Bridge Geometry Research Articles

Engineering Chromosome Bridges Through CRISPR/Cas9 to Decipher the Impact of Intercentromeric Distance on Resolution Dynamics.

Resolution of chromosome bridges during mitosis is a critical yet incompletely understood process with implications for genomic stability and cancer development. In this study, we investigated the impact of the bridging chromatin length on the timing and mechanism of chromosome bridge resolution. Using CRISPR/Cas9 technology, we engineered chromosome bridges with precisely defined intercentromeric distances in human RPE-1 cells. Our study revealed a decline in the frequency of chromosome bridges as cells progressed from early anaphase to late telophase, indicating resolution during mitosis. Moreover, the longer the bridging chromatin length, the higher the frequency of chromosome bridges observed at the mitotic exit, demonstrating that the size of the bridge influences its resolution during mitosis. Additionally, the separation between the bridge kinetochores needed for bridge breakage was strongly dependent on the megabase length of the bridging chromatin, with longer chromosome bridges requiring greater separation for their resolution. Given that chromosome bridge resolution occurs in a concerted manner with spindle elongation and is influenced by the length of the bridging chromatin, we posit that the traction forces generated by microtubules attaching to dicentric chromosomes play a significant role in resolving chromosome bridges during mitosis. Our study underscores the intricate interplay between chromosome bridge geometry and mechanical forces in mitotic chromosome bridge resolution. Our model offers a valuable framework for future investigations into the molecular mechanisms underlying chromosome bridge resolution, with potential implications for cancer biology and genomic stability maintenance.

The influence of bridge geometry and welding chamber height on microstructure and mechanical properties for porthole die extrusion of AA6082

The influence of bridge geometry and welding chamber height on microstructure and mechanical properties for porthole die extrusion of AA6082

Cyclic soil-structure interaction of integral railway bridges

Integral bridges with larger spans experience increased cyclic interaction with their backfill, particularly due to seasonal temperature changes. This can result in a continuous increase of earth pressure (during the summer positions) as well as an accumulation of settlements in the granular backfill over the bridge’s lifespan. While the soil stresses must be accounted for in the structural design through appropriate calculation methods, the settlements negatively impact the serviceability and the maintenance demands of the railway track and can only be accepted to a very limited extent. Therefore, this paper presents a detailed numerical investigation on the cyclic interaction behavior of integral railway bridges. For this purpose, an elastoplastic soil material model (DeltaSand), which has been calibrated based on a comprehensive experimental program for a well-graded gravel backfill material, and validated 2D and 3D FE models are used. Extensive parametric studies are conducted with varying bridge geometries (lengths, heights), as well as abutment, backfill, and foundation stiffnesses. The numerical results for both, the lateral stress loading and the bending moment of the abutment are compared to analytical design approaches used in Germany, Austria and United Kingdom. Lateral stresses on the abutment and settlements of the backfill show a clear increase with cycles and bridge lengths. The stiffness of both the backfill material and the underground soil highly influences the earth pressure mobilization and its distribution on the abutment. The study also highlights that existing design approaches are not conservative in all cases and should be adjusted.

An Experimental Study of the Pull-In Voltage in RF MEMS Switches Fabricated by Au Electroplating and Standard Wet Release: Considering the Bridge Geometry.

Radio Frequency Micro Electro Mechanical Systems (RF MEMS) are devices showing exceptional potential to satisfy the demands of emerging RF electronic technologies, including those considered for high-power applications, such as for long distance communication systems. Operation in this regime requires an alternative way of thinking for these devices and, for example, a more accurate control of the pull-in voltage is of major importance due to the self-actuation effect. Therefore, the studies focusing on the features of the moving bridges are of great importance. This work presents the fabrication of a full family of RF MEMS switches suitable for high-power implementations having bridges deposited by Au electroplating and released using purely standard wet processes, as well as a carefully designed experimental study of their pull-in voltage. Depositing the bridge of the high-power RF MEMS by using only a single electroplating step makes the device fabrication easier, whilst the utilization of a purely wet release process is an asset. This method relies on low temperature processes, applicable simultaneously in bridges with various geometrical and perforation details without the need of any specialised infrastructure. The experimentally obtained results suggest that for this technology the bridge thickness is a critical factor for controlling the pull-in characteristics between devices fabricated in the same run. Moreover, it is revealed that for thicker bridges, geometry and hole perforation effects are more pronounced. This technology is therefore suitable for developing RF MEMS where the bridge thickness could be potentially utilized for enabling optimization engineering between devices that should be fabricated in the same run but need to satisfy diverse specifications during their operation.

Sulfur Bridge Geometry Boosts Selective FeIV═O Generation for Efficient Fenton-Like Reactions.

High-valent iron-oxo species (FeIV═O) is a fascinating enzymatic agent with excellent anti-interference abilities in various oxidation processes. However, selective and high-yield production of FeIV═O remains challenging. Herein, Fe diatomic pairs are rationally fabricated with an assisted S bridge to tune their neighbor distances and increase their loading to 11.8 wt.%. This geometry regulated the d-band center of Fe atoms, favoring their bonding with the terminal and hydroxyl O sites of peroxymonosulfate (PMS) via heterolytic cleavage of O─O, improving the PMS utilization (70%), and selective generation of FeIV═O (>90%) at a high yield (63% of PMS) offers competitive performance against state-of-the-art catalysts. These continuous reactions in a fabricated device and technol-economic assessment further verified the catalyst with impressive long-term activity and scale-up potential for sustainable water treatment. Altogether, this heteroatom-bridge strategy of diatomic pairs constitutes a promising platform for selective and efficient synthesis of high-valent metal-oxo species.

In situ experimental study on the evolution of liquid bridge geometry and adhesion under shear: Effects of volume, separation distance, and velocity

In situ experimental study on the evolution of liquid bridge geometry and adhesion under shear: Effects of volume, separation distance, and velocity

Driving conditions and safety analyses of vehicles moving on highway bridges under seismic excitations

This study introduces an analytical framework and case study to evaluate driving conditions and safety of vehicles on highway bridges subjected to seismic excitation. The driving conditions, namely, driver perceptibility and comfort were examined using overall vibration total value (OVTV) criterion defined in the ISO 2631-1, while driver reaction was simulated using second-order predictable-correction (SOPC) model. A case study was presented using 3D-finite element (FE) model of an existing highway interchange and vehicle-bridge-seismic dynamics (VBSD) model. In this case study, site-specific ground motions at two intensity levels were used to simulate bridge responses. Influences of earthquake intensity, bridge geometry, and road conditions were investigated on five non-articulated vehicles: light vehicle, SUV, small truck, bus, and large truck. Simulations reveal that the driving comfort level for most vehicles has surpassed the uncomfortable and extremely-uncomfortable level defined in the ISO standard under L1 earthquake and L2 earthquake, respectively. Driving conditions worsened on a curved bridges compared to straight bridges. Three driver reaction scenarios were simulated to examine risks and safety indices. The results showed that deceleration action was the most effective response, followed by a combination of deceleration and changing course, while changing course only was the least favorable outcome.

Structural Assessment of Mahakam Bridge Geometry Using Geodetic GPS and Terrestrial Laser Scanner

This study employs a terrestrial laser scanner and geodetic GPS to assess the camber elevation, lateral drift, and pilecap inclination of the Mahakam I Bridge in Samarinda, East Kalimantan. The camber inspection results reveal variations in the elevation of spans B3, B4, and B5, with the lowest measured at 68.74 m and the highest at 70.35 m. The lateral drift analysis on piers P2, P3, and P4 indicates minimal displacements, with maximum deviations ranging from -0.05% to 0.29%. The inclination angles of the pilecaps on P2, P3, and P4, measured at 90.411˚, 90.128˚, and 90.112˚, respectively, exhibit slight deviations from the optimal 90˚ alignment. These findings highlight the need for continuous monitoring and potential structural adjustments. The study underscores the critical role of precise geometric assessment in preserving bridge integrity and ensuring long-term structural stability. Further investigations and mitigation strategies are recommended to prevent potential risks and deterioration.

Mainshock-Aftershock Ground Motion Sequences Selection and its Implication on Bridge Seismic Fragility

ABSTRACT In seismic-prone regions, the evaluation of structural performance of bridges under mainshock-aftershock ground motion sequences is imperative for ensuring their safety and facilitating effective response measures. However, the limited availability of real-recorded mainshock-aftershock ground motion sequences for region-specific condition results in the adoption of artificially generated sequences for seismic fragility assessment of bridges. This study presents a new approach for the artificial generation of ground motion sequences by quantifying the relationship between parameters of real-recorded mainshock-aftershock sequences, while also considering regional seismicity. The proposed framework is employed to obtain a suite of region-specific mainshock-aftershock sequences for the Himalayan region, and is subsequently applied to a case-study bridge for vulnerability assessment. An experimentally validated bridge numerical model is developed to simulate the degradation caused by multiple cyclic loadings of mainshock-aftershock sequences. An optimal engineering demand parameter is identified to capture the cumulative damage under mainshock-aftershock sequences and seismic fragility curves are developed using incremental dynamic analysis-based approach. Results reveal a higher seismic fragility under ground motion sequences compared to mainshocks alone, with similar trends observed across different bridge geometries. Notably, the finding indicates a close match between the seismic fragility curves developed using mainshock-aftershock sequences selected through the proposed framework and those derived using real-recorded sequences.

Combinatorial Data Augmentation: A Key Enabler to Bridge Geometry- and Data-Driven WiFi Positioning

Combinatorial Data Augmentation: A Key Enabler to Bridge Geometry- and Data-Driven WiFi Positioning

Interoperability level for bridge structural analysis from the IFC data interpretation

Importing IFC (Industry Foundation Classes) data from bridge structural models into structural analysis software is common in the BIM (Building Information Modeling) workflow. However, some software tools still do not import IFC data in the extended version that covers bridge models. In addition, there is a lack of a holistic framework for determining indicators that effectively represent the interoperability level for bridge structural analysis. To prevent data loss in bridge models, this work proposes a tool for interpreting IFC data related to the semantics of bridge elements, geometry, and material properties. A new methodology was developed to quantitatively evaluate an interoperability level for bridges structural analysis, considering the relevance of the imported information by defining numerical weight values. Then, a new framework was proposed for determining each data flow’s Interoperability Level for Bridge Structural Analysis (ILBSA). The interoperability level results showed that commercial bridge structural analysis software requires significant advances in interpreting IFC data.

Extensible portal frame bridge synthetic dataset for structural semantic segmentation

A number of bridges have collapsed around the world over the past years, with detrimental consequences on safety and traffic. To a large extend, such failures can be prevented by regular bridge inspections and maintenance, tasks that fall in the general category of structural health monitoring (SHM). Those procedures are time and labor consuming, which partly accounts for their neglect. Computer vision and artificial intelligence (AI) methods have the potential to ease this burden, by fully or partially automating bridge monitoring. A critical step in this automation is the identification of a bridge’s structural components. In this work, we propose an extensible synthetic dataset for structural component semantic segmentation of portal frame bridges (PFBridge). We first create a 3 dimensional (3D) generic mesh representing the bridge geometry, while respecting a set of rules. The definition of new, or the extension of the existing rules can adjust the dataset to specific needs. We then add textures and other realistic elements to the model, and create an automatically annotated synthetic dataset. The synthetic dataset is used in order to train a deep semantic segmentation model to identify bridge components on bridge images. The amount of available real images is not sufficient to entirely train such a model, but is used to refined the model trained on the synthetic data. We evaluate the contribution of the dataset to semantic segmentation by training several segmentation models on almost 2,000 synthetic images and then finetuning with 88 real images. The results show an increase of 28% on the F1-score when the synthetic dataset is used. To demonstrate a potential use case, the model is integrated in a 3D point cloud capturing system, producing an annotated point cloud where each point is associated with a semantic category (structural component). Such a point cloud can then be used in order to facilitate the generation of a bridge’s digital twin.

Failure analysis of multi-span masonry arch bridges using combination of point cloud data and three-dimensional numerical modeling

Historical structures, including historical bridges, are part of cultural heritage, conveying the traces and characteristic features of past civilizations. To protect historical structures, it is necessary to prepare their 3D photogrammetric documentation, determine detailed geometric and material properties and perform computer-aided structural analysis using appropriate modeling techniques. The aim of this study is to present an effective, reliable and fast multidisciplinary approach for the analysis of historical masonry bridges. The aforementioned approach was illustrated with an example of the historical Halilviran masonry arch bridge and its behavior under possible loadings. Terrestrial laser scanning (TLS) was used to determine the bridge geometry with high accuracy. Point cloud data obtained from TLS was simplified and a three-dimensional CAD-based solid model of the structure was created. The Halilviran Bridge case study summarized in this report was conducted to examine the technical feasibility of using la¬ser scanning technologies for obtaining as-built records for similar historic bridges. A secondary objective was to identify other applications of this technology, notably for other transportation structures, and use numerical methods to assess the seismic behavior and failure model of the bridge. The seismic behavior of the bridge was examined using a finite-element- based macromodeling technique. Nonlinear dynamic analyses were carried out subsequently to identify the most susceptible regions of the bridge. Interpretation of the results, presented in the form of contour plots illustrating tensile damage and maximum displacements, offered a comprehensive depiction of the seismic response across the entire bridge. The methodology employed in this investigation can be viewed as a robust framework for evaluating the seismic response and potential failure of historical structures.

Accelerated construction and geometry control of cable-stayed bridge: cable crane method

Mountainous regions with rugged terrain, steep valleys and restricted access to roads and rivers present distinctive challenges for segmented erection of cable-stayed bridges (CSBs). In recent years, the cable crane method (CCM) has emerged as an innovative solution for CSB construction to address the difficulties associated with vertically lifting and horizontally delivering girder segments in such challenging environments. However, integrating the CCM with a CSB introduces a coupling effect, significantly complicating the control of bridge geometry. In this work, the accelerated construction and geometry control for CSBs employing the CCM in mountainous regions were systematically studied. The characteristics of 1521 bridges in mountainous regions were investigated, followed by a numerical analysis of geometry control and field measurements of as-built geometries, forces and ambient conditions during construction. Critical techniques for CSB construction using the CCM are also clarified. The mechanical behaviour of a bridge during construction was comprehensively evaluated to improve geometry control. The numerical results were validated through field measurements, offering valuable insights for future CSB practices using the novel CCM.

Improving a 1D Hydraulic Model to Include Bridges as Internal Boundary Conditions

The paper describes the implementation of internal boundary conditions in the 1D ORSADEM hydraulic model to simulate the effect of a hydraulic in-line structure. The proposed model introduces a simplified representation of the bridge geometry by imposing an equivalent narrowing, computed according to the opening size and characteristics, combined with the mass and energy balance at the structure. The model is then applied to a series of experimental tests concerning the propagation of shock waves through different types of bridges, representing different flow conditions, from free surface flow to overflow. The tests are also simulated with the original 1D ORSADEM model, including the standard head losses and the cross-section narrowing due to the presence of a structure. The comparison with the experimental measurements shows that the proposed model can simulate the shock wave flow through the bridges with a higher accuracy than the standard formulation. These findings highlight the possibility of properly evaluating the backwater effect at bridges even with a simple 1D model if the physical narrowing of the cross-section is modeled.

Correction: Cabral et al. Railway Bridge Geometry Assessment Supported by Cutting-Edge Reality Capture Technologies and 3D As-Designed Models. Infrastructures 2023, 8, 114

In the original publication [...]

Efficient in-site laser scanning scheme with adaptive angular resolution for long-span bridge geometry measurement

Efficient in-site laser scanning scheme with adaptive angular resolution for long-span bridge geometry measurement

Satellite Synthetic Aperture Radar, Multispectral, and Infrared Imagery for Assessing Bridge Deformation and Structural Health—A Case Study at the Samuel de Champlain Bridge

A space-borne remote sensing method was applied, validated, and demonstrated in a case study on the Samuel de Champlain Bridge in Montreal, Canada. High-resolution C-band radar satellite imagery was analyzed using the Persistent Scatterer Interferometric Synthetic Aperture Radar technique to derive bridge displacements and compare them against theoretical estimates. Multispectral and long-wave thermal infrared satellite imagery acquired during the InSAR observation period and historical environmental data were analyzed to provide context for the interpretation and understanding of InSAR results. Thermal deformation measurements compared well with their theoretical estimates based on known bridge geometry and ambient temperature data. Non-thermal deformation measurements gave no evidence of settlement during the 2-year monitoring period, as would normally be expected for a newly constructed bridge with its foundation on bedrock. The availability of environmental data obtained from multispectral and thermal infrared satellite imagery was found to be useful in providing context for the bridge stability assessment. Ambient temperature measurements from thermal infrared satellite imagery were found to be a suitable alternative in cases where data from in situ temperature sensors or nearby weather stations are not available or not fit for purpose. No strong correlation was found between the river conditions and bridge deformation results from the InSAR analysis; this is partly due to the fact that most of these effects act along the river flow in the north–south direction, to which the satellite sensor is not sensitive.

Coupled heat transfers resolution by Monte Carlo in urban geometry including direct and diffuse solar irradiations

Coupled heat transfers resolution by Monte Carlo in urban geometry including direct and diffuse solar irradiations

UAV photogrammetry and laser scanning of bridges: a new methodology and its application to a case study

UAV photogrammetry and laser scanning of bridges: a new methodology and its application to a case study