Width Of Bridges Research Articles

Effective width of steel-concrete composite box girder bridges: a review and method comparison

Steel-concrete composite girders have non-uniform stress distribution on the slab, presenting maximum stresses next to the webs of the girder. This phenomenon is known as shear lag effect. To understand this effect, there is the effective width concept, in which only a portion of the slab width is considered effective in contributing to the composite element’s resistant capacity. However, in the technical standards, there is no recommendation for calculating the effective width in steel-concrete composite box girder bridges. In view of this situation, the purpose of this paper is to carry out a systematic review on effective width and/or the shear lag effect in steel-concrete composite bridges, in order to raise the main existing recommendations and compare them. Through a bibliometric scan with carefully chosen keywords, it was found that of all research on shear lag or effective width in steel-concrete composite structures, only 31.19 are on bridges and 14.97% are on bridges with box girders. Among the papers, those that have a method for calculating the effective width of steel-concrete composite girder bridges have been compared quantitatively and qualitatively with the procedures of AASHTO and EN 1994-2-2. In these procedures were also identified that the, for the boundary conditions of the present paper, the parameters that most influencing the effective width are, in that order, the span length, the distance between girders, the concrete slab height, the longitudinal position and the type of load.

Acoustic effects of varying the waist width of violin bridges: A physical experiment

We explore the relationship between the bridge waist and sound production in the violin. Models of violin acoustics suggest that the stiffness of this portion of the bridge has a considerable effect on an instrument’s sound production. In practice, the proportions of the waist vary significantly from bridge to bridge and instrument to instrument, which suggests there are many ways that a luthier can influence a bridge’s stiffness. Our experiment connects modeling and real-world instrument sound adjustment. We incrementally remove material symmetrically from the bridge in the waist area, recording sound production at each increment. The bridges are destroyed in the process, which is repeated across multiple bridges. Sound stimuli include a sine wave at the bridge with dampened strings and a weighted bow drawn across freely ringing strings. We map changes in bridge geometry to changes in maximum output and acoustic measures of tone quality across several instruments. Since stiffness correlates with thickness, subject to the nature of the bridge material, there may be optimal shape adjustments for maximizing sound production, tone quality, or both.

Width of Tissue Bridges Predicts Neurologic Recovery 3 Months After Spinal Cord Injury: a Multi-Center Study (P15-6.004)

Width of Tissue Bridges Predicts Neurologic Recovery 3 Months After Spinal Cord Injury: a Multi-Center Study (P15-6.004)

Prediction of Effective Width of Varying Depth Box‐Girder Bridges Using Convolutional Neural Networks

Effective flange width is widely used in bridge design to consider the effect of shear lag. The simplified formula for the effective flange width of box girder bridges of variable depth in existing codes and studies may not be conservative, and accurate methods, such as the finite element method, are time‐consuming. The purpose of this research is to develop a method that uses a convolutional neural network (CNN) to predict the effective width of box girder bridges of varying depths. These models have been trained, validated, and tested on datasets generated from thousands of finite element models. The lower error in the test set indicates that the CNN model can be used to predict the effective width. In addition, the impact of different architectures is also studied. The proposed method makes real‐time analysis possible and has a wide range of applications in the analysis and design of box‐girder bridges at different depths.

Numerical assessment of effective width in steel-concrete composite box girder bridges with partial interaction

This present paper aims to analyze numerically, through the Abaqus® software, the influence of the interaction degree (partial or total) on the effective width of steel-concrete composite box girder bridges. These structures present advantages such as greater torsional rigidity, construction and maintenance benefits, durability and aesthetic appeal. In the case of steel-concrete composite beams for buildings, the use of partial interaction design is a common practice. However, dimensioning of bridges with partial interaction is a less used method and is not even recommended by some regulations. Due to this reason, the influence of the steel-concrete interaction degree is investigated to evaluate the behavior of the composite section with partial interaction, since the dimensioning in such conditions would offer economic advantages. For this purpose, the effective numerical width of 120 models of steel-concrete composite box girder bridges was determined, the study variables being the degree of steel-concrete interaction, configuration of the cross section, height of the concrete slab, length of the longitudinal span and arrangement of elements in the cross section. It was verified that the effective numerical width is directly proportional to the slab height and the longitudinal span’s length. Furthermore, the greater the steel-concrete interaction degree, the higher is the effective width observed. However, in most models, the interaction degree no longer significantly influenced the effective width from the 60% interaction, at which the numerical effective width remained practically constant. Based on the analyses performed, an expression was proposed to calculate an effective width adjustment coefficient depending on the interaction degree in the design of steel-concrete composite box girder bridges with partial interaction, in order to compensate for the non-consideration of the steel-concrete interaction’s degree in the standard procedures and adjust the recommendations of I-girders for box girders.

Bi2Se3-Functionalized Metasurfaces for Ultrafast All-Optical Switching and Efficient Modulation of Terahertz Waves

Because of the wealth of fascinating physical phenomena observed in topological insulators (TIs), their exciting properties have been intensively investigated for electronic and optoelectronic applications, such as quantum devices, saturable absorbers, and photodetectors, in the visible to terahertz (THz) spectral range. However, their potential for metaphotonic devices has yet to be explored. Here, we present a comprehensive investigation on the active photonic performance of a novel metaphotonic device by hybridizing ultrathin Bi2Se3 bridges into metamaterials in the THz range. Unlike THz modulation via Fano-like plasmon-phonon destructive interference in the pure Bi2Se3 structure, our Bi2Se3 microribbon arrays with high photoconductivity can short-circuit the circulating surface currents in the proposed metasurfaces, leading to remarkable electromagnetically induced transparency (EIT) transmission and group delay modulations at the operational frequency. Additionally, the width of the Bi2Se3 bridges is optimized to 20 μm to maximize the modulation depth, with the modulation of the transmission resonance amplitude and the group delay as high as 31% and 2.7 ps, respectively. Due to the short photocarrier lifetime in Bi2Se3 films (within a few picoseconds), the full recovery time after photoinjection is less than 9.5 ps, enabling an ultrafast switching speed up to a hundred GHz. The ultrafast and effective control of the light spectrum in Bi2Se3-functionalized metaphotonic systems lays the foundation for promoting the emergence of TI-based optoelectronics.

Numerical evaluation of the slab effective width in steel-concrete composite box girder bridges

ABSTRACT: Bridges are structures built to overcome obstacles and allow continuity of transport routes. In the search for efficient construction systems, steel-concrete composite structures, especially box girder bridges, emerged. The American AASHTO and European EN 1994-2-2 standards present design procedures for this type of bridge, but there are still doubts about which portion of the concrete slab contributes to each web strength in composite section (effective width). The present paper aims to evaluate, by numerical analysis in the Abaqus® software, the concrete slab effective width and to verify whether the expressions for its calculation in composite I-girder bridges are valid for box girder sections. After analyzing the results, it was found that the standards recommendations for composite I-girder cannot be applied directly to box girders. Finally, based on the numerical analysis, an equation was proposed to calculate the effective width of steel-concrete composite box girder bridges.

Highway Cost Prediction Based on LSSVM Optimized by Intial Parameters

The cost of highway is affected by many factors. Its composition and calculation are complicated and have great ambiguity. Calculating the cost of highway according to the traditional highway engineering estimation method is a completely tedious task. Constructing a highway cost prediction model can forecast the value promptly and improve the accuracy of highway engineering cost. This work sorts out and collects 60 sets of measured data of highway engineering; establishes an expressway cost index system based on 10 factors, including main route mileage, roadbed width, roadbed earthwork, and number of bridges; and processes the data through principal component analysis (PCA) and hierarchical cluster analysis. Particle swarm optimization (PSO) is used to obtain the optimal parameter combination of the regularization parameter and the kernel function width coefficient in least squares support vector machine (LSSVM). Results show that the average relative and mean square errors of the PCA-PSO-LSSVM model are 0.79% and 10.01%, respectively. Compared with BP neural networks and unoptimized LSSVM model, the PCA-PSO-LSSVM model has smaller relative errors, better generalization ability, and higher prediction accuracy, thereby providing a new method for highway cost prediction in complex environments.

Numerical assessment of effective width in steel-concrete composite box girder bridges

The present paper aims to determine numerically in the Abaqus® software the parameters that have the greatest influence on the effective width of steel-concrete composite box girder bridges. In the technical standards and in the literature, there is no specific recommendation for calculating the effective width in steel-concrete composite box girder bridge. As an alternative, the existing recommendations for steel-concrete composite I-girders are adopted. Therefore, in the absence of standards recommendations for steel-concrete composite box girder bridges, there is a need for an investigation into the distribution of stresses at the steel-concrete interface, because if the effective width was admitted incorrectly, may result in costly or even unsafe solutions. For this purpose, the effective numerical width of 160 models of steel-concrete composite box girder bridges was determined, in which the study variables were the configuration of the transversal section, the slab height, the span length and the elements arrangement in the cross section. After analyzing the results, it was proposed a recommendation to determine effective width of steel-concrete composite box girder bridges.

Predictive Value of Midsagittal Tissue Bridges on Functional Recovery After Spinal Cord Injury

Background The majority of patients with spinal cord injury (SCI) have anatomically incomplete lesions and present with preserved tissue bridges, yet their outcomes vary. Objective To assess the predictive value of the anatomical location (ventral/dorsal) and width of preserved midsagittal tissue bridges for American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade conversion and SCI patient stratification into recovery-specific subgroups. Methods This retrospective longitudinal study includes 70 patients (56 men, age: 52.36 ± 18.58 years) with subacute (ie, 1 month) SCI (45 tetraplegics, 25 paraplegics), 1-month neuroimaging data, and 1-month and 12-month clinical data. One-month midsagittal T2-weighted scans were used to determine the location and width of tissue bridges. Their associations with functional outcomes were assessed using partial correlation and unbiased recursive partitioning conditional inference tree (URP-CTREE). Results Fifty-seven (81.4%) of 70 patients had tissue bridges (2.53 ± 2.04 mm) at 1-month post-SCI. Larger ventral (P = .001, r = 0.511) and dorsal (P < .001, r = 0.546) tissue bridges were associated with higher AIS conversion rates 12 months post-SCI (n = 39). URP-CTREE analysis identified 1-month ventral tissue bridges as predictors of 12-month total motor scores (0.4 mm cutoff, P = .008), recovery of upper extremity motor scores at 12 months (1.82 mm cutoff, P = .002), 12-month pin-prick scores (1.4 mm cutoff, P = .018), and dorsal tissue bridges at 1 month as predictors of 12-month Spinal Cord Independence Measure scores (0.5 mm cutoff, P = .003). Conclusions Midsagittal tissue bridges add predictive value to baseline clinical measures for post-SCI recovery. Based on tissue bridges’ width, patients can be classified into subgroups of clinical recovery profiles. Midsagittal tissue bridges provide means to optimize patient stratification in clinical trials.

Tissue bridges predict neuropathic pain emergence after spinal cord injury

ObjectiveTo assess associations between preserved spinal cord tissue quantified by the width of ventral and dorsal tissue bridges and neuropathic pain development after spinal cord injury.MethodsThis retrospective longitudinal study includes...

Contact of an Elastic Body with a Rigid Base Containing Grooves Partially Filled with Nonwetting Liquid

We study the frictionless contact of an elastic half space with a rigid base textured by quasielliptic grooves in the presence of an incompressible liquid that does not wet the surfaces of bodies in the interface gaps. Under the action of surface tension, the liquid forms bridges in the middle parts of the gaps. At the same time, the edges of the gaps are filled with a gas whose pressure is constant. The pressure drops in the liquid and in gas are described by the Laplace formula. The formulated contact problem is reduced to a singular integral equation for the derivative of the height of interface gaps and to a transcendental equation for the width of liquid bridges. The dependences of the width of liquid bridges, contact pressure, shape of the gaps, contact distances, and contact compliance of the half space on the applied load and surface tension in the liquid are analyzed.

Journal Club: Width and neurophysiologic properties of tissue bridges predict recovery after cervical injury.

Long-term functional recovery following spinal cord injury (SCI) is difficult to prognosticate accurately.1 Spontaneous neurologic recovery occurs in some but not all cervical lesions that are initially classified as complete.2 The ability to predict the likelihood of recovery is of obvious value for the individual who has sustained an SCI, and in stratifying patients for clinical trials.3 A greater total width of spared tissue is correlated with improved functional outcomes.4 A recent study by Vallotton et al.5 takes advantage of the anatomical segregation of sensory and motor pathways along the spinal cord to demonstrate the utility of considering individual widths of the dorsal and ventral tissue bridges to predict sensory and motor recovery independently.

Tissue bridges predict recovery after traumatic and ischemic thoracic spinal cord injury.

ObjectiveTo investigate the spatiotemporal evolution and predictive properties of intramedullary damage and midsagittal tissue bridges at the epicenter of a thoracic spinal cord injury (SCI) using MRI.MethodsWe retrospectively assessed midsagittal T2-weighted scans from 25 patients with thoracic SCI (14 traumatic, 11 ischemic) at 1 month post-SCI. In 12 patients with SCI, linear mixed-effects models on serial MRI explored temporal trajectories of quantifiable lesion markers (area, length, and width) and tissue bridges. Using partial correlation analysis, we assessed associations between structural lesion characteristics at 1 month post-SCI and recovery at 1 year postinjury, adjusting for baseline clinical status, age, and sex.ResultsLesion area decreased by 5.68 mm2 (p = 0.005), lesion length by 2.14 mm (p = 0.004), and lesion width by 0.13 mm (p = 0.004) per month. Width of tissue bridges increased by 0.06 mm (p = 0.019) per month, being similar in traumatic and ischemic SCI (p = 0.576). Smaller lesion area, length, width, and wider tissue bridges at 1 month post-SCI predicted better recovery at 1-year follow-up.ConclusionsOver time, the immediate area of cord damage shrunk while the cystic cavity became demarcated. Adjacent to the cyst, midsagittal tissue bridges became visible. The width of tissue bridges at 1 month post-SCI predicted recovery at 1 year follow-up. Measures of lesion area and tissue bridges early after traumatic and ischemic thoracic SCI therefore allow characterizing the evolution of focal cord damage and are predictive of recovery in thoracic SCI. Thus, lesion extent and tissue bridges hold potential to improve diagnosis and patient stratification in interventional trials.

Width and neurophysiologic properties of tissue bridges predict recovery after cervical injury.

ObjectiveTo assess whether preserved dorsal and ventral midsagittal tissue bridges after traumatic cervical spinal cord injury (SCI) encode tract-specific electrophysiologic properties and are predictive of appropriate recovery.MethodsIn this longitudinal study, we retrospectively assessed MRI scans at 1 month after SCI that provided data on width and location (dorsal vs ventral) of midsagittal tissue bridges in 28 tetraplegic patients. Regression analysis assessed associations between midsagittal tissue bridges and motor- and sensory-specific electrophysiologic recordings and appropriate outcome measures at 12 months after SCI.ResultsGreater width of dorsal midsagittal tissue bridges at 1 month after SCI identified patients who were classified as being sensory incomplete at 12 months after SCI (p = 0.025), had shorter sensory evoked potential (SEP) latencies (r = −0.57, p = 0.016), and had greater SEP amplitudes (r = 0.61, p = 0.001). Greater width of dorsal tissue bridges predicted better light-touch score at 12 months (r = 0.40, p = 0.045) independently of baseline clinical score and ventral tissue bridges. Greater width of ventral midsagittal tissue bridges at 1 month identified patients who were classified as being motor incomplete at 12 months (p = 0.002), revealed shorter motor evoked potential (MEP) latencies (r = −0.54, p = 0.044), and had greater ratios of MEP amplitude to compound muscle action potential amplitude (r = 0.56, p = 0.005). Greater width of ventral tissue bridges predicted better lower extremity motor scores at 12 months (r = 0.41, p = 0.035) independently of baseline clinical score and dorsal tissue bridges.ConclusionMidsagittal tissue bridges, detectable early after SCI, underwrite tract-specific electrophysiologic communication and are predictors of appropriate sensorimotor recovery. Neuroimaging biomarkers of midsagittal tissue bridges may be integrated into the diagnostic workup, prediction of recovery, and patients' stratification in clinical trials.

In vivo evidence of remote neural degeneration in the lumbar enlargement after cervical injury.

ObjectiveTo characterize remote secondary neurodegeneration of spinal tracts and neurons below a cervical spinal cord injury (SCI) and its relation to the severity of injury, the integrity of efferent and afferent pathways, and clinical impairment.MethodsA comprehensive high-resolution MRI protocol was acquired in 17 traumatic cervical SCI patients and 14 controls at 3T. At the cervical lesion, a sagittal T2-weighted scan provided information on the width of preserved midsagittal tissue bridges. In the lumbar enlargement, high-resolution T2*-weighted and diffusion-weighted scans were used to calculate tissue-specific cross-sectional areas and diffusion indices, respectively. Regression analyses determined associations between MRI readouts and the electrophysiologic and clinical measures.ResultsAt the cervical injury level, preserved midsagittal tissue bridges were present in the majority of patients. In the lumbar enlargement, neurodegeneration—in terms of macrostructural and microstructural MRI changes—was evident in the white matter and ventral and dorsal horns. Patients with thinner midsagittal tissue bridges had smaller ventral horn area, higher radial diffusivity in the gray matter, smaller motor evoked potential amplitude from the lower extremities, and lower motor score. In addition, smaller width of midsagittal tissue bridges was also associated with smaller tibialis sensory evoked potential amplitude and lower light-touch score.ConclusionsThis study shows extensive tissue-specific cord pathology in infralesional spinal networks following cervical SCI, its magnitude relating to lesion severity, electrophysiologic integrity, and clinical impairment of the lower extremity. The clinical eloquence of remote neurodegenerative changes speaks to the application of neuroimaging biomarkers in diagnostic workup and planning of clinical trials.

Heterogeneous Integration of Three-Primary-Color Photoluminescent Nanoparticle Arrays with Defined Interfaces.

Minimized photoluminescent devices require both high-density fluorescent arrays and minimal cross-talk between neighboring pixels on the limited area. However, the challenges to achieve the overall integration of nanomaterial-based devices hinder the development of microscale full-color displays, including micro/nanoarray density, orientation control, multimaterial interface morphology, and uniform colors. Here, we report a heterogeneous integration approach to control the orientation, combination, and density of fluorescent micro/nanoarrays on flexible substrates. By controlling the defined interface and critical shrinkage width of liquid bridges, the width of three-primary-color micro/nanolines reached 100 nm. The interval between two parallel luminous lines is down to 40 μm, and the optical cross-talk effect is remarkably reduced. This work provides a facile approach to prepare high-performance micro-photoluminescent and imaging arrays for next-generation flexible display and lighting technology.

Relationship between ancient bridges and population dynamics in the lower Yangtze River Basin, China.

It has been suggested that population growth dynamics may be revealed by the geographic distribution and the physical structure of ancient bridges. Yet, this relationship has not been empirically verified. In this study, we applied the archaeological records for ancient bridges to reveal the population growth dynamics in the lower Yangtze River Basin in late imperial China. We investigated 89 ancient bridges in Yixing that were built during the Ming and Qing dynasties (AD1368–1911). Global Position System information and structure (length, width, and span) of those bridges was measured during our field investigations. Their distribution density was calculated by ArcGIS. The historical socio-economic dynamics of Yixing was inferred from the distribution and structure of ancient bridges. Based on the above information, the population growth dynamics in Yixing was projected. Our results show that 77 bridges were built in Yixing during the Qing dynasty, which is 6.41 times more than the number built during the Ming dynasty. In the Ming dynasty, bridges were built on pivotal routes; in the Qing dynasty, bridges were scattered across various places. Over the period, the density distribution of bridges shifted northwestward, while the average length and width of bridges decreased. The increasing number of bridges corresponded to population growth, largely attributable to massive clan migration from northern China during the Little Ice Age. The shift in the density distribution of bridges corresponded to the formation of settlements of large clans and the blossoming of Yixing Teapot handicrafts. The scattering and the reduction in average length and width of bridges was due to the dispersal of population and the associated formation of small settlements in the latter period. Our approach is innovative and robust, and could be employed to recover long-term historical population growth dynamics in other parts of China.

Highly Birefringent Microstructured Fibers With Low Mode Asymmetry

Highly birefringent microstructured fibers (HB MSFs) with similar mode field sizes along the two orthogonal axes have been presented. The core of the HB MSF is surrounded by two or more concentric rings having identical circular air holes. The key feature of this setup is that the first ring contains one or two pairs of holes, which are more widely spaced than others, i.e., they have one or two wider bridges. The shape of the core may be circular or elliptical. The HB MSFs were characterized using the finite element method. Simulation results show that HB MSFs with a certain relationship between the width of the wider bridges and the core ellipticity may have high birefringence (more than 2.7 × 10−3) and equal mode sizes along the two orthogonal axes. We have fabricated and investigated several such fibers, that have birefringence up to 2.9 × 10−3 and almost equal measured mode field sizes along the two orthogonal axes.

Effective shear width of concrete slab bridges

For the shear assessment of existing concrete slab bridges in the Netherlands, different levels of approximation are used. Shear stress resulting from the dead loads and live loads is determined in a spreadsheet or from a linear finite-element model. In a spreadsheet-based approach the effective width for the wheel prints needs to be assumed and in finite-element methods, the length over which the peak shear stress can be distributed needs to be assumed. To recommend a load-spreading method, experiments were executed on slab strips of increasing widths. The experiments, a statistical analysis and non-linear finite-element models support a distribution from the far side of the wheel print to the face of the support. To find the distribution width in a finite-element method, a numerical model is compared to an experiment in which the reaction forces were measured. These measurements were compared to the stress profile at the support from the model, showing that the peak stress can be integrated and distributed over 4dl.