Determination of Load and Flexural Capacity of Press Brake Formed Tub Girder Bridges
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Financial Summary |
|
| Suggested Contribution: | $25,000.00 |
| Commitment Start Year: | 2027 |
| Commitment End Year: | 2030 |
| 100% SP&R Approval: | Pending Approval |
| Commitments Required: | $500,000.00 |
| Commitments Received: | |
| Estimated Duration Month: | 48 |
| Waiver Requested: | Yes |
Contact Information |
|
| Lead Study Contact(s): | David Chappell |
| david.c.chappell@wv.gov | |
| FHWA Technical Liaison(s): | Patricia Sergeson |
| Patricia.sergeson@dot.gov | |
| Phone: 202-493-3166 | |
| Study Champion(s): | Tracy Brown |
| tracy.w.brown@wv.gov | |
Commitments by Organizations
| Organization | Year | Commitments | Technical Contact Name | Funding Contact Name | Contact Number | Email Address |
|---|
Study Description
Background
?Accelerated Bridge Construction (ABC) has been widely used in the US since the late 90’s following a national ABC initiative promoted by the Transportation Research Board (TRB) in 1996. Press Brake Formed Tub Girder (PBFTG) systems are one of the innovative bridge systems that have been developed recently for the accelerated construction of simple and short span bridges. The PBFTG shape is optimized to achieve the maximum structural capacity and torsional stiffness due to the distribution of the steel around the centroid of the shape, a major limitation in conventional W-shape and plate I-girders. The optimized shape of PBFTGs also results in less weight than conventional W-shape and plate I-girders especially for short span bridges. For example, a skewed 75 ft span, 46 ft wide bridge will require 7 PBFTG beams with total depth of 30 inch and weight of 80 kips. However, using hot-rolled shape girders for the same bridge will result in using W36x256 sections, leading to a total weight of 134 kips (68% higher than PBFTG).
Despite the promising advantages of using PBFTG systems in short span bridges, current AASHTO Load and Resistance Factor Live Load Distribution Factors (LRFD LLDFs) (AASHTO 2020) for this type of superstructure have many limitations. The first limitation is related to the narrow range of applicability of such LLDFs. For example, current AASHTO LRFD LLDFs are not applicable to skewed box girder bridges (see section 6.11.2.3 in AASHTO 2020). Also, they are only applicable to bridges with number of lanes to number of beams (NL/NB) between 0.5 and 1.5 (see Table 4.6.2.2.2b-1 in AASHTO 2020). However, most short span bridges are used on local roads with only two lanes which produces NL/NB ratio less than 0.5. Another key limitation for AASHTO LLDFs of PBFTG bridges is that only one expression specified for live load distribution factor for moment and shear regardless of number of traffic lanes. However, AASHTO separates all these expressions for other types of superstructures (see section 4.6.2.2 in AASHTO 2020). Also, section 6.11.6.2.2 in AASHTO 2020 states that girders consisting of two or more single-cell box sections shall be designed as noncompact, thus limiting the capacity of these girders. The main reason behind this limitation is the lack of research on the ultimate capacity of skewed PBFTG bridges which will be addressed in the proposed research effort.
Objectives
?The proposed research is for investigating the live load distribution factors (LLDFs) for moment and shear of one, two or more lanes for fascia and interior beams in Press Brake Formed Tub Girder (PBFTG) bridges. The proposed research is also for determining the ultimate flexural capacity of skewed PBFTG bridges and to determine if PBFTGs can qualify as compact sections if the bearing lines are skewed. This will be achieved numerically through a parametric study including a wide range of geometric parameters of PBFTG bridges, including span length, beam spacing, skew angle, beam size, and number of traffic lanes, web depth to web thickness ratio, flange width to flange thickness ratio, and lateral bracing.
Scope of Work
?Planned tasks for this new study are as follows:
Detailed finite element models (FEM) will be developed using commercial finite element software.
Each model will study one of the parameters described in the objectives.
In the model, the deck and girders will be modelled using shell elements.
Validate the model against results from an experimental research project performed by others on the PBFTG.
The validated FE model will then be used in a parametric study to investigate:
the effects of different geometric parameters of the bridge on the live load distribution factors for moment and shear of one, two or more traffic lanes for fascia and interior beams in PBFTG bridges.
the effects of the parameters discussed above, on the ultimate flexural capacity of skewed PBFTG bridges.
The results of the parametric study will also be used in a regression analysis to propose new equations for the calculation of LLDFs for moment and shear of single and multiple traffic lanes for fascia and interior beams in PBFTG bridges.
The research project will propose revisions to current AASHTO, if necessary, to address cross section compactness for PBFTG with skewed bearing lines.
Comments
?The West Virginia Department of Transportation will be the lead agency for this study, with Tracy Brown (Tracy.w.brown@wv.gov) and Rebecca Curtis (curtisr4@michigan.gov) as the overall project champions.
The study will begin as early as 2026 and is expected to take four years to complete.
The minimum partner commitment is expected to be between $20,000.00 and $25,000.00 per year (for four years) beginning in FFY 2027 or after. The final commitment per state will be determined by the number of interested states. 100% SP&R funding approval will be requested.
Subjects: Bridges, Other Structures, and Hydraulics and Hydrology
Documents
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Determination of Load and Flexural Capacity of Press Brake Formed Tub Girder Bridges
General Information |
|
| Solicitation Number: | 1648 |
| Status: | Solicitation posted |
| Date Posted: | Oct 22, 2025 |
| Last Updated: | Oct 23, 2025 |
| Solicitation Expires: | Oct 22, 2026 |
| Lead Organization: | West Virginia Department of Transportation |
Financial Summary |
|
| Suggested Contribution: | $25,000.00 |
| Commitment Start Year: | 2027 |
| Commitment End Year: | 2030 |
| 100% SP&R Approval: | Pending Approval |
| Commitments Required: | $500,000.00 |
| Commitments Received: | |
Contact Information |
|
| Lead Study Contact(s): | David Chappell |
| david.c.chappell@wv.gov | |
| FHWA Technical Liaison(s): | Patricia Sergeson |
| Patricia.sergeson@dot.gov | |
| Phone: 202-493-3166 | |
Commitments by Organizations
Study Description
Background
?Accelerated Bridge Construction (ABC) has been widely used in the US since the late 90’s following a national ABC initiative promoted by the Transportation Research Board (TRB) in 1996. Press Brake Formed Tub Girder (PBFTG) systems are one of the innovative bridge systems that have been developed recently for the accelerated construction of simple and short span bridges. The PBFTG shape is optimized to achieve the maximum structural capacity and torsional stiffness due to the distribution of the steel around the centroid of the shape, a major limitation in conventional W-shape and plate I-girders. The optimized shape of PBFTGs also results in less weight than conventional W-shape and plate I-girders especially for short span bridges. For example, a skewed 75 ft span, 46 ft wide bridge will require 7 PBFTG beams with total depth of 30 inch and weight of 80 kips. However, using hot-rolled shape girders for the same bridge will result in using W36x256 sections, leading to a total weight of 134 kips (68% higher than PBFTG).
Despite the promising advantages of using PBFTG systems in short span bridges, current AASHTO Load and Resistance Factor Live Load Distribution Factors (LRFD LLDFs) (AASHTO 2020) for this type of superstructure have many limitations. The first limitation is related to the narrow range of applicability of such LLDFs. For example, current AASHTO LRFD LLDFs are not applicable to skewed box girder bridges (see section 6.11.2.3 in AASHTO 2020). Also, they are only applicable to bridges with number of lanes to number of beams (NL/NB) between 0.5 and 1.5 (see Table 4.6.2.2.2b-1 in AASHTO 2020). However, most short span bridges are used on local roads with only two lanes which produces NL/NB ratio less than 0.5. Another key limitation for AASHTO LLDFs of PBFTG bridges is that only one expression specified for live load distribution factor for moment and shear regardless of number of traffic lanes. However, AASHTO separates all these expressions for other types of superstructures (see section 4.6.2.2 in AASHTO 2020). Also, section 6.11.6.2.2 in AASHTO 2020 states that girders consisting of two or more single-cell box sections shall be designed as noncompact, thus limiting the capacity of these girders. The main reason behind this limitation is the lack of research on the ultimate capacity of skewed PBFTG bridges which will be addressed in the proposed research effort.
Objectives
?The proposed research is for investigating the live load distribution factors (LLDFs) for moment and shear of one, two or more lanes for fascia and interior beams in Press Brake Formed Tub Girder (PBFTG) bridges. The proposed research is also for determining the ultimate flexural capacity of skewed PBFTG bridges and to determine if PBFTGs can qualify as compact sections if the bearing lines are skewed. This will be achieved numerically through a parametric study including a wide range of geometric parameters of PBFTG bridges, including span length, beam spacing, skew angle, beam size, and number of traffic lanes, web depth to web thickness ratio, flange width to flange thickness ratio, and lateral bracing.
Scope of Work
?Planned tasks for this new study are as follows:
Detailed finite element models (FEM) will be developed using commercial finite element software.
Each model will study one of the parameters described in the objectives.
In the model, the deck and girders will be modelled using shell elements.
Validate the model against results from an experimental research project performed by others on the PBFTG.
The validated FE model will then be used in a parametric study to investigate:
the effects of different geometric parameters of the bridge on the live load distribution factors for moment and shear of one, two or more traffic lanes for fascia and interior beams in PBFTG bridges.
the effects of the parameters discussed above, on the ultimate flexural capacity of skewed PBFTG bridges.
The results of the parametric study will also be used in a regression analysis to propose new equations for the calculation of LLDFs for moment and shear of single and multiple traffic lanes for fascia and interior beams in PBFTG bridges.
The research project will propose revisions to current AASHTO, if necessary, to address cross section compactness for PBFTG with skewed bearing lines.
Comments
?The West Virginia Department of Transportation will be the lead agency for this study, with Tracy Brown (Tracy.w.brown@wv.gov) and Rebecca Curtis (curtisr4@michigan.gov) as the overall project champions.
The study will begin as early as 2026 and is expected to take four years to complete.
The minimum partner commitment is expected to be between $20,000.00 and $25,000.00 per year (for four years) beginning in FFY 2027 or after. The final commitment per state will be determined by the number of interested states. 100% SP&R funding approval will be requested.
Subjects: Bridges, Other Structures, and Hydraulics and Hydrology
