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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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      <link>https://rip.trb.org/</link>
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    <item>
      <title>Improved Resiliency of Transportation Networks through Connect Mobility</title>
      <link>https://rip.trb.org/View/2329687</link>
      <description><![CDATA[A significant number of bridges (older bridges in particular) in the Southeastern and Central region of United States have been designed and constructed according to older seismic provisions. Based on an article by Wong et al. (2005), the economic loss from the Charleston region could reach over $14 billion if the 1886 Charleston earthquake were to happen again. Due to outdated seismic design strategies used for older bridges, recent research has investigated potential damage in Charleston. However, most of these investigations do not account for the simultaneous aspects of bridge importance (such as centrality, historical significance, and traffic capacity).  Furthermore, these prior investigations do not consider the actual detailing of critical structural connections, such as the critical pile to bent cap connection. This connection region is depended upon for energy dissipation while simultaneously providing structural integrity during an event. Full-scale experimental studies performed at the University of South Carolina were used to assess projected performance of these connections in a seismic event. This project develops a new tool that is informed with actual structural behavior gained through full-scale experimental investigations and combines centrality, historical significance, and traffic capacity to assess expected damage. The results are useful for informing placement of monitoring systems, identification of potential retrofit strategies, and optimizing network performance.  One goal of the work is technological transfer. The research findings can be used to assist the Department of Transportation in identification of the most critical bridges in the network for purposes of instrumentation, meaning which bridges should be monitored and, for those bridges, which specific regions should be monitored to rapidly assess damage after a seismic event. This information can then be utilized for routing of traffic and for the assessment of potential retrofitting strategies, thereby improving reliability of the transportation system. The tool runs on Matlab and includes transportation network and seismic demand visualization. Results are presented in sets of graphics and tables through a multi-window graphical user interface.]]></description>
      <pubDate>Tue, 30 Jan 2024 10:10:26 GMT</pubDate>
      <guid>https://rip.trb.org/View/2329687</guid>
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    <item>
      <title>Super-Elastic Copper-Based and Iron-Based Shape Memory Alloys and Engineered Cementitious Composites for Extreme Events Resiliency</title>
      <link>https://rip.trb.org/View/1903711</link>
      <description><![CDATA[Displacement capacity and energy dissipation in conventional RC columns comes at the cost of severe damage to concrete and steel and permanent displacement of the bridges and other structures including marine structures during extreme events such as earthquake, ice load, collision by vessels and vehicles, tsunamis, check floods, and blasts. The resiliency of these structures can be significantly increased if these problems can be eliminated using shape memory alloy (SMA) and engineered cementitious composite (ECC). Comparison of residual displacement in laboratory testing of column models demonstrated that residual displacement was 86% lower than that the columns with conventional materials. The Washington State Department of transportation (WSDOT) implemented SMA/ECC in the columns of the SR-99 on-ramp bridge in downtown Seattle. With the price of Nickel-Titanium SMA (NiTi) being 90 times the mild steel cost, bridge owners may be reluctant to adopt the material. To offset SMA material costs, a new generation of Copper-Aluminum-Manganese (CAM) SMA bar that is approximately 80-90% less expensive than NiTi is emerging. The alloy is composed of 72% Copper, 17% Aluminum, and 11% Manganese. No. 10 CAM bars have been developed and were recently tested along with Headed Reinforcement Corp’s (HRC) couplers at University of Nevada – Reno (UNR) with good results, i.e. large-diameter bars for use in actual bridges have already proven to be feasible. CAM bars are connected to steel bars that extend into the column and footings or cap beams. No CAM-reinforced columns incorporating the (HRC) splice has yet been studied, however, an exploratory study was conducted by shake table testing of a column model incorporating threaded CAM bars. These bars had to be machined to a dog bone shape to avoid fracture at the threaded ends. Engineered Cementitious Composite (ECC) was used in the plastic hinge region. ECC is a fiber-reinforced cement-based concrete which has high tensile ductility and high compressive and tensile strengths.. The column performed very well in limiting residual displacement while eliminating plastic hinge damage. Another SMA type, the low-cost iron-based SMA is also emerging, although its performance under extreme loads is yet to be studied. The advantage of Fe-SMA over CAM, should it prove successful, is having material characteristics that are similar to those of conventional steel that is readily used in bridge construction while being at a low cost.
The objective of this research project is to: 
(1) evaluate and test several innovative columns which have self-centering feature to provide minimum residual displacement after earthquake. 
(2) improve column serviceability after earthquake by decreasing damage and spalling of concrete within column plastic hinge region; and 
(3) provide cost comparison among columns having different engineered materials; and 
(4) develop self-centering column design specifications. Particularly, in this proposed research, the low-cycle fatigue characteristics, corrosion resistance, machinability and coupling mechanisms with traditional steel rebar, and cost of CAM and Fe-SMA super-elastic alloy (SEA) bars will be studied. 
Direct comparisons will be made with Nickel-Titanium (NiTi) SEAs (and traditional steel reinforcing bars as applicable) to illustrate the advantages/disadvantages of each material. If successfully demonstrated for their suitable characteristics, the CAM and Fe-SMA SEA bars could replace their NiTi counterparts at a significantly lower (up to ten times) cost and accelerate their applications in bridges. Therefore, the outcomes of this project are directly relevant to state departments of transportation and bridge and structural engineers and designers. This proposed project will build on the success of previously implemented WSDOT’s application of shape memory alloy/engineered cementitious composite (SMA/ECC) in the columns of the SR-99 on-ramp bridge in downtown Seattle while making a direct impact on advancing and securing the national transportation network.]]></description>
      <pubDate>Thu, 13 Jan 2022 17:36:01 GMT</pubDate>
      <guid>https://rip.trb.org/View/1903711</guid>
    </item>
    <item>
      <title>Seismic Performance and Fragility of Retrofitted Reinforced Concrete Bridge Columns to Long-Duration Earthquakes</title>
      <link>https://rip.trb.org/View/1856847</link>
      <description><![CDATA[Long duration earthquakes are characteristic of the Cascadia Subduction Zone, which has the potential to generate a Magnitude-9.0 earthquake with strong shaking in Washington, Oregon, northern California, and Alaska. The proposed research is focused on characterization of the probability of failure of retrofitted bridge columns due to fatigue fracture of reinforcement under long-duration earthquakes. The proposed research will include the formulation of fatigue fracture models based on actual earthquake strain histories, as previous research on fatigue modeling of reinforcement has used idealized reversed cyclic loading histories. Ongoing research by the PIs on this topic has generated test data for legacy grade 40 reinforcement, typical of 1950s-1970s bridges. The proposed research will include additional testing of modern grade 40 and grade 60 reinforcement to better characterize the influence of earthquake cycle content on fatigue life. Nonlinear time history analyses, incorporating the improved fatigue fracture models, will be conducted for a range of bridges subjected to Cascadia Subduction Zone demands, and results will be used to develop failure fragilities.
]]></description>
      <pubDate>Sat, 05 Jun 2021 17:08:20 GMT</pubDate>
      <guid>https://rip.trb.org/View/1856847</guid>
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    <item>
      <title>Risk and Resilience of Bridges: Toward Development of Hazard-Based Assessment Framework, Research Needs, and Benefits of Accelerated Construction</title>
      <link>https://rip.trb.org/View/1838446</link>
      <description><![CDATA[Transportation networks are modeled in the form of links and nodes. Links represent the highways, while the nodes representing bridges connecting the highways which act as hubs for several links. Closure of a single bridge within the transportation network can lead to substantial disruption to the entire network. For example, the local damage of the I-65 North overpass bridge in Alabama in January 2002 (due to truck accidental explosion) caused a traffic interruption for almost 50 days. Assessment of risk and resilience of existing bridges and new bridges, including accelerated bridge construction (ABC) bridges, accelerated upgrade, and accelerated repair is important to devise pre-hazard preparedness plans and post-hazard mitigation response strategies and recovery time. This project seeks to document and synthesize the current state of practice related to assessment of risk and resilience of bridges and other structures and conducting target surveys to identify the current state of practice with transportation agencies and cities. The collected information will be utilized to develop holistic resilience and risk assessment framework for existing and new bridges, including ABC bridges, accelerated upgrade (enhanced robustness), and accelerated repair (enhanced rapidity), under multi-hazards to emphasis on accelerated construction benefits. Finally, the project will develop a specific resilience framework for seismic hazard. Other hazards will be developed in future research opportunities. The success of this project will promote ABC nationwide to stakeholders as the most suited construction method for resilient bridges and transportation infrastructures.
Project objective are as follows: 
(1) Documenting the current state of practice related to assessment of risk and resilience of bridges nationally and internationally.
(2) Synthesizing the state of practice related to assessment of risk and resilience of other structures (such as buildings and nuclear facilities) against man-made and natural hazards with the goal of identifying frameworks and assessment tools can be readily adopted for bridges.
(3) Conducting target online survey for state DOTs and cities to evaluate the practice and efficacy of existing bridge performance tools.
(4) Developing a holistic resilience and risk assessment framework for existing and new bridges, including ABC bridges, accelerated upgrade, and accelerated repair, under multi-hazards to emphasis on accelerated construction benefits, and
(5) Developing a specific resilience framework for seismic hazard as an example of natural hazards. The success of this project will motivate the multi-institutional team to continue seeking funds in Cycle 5 and from other sources to complete the entire
framework for different hazards such as flooding, fire, tsunami and chronic environmental stressors.]]></description>
      <pubDate>Tue, 09 Mar 2021 11:41:11 GMT</pubDate>
      <guid>https://rip.trb.org/View/1838446</guid>
    </item>
    <item>
      <title>Fiber Reinforced Polymer (FRP) Seismic Retrofit of Reinforced Concrete Bridge Columns Vulnerable to Long-duration Subduction Zone Earthquakes</title>
      <link>https://rip.trb.org/View/1743221</link>
      <description><![CDATA[Many bridges in the western United States, including those built for the Interstate Highway System in the 1950s and 1960s, have seismically vulnerable reinforced concrete (RC) columns. The seismic performance of many of these bridges is essential to post-earthquake mobility, as bridges are relied upon as critical lifelines into urban centers after natural disasters. Some states, including California and Washington, have introduced retrofit programs to enhance the seismic ductility of vulnerable columns. The retrofit involves wrapping the column with either a structural steel or fiber reinforced polymer (FRP) jacket, which enhances the deformation capacity of the column to improve the seismic performance. Previous research on jacketed columns has focused on strike-slip earthquakes, rather than long-duration, subduction-type earthquakes. Long duration earthquakes are characteristic of the Cascadia Subduction Zone, which has the potential to generate a Magnitude-9.0 earthquake with strong shaking in Washington, Oregon, northern California, and Alaska. The objective of this research is to characterize the behavior of FRP jacketed bridge columns under long-duration earthquakes and formulate recommendations for column retrofit implementation. This research will build upon current research being conducted by the PIs on the behavior of steel jacket retrofitted columns under long-duration earthquakes. Although steel jackets have been used in locations in the northwest U.S. (e.g., Washington), it is anticipated that FRP jackets will provide better seismic performance than steel jackets under long-duration earthquakes. The improved seismic performance, characterized by enhanced ductility, is the result of the bi-directional properties of the FRP, which allow better spread of controlled plasticity in the jacketed region. The proposed research includes the formulation of a model to predict the deformation capacity of FRP jacketed columns, with validation/calibration of the model using large-scale testing to address the lack of test data for FRP-jacketed columns under long-duration earthquake demands.]]></description>
      <pubDate>Tue, 06 Oct 2020 14:01:09 GMT</pubDate>
      <guid>https://rip.trb.org/View/1743221</guid>
    </item>
    <item>
      <title>Extending Application of Simple for Dead and Continuous for Live Load Steel Bridge System to ABC Applications in Seismic Regions - Phase II - Component Testing</title>
      <link>https://rip.trb.org/View/1410737</link>
      <description><![CDATA[During Phase I of the project, suitable details were developed using numerical analysis. The next step is performing component level testing on the connection details prior to a large scale shake table test. The goal of the component test is to proof load the connection between the substructure and superstructure. If designed properly, the failure should not occur within the connection itself. The objective of the proposed project is the design and testing of the component level specimen.]]></description>
      <pubDate>Wed, 08 Jun 2016 17:36:10 GMT</pubDate>
      <guid>https://rip.trb.org/View/1410737</guid>
    </item>
    <item>
      <title>Structural Assessment of Highway "N" Power Substation under Earthquake Loads</title>
      <link>https://rip.trb.org/View/1231007</link>
      <description><![CDATA[A research plan is developed for Ameren to consider over the next two years. It includes two major tasks: seismic analysis and evaluation of substation performance, and shake table tests of critical non-structural components such as rigid bus connectors. Each major task can be completed in approximately one year. This project is aimed at evaluating the seismic vulnerabilities of the highway "N" power substation. The proposed study involves both numerical analysis and experiment. The findings from this study will be summarized in a final report that will be submitted to sponsors.]]></description>
      <pubDate>Thu, 03 Jan 2013 14:10:21 GMT</pubDate>
      <guid>https://rip.trb.org/View/1231007</guid>
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