<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Research in Progress (RIP)</title>
    <link>https://rip.trb.org/</link>
    <atom:link href="https://rip.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Research in Progress (RIP)</title>
      <url>https://rip.trb.org/Images/PageHeader-wTitle-RIP.jpg</url>
      <link>https://rip.trb.org/</link>
    </image>
    <item>
      <title>Efficacy, Advancement, and Monitoring of Carbon Fiber Composite Cable (CFCC)</title>
      <link>https://rip.trb.org/View/2724770</link>
      <description><![CDATA[Carbon Fiber Composite Cable (CFCC), and the Carbon Fiber Reinforced Polymer (CFRP) materials are being used for prestressing
applications in Michigan bridge rehabilitation and replacement projects with the most recent generation of CFCC is a 0.7-inch strand
configuration. The quantity of stands is similar to conventional strands, and concomitant updated design criteria. Determining the
efficacy of the new 0.7-inch CFCC strand long-term behavior is essential for future design and construction considerations.
Monitoring the CFCC elements in newly constructed bridges (with 0.7-inch strands) and some prior construction (from OR14-039)
will provide an understanding of the long-term behavior and realizations of recommendations on future designs, and continued
considerations of field deployment.]]></description>
      <pubDate>Tue, 07 Jul 2026 10:05:57 GMT</pubDate>
      <guid>https://rip.trb.org/View/2724770</guid>
    </item>
    <item>
      <title>Evaluation of UHPC Shell Stay-in-Place Formwork and BCSA Cement Concrete Prestressed Girders</title>
      <link>https://rip.trb.org/View/2646949</link>
      <description><![CDATA[Precast prestressed bridge girders are used for a large percentage of bridges in the United States. These bridges are susceptible to deterioration at the supports due to leaking expansion joints and end region cracking caused by high stresses at the beam ends. This project will evaluate the feasibility and structural performance of a hybrid precast, prestressed concrete girder system that utilizes an ultra-high performance concrete (UHPC) shell stay-in-place formwork or end region insert and rapid setting belitic calcium sulfoaluminate (BCSA) cement concrete. UHPC is a relatively recent advancement in cementitious composite materials with mechanical and durability properties far exceeding those of conventional concrete. This research is intended to address the concern of end region durability by encapsulating the girder concrete with a nearly impermeable layer of UHPC that is also resistant to cracking. The rapid setting of BCSA cement concrete and use of stay-in-place forms can increase the speed of production of the prestressed girders and BCSA cement concrete has reduced prestress losses over time.  

The research will consist of evaluating small-scale behavior of composite UHPC shell and BCSA cement concrete compression and flexural elements, and construction and testing of large-scale prestressed beam elements. The objectives of the project are to evaluate the feasibility of using rapid setting BCSA cement concrete in conjunction with a UHPC shell for prestressed concrete elements, determine flexure and shear failure mechanisms and associated capacity for composite UHPC shell elements, and develop effective interface details for the UHPC shell to BCSA cement concrete. This work will be conducted through a series of five tasks. Task 1 will evaluate the surface preparation and deformation compatibility using small-scale testing. Task 2 will consist of the design of prestressed beam specimens using different shell surface preparations and locations along the beam. Task 3 will consist of prestressed beam specimen construction. Task 4 will include flexural and shear testing of the prestressed beam elements. Task 5 will consist of preparing reports and disseminating the project information. ]]></description>
      <pubDate>Tue, 06 Jan 2026 09:02:05 GMT</pubDate>
      <guid>https://rip.trb.org/View/2646949</guid>
    </item>
    <item>
      <title>Design Guidance Development for Continuous Prestressed CFCC Strand Beams</title>
      <link>https://rip.trb.org/View/2562256</link>
      <description><![CDATA[The analysis of continuous bridge beams is more complicated than that of simply-supported beams. In much the same
way, construction of simply-supported beams is also much simpler than continuous prestressed beams. Yet, continuous
beam spans can be the best option in unique bridge projects. One project type includes bridge superstructures
replacement with limited clearance. The depth of the new bridge beam is limited by road clearance or high-water flood
elevation. Continuous span design with a reduced beam depth may be the best design alternative as the continuous
beam meets the loading requirements with a thinner cross section. 
Michigan Department of Transportation (MDOT) does not typically build continuous
superstructures where beams are designed to perform continuously with regard to loads. Additionally, the length of
beams is limited by shipping constraints, so deploying CFCC beams on short and medium span bridges seems more
feasible. CFCC has not been utilized in Michigan in draped conditions required for continuous beams, so the
configuration and design requirements need to be developed. This project will explore the possible application of new
materials and new designs in a combined effort.]]></description>
      <pubDate>Fri, 06 Jun 2025 14:21:49 GMT</pubDate>
      <guid>https://rip.trb.org/View/2562256</guid>
    </item>
    <item>
      <title>Evaluate the Effectiveness of Dowels for Lateral Restraint of Prestressed Concrete Beams</title>
      <link>https://rip.trb.org/View/2437677</link>
      <description><![CDATA[The Texas Department of Transportation (TxDOT) has utilized dowels in bents to provide lateral restraint of prestressed concrete beams.  These dowels are often misplaced, which creates various construction issues, while their presence complicates bearing pad replacement. The research team will provide research findings to the TxDOT to make informed decisions on stopping the use of such dowels, the researchers will perform a thorough literature review to: (i) summarize the state-of-art, state-of–the-practice and key findings, and (ii) address questions relating to unintended consequences from removal of these dowels during erection of the girders, construction of the deck, and long-term performance and stability. The researchers will perform an investigation on the state-of-the-practice of all state Department of Transportations (DOTs) throughout the country, focusing on practices from DOTs with similar hazard exposure. The researchers will perform a parametric finite element (FE) study on multiple the TxDOT bridge (and girder) designs to investigate the performance under all major load combinations and limit states (from service to ultimate conditions) over the lifetime of the bridge accounting for Texas-related exposure conditions. The researchers will perform six (6) large-scale tests on girder-to-bent/abutment connections to quantify the contribution of dowels in the performance of the connections.]]></description>
      <pubDate>Thu, 03 Oct 2024 09:35:30 GMT</pubDate>
      <guid>https://rip.trb.org/View/2437677</guid>
    </item>
    <item>
      <title>Investigating the Durability and Resilience of Precast Post-Tensioned Concrete Box Girder Bridges with External Tendons</title>
      <link>https://rip.trb.org/View/2406778</link>
      <description><![CDATA[Precast box girders are often used by DOTs to construct bridges with relatively long spans. The use of either internal or a mix of internal and external post-tensioning (PT) tendons is typical in these bridges to achieve the high strength and limited cracking needed for the bridges to meet the AASHTO design specifications for strength and serviceability limit states. The recent discovery by the Illinois DOT (IDOT) of the fracture of one of the external PT tendons of the I-39 Northbound bridge crossing the Kishwaukee river south of Rockford, Illinois illustrates the vulnerability of these types of bridges. The bridge was constructed in 1979/1980 and external PT tendons were added in 2008.  The unexpected fracture of one the tendons raised IDOT’s concerns about the cause of the tendon’s fracture and the vulnerability of other tendons as well as whether the missing of one of the external PT tendons would impact the safety of the bridge. Hence, this Industry Partnership (IP) research project is a collaborative effort between IDOT, TRANS-IPIC researchers, and the consulting firm, Jacobs to investigate through on-site work, experimental testing, and numerical analysis the durability and corrosion resistance of external PT tendons in precast box girder bridges. The project will result in recommendations for IDOT and other State DOTs related to improving the durability and extending the life of precast box girder bridges. ]]></description>
      <pubDate>Wed, 24 Jul 2024 12:44:31 GMT</pubDate>
      <guid>https://rip.trb.org/View/2406778</guid>
    </item>
    <item>
      <title>Innovative Precast Concrete Truss Using Adaptive Shape Memory Prestressing System</title>
      <link>https://rip.trb.org/View/2250305</link>
      <description><![CDATA[The ever-growing demand for making transportation infrastructure more durable and sustainable requires serious efforts to reduce carbon emissions associated with the concrete and steel used in transportation infrastructure. Almost half of the CO2 emission in the construction industry is related to steel and cement production. Cement alone is the source of about 8% of the world's CO2 emissions, and concrete is the second most used substance by mass after water. One way to achieve sustainability is by optimizing the materials used in transportation infrastructure. Taking precast concrete (PC) prestressed bridge components as an example, the geometric configurations of PC bridge girders have not significantly changed over the last several decades. Part of this could be attributed to the constraints imposed by the prestressing system and how the prestressing force is applied, which has not changed much over the years. This research will help address this issue by studying the application of an innovative Adaptive Prestressing System (APS) in a geometrically optimized (truss) PC system. The new APS can apply localized prestressing in any direction without mechanical tensioning or special hardware, which is ideal for prestressing short diagonal or vertical members of a PC truss. Additive manufacturing (3D printing) technology advancements make casting concrete trusses more feasible. Reusable, durable 3-D printed molds can be used in precast plants to construct trusses with various complex geometries. This research will investigate the APS technology to overcome the issue of cracking in lightweight PC trusses. APS utilizes shape memory alloys (SMAs); a class of smart metallic material that can remember their original shape by heating after being excessively deformed. APS is based on utilizing the permanent force associated with the shape recovery of the deformed SMAs to prestress members subjected to tension in a truss that are hard to prestress using conventional methods. The research will include experimental testing and numerical simulation of reduced-scale PC truss structures with APS placed in tension members that are hard to prestress using conventional methods. ]]></description>
      <pubDate>Mon, 18 Sep 2023 21:56:33 GMT</pubDate>
      <guid>https://rip.trb.org/View/2250305</guid>
    </item>
    <item>
      <title>Shape Memory Alloy Transverse Reinforcement for Precast Bridge Girders End Regions</title>
      <link>https://rip.trb.org/View/2250299</link>
      <description><![CDATA[Despite the success of using concrete prestressing technology in the longitudinal direction, it has not been implemented in the transverse direction due to many practical challenges. The reason is that no practical method exists for prestressing internal shear reinforcement such as hoops, stirrups, or spirals because these reinforcements are fully embedded in the concrete; hence, gripping the reinforcement ends for prestressing is not feasible. This research will investigate a new technology for applying prestressing in the transverse direction using a class of smart metallic materials known as shape memory alloys (SMAs). Excessively deformed bars and wires made of SMAs can remember their original shape when subjected to a temperature of approximately 200⁰C. This project will use this novel material to solve the longstanding problem of splitting and bursting cracking at the end regions of precast concrete (PC) bridge girders. Applying prestressing in the transverse direction (i.e., vertically) within that local region will help mitigate concrete cracking during prestressing and reduce steel congestion in this region. The research plan for this project includes performing numerical investigation and experimental testing of the new technology.  ]]></description>
      <pubDate>Mon, 18 Sep 2023 19:20:10 GMT</pubDate>
      <guid>https://rip.trb.org/View/2250299</guid>
    </item>
    <item>
      <title>Evaluate Use of 300ksi Strands for TxDOT Prestressed Girders</title>
      <link>https://rip.trb.org/View/2056300</link>
      <description><![CDATA[Advances in material and fabrication processes have allowed the prestressing-strand industry to increase the strength of strands from 270 ksi to 300 ksi. Several state DOTs around the nation are already considering incorporating higher strength strands into their designs. The impetus is to obtain longer bridge span lengths for a given section depth. The main goal of this research project is to update the designs of standard Texas DOT prestress girders to incorporate 300 ksi 0.6 inch diameter strands. The main concern for upgrading to 300 ksi strands revolves around the increased spalling and bursting stresses associated with higher prestressing forces. Such increases in stresses can cause increased cracking in girders at prestress transfer. The research team will conduct tests on full-scale prestressed girders for all standard TX girder section sizes. These tests will allow the research team to hone in on optimal detailing for girders using 300 ksi strands. As a result, new designs for all TX girder sections shall be produced for 300 ksi strands. Updates to design specifications shall also be proposed to reflect research findings. The expected benefits are more economical bridges that can span longer distances for a given section depth.]]></description>
      <pubDate>Thu, 03 Nov 2022 16:43:40 GMT</pubDate>
      <guid>https://rip.trb.org/View/2056300</guid>
    </item>
    <item>
      <title>Synthesis of available methods for repair of prestress girder ends</title>
      <link>https://rip.trb.org/View/1596192</link>
      <description><![CDATA[Many bridges in the Unites States are aging and due for repair or strengthening. Corrosion of prestressed girder ends is a prevalent problem that significantly reduces the bearing capacity of bridges. Moreover, over-height vehicles continue to collide and impact bridge girders around the country, which compromise the flexural capacity of bridge girders. Several research studies and state DOTs initiatives looked into innovative repair and strengthening methods for girders end zones and/or mid span impacts. The goal of this project is to synthesize the available literature on bridge girders repair methods with focus on prestressed girders and end zones damage. The synthesis will summarize and compare the design and application procedure of different methods to provide a guide or catalog for bridge engineers working on girders end repair.]]></description>
      <pubDate>Sat, 30 Mar 2019 14:24:14 GMT</pubDate>
      <guid>https://rip.trb.org/View/1596192</guid>
    </item>
    <item>
      <title>Flexural Capacity of Concrete Elements with Unbonded Prestressing</title>
      <link>https://rip.trb.org/View/1501618</link>
      <description><![CDATA[The objective of this research is to provide design guidelines and analysis procedures for bridges with unbonded tendons with particular focus on a combination of unbonded tendons and bonded prestress and/or mild reinforcement. The research will evaluate various ratios of bonded and unbonded prestressing, with consideration of bonded mild reinforcement and PT bars within certain structural members. Guidance on the appropriate resistance factors for these conditions will also be provided.]]></description>
      <pubDate>Wed, 07 Feb 2018 11:49:03 GMT</pubDate>
      <guid>https://rip.trb.org/View/1501618</guid>
    </item>
    <item>
      <title>Pre-stressed Losses in Decked Bulb-tee Girders</title>
      <link>https://rip.trb.org/View/1466349</link>
      <description><![CDATA[The American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Bridge Design Specifications provides guidance for the calculation of pre-stress losses in precast concrete beams. Changes (2007) in the AASHTO code results in inconsistent pre-stress loss predictions for decked bulb-tee girders such as those used by the Department. Specifically, the simplified procedure for pre-stress loss prediction results in much less loss than that predicted from the previous versions of the AASHTO codes and are less than that resulting from the "refined" method of the current code. 

Better design predictions for long-term pre-stress losses may result in longer spans, few girder lines or shallower girders. Saving one girder line would save the Department about $75k per span (~5% of bridge cost) for the typical highway bridge. More accurate per-stress loss values would result in more accurate girder strength predictions.]]></description>
      <pubDate>Thu, 04 May 2017 15:42:06 GMT</pubDate>
      <guid>https://rip.trb.org/View/1466349</guid>
    </item>
    <item>
      <title>Creep and Shrinkage Effects On Columns</title>
      <link>https://rip.trb.org/View/1441771</link>
      <description><![CDATA[Creep (CR) and Shrinkage (SH) forces due to long term prestress shortening produce imposed deformations on bridge columns at the bents.  These deformations, in turn, produce column moments and shears which must be considered as part of the design process.  The magnitude of the imposed deformations on the columns is in question and should be investigated by looking at various frame configurations and foundation types.  Phenomena such as relaxation and foundation flexibility can reduce the effects of these forces and should be quantified.]]></description>
      <pubDate>Wed, 04 Jan 2017 10:51:59 GMT</pubDate>
      <guid>https://rip.trb.org/View/1441771</guid>
    </item>
    <item>
      <title>The NASP Bond Test as a Predictor of Strand Bond, Transfer Length, and Development Length</title>
      <link>https://rip.trb.org/View/1319702</link>
      <description><![CDATA[The objective of the proposed study is to design, test, and evaluate high-volume fly ash concrete mixtures (HVFA). Traditional specifications limit the amount of fly ash to 40% or less cement replacement. This program attempts to increase the ash content to 75% while maintaining strength and durability characteristics. Various mixtures and chemical additives will be tested. The funding would allow calorimetry studies of potential admixtures and additives necessary to increase the percentage of fly ash (FA) in the various concrete mixes. The calorimetry would allow a more diverse and extensive set of variables to be studied, and would assist the researchers in developing mixes specific to each type of fly ash available. The funding would also allow testing for leachability of the HVFA concrete to existing FA concrete and non-FA concrete using TCLP, ASTM 3987, and the new LEAF methods, and to potentially evaluate the various products for radioactivity.]]></description>
      <pubDate>Sat, 09 Aug 2014 01:00:47 GMT</pubDate>
      <guid>https://rip.trb.org/View/1319702</guid>
    </item>
    <item>
      <title>Enhancement of National LRFD Codes for California Bridge Design: Hinge Curl Research</title>
      <link>https://rip.trb.org/View/1234214</link>
      <description><![CDATA[This task is intended to provide resources needed to research multi-frame prestressed box girder structures that require hinges to allow expansion and contraction due to thermal effects. The construction of these hinges is complicated by the fact that prestressing causes time dependent deformation. In particular, the short cantilever side of the hinge tends to "curl" upward due to the effect of prestressing. This curl continues until load transfer is completed from the suspended side of the hinge (usually after false work is removed). This makes it difficult to set screed line elevations since it depends on the amount of curl as well as the time until load transfer. This issue has been addressed in Memo to Designers (MTD) 11-34. However, the equations and methodology used in this memo are unproven and easily misinterpreted. A proposed revision to this memo is recommended (and will be attached to the proposal).]]></description>
      <pubDate>Thu, 03 Jan 2013 15:08:38 GMT</pubDate>
      <guid>https://rip.trb.org/View/1234214</guid>
    </item>
    <item>
      <title>Determination of Acceptance Criteria for Prestressing Strand in Pretensioned Applications</title>
      <link>https://rip.trb.org/View/1231574</link>
      <description><![CDATA[The objective of this research project is to quantify the repeatability and reproducibility of the Standard Test Method for the Bond of Prestressing Strands (STSB) test method being considered by ASTM International. In Phase 1, testing will be performed in order to determine if the test is sufficiently rugged to ensure reproducibility of test results between different laboratories, and possible modifications suggested if shown by testing that these would lead to increased reproducibility. The reproducibility of the test will then be established through Round Robin testing. Phases II and III outlined in the proposal are geared towards determining an appropriate threshold acceptance value for prestressing steel strand to ensure reliable bonding performance in concrete beams. The key to being able to set a reasonable threshold value with a high confidence level is to maximize the repeatability and reproducibility of the test.]]></description>
      <pubDate>Thu, 03 Jan 2013 14:22:08 GMT</pubDate>
      <guid>https://rip.trb.org/View/1231574</guid>
    </item>
  </channel>
</rss>