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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Research in Progress (RIP)</title>
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      <title>Mechanical Characterizations of Joints in Segmented Tunnel Liners Due to Flexural and Thrust Jack Loading (UTI-UTC 28)
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      <link>https://rip.trb.org/View/2543421</link>
      <description><![CDATA[This research investigates the structural behavior of joints in segmented tunnel liners subjected to flexural and thrust jack loading, which are critical conditions encountered during tunnel construction and operation. The project focuses on quantifying the mechanical response of these joints, particularly under load scenarios simulating bending moments and axial forces applied by tunnel boring machines (TBMs). Experimental testing is conducted on full-scale precast concrete segments, including those from the Chesapeake Bay Tunnel project, to assess parameters such as joint stiffness, rotational capacity, and load-bearing performance. The study is complemented by detailed numerical modeling and analytical evaluations to validate test results and improve segmental design methodologies. The outcomes are expected to inform design guidelines and enhance the durability, safety, and reliability of segmented tunnel systems used in modern underground transportation infrastructure.
]]></description>
      <pubDate>Wed, 07 May 2025 17:37:37 GMT</pubDate>
      <guid>https://rip.trb.org/View/2543421</guid>
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      <title>Understanding cross passage ground-structure interaction using data from the Seattle Northgate Link transit extension project (UTI-UTC 39)
</title>
      <link>https://rip.trb.org/View/2543429</link>
      <description><![CDATA[This research project investigates the complex ground-structure interaction that occurs during the construction of cross passages in soft ground tunneling environments. Utilizing detailed instrumentation and monitoring data from the Seattle Northgate Link Transit Extension Project, the study aims to quantify the effects of cross passage excavation on segmental tunnel linings and the surrounding ground. It focuses on assessing deformation patterns, ground movement, and changes in internal tunnel forces induced by cross passage construction activities. The project employs numerical modeling and empirical analysis to validate field observations, offering insights into stress redistribution and liner performance. By improving the understanding of these interactions, the research supports the development of safer and more efficient design guidelines for cross passages, particularly in challenging geotechnical conditions common in urban tunneling projects.
]]></description>
      <pubDate>Wed, 07 May 2025 16:51:41 GMT</pubDate>
      <guid>https://rip.trb.org/View/2543429</guid>
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      <title>Mechanical Characterizations of Joints in Segmented Tunnel Liners Due to Flexural and Thrust Jack Loading (UTI-UTC 43)
</title>
      <link>https://rip.trb.org/View/2543433</link>
      <description><![CDATA[This project investigates the mechanical behavior of joints in segmented tunnel liners subjected to flexural and thrust jack loading conditions commonly encountered during tunnel construction and operation. Utilizing both experimental testing and numerical modeling, the research aims to understand the load-deformation response and failure mechanisms at segment joints, particularly under combined loading scenarios. The study is based on data and specimen segments from the Chesapeake Bay Tunnel expansion, with testing conducted to evaluate performance under controlled thrust and bending loads. Analytical models are developed and calibrated to replicate observed behaviors, contributing to more accurate predictions of joint behavior. The outcomes of this project will inform the design and construction of more resilient and efficient segmental tunnel linings, supporting improved safety and performance in underground transportation infrastructure.
]]></description>
      <pubDate>Wed, 07 May 2025 15:59:38 GMT</pubDate>
      <guid>https://rip.trb.org/View/2543433</guid>
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      <title>Proposed AASHTO Guideline for Load Rating of Segmental Bridges</title>
      <link>https://rip.trb.org/View/1707221</link>
      <description><![CDATA[NCHRP Research Report 1128: Load Rating of Segmental Bridges presents procedures for load rating of segmental bridges. The proposed recommendations were developed based on extensive review of the state of practice of the evaluation of segmental bridges and comprehensive analytical programs. The research findings will be used by bridge load rating professionals at state departments of transportation. A segmental bridge is constructed in short sections or segments that are either precast or cast-in-place concrete. Segmental bridges were first built in the United States in the 1970s and have proven to be an efficient design for long-span bridges. The earliest segmental bridges were designed, constructed, and load rated using methods that were not codified by the American Association of State Highway and Transportation Officials (AASHTO) and differ significantly from the current AASHTO load and resistance factor design (LRFD), load factor rating (LFR), and load and resistance factor rating (LRFR) methodologies. As a result, the use of current AASHTO LFR and LRFR methodologies to load rate existing segmental bridges has resulted in a significant capacity reduction in comparison to the old load rating procedures. In addition, there are limited resources for owners and consultants to accurately load rate segmental bridges. There was a need to develop load rating procedures to accurately determine the load rating capacity of segmental bridges to ensure safety and mobility. Under NCHRP Project 12-123, “Proposed AASHTO Guideline for Load Rating of Segmental Bridges,” Auburn University was asked to (1) develop procedures for load rating of segmental bridges, (2) propose revisions to the current segmental bridge evaluation and design requirements, and (3) develop rating examples with supporting training materials to demonstrate the proposed procedures and revisions. In addition to the proposed Guideline, the research team proposed draft language for consideration by AASHTO in the next update of The Manual for Bridge Evaluation and the LRFD Bridge Design Specifications for the rating of segmental bridges.]]></description>
      <pubDate>Tue, 19 May 2020 17:34:10 GMT</pubDate>
      <guid>https://rip.trb.org/View/1707221</guid>
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      <title>Seismic Performance of Bridge Superstructure in Accelerated Bridge Construction</title>
      <link>https://rip.trb.org/View/1441865</link>
      <description><![CDATA[Accelerated bridge construction (ABC) methods utilizing prefabricated components and segmental construction techniques continue to be advanced around the country and have already been implemented in many states, including Texas, Washington, New York, and Massachusetts, to name a few (Federal Highway Administration [FHA] 2009). The ABC method has also been adopted by the California Department of Transportation (Caltrans) on a case by case basis, especially for bridge widening projects such as the San Mateo Bridge (Caltrans 2008). However, to date there has been very little experimental research conducted to validate seismic load capacities of connection details for such methods, and there has not been a systematic undertaking to introduce ABC in high seismic regions.]]></description>
      <pubDate>Wed, 04 Jan 2017 10:54:58 GMT</pubDate>
      <guid>https://rip.trb.org/View/1441865</guid>
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