dynamic truck runs were also performed to

measure the dynamic characteristics of this structure. This paper will exclusively focus on the quasi static

test and aims to interpret the corresponding collected data to describe the overall load distribution

characteristics as well as the element load sharing behavior of the selected structure. Further information

with regards to the dynamic behavior of HCB systems can be found in previous works of the authors

(Civitillo 2014; Harris and Civitillo 2014).

Fig. 5 Load testing (a) transverse load positions (b) truck configuration (c) guiding truck driver

FINITE ELEMENT SIMULATION

Modeling Details/Assumptions

A commercial finite element package, ANSYS 14.0, was used in this study to generate a numerical model

for the tested structure. Due to the complex geometry of the HBCs together with the skewed configuration

of the selected bridge superstructure, all of the geometrical properties included in the model were extracted

directly from the VDOT plans and the corresponding design documents (VDOT 2011). In the model, the

concrete components of the bridge system, including the slab and the arch within the HCBs, were modeled

using eight-node solid elements (SOLID65). Uniaxial tension-compression spar elements, LINK180, were

used to discretely model the internal reinforcement within the deck and the arch, as well as the tensile tie

strands at the bottom of the HCB girders. The foam sections surrounding the concrete arch were also

included in the model using 3D brick elements (SOLID185). Four-node reduced integration shell

elements, SHELL181, were used to model different parts of the FRP box shell which encases the

components of the HCB girders. Linear elastic material properties assumed for each of these component

were extracted from the design documents and included in the model (see Table 1). During the

construction, each HCB was infused with a vinyl ester resin using the vacuum assisted resin transfer

method (VARTM). As a result, perfect bond was assumed for the surface-to-surface contact elements that

provided connections between the FRP shell box, tie reinforcement and the foam sections (Snape and

Lindyberg 2009). In addition. the concrete arch was also assumed to be in ideal fully-bonded connection

with the foam sections. Fig. 6 illustrates the details of the numerical model developed for a single HBC

girder. The bridge model was then developed by replicating the beam element following the skewed

configuration of the system. Similar surface-to-surface contact algorithm was used in the model to

simulate the interaction between the reinforced concrete deck and eight HCBs. With no evidence of loss

in the composite action of the system during the live-load testing, fully-bonded characteristics were

assigned to the implemented contact elements (Aboelseoud and Myers 2014). It should be noted that the

wings of the FRP lid within HCBs were not included in the model, as they provided a stay-in-place

formwork for the deck during the construction, with no major contribution to the structural integrity and

system behavior subjected to service loads.

Fig. 6 Developed FE model for HCB (shrink view).

Numerical Analysis

The developed numerical model was fully restrained at the either end of the HCB’s FRP box shells to

simulate the continuous integral abutment and the associated concrete diaphragm of the actual structure

(see Fig. 2a). Based on the loading configurations illustrated in Fig. 5a, the model was loaded, in eight

different analysis cases, with a series of concentrated loads applied over the tire patch area independent

of the generated mesh pattern of the concrete deck (Gheitasi and Harris 2014). The longitudinal positions

of the applied loads in the model were defined based on the data collected from the autoclicker node during

the static run for each load case. The small values of strains collected during the live-load test indicated

that the system is behaving within the linear-elastic range under the impact of service loads, but also put

aside the necessity to perform a large-deformation (nonlinear geometry) analysis. As a result, linear static

analysis with small displacements were selected in this study for the numerical investigation of the tested

HCB bridge superstructure under the assumed loading scenarios.

RESULTS AND DISCUSSION

Following completion of the load testing program and the numerical analysis, the data was retrieved and

post-processed to evaluate the specific behavioral characteristics including lateral load distribution and

internal/external load sharing behavior of the selected structure. Additional details on these characteristics

together with comparison of the results to those recommended by the AASHTO LRFD specification are

provided in the following sub-sections.

Lateral Load Distribution Behavior

In this study, the flexural lateral load distribution behavior was analyzed to help evaluate the in-service

behavior of the HCB bridge because such in-situ performance is critical to the end user, as there are very

few HCB bridges currently in use. Within a typical beam bridge structure, the expected behavior under

load is that the girders most directly under the loading will resist the majority of the load, with the girders

further away resisting less (Gheitasi and Harris 2014; Harris and Gheitasi 2013). For the HCB load testing

program this phenomena is illustrated in Fig. 7, which presents a sample of time series strain data collected

at midspan of the structure for each of the three runs for LC A and LC H, using external BDI stain gauges.

Similar trends were observed in both of these representative cases, where the further girders to the applied

loads contribute less to the overall load distributing mechanism of the system. However, it is interesting

to note that G1 and G8 would be expected to also have significant response under the assumed loading

scenarios (LC A and LC H, respectively), but this effect appears to be somewhat muted by the influence

of the parapet. The complete set of strain responses at midspan and quarter point maintain different

characteristics affected by skew, loading positions, and support conditions of the tested bridge, which are

available in Civitillo (Civitillo 2014).

Fig. 7 Time series strain data at midspan for LC A and LC H.

Using the occurrence of maximum strain within the most heavily loaded beam as the point of reference,

the average transverse lateral load sharing behavior throughout the bridge cross section was evaluated for

various load cases. Fig. 8 illustrates a sample of this data for three representative cases (LC D, LC F, and

LC H) at midspan of the structure. As previously highlighted, the most heavily loaded girders experience

the greatest bottom flange strain, while girders further away experience less. Also included in Fig. 8, are

the results obtained from the corresponding numerical analysis, considering the impact of parapets on the

lateral load distribution mechanism of the system. FEA1 represents the model without parapets, while

FEA2 represents the model with parapets included. For the exterior beams, it is evident from the decrease

in strain that the parapets carry a significant fraction of the applied loads. Average compressive strains

(up to -31 µε) collected from the external gauges attached to the critical parapet also support the fact that

the lateral distribution behavior of the exterior girders are significantly affected by the stiffness of the

parapets. Analogous results have been also reported by Aboelseoud and Myer (Aboelseoud and Myers

2014), who performed similar live load test program on a HCB bridge superstructure in the State of

Missouri.

When comparing the strains observed on the exterior (BDI) with those measured internally (VWG) at the

level of strands (S), the VWG strains do not consistently match the trend or magnitude of strain. The

internal strain readings are consistently lower than the external FRP strains, with the exception of the

exterior girder (G8). The cause of this non-correspondence is not definite, but may be attributed to the

non-composite behavior of the HCB components. One possible theory is that the tension steel pulls away

from the FRP shell because of the lack of support provided by the foam at mid-span. In other words, as

the beam generates curvature in flexure, the steel strands may pull away from the FRP shell to remain as

linear as possible in tension, while the curvature of the bottom flange of the FRP is enforced by the

stiffness of the side webs tying into the remainder of the system and the curvature of the deck.

Fig. 8 Strain distribution across midspan for LC D, LC F, and LC H.

The flexural lateral load distribution factors at the midspan of the structure were evaluated based on the

results obtained from the experimental and numerical studies. The maximum distribution factors for each

run and each of the load configurations are summarized in Table 3. Also included in this table are the

critical distribution factors that were calculated based on the AASHTO LRFD (AASHTO 2012) as well

as AASHTO Standard Specification (AASHTO 2002). It should be emphasized that these specifications

do not contain provisions for this type of system, but when considering the anticipated HCB element

behavior, it would be expected that the system behavior might mimic that of a conventional slab-girder

bridge system such as a concrete deck on reinforced concrete girders (AASHTO Type A) or a concrete

deck on box girders (AASHTO Type B). For the load testing program, the controlling distribution factor

for the interior girder resulted from LC A, while the controlling value for the exterior girder occurred for

LC H. For the numerical analysis, the controlling distribution factor for both interior and exterior girders

resulted for LC H. Comparing the experimental and numerical results indicates that the model

overestimates the critical distribution behavior for the exterior girder, while underestimate the

corresponding value for the interior girder. Moreover, when comparing the measured distribution behavior

from the live-load testing program to the code specified values with adjustments for skew, it is clear that

AASHTO LRFD Type B designation and AASHTO standard specification yield conservative estimates

for exterior girders, while only the AASHTO LRFD Type B design value is conservative for the

controlling interior distribution factor.

Table 3 Summary of mid-span flexural distribution factors (lanes/beam)

Truck Position Run 1 Run 2 Run 3 FE Analysis (FEA2)

Ext. Int. Ext. Int. Ext. Int. Ext. Int.

LC A 0.166 0.297 0.177 0.336 0.211 0.375 0.218 0.276

LC B 0.135 0.315 0.131 0.308 0.127 0.259 0.161 0.247

LC C 0.096 0.262 0.093 0.249 0.082 0.201 0.073 0.233

LC D 0.060 0.220 0.060 0.227 0.057 0.180 0.028 0.256

LC E 0.051 0.200 0.050 0.201 0.065 0.182 0.038 0.268

LC F 0.102 0.227 0.105 0.231 0.105 0.233 0.110 0.247

LC G 0.162 0.279 0.168 0.281 0.185 0.275 0.237 0.254

LC H 0.227 0.296 0.227 0.297 0.257 0.286 0.365 0.304

AASHTO Provision Ext. Int.

LRFD – Type A 0.247 0.360

LRFD – Type B 0.288 0.306

Standard Specification 0.371 0.371

Note: critical distribution values are highlighted in bold

Element Load Sharing Behavior

An understanding of the internal load sharing behavior is essential for maintenance and decision-making

processes of the HCB system as it ages. In this study, the internal and external instrumentation allowed

for the measurement of the strain during live load testing and provided critical information on the load

sharing behavior between the concrete arch, FRP shell, and reinforcing steel, as well as the location of the

neutral axis of the composite cross-section. Fig. 9 illustrates the midspan strain profile through the depth

of the cross-section for beams 5, 7, and 8 subjected to Load Cases F, G, and H. These load cases were

selected because the load truck was in close proximity to the three girders that maintained both internal

and external instrumentation, and thus yielded the most relevant results.

G5 G7 G8

LC F

LC G

LC H

Fig. 9 Strain profiles at midspan cross section.

The transition from positive strain at the tension steel to negative strain within the deck defined the

location of the neutral axis, i.e. zero strain. The occurrence of the neutral axis varied for each of the load

cases and it was difficult to define a consistent neutral axis location because the profile through the depth

was not linear as might be expected for full composite action. Moreover, there exists a disparity between

the bottom flange strains and the internally collected strains in the tension steel, which could be explained

by slippage of the steel within the FRP flange. In all of the selected girders (G5, G7, and G8), the strain

profiles demonstrated that the concrete arch functions in tension at midspan of the structure. As previously

reported in an experimental study by Van Nosdall (Nosdall 2013), the neutral axis of the HCB system

occurs in the deck, although the system is designed as a tied arch. Thus, the entire HCB is expected to be

in tension at mid-span under the superimposed loads.

Similar to midspan, the strain profiles were also derived at the quarter-span location for the internally-

externally instrumented girders (G5, G7, and G8). After evaluation of the quarter-span strain profiles, it

was observed that the tensile strains in the arch section of G5, obtained from internal VWG, are in

significant tension and well beyond the cracking strain of the arch concrete, yet the arch continues to

strain. Rather than cracking in the arch, Ahsan (Ahsan 2012) hypothesized that there exists a local bending

phenomenon within the concrete arch. In other words, the arch would be able to experience local bending,

especially at higher levels of overall HCB curvature where the arch begins to flatten out. In this case, the

two steel strands resting along the bottom of the arch profile, which were used to anchor the stirrups, may

be carrying significant levels of tension, despite their absence in design calculations. The data collected

in this experimental program aligns with the theory, as the quarter-span arch gauges of selected girders

experience uncharacteristically high levels of tensile strain, often greater than the maximum tensile strain

in the bottom flange of midspan girders. The results obtained from the numerical analysis also support

this hypothesis. Fig. 10 illustrates the deflection pattern and the corresponding longitudinal strain

distribution in the concrete arches of the HCBs, as the model was loaded according to LC F configuration.

As depicted, the concrete arches experience local bending, especially for the girders that are closer to the

location of the applied loads. In addition, negative compressive strains developed at the bottom surface of

the concrete arches at the quarter-span locations also demonstrate the state of bending in the arch, which

clearly contradicts with the current design methodology of the HCB systems (Hillman 2012). These results

are compatible with those reported in the literature (Aboelseoud and Myers 2014), in which similar FE

modeling approach was implemented to analyze the structural behavior and characterize internal state of

stresses in the HCB bridge superstructures.

Fig. 10 FE results for LC F (a) deflection of the arches (b) strain distribution in the arches.

CONCLUSIONS

This study was comprised of an in-service live load test of a HCB bridge system recently constructed in

Virginia. A compatible FE simulation and analysis was also conducted to support the results of a

companion live-load testing program with the main focus on critical bridge behavior characteristics

including lateral load distribution and internal load sharing behavior. Based on the results obtained from

the live load testing, the findings of this study can be summarized as follow:

• Distribution behavior determined from the externally mounted strain gauges was consistent with

expected trends. The highest strains were registered directly under the load vehicle, and dissipated

further away for the point of load application. The parapet walls offered a significant stiffening

contribution to the exterior girders.

• It was concluded that the FRP shell does not act compositely with the internal HCB components

(concrete arch and prestressed strand tie). This phenomenon demonstrates that the arch does not act

compositely with the system and the assumption that plane sections remain plane in flexure is not valid

for HCB. In fact, the arch may exhibit local flexural bending within the girder.

REFERENCES AASHTO (2002). "Standard Specification for Highway Bridges." American Association of State Highway and

Transportation Officials, Washington D.C.

AASHTO (2012). "LRFD Bridge Design Specifications, 6th ed.", American Association of State Highway and

Transportation Officials Washington D.C.

Aboelseoud, M., and Myers, J. (2014). "Finite-Element Modeling of Hybrid Composite Beam Bridges in Missouri."

Journal of Bridge Engineering, 0(0), 04014054.

Ahsan, S. (2012). "Evaluation of Hybrid-Composite Beam for Use in Tide Mill Bridge." Master's Thesis, Virginia

Polytechnic Institute and State University, Blacksburg, VA.

ASCE (2013). "Report Card for America’s Infrastructure Findings." American Society of Civil Engineers.

Carbonell Munoz, M., Harris, D., Ahlborn, T., and and Froster, D. (2014). "Bond Performance between Ultra high-

Performance Concrete and Normal-Strength Concrete." Journal of Materials in Civil Engineering, 26(8),

04014031.

Civitillo, J. M. (2014). "In-Service Performance and Behavior Characterization of the Hybrid Composite Bridge

System." Master 's Thesis, University of Virginia, Charlottesville, VA.

FHWA (2013). "Status of the Nation's Highway, Bridges, and Transit: Conditions and Performance." US

Department of Transportation, Federal Highway Administration, McLean, VA.

Fuhrman, D., Rafiee-Dehkharghani, R., Lopez, M., Aref, A., and and O’Connor, J. (2014). "Field Performance of

a New Fiber-Reinforced Polymer Deck." Journal of Performance of Constructed Facilities, 0(0), 04014162.

Gheitasi, A., and Harris, D. (2014). "Failure Characteristics and Ultimate Load-Carrying Capacity of Redundant

Composite Steel Girder Bridges: Case Study." Journal of Bridge Engineering, 0(0), 05014012.

Gheitasi, A., and Harris, D. (2014). "Overload Flexural Distribution Behavior of Composite Steel Girder Bridges."

Journal of Bridge Engineering, 0(0), 04014076.

Grace, N., Jensen, E., Matsagar, V., and and Penjendra, P. (2013). "Performance of an AASHTO Beam Bridge

Prestressed with CFRP Tendons." Journal of Bridge Engineering, 18(2), 110-121.

Harris, D., Carbonell Munoz, M., Gheitasi, A., T., A., and Rush, S. (2015). "The Challenges Related to Interface

Bond Characterization of Ultra-High-Performance Concrete With Implications for Bridge Rehabilitation

Practices." ASTM International - Advances in Civil Engineering Materials, doi:10.1520/ACEM20140034.

Harris, D., and Civitillo, J. M. (2014). "In-Service Performance Evaluation and Monitoring of the Hybrid Composite

Beam Bridge System on Route 205 Over Tides Mill Stream." Final Report Submitted to Virginia Center for

Transportation Innovation and Research (VCTIR), Charlottesville, VA.

Harris, D., Cousins, T., Murray, T., and and Sotelino, E. (2008). "Field Investigation of a Sandwich Plate System

Bridge Deck." Journal of Performance of Constructed Facilities, 22(5), 305-315.

Harris, D. K., and Gheitasi, A. (2013). "Implementation of an energy-based stiffened plate formulation for lateral

load distribution characteristics of girder-type bridges." Engineering Structures, 54(0), 168-179.

Hillman, J. R. (2003). "Investigation of a Hybrid-Composite Beam System." Final Report for High-Speed Rail

IDEA Project 23, Transportation Research Board of National Academics, Washington D.C.

Hillman, J. R. (2008). "Product Application of a Hybrid-Composite Beam System." IDEA Program Final Report,

Transportation Research Board, National Research Council, Wahington D.C.

Hillman, J. R. (2012). "Hybrid-Composite Beam (HCB), Design and Maintenance Manual." Final Report Prepared

for the Missouri Department of Transportation, Jeffreson City, MO.

Myers, J. J., Aboelseoud, M. A., Earley, C. R., Washer, G., and Schmidt, a. J. (2014). "Field Evaluation of Hybrid-

Composite Girder Bridges in Missouri." Final Report prepared for Missouri Department of Transportation,

Jefferson City, MO.

Nosdall, S. V. (2013). "Experiments on a Hybrid Composite Beam for Bridge Applications." Master's Thesis,

Virginia Polytechnic Institute and State University, Blacksburg, VA.

Russell, H. G., and Graybeal, B.A. (2013). "Ultra-high performance concrete: a state-of-the-art report for the bridge

community." Technical report, FHWA-HRT-13-060, Federal Highway Administration, McLean, VA.

Snape, T., and Lindyberg, R. (2009). "Test Results: HC Beam for the Knickerbocker Bridge." AEWC Report 10-

16, University of Maine, Orono, ME.

VDOT (2011). "Tide Mill Interim Plan." Virginia Department of Transportation, Richmond, VA.