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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <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>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Experimental and Theoretical Investigations of the Shear Resistance of SCS Composite Structures with Web Openings</title>
      <link>https://trid.trb.org/View/2617659</link>
      <description><![CDATA[Steel–concrete–steel (SCS) composite structures with continuous steel webs offer significant advantages in terms of structural capacity, waterproofness, construction efficiency, and others, and these structures constitute new options in large-scale subsea tunnel projects, nuclear structures, and offshore engineering. The shear performance of SCS structures is a critical design issue, and the presence of unavoidable opening configurations in steel webs magnifies this problem. Because of the lack of studies on the shear behavior of SCS structures with web openings, experimental and theoretical investigations were performed. Three-point shear tests were first conducted. The effects of the size and shape of web openings on the shear capacity were studied, and the failure modes, crack development, and load transfer mechanisms of these structures were analyzed in detail. On the basis of test observations, a theoretical method was proposed to account for the influence of web openings on SCS structures and to predict their shear resistance. Through comparisons with existing methods, the proposed theoretical approach can be used to quantify the effect of web openings on the shear capacity reasonably accurately, thereby providing guidance for engineering design practice.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:14:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/2617659</guid>
    </item>
    <item>
      <title>Performance assessment of subway station structure considering site shear-wave velocity uncertainty using probability density evolution method</title>
      <link>https://trid.trb.org/View/2679335</link>
      <description><![CDATA[As a critical underground structure, the seismic response of a subway station is not only governed by seismic motions but is also influenced by uncertainties in site conditions. This study employs the probability density evolution method (PDEM) to systematically investigate the seismic fragility of a three-story, three-span subway station, explicitly considering the uncertainty of site shear-wave velocity (Vₛ). Sobol sampling is first used to generate the composite samples that simultaneously incorporate the uncertainties of seismic motion and Vₛ. Based on these samples, a soil–structure interaction finite element model is established to provide training data. A one-dimensional convolutional neural network (1D-CNN) is introduced to achieve rapid prediction of inter-story drift ratio time histories. Subsequently, PDEM is applied to compute the time-varying probability density distribution of structural responses. Based on this, the seismic fragility curves and time-dependent fragility surfaces were developed to assess the damage probabilities of the subway station. It was found that Vₛ uncertainty significantly increases the dispersion of structural responses, particularly at higher seismic intensities, and that neglecting it may overestimate damage probabilities. Compared with the lognormal model, PDEM provides a more accurate characterization of probabilistic response features and reveals the temporal evolution of structural damage.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:13:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2679335</guid>
    </item>
    <item>
      <title>Influence of fines content on shear strength and fabric evolution of unbound aggregate base: An experiment and simulation study</title>
      <link>https://trid.trb.org/View/2676297</link>
      <description><![CDATA[Fines content (Fc) strongly affects the performance of unbound aggregate bases by altering micromechanical load transfer and fabric evolution. Laboratory compaction, California bearing ratio (CBR), and triaxial compression tests were conducted on specimens with different Fc. Complementary DEM simulations (triaxial compression and CBR) were performed to quantify coordination, force–fabric anisotropy, and particle kinematics. Peak deviator stress and CBR strength show a non-monotonic dependence on Fc, peaking at Fc = 2.5%. During triaxial loading, coordination first increases and then decreases with axial strain; increasing Fc reduces coordination and increases floating particles. Contact normals progressively align with the major principal stress direction. Normal-force fabric anisotropy increases with strain, and the major principal value of the normal-force fabric tensor is maximal at Fc = 2.5%. Tangential-force fabric shifts from a single dominant orientation at low Fc to a more multidirectional pattern at high Fc, consistent with enhanced localization. Particle rotation is minimized at Fc = 2.5% and increases at higher Fc, indicating a transition from skeleton-dominated load transfer to a rotation-dominated, weakly constrained state. In CBR penetration, force chains beneath the plunger become predominantly vertical and reorganize into fewer, stronger load-bearing paths, while displacements spread laterally under boundary constraints. These findings provide a micromechanical basis for fines control in unbound aggregate base design.]]></description>
      <pubDate>Wed, 17 Jun 2026 12:23:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2676297</guid>
    </item>
    <item>
      <title>Transportation-induced acceleration and shear deformation responses of volumetric steel modules with light-framed gypsum walls: Road test results</title>
      <link>https://trid.trb.org/View/2674496</link>
      <description><![CDATA[Prefabricated, prefinished volumetric modular buildings consist of three-dimensional units called “modules” that include exterior and partition walls, as well as mechanical, electrical, and plumbing systems, all incorporated in the factory. These units are transported to the construction site, where they need to be handled and assembled. Volumetric modules are often transported by truck across varying road conditions, where they are subjected to different dynamic loads. Although structural components generally resist transportation-induced loads, damage to the non-structural elements of the modules remains relatively common. Damage to nonstructural components necessitates additional repairs on-site, increasing the construction costs of modular building projects. A comprehensive understanding of module performance during transportation is essential for developing effective design strategies and practical solutions aimed at minimizing non-structural damage. This study investigates the acceleration and shear deformation responses of a modular unit during road transportation, with particular focus on the potential for damage to non-structural components. A modular unit was instrumented with accelerometers at various locations and diagonal potentiometers on the longitudinal and transverse walls, as well as the ceiling. Three road trips of approximately 25 km each were conducted. Data were analyzed in time and frequency domains, and a post-test visual inspection was performed to assess damage. Results revealed that there is a strong relationship between the extent of damage in the non-structural components and both the amplitude of shear deformations and the number of instances where the shear deformation angle exceeded the serviceability limit state threshold. Based on these findings, recommendations are proposed to enhance the dynamic performance of modular units during transport and reduce non-structural damage.]]></description>
      <pubDate>Wed, 17 Jun 2026 12:23:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2674496</guid>
    </item>
    <item>
      <title>The Use of Groundspeed in a Wind Shear and the Flight Evaluation of a Radar-Altimeter-Based System for the Measurement of Groundspeed</title>
      <link>https://trid.trb.org/View/2703885</link>
      <description><![CDATA[The use of groundspeed in combination with airspeed has been considered and shown to be an effective aid in the execution of an approach and landing in a heavy jet transport airplane. A flight dynamics analysis shows that the response of such aircraft to sudden changes in headwind is quite sluggish, requiring more than 100 seconds for equilibrium conditions to be regained in the worst case. A feasibility demonstration model of a radar-altimeter-based system for the measurement of groundspeed has been subjected to a limited in-flight evaluation. It is a self-contained unit requiring no ground-based equipment and no on-board equipment other than the small flush transmit and receive antennas and the associated cable runs. While the current unit does not meet the desired accuracy standard (Δ = ± 3 knots, or less), it approaches it at times, and greater accuracy can be achieved with further development. Responsiveness to rapidly changing groundspeed matched that of the reference inertial navigation system; and satisfactory groundspeed tracking was maintained during turning, climbing, and descending flight.]]></description>
      <pubDate>Sun, 07 Jun 2026 17:29:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2703885</guid>
    </item>
    <item>
      <title>Immediacy and Accuracy of the Earthquake Early Warning Method Based on the P-wave Threshold Exceedance: Application to the 2016 Kumamoto Earthquake Sequence</title>
      <link>https://trid.trb.org/View/2675870</link>
      <description><![CDATA[Earthquake Early Warning (EEW) systems are essential for ensuring the safety of trains in Japanese railways during earthquakes. The conventional warning method takes over one second to issue alerts, which is often too long for events near the fault plane. We propose an on-site EEW method using the amplitude ratios of S-waves to P-waves, reflecting local ground characteristics. This method enables real-time prediction of S-waves through simple arithmetic, which does not depend on estimating epicentral distance. When applied to the main shock of the 2016 Kumamoto Earthquake, the method issued alerts within one second and accurate S-wave amplitude predictions, with a logarithmic standard deviation of 0.308. This demonstrates its effectiveness in ensuring railway safety.]]></description>
      <pubDate>Fri, 05 Jun 2026 16:41:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2675870</guid>
    </item>
    <item>
      <title>Danish concrete bridge in-situ load testing: considerations and test results</title>
      <link>https://trid.trb.org/View/2708290</link>
      <description><![CDATA[A Danish concrete bridge proof loading project (V1) was initiated in 2016, followed by a project extension (V2) in 2023. The primary objective of V1 was to establish a classification-based proof loading procedure utilising the Danish classification system. In the V1 project, a multidisciplinary approach was developed for the evaluations involving multi-scale testing, theoretical response evaluations, and probabilistic assessments. Several bridges were successfully reclassified to a higher capacity through pilot projects using the developed procedure. Based on the findings, a Danish national guideline was published in December 2024. The V2 project builds on this foundation, expanding its scope to include multi-span and non-shear-reinforced concrete slab bridges. This paper presents key findings and milestones from the V1 project, encompassing the background, design, and execution of the first V2 in-situ tests on a Danish highway bridge, with representative results on non-shear reinforced wings and slabs. Shear failure in the concrete slab occurred at an axle load of approximately 250 tonnes. Shear failure initiation in the tested wing was reached at a wheel load of approximately 50 tonnes. The margin from crack identification to failure is currently under investigation, and extensive information is being generated to support a multidisciplinary approach, thus aiming to provide a basis for shear-related stop criteria.]]></description>
      <pubDate>Wed, 03 Jun 2026 09:07:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2708290</guid>
    </item>
    <item>
      <title>Investigation of Shear Capacity in Girders with Undersized Transverse Stiffeners</title>
      <link>https://trid.trb.org/View/2709244</link>
      <description><![CDATA[The design of transverse shear stiffeners in steel plate girder bridges has changed over the years. Earlier AASHTO Standard Specifications and AASHTO Bridge Design Specifications (BDS) required transverse stiffeners to have sufficient flexural rigidity to develop the shear buckling resistance of a steel girder web. The current AASHTO Load and Resistance Factor Design Bridge Design Specifications (LRFD BDS) use a different approach based on minimum geometric dimensions of the stiffener. 

This change affects the load rating of older bridges that do not meet current criteria. The AASHTO LRFD BDS and the AASHTO Manual for Bridge Evaluation (MBE) do not include provisions for determining the shear capacity of girders with undersized stiffeners or the effectiveness of an undersized stiffener. In current practice, load rating engineers may assume existing undersized transverse stiffeners are adequate based on inspection or original design practice; however, when these stiffeners are evaluated against current geometric requirements, even slightly undersized stiffeners may be treated as ineffective, and the girder may be rated as unstiffened. This can significantly reduce the calculated shear resistance of the girder and may result in unnecessary strengthening, load posting, or bridge closure. 

Engineering judgment indicates that slightly undersized stiffeners may still provide some resistance; however, there is currently no mathematical basis or load rating procedure to quantify that resistance. Therefore, research is needed to investigate the resistance of steel girders with undersized transverse stiffeners. This research would help state departments of transportation (DOTs) and bridge owners more accurately evaluate existing steel girder bridges, reduce unnecessary load postings or strengthening, and extend the service life of bridges that have reserve capacity. 

OBJECTIVE: The objective of this research is to develop load rating provisions for bridges with undersized transverse stiffeners. The research should be presented through a white paper with proposed revisions to the AASHTO MBE. ]]></description>
      <pubDate>Tue, 02 Jun 2026 15:10:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2709244</guid>
    </item>
    <item>
      <title>Geotechnical and Geophysical Railway Embankment Auscultation</title>
      <link>https://trid.trb.org/View/2113146</link>
      <description><![CDATA[As part of the understanding of the phenomena affecting tracks geometry on the Northern Europe high-speed line (LGV-Nord), a study was carried out on an area with occasional maintenance efforts. The goal is to identify the causes of structural disorders on railway embankment (RE). To better understand the origins of these issues, geotechnical characterization and bender elements (BE) tests were performed in the laboratory on soils collected on the field. Measurements of water content, density, and Atterberg limits cannot explain the anomalies observed along the tracks. However, when it comes to mechanical properties and more precisely to shear wave velocities (VS), we can clearly see strong contrasts between areas where the phenomena were observed and where it was not. Thus, VS obtained with BE tests seems to be a good indicator of the quality of soils constituting the RE. At the site scale, surface-wave methods were identified as a possible tool to estimate the mechanical properties of the RE. In this context, we dimensioned and designed specific acquisition setups. To estimate 1D profiles of shear wave velocities, we performed many tests to show the robustness of this method, when inversions are constrained by railway a priori. Those tests allowed us to determine the geometry of the platforms and to characterize the VS of the supporting soil. These results show a difference between the sections of RE with disorders and those without. The reliability of these results is also highlighted since they coincide with geotechnical data.]]></description>
      <pubDate>Thu, 28 May 2026 17:09:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113146</guid>
    </item>
    <item>
      <title>Steel Slag Aggregate Characteristics Evaluation as Railway Ballast</title>
      <link>https://trid.trb.org/View/2113124</link>
      <description><![CDATA[The use of recycled materials is a new tendency in the field of railway engineering. Steel slag aggregates (SSA) are one of the recycled materials derived from the steel industry. The application of SSA in ballasted railway tracks requires mechanical examination. In the present paper, the shear behavior of the ballast layer constructed by SSA and basalt aggregates was considered to assess the use of SSA as a substitution for basalt. In this regard, a series of large-direct shear tests were performed on basalt and SSA under various normal stresses. Based on the results, basalt aggregates have higher shear resistance than SSA for all normal stress. However, steel slag has sufficient shear strength as well as particle abrasion resistance. Overall, it was proven that the SSA has suitable stability against shear forces that could be applied on railway ballast.]]></description>
      <pubDate>Thu, 28 May 2026 17:09:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113124</guid>
    </item>
    <item>
      <title>Railway Subgrade Characterization Through Repeated Loading Triaxial Testing</title>
      <link>https://trid.trb.org/View/2113115</link>
      <description><![CDATA[Currently, the improvement of means of transportation is a great challenge. Brazil has a large ore production, which will continue in the next decades, and seeks to reduce the transportation times between production and export centers, as well as reduce the emission of contaminants to the environment. In this sense, railways are a more efficient and environmentally friendly means of land transportation, and their proper conservation and operability affect the net gains that Brazil receives from the export of commodities. The implementation of this program proposed in the engineering practice would allow taking more precise decisions regarding the activities of maintenance of railroads, generating significant savings. The first step of the research is the analysis and interpretation of results of repeated load triaxial tests carried out in Brazil on railway subgrade soils. An engineering methodology is presented considering the geotechnical properties of the foundation soil obtained through field and laboratory tests for performing of geotechnical analysis. To ensure the railway stability, criteria of bearing capacity, elastic deflection and permanent deformation for the railway substructure must be met. A prediction model of permanent deformation is used, as well as the influence of moisture on the behavior of the foundation soil. This study aims to contribute to the finding of a comprehensive methodology for evaluating the useful service life of the track substructure so that the most appropriate material can be selected for use as a railroad formation material in order to limit stresses on the railway subgrade, which in turn cause progressive loss of geometric profile of the railway, and to maintain a safe operation of the trains. This will allow significant savings in the periodic maintenance of the substructure, which are one of the activities to restore the track geometry of railways.]]></description>
      <pubDate>Thu, 28 May 2026 17:09:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113115</guid>
    </item>
    <item>
      <title>Regression Model for Soil Compaction Assessment via Shear Wave Velocity in Kaolin-sand Mixtures</title>
      <link>https://trid.trb.org/View/2703655</link>
      <description><![CDATA[This study developed a regression-based model to predict shear wave velocity (Vs) for compaction assessment in kaolin–sand mixtures with different fines contents. Four mixtures (K100, K70, K50, K30) were compacted using the Standard Proctor method to determine maximum dry density (MDD) and optimum moisture content (OMC). A total of 16 specimens (of 4 Sets Soil mixtures) were tested, and Vs was measured using Bender Element (BE) testing with an improved clay–foam coupling interface to enhance signal clarity. Results showed that Vs increased with dry density and decreased with void ratio and porosity, reflecting its sensitivity to soil stiffness and particle contact conditions. A positive correlation between Vs and MDD and an inverse relationship with OMC were observed. A multiple linear regression model incorporating of different 16 types of fines content and dry density achieved strong predictive performance (R² = 0.9207). Compared to conventional density-based regression and machine learning approaches, the proposed model provides a physically interpretable relationship between soil composition and stiffness. The model is applicable to controlled fine–coarse mixtures and demonstrates the potential of Vs as a non-destructive parameter for compaction assessment. However, it remains preliminary and requires validation on various natural soils and under field conditions.]]></description>
      <pubDate>Thu, 21 May 2026 14:14:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2703655</guid>
    </item>
    <item>
      <title>Precast RC Blocks with Detachable Connections for Emergency Temporary Bridges: Wave-Shaped Concrete Shear Keys Fabricated from 3D-Printed Molds and Steel Couplers</title>
      <link>https://trid.trb.org/View/2689751</link>
      <description><![CDATA[Although structural design and technology remain challenges in preventing bridges, especially their superstructure, from being washed out by hydrodynamic forces due to tsunamis, floods, and storm surges, bridges must be functional after disasters to ensure rapid recovery. Consequently, countermeasures that account for the potential for bridge failure are crucial for enhancing resilience. This paper proposes a temporary bridge using precast reinforced concrete (RC) blocks with connections composed of wave-shaped concrete shear keys fabricated using three-dimensional (3D)-printed molds and mechanical couplers. The proposed RC blocks can be easily assembled and disassembled for reuse in future disasters. Loading test results demonstrate that RC blocks joined with adequately waved concrete shear keys, classified as the 1.0 cosine shape in this study, exhibit an expected flexural failure and an equivalent load–deflection relationship to the reference specimen without any connections (i.e., ordinary RC beam). The maximum load and corresponding displacement of the integrated full-scale RC blocks are 1.01 and 4.46 times those of the ordinary RC beam, respectively. A two-dimensional finite-element (FE) model incorporating Coulomb friction between concrete shear keys is developed and validated by comparing results with bending test data. The FE model is used to explore the effects of the amplitude of the wave-shaped concrete shear key on the entire structural performance.]]></description>
      <pubDate>Tue, 19 May 2026 15:12:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2689751</guid>
    </item>
    <item>
      <title>Prediction of shear capacity for PBL connectors in concrete using visualization-based machine learning</title>
      <link>https://trid.trb.org/View/2685417</link>
      <description><![CDATA[Accurately predicting the ultimate shear capacity of perfobond rib (PBL) connectors is of great significance for the design of steel–concrete composite structures. This study predicted the ultimate shear capacity of PBL using machine learning (ML) methods. Initially, a dataset comprising 233 sets of PBL push-out test data was established. To enhance data quality, an Isolation Forest was used to identify and eliminate outliers from the dataset. Subsequently, four ML models—XGBoost, DT, RF, and ANN—were trained on this dataset to predict the ultimate shear capacity of PBL. By comparing and analyzing the prediction results, XGBoost demonstrated the best predictive performance with an R2 value of 0.97, outperforming other models. Then, a visual analysis, including SHAP and PDP, was conducted on the XGBoost model, revealing the contribution levels of different features to the predicted values. The analysis found that the number of perforated holes (n) had the greatest impact. Moreover, based on the analysis of visualizations, recommended ranges of values for the input features are provided to maximize the ultimate shear capacity of the PBL connectors. In comparison with traditional formulas, the trained ML models exhibit superior accuracy. The MAE of XGBoost is approximately 10% of that of the traditional formulas, and its RMSE value is less than 20% of those.]]></description>
      <pubDate>Tue, 19 May 2026 15:12:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/2685417</guid>
    </item>
    <item>
      <title>Field monitoring study on a highway geogrid-reinforced embankment in Xinjiang, China</title>
      <link>https://trid.trb.org/View/2673159</link>
      <description><![CDATA[In this study, a 19.3 m high geogrid reinforced soil embankment with a slope of 1 V:1H was monitored for 260 days during and after construction. The monitoring included measurements of soil temperature and humidity, vertical earth pressure, and tensile strain in the geogrid. Laboratory tests, including geogrid tensile tests, soil direct shear tests, and soil-reinforcement interface direct shear tests, were performed at various temperatures. The results indicate that the peak strengths of both the unreinforced soil and the geogrid-soil interface significantly increased under subzero temperatures. The surrounding valley topography of the monitoring section intensified the soil arching effect within the fill soil. Combined with the reduced soil humidity and the membrane effect of the geogrid, these factors may be the primary reasons for the downward trend of the vertical earth pressure and geogrid strain during the initial period after completion. Additionally, owing to nonstandard compaction operations, the strains in the 8th, 13th, and 30th layers of the geogrid were excessively large, resulting in tensile forces that were significantly greater than the predicted values. This study provides a theoretical basis and data support for the service performance evaluation of reinforced soil embankments under similar climatic and geological conditions.]]></description>
      <pubDate>Fri, 15 May 2026 09:18:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2673159</guid>
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