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Inspired by liquid bridge bearings, a kind of ferrofluid (FF) bearing is proposed in this work. The bearing contains two plates with a drop of FF sandwiched between them. To restrain and position the FF, a cylindrical magnet is implanted in the lower plate. The carrying capacity of the liquid bridge and FF bearing is tested and compared. The results indicate that both bearings can provide a certain amount of liquid supporting force. For similar geometries, the maximum force generated by the FF bearing (1.60 N) is about 20 times higher than that of the liquid bearing (0.08 N). Moreover, due to the effect of the magnetic field, the supporting performance of the FF bearing is more stable, especially in small gap heights. To further understand the supporting mechanism, a model of the FF bearing for the carrying capacity was built and validated by the experiment. Theoretical analysis manifests that, compared with the Laplace force, the magnetic force acts as a dominant contribution to the FF bearing. This work provides an interesting way to create liquid support for MEMS applications that demand controllable micro-platforms or frictionless bearings. [ABSTRACT FROM AUTHOR]

The design of high-speed simply supported bridges in critical conditions, such as road or canal crossings, is a matter of concern, particularly under two-way crossings with sequential wheel loads. Contrarily to simple classical support, elastic bearings can serve towards vibration mitigation under high speed. In this paper, a non-dimensional framework is developed to understand the impact mechanism of an elastically supported (ES) beam under the action of single as well as opposite traversing loads. A good agreement with the available literature has been confirmed for the one-way crossing using the present methodology. Moreover, a parametric study is conducted for an ES beam, in which the effects of speed parameter (η), speed parameter ratio between two trains (R), interspatial distance between loads to the length of the bridge (ϵ), damping ζ, stiffness parameter (κ), and traversing time difference between two trains (t os ) are investigated. The theoretical results suggest the effective use of the ES beam under higher values of η for one-way and R for two-way traffic. Additionally, various resonances and cancellation speed ratios under particular values of ϵ have been identified under varying values of κ. [ABSTRACT FROM AUTHOR]

The paper investigates the seismic performance of a novel passive vibration isolation and damping device termed Extended KDamper (EKD). The concept is applied to a representative two-span highway bridge, initially designed on conventional seismic isolation (CSI) bearings. An optimization process is developed and executed to design the EKDs, underscoring the importance of accounting for seismic motion variability. Compared to CSI, the incorporation of EKDs leads to a 40% to 70% reduction in deck drifts. In contrast to the CSI bridge, which may sustain excessive bearing shear strains when subjected to the most adverse seismic motions within the examined set, the bearings of the EKD bridge never exceed the 200% threshold. Through the use of nonlinear 3D time-history analyses, it is demonstrated that the nonlinearity of the EKD elements may result in residual deck drifts. The nonlinear EKDs exhibit a variation in maximum drifts and accelerations on the order of ±20% compared to the preliminary (linear elastic) design for the examined set of spectrum-compatible motions. The increased accelerations result from the stiffening of the negative stiffness elements (NSEs), being more pronounced for seismic motions that entail large displacement demands. With the aid of a fully nonlinear 3D model of the entire soil – foundation – structure system, the effects of soil-structure interaction (SSI) are explored and shown to significantly influence the seismic response of the system. Deck collision with the abutments restricts the movement of the deck and pier; however, it compromises the performance of the EKDs and leads to a substantial increase in deck accelerations. Overall, EKDs may facilitate a more economical design and enhanced seismic performance, particularly for displacement-sensitive structures like rail bridges. [ABSTRACT FROM AUTHOR]

As a critical characteristic curve of bridge structures, the influence line (IL) is effective in evaluating the bridge damage and bearing capacity. Contrary to conventional methods using static loading to obtain IL, this study proposes a methodology to determine the rotation influence line (RIL) based on the vehicle–bridge interaction (VBI) under random traffic loads. A key feature is the employment of the machine learning algorithm to determine the RIL from the upper and lower bridge response data induced by traffic flow, which is simulated using the cellular automata (CA) approach. Subsequently, by establishing a relationship between the RIL difference and the structural damage coefficient, this study identifies the bridge damage location and degree effectively. The numerical example results validate the accuracy in identifying both single- and multi-damage cases. The parameter analysis indicates that larger vehicle speed induces higher errors in identifying the RIL and the bridge damage. [ABSTRACT FROM AUTHOR]

The mechanical properties of bridge bearings gradually deteriorate over time, resulting from daily traffic loading and harsh environmental conditions. However, efficient detection of in-service bridge bearings is still challenging, especially in quantifying support stiffness. This study presents a bridge bearing condition assessment framework of a simply elastic supported beam based on impact vibration testing and structural flexibility identification. Firstly, the dynamic response equation of a simply supported beam with elastic boundary constraints is established. The modal orthogonality of Euler-Bernoulli beams and the corresponding overall matrix of undetermined coefficients are derived using the separate variable method. Subsequently, the flexibility matrix of the simply elastic supported beam is derived and verified in the cases of forward and inverse analysis, respectively. Furthermore, the vertical and rotational stiffness of the bearings are established based on the structural flexibility matrix. Finally, experimental verification is performed to identify the flexibility and the vertical support stiffness of the simply elastic supported beam based on impact vibration tests. The results indicate that the proposed the bearing condition assessment framework can straightforwardly quantify support stiffness. [ABSTRACT FROM AUTHOR]

Because of the uncertainty of the structure and environment of the electric driving system (EDS), the fault signature of the rotating mechanism is complicated. A novel method based on Hilbert transform with modified fast kurtogram (HTMFK), which is used for identifying the bearing faults in the EDS, is proposed. The modified principle and algorithm flow of the proposed method are derived. A high pass filter based on the frequency band identified by HTMFK is constructed and applied to fault diagnosis. Simulation signals demonstrate the ability of demodulating signals and identifying the fault resonance band. The bearing fault bench experiment of EDS is carried out in a semianechoic chamber. The corresponding fault tests are conducted according to different operating conditions. The applicability of HTMFK is verified by comparing the square envelope spectrums. Compared with other methods, the proposed method identifies the fault resonance frequency band more effectively and expands the application range of bearing fault diagnosis in EDS. [ABSTRACT FROM AUTHOR]

Assessment of the historic bearings of the Chemnitz viaduct The Chemnitz viaduct was built at the beginning of the 20th century and has been refurbished in recent years in line with its listed status. This required, among other things, an assessment of the reuse of the bearings consisting of individual cast components. The assessment included standard non‐destructive and destructive testing as well as numerical calculations to verify the load‐bearing capacity. As a novel addition, casting simulations, 3D scans of the bearings to record the actual condition and fracture mechanical investigations to assess the risk of brittle fracture and possible crack propagation were carried out. Among other things, difficult accessibility and complex load conditions posed a challenge. This paper presents the bearing concept and the methodology of the assessment and describes the individual components with the associated results. The extensive assessment allowed for the continued use of most of the bearing components. [ABSTRACT FROM AUTHOR]

Temperature-induced bridge responses are highly sensitive to changes in bridge properties. Thus, the relationship between temperature and associated responses can be used as a surrogate to assess the health of bridges. However, the relationship between temperature and temperature-induced displacement is influenced significantly by bridge bearing properties. The temperature variation cannot cause longitudinal displacements until the longitudinal restraint of bearings is overcome. Additionally, the temperature-induced strains highly depend on spatial temperature distributions in bridges. The developed mappings seldom consider the aforementioned issues, resulting in errors that can conceal the variation produced by the changes in bridge conditions. Focusing on long-span steel truss arch bridges with spherical bearings, this study seeks to accurately map the temperature-induced responses considering the bearing properties and spatial temperature distributions. The relationship between temperature variation and temperature-induced responses is explored initially using the elastic beam theory. Subsequently, the mapped relationship is validated using field monitoring data. Results show that the relationship produces unique flat planes in 3 D space; the plane parameters, including the orientation and boundary, are determined by the structural parameters, especially the bridge cross-section properties and bearing properties. Accordingly, the 3 D baseline can provide a feasible signature for bridge conditions. [ABSTRACT FROM AUTHOR]

In this paper, a vehicle track coupling dynamic model including bearing outer ring defects is built, the time history of the axle‐box vibration acceleration and the time history of the bearing roller‐outer raceway contact load under the condition of random track irregularity on the Beijing‐Tianjin line are obtained by simulation calculation. The results show that when the outer ring defect of the bearing occurs, the axle box will generate high‐frequency vibration at the resonance peak in the vertical and lateral directions. When the defect on the bearing outer ring is in the small width of 1 mm, the roller only imposes one impact when passing through the defect area. However, when the width exceeds 3 mm, the large defect causes the roller to impose a double impact on the lateral direction of the axle box, due to changes in bearing clearance in the passing‐through process. When the running speed of the train is about 250 km h−1, the width of bearing outer ring defects needs to be limited to within 1 mm, to minimize a series of problems such as structural fatigue caused by the increased bearing roller‐outer raceway contact load caused by bearing outer ring defects. [ABSTRACT FROM AUTHOR]

Based on the theory of highway vehicle-bridge coupled vibration analysis, a program for vehicle-bridge coupling vibration analysis of highway bridges is developed using Intel Visual Fortran language. An accurate finite element model of the axle was established by measuring the parameters of the axle test model. And an experimental system of vehicle-bridge coupled vibration was designed. Then, based on theoretical analysis and experimental research, the reliability of the analysis program and test system was verified and analyzed the influence factors of vehicle-bridge coupling vibration test were analyzed, including carriageway location, vehicle-bridge mass ratio and bridge support form were discussed. The results show that: a lateral shift of 10 cm at different lane positions has little effect on the dynamic response of the axle. The axle mass ratio is an important factor affecting the dynamic response of the axle. With a vibration response being most obvious when the mass ratio is between 0.10 and 0.16 during the test process, the vertical acceleration response of bridge bearing 1 model (one end pad bearing, the other end roller bearing) was shown to be significant. This research will provide a helpful reference for others to analyze highway vehicle-bridge coupled vibration in the laboratory. [ABSTRACT FROM AUTHOR]

As an important part of a bridge, bearings are vulnerable to damage when exposed to various loading and environmental changes during their lifetime, resulting in the necessitating repair or replacement operations. The investigation and maintenance of bearings' diseases are helpful to prolong their durability. Compared with laboratory research, the field investigation of bearing diseases is more representative due to the realistic working environment. In this paper, the defects of 10,486 bearings in 19 expressway bridges and 8,862 bearings in 5 high-speed railway (HSR) bridges in Eastern China are inspected through manual on-site visual observation and parameter measurement, followed by a large amount of bearing diseases data obtained to perform a statistical analysis for evaluating many aspects, including the classification and the potential causes of the bearing diseases, the service status. Finally, a three-level maintenance strategy for bearings is developed and applied to the replacement of 1,166 bearings in eight expressway bridges and 15 bearings in seven girders of HSR bridges. The results show that most diseases of elastomeric bearings are caused by design defects but for pot or spherical by the problems remaining from bearings installation, and the proposed bridge jacking scheme and bearing replacement technologies are efficient, labour- and material-saving. [ABSTRACT FROM AUTHOR]

Bridges are structures subjected to multiple types of loads and combinations during their service life. The uncertainties linked with the materials' behavior and manufacturing processes often necessitate the testing of produced elements on a real scale. This is particularly true for bridge concrete precast girders, which are frequently tested to predict the ultimate carrying load. Testing procedures are time-consuming, expensive in terms of both time and money, and involve a large amount of logistics and auxiliary equipment and devices. Thus, testing scaled-down models in laboratory conditions and extrapolating the obtained results with respect to the real-scale element using similitude theory has become a very common alternative method in the last decade. In this paper, experimental data regarding the efficiency of dimensional analysis computation are discussed. The proposed method involves comparing the values at which failure in bending and shear occurs for a 1:10 cementitious concrete bridge beam model with respect to the values computed for the prototype beam. Regarding the obtained results, a very small difference between the test results and the calculated values can be noticed. [ABSTRACT FROM AUTHOR]

As an important component connecting the upper and lower structures of a bridge, bridge bearings can reliably transfer vertical and horizontal loads to a foundation. Bearing capacity needs to be monitored during construction and maintenance. To create an intelligent pot bearing, a portable small spot welding machine is used to weld pipe-type welding strain gauges to the pot bearing to measure strain and force values. The research contents of this paper include the finite element analysis of a basin bearing, optimal arrangement of welding strain gauges, calibration testing, and temperature compensation testing of the intelligent basin bearing of the welding strain gauges. Polynomial fitting is used for the fitting and analysis of test data. The results indicate that the developed intelligent pot bearing has a high-precision force measurement function and that after temperature compensation, the measurement error is within 1.8%. The intelligent pot bearing has a low production cost, and the pipe-type welding strain gauges can be conveniently replaced. The novelty is that the bearing adopts a robust pipe-type welding strain gauge and that automatic temperature compensation is used. Therefore, the research results have excellent engineering application value. [ABSTRACT FROM AUTHOR]

This paper introduces a new bridge damage indicator, the moving reference influence function (MRIF), to detect bridge bearing damage using deflections inferred from vehicle accelerations. Recently, vehicle acceleration has been used to find the apparent profile (AP) of a bridge when a vehicle passes. This AP consists of bridge profile elevations and bridge deflection components. To describe the relationship between these deflection components and load, a MRIF is proposed for the first time in this paper. An error minimization process is used to find the MRIF and the road surface profile on the bridge. The vehicle acceleration signals used in the paper are assumed to be collected from a partially instrumented vehicle fleet. In the fleet, only the first axle acceleration is collected from each vehicle. To simplify the minimization process, both the MRIF and the bridge profile are represented by kernel density functions. The results show that the bridge profile can be accurately obtained and that bridge bearing damage can be identified from the MRIF. Both area and skewness of the MRIF are damage sensitive and can be used together to find the location and severity of bridge bearing damage. [ABSTRACT FROM AUTHOR]

One mono-nuclear Ni(II) complex [NiL(CH3COO)] (1) and one di-nuclear Cu(II) complex, [Cu2L2(CH3-COO)2] (2), with pendant and bridging acetate moieties, respectively, have been synthesized using a novel N,N,O donor Schiff base ligand HL, 1-(((piperidine-2-ylmethyl)imino)methyl)naphthalene-2-al, prepared by the simple condensation of 2-hydroxy-1-naphthaldehyde and 2-amino methyl piperidine. With the aid of numerous spectroscopic studies, the three compounds described above have been properly characterized. The single crystal data analyses of both the complexes reveal that in complex 1, one deprotonated ligand, one pendant acetate ion, and one Ni(II) ion form a mononuclear distorted square planar geometry and in complex 2, each Cu(II) center connects with one deprotonated ligand and a double m1.1-acetato-bridge forming a distorted trigonal bipyramidal geometry, while two acetate bridges connect two Cu(II) centers forming a dinuclear complex. After rigorous characterization, both the complexes are investigated to check their binding efficacy with biomacromolecules like DNA and HSA, and the results, obtained from a variety of biophysical studies like absorption, fluorescence, and circular dichroism-based titrations, clearly disclose that both the complexes have an affinity for binding with DNA and HSA. Fluorescence displacement analysis and a DNA melting study demonstrate different modes of binding for the two complexes with the DNA host, namely intercalative mode associated with groove binding for complex 1 and only groove binding for complex 2. Circular dichroism spectral analysis of HSA during interaction with the complexes confirms some structural changes in HSA upon binding. Determination of the thermodynamic parameters implies the binding interactions of HSA with the two complexes to be spontaneous. After a convincing study of the complex--biomacromolecule binding interactions, an MTT assay study on both cancer and normal cells reveals that of the two complexes, complex 2 is the better one, showing superior anticancer properties together with low toxicity to a normal cell. Finally, an apoptotic cell-killing pathway of the studied complexes has been confirmed by a nuclear staining study. [ABSTRACT FROM AUTHOR]

Reducing costs and improving durability are essential factors for commercializing gas foil bearings, crucial components of fuel cell vehicle air compressors. In this paper, a two-pad gas foil bearing is proposed. By reducing the number of top foils, adopting a symmetrical design, and eliminating the welding step, the cost of processing and assembly is reduced, and the potential source of failure caused by welding is eliminated. The feasibility of the two-pad gas foil bearing was verified through testing on a commercial fuel cell vehicle air compressor. Then, durability testing was performed in accordance with fuel cell vehicle usage requirements, including an accelerated random vibration test equivalent to 6,000 h of on-board operation and a 200,000-cycle start-stop test. These tests simulated the damage caused to the bearings during fuel cell vehicle operation and start-stop periods, respectively. The durability test results indicated that the two-pad gas foil bearing provides good start-stop durability but insufficient durability against on-board random vibration. The failure causes were analyzed, and improvement measures were proposed. Our findings can be utilized to guide the manufacturing of low-cost and highly durable gas foil bearings. [ABSTRACT FROM AUTHOR]

In this study, a model of two nonlinear spring masses subjected to a smooth friction-velocity curve is examined. The second order governing system of motion is obtained in view of the system friction forces. This system is transformed to another suitable one of first order to investigate the points of equilibrium using Hurwitz's theory. The excitation and critical stick-slip (SS) speeds are determined in accordance with the characteristic equation for the Jacobian matrix of the system. The stability and behavior of the system motion, along with the behavior of the SS movement, are examined. The effect of various parameters, such as excitation speed, damping and fraction coefficients, linear and nonlinear stiffness of springs, and masses that affect the motion and stability of the system is analyzed and studied. This research has numerous practical applications in a variety of industries, including airports, modern car brakes, well drilling, explaining and understanding seismic events, mechanical transportation, friction in bridges, and civil systems, which all exhibit impacted friction in dynamics and stick-slip phenomena. [ABSTRACT FROM AUTHOR]

In light of intensifying global climatic shifts, the durability analysis of bridge structures under fluctuating and intricate environmental conditions has gained paramount importance. Historically, durability assessment methodologies for bridges have been predominantly centered on static and dynamic stress analyses, with the multifaceted influences of climate change largely overlooked. Furthermore, a linear hypothesis underpins many of these methodologies, rendering them less adept at encapsulating complex thermal-mechanical interactions and inherent non-linear behaviours. In response to these limitations, a novel thermodynamic model, which duly incorporates climate change determinants, was introduced in this study. Emphasis was placed on two pivotal domains: the computation of shear bearing capacities in oblique bridge sections influenced by thermal-mechanical coupling, and the intricate nonlinear thermal-mechanical coupling analyses of bridges. By addressing these gaps, the study endeavours to present a more holistic and precision-driven methodology for evaluating bridge structure durability. Beyond its theoretical significance, this research is posited to further the pursuit of resilient and sustainable bridge design paradigms. [ABSTRACT FROM AUTHOR]

Bridge bearings are critical components in bridge structures because they ensure the normal functioning of bridges by accommodating the long-term horizontal movements caused by changing environmental conditions. However, abnormal structural behaviors in long-term horizontal displacement are observed when the structural integrity of bridge structures is degraded. This study aims to construct an accurate prediction model for long-term horizontal displacement under varying external environmental conditions to support the reliable assessment of bridge structures which has not been fully explored in previous studies. The main challenge in developing an accurate prediction model lies in modeling the influencing factors that accurately simulate the effect of external environmental conditions on long-term horizontal displacement. To enhance the prediction accuracy in the proposed study, the surrounding environmental effects by considering the relationship between the current and past displacements in addition to air temperature, thermal inertia, and solar radiation are modeled as critical influencing factors. In addition, a data-driven method based on an artificial neural network (ANN) integrated with Bayesian optimization (BO) is employed to model and predict long-term horizontal displacement with the adopted critical influencing factors. An overpass bridge equipped with bearing displacement monitoring and temperature sensors is used to validate the robustness and effectiveness of the proposed method. The analysis of the results concludes that the proposed method can generate an accurate and robust long-term horizontal displacement prediction model that supports a reliable anomaly detection approach for early warning systems of bridge structures. [ABSTRACT FROM AUTHOR]

Most multi‐resonance (MR) induced thermally activated delayed fluorescence (TADF) emitters generally exhibit strong aggregation and relatively worse solubility due to their rigid and planar molecule structures, which is highly undesirable for solution‐processible devices. Herein, a simple but feasible approach for solution‐processible small‐molecule MR‐TADF emitters is developed by incorporating two MR‐TADF units onto carbazole bridge bearing long alkyl chains. The obtained emitters demonstrate supreme film‐forming capability and narrowband emissions with full‐width at half‐maximums (FWHMs) of 22 nm. The resulting solution‐processed narrowband electroluminescent devices achieve maximum external quantum efficiency of 27.1 %, which represents the highest efficiency among the solution‐processed OLEDs based on MR‐TADF emitters. This simple approach reveals great potential of developing solution‐processible emitters for rigid and planar molecular structures. [ABSTRACT FROM AUTHOR]

Most multi‐resonance (MR) induced thermally activated delayed fluorescence (TADF) emitters generally exhibit strong aggregation and relatively worse solubility due to their rigid and planar molecule structures, which is highly undesirable for solution‐processible devices. Herein, a simple but feasible approach for solution‐processible small‐molecule MR‐TADF emitters is developed by incorporating two MR‐TADF units onto carbazole bridge bearing long alkyl chains. The obtained emitters demonstrate supreme film‐forming capability and narrowband emissions with full‐width at half‐maximums (FWHMs) of 22 nm. The resulting solution‐processed narrowband electroluminescent devices achieve maximum external quantum efficiency of 27.1 %, which represents the highest efficiency among the solution‐processed OLEDs based on MR‐TADF emitters. This simple approach reveals great potential of developing solution‐processible emitters for rigid and planar molecular structures. [ABSTRACT FROM AUTHOR]

A finite element model is created using OpenSees software to perform a time history analysis in order to analyze the seismic response law of a skew bridge and the damage volume of its key components, using a typical 3×20 m skew continuous girder bridge as an example. The seismic response of the skew continuous girder bridge under various factors such as the size of the abutment expansion joint, shear key gap, and shear key strength is studied then the damage rate is assessed for the bearing, shear key, and pier. The research results show that under the action of earthquake ground motion with 0.3 g PGA, the seismic force transmitted to the pier is small, and the pier is elastic owing to the sliding of the bearing, but the damage degree of the shear key is larger than that of the bearing and pier. The impact increases the rotation effect of the main beam in the direction of off acute angle, resulting in a greater damage to the shear key at the acute angle than that at the obtuse angle. The damage of bearing and shear key increases and then decreases with the increasing of expansion joint, and the larger the skew angle is, the smaller the expansion joint will be corresponding to the maximum displacement of bearing and shear key. With the increase of the shear key gap, the deformation limitation effect of the shear key on the main beam decreases significantly, resulting in a linear increase in the bearing slip, which increases the risk of the main beam subsidence. With the increase of the shear key strength, the bearing and shear key damage decreases greatly at first, and then increases slightly. However, the pier damage increases obviously. In an area with a high risk of earthquake, it is recommended that the shear key can be a “fuse element”. For any oblique angle, the shear key gap can be reduced to 2 cm, and the shear key strength can be increased to 125 % or 150 %. When the skew angle is between 30 and 60, the expansion joint size can be increased to 12 cm or 16 cm. [ABSTRACT FROM AUTHOR]

Salen ligands and relative metal complexes are widely used in many fields, such as catalysis, sensing, optical and electronic materials. The introduction of a wide range of substituents in different positions, both in the salen scaffold and in the diamine bridge, allows the tuning of chemical, catalytic and spectroscopic properties. In this contribution, we report the synthesis and characterization of a new salen ligand and relative Co(II) complex bearing a maleonitrile bridge and two chlorine atoms in the salen backbone. [ABSTRACT FROM AUTHOR]

A bearing‐vehicle‐track coupling dynamic model is built in this paper and the validity of the model is proved by comparing the simulation data with the theoretical data. Based on this model, the influence of wheel diameter difference (WDD) on the dynamic behavior of wheelset bearing is studied. The results demonstrate that when the bogie has a rear WDD, lateral displacement (LaD) of the front wheelset is the smallest. When the bogie has an anti‐phase WDD, LaD of the rear wheelset is the smallest, while when the bogie has an in‐phase WDD, LaD of the front and rear wheelsets is the largest, and LaD of the front and rear WDD is between the two, which is in line with the theoretical analysis results. Compared with LaD results of the wheelset bearing outer raceway under normal conditions, when the wheel has a diameter difference, LaD distance of the outer race increases with the WDD increasing, and the frequency of lateral movement also increases with the increase against the WDD gradation. The high‐frequency and large‐distance lateral movement of the wheelset bearing outer race under the WDD will increase the roller‐outer raceway force, and accelerate the failure of the bearing. [ABSTRACT FROM AUTHOR]

The uplifting slide shoe (UPSS) bearing, consisting of multiple sliding surfaces, is a new type of bearing which has been proposed to achieve reduced displacement under strong earthquakes without losing advantage of the slide bearing to deal with the thermal effects on bridges girders. In the present study, bi-directional implementation of the UPSS devices is proposed to achieve effectiveness in controlling the bi-directional seismic response of girder bridges induced by bi-directional ground motions. A simplified multi-spring model of the bi-directional UPSS, considering the coupling effect of the friction mechanism and the geometric contact condition of the slider, is established to assess the bi-directional bridge response including the integrated nonlinear interaction between the longitudinal and transverse components. Numerical simulations demonstrate that the bi-directional UPSS is effective in reducing the pier response in the transverse direction compared with the conventional UPSS. The seismic performance of the bridge with the application of the bi-directional UPSS is shown to be superior to that of the functionally discrete bearing (FDB) systems in effectively reducing both the bearing displacement and the pier response ductility factor. [ABSTRACT FROM AUTHOR]

In order to investigate the seismic damage features of high-speed railway (HSR) China Railway Track Slab III (CRTSIII) slab ballastless track (SBT) simply supported bridge systems, a nonlinear finite element model of HSR CRTS III SBT simply supported bridge system was established. The damage mechanisms and peak and residual displacement distribution patterns of their critical components under seismic action were investigated. In addition, the sensitivity of rail irregularity to the seismic residual deformation in such critical components was analyzed. The results indicated that midspan piers and bearings are more susceptible to failure than side span piers and bearings, and fixed bearings are more prone to failure than sliding bearings. Fastener and isolation layer deformation increases sharply on both sides of the beam joint. Rail deformation exhibits a parabolic shape that is large in the middle and small at both ends. The critical components of even-span and odd-span systems have significantly different patterns of seismic deformation distribution. Rail irregularity is mainly attributable to bearing residual deformation, pier residual deformation, and fastener residual deformation successively, and the superposition of bearing residual deformation and pier residual deformation is approximately equivalent to rail deformation. Rail irregularity is most sensitive to pier deformation, followed successively by bearing and fastener deformation. [ABSTRACT FROM AUTHOR]

It is generally perceived that ground motion duration has an effect on structural seismic response and damage, despite the neglect of current seismic codes. Based on friction SDOF systems, this paper investigates the duration effect of ground motions on seismic responses and damage of sliding bearings. Ground motions are divided into long-duration (LD) and short-duration (SD) cases, taking the significant duration of 25 s as the boundary. Each case consists of natural records and spectrally equivalent artificial ground motions to decouple duration from other earthquake characteristics. Results from response history analyses implicate that duration has hardly any effect on seismic responses of the system exhibiting an approximate linear elasticity. Nevertheless, for systems with distinct frictional nonlinearity, selecting LD ground motions as seismic inputs usually leads to a conservative result. By performing incremental dynamic analysis (IDA), nonlinear systems in SD cases bear 10% higher damage risk than those in LD cases without considering the influence of temperature rise. The same is true for systems with a small friction coefficient of 0.005 when earthquakes are in the low intensity range. It was also found that damage exceedance probabilities of these small friction coefficient systems are almost unaffected by the duration as the peak ground acceleration increases to more than 0.6 g. When the effect of temperature rise caused by friction is considered, the damage exceedance probability in LD cases is higher than SD cases. The damage probability of friction SDOF system under LD earthquake will be underestimated without considering the influence of temperature rise. [ABSTRACT FROM AUTHOR]

The key issues in designing ballastless track for high-speed railway bridges are to reduce maintenance and improve track smoothness by understanding fatigue damage characteristics. This paper is based on the principle of bridge-rail interaction and train-track-bridge coupling dynamics, the refined simulation model of bridge-CRTS I Bi-block ballastless track system is established by using the finite element method. The longitudinal force distribution law of CWR (Continuously Welded Rail) and the dynamic response characteristics of coupling systems are studied, based on the Miner rule and S-N curve. The fatigue characteristics of ballastless track system laying on long-span bridge under the dynamic train load and the effect of ballastless track system design parameters changes on fatigue characteristics are discussed. The results show that the extreme values of longitudinal force of CWR all appear in the middle of the bridge span or near the bridge bearing, and attention should be paid to the strength checking of CRW laying on long-span bridge. Under the dynamic train load, the fatigue life curve of rail on the bridge is relatively smooth and the minimum life of rail which is laying on continuous bridge decreases from 27.1 years to 17 years that which is laying on cable-stayed bridge. The life curve of track plate laying on continuous bridge is relatively smooth, and the life curve of track plate laying on cable-stayed bridge is related to the stiffness of elastic cushion, which decreases in a stepped manner, and there will be no fatigue failure on the track plate during service. The life curve of the baseplate is related to the type of bridge, the minimum life value of the baseplate appears near the bridge bearing, and there will be no fatigue failure on the baseplate during service. Increasing the stiffness of elastic cushion can effectively improve the fatigue life of track plate, and increasing the vertical stiffness of fasteners can enhance the connection between rail and track plate and improve the fatigue life of rail. The increase in train speed will increase the dynamic stress amplitude of track structure and reduce the fatigue life of the rail. [ABSTRACT FROM AUTHOR]

Elastomeric bearings are widely used in bridges to support the superstructure, to transfer loads to substructures, and to accommodate movements induced by, for example, temperature changes. Bearing mechanical properties affect the bridge's performance and its response to permanent and variable loadings (e.g., traffic). This paper describes the research carried out at Strathclyde towards the development of smart elastomeric bearings that can be used as a low−cost sensing technology for bridge and/or weigh−in−motion monitoring. An experimental campaign was performed, under laboratory conditions, on various natural rubber (NR) specimens enhanced with different conductive fillers. Each specimen was characterized under loading conditions that replicated in−situ bearings to determine their mechanical and piezoresistive properties. Relatively simple models can be used to describe the relationship between rubber bearing resistivity and deformation changes. Gauge factors (GFs) in the range between 2 and 11 are obtained, depending on the compound and the applied loading. Experiments were also carried out to show that the developed model can be used to predict the state of deformation of the bearings under random loadings of different amplitudes that are characteristic of the passage of traffic over a bridge. [ABSTRACT FROM AUTHOR]

As the key safety-critical component of a bridge support system, bridge bearings are extensively used to accommodate, balance, and transfer differential displacements and loads between the superstructure and substructure of a bridge during operations. Several studies have been conducted to obtain dynamic modal parameters of traditional bridge bearings only in perfectly dry environments. However, in extreme weather conditions (e.g., heavy rain, flash floods, etc.), water can ingress and change the bearings' properties. In this study, novel 3D-printed porous bridge bearings (3DPPBBs) have been fabricated by Fused Deposition Modeling (FDM) with thermoplastic polyurethane (TPU) filaments. This study is the first to determine the influences of flood conditions on their dynamic properties, which has never been done before. An idealised single degree of freedom (ISDOF) for these novel bearings is considered for the non-destructive field-testing technique of the critical bridge component. A series of experimental tests have been performed under several conditions of flooding levels. The new results unprecedentedly indicate that relatively higher dynamic damping ratios can be found with the increasing flood levels. In contrast, the natural frequencies and dynamic stiffness decrease with the same conditions. Novel insights are essential for bridge engineers to assess and monitor bridge vibrations exposed to extreme weather conditions. [ABSTRACT FROM AUTHOR]

Bridges are essential structures in the logistic chain of countries, making it critical to design them to be as resilient as possible. One way to achieve this is through performance-based seismic design (PBSD), which involves using nonlinear Finite Element (FE) models to predict the response and potential damage of different structural components under earthquake excitations. Nonlinear FE models need accurate constitutive models of material and components. Among them, seismic bars and laminated elastomeric bearings play an important role in a bridge's response to earthquakes; therefore, properly validated and calibrated models should be proposed. Only default parameter values from the early development of the constitutive models widely used by researchers and practitioners for these components tend to be used, and low identifiability of its governing parameters and the high cost of generating reliable experimental data have prevented a thorough probabilistic characterization of their model parameters. To address this issue, this study implements a Bayesian probabilistic framework using Sequential Monte Carlo (SMC) for updating the parameters of constitutive models of seismic bars and elastomeric bearings and proposes joint probability density functions (PDF) for the most influential parameters. The framework is based on actual data from comprehensive experimental campaigns. The PDFs are obtained from independent tests conducted on different seismic bars and elastomeric bearings, to then consolidate all the information in a single PDF for each modeling parameter by means of the conflation methodology, where the mean, coefficient of variation, and correlation between calibrated parameters are obtained for each bridge component. Finally, findings show that the incorporation of model parameter uncertainty through a probabilistic framework will allow for a more accurate prediction of the response of bridges under strong earthquakes. [ABSTRACT FROM AUTHOR]

Dynamic designs for ship propulsion shafting can be categorised as complex multi-disciplinary coupling systems. The traditional single disciplinary optimisation design method has become a bottleneck, restricting the further improvement of shafting design. In this paper, taking a complex propulsion shafting as the object, a dynamic analysis model of the propeller-shafting-hull system was established. In order to analyse the coupling effect of propeller hydrodynamics on shafting dynamics, the propeller's hydrodynamic force in the wake flow field was calculated as the input for shafting alignment and vibration analysis. On this basis, the discipline decomposition and analysis of the subdisciplines in design of shafting dynamics were carried out. The coupling relationships between design variables in the subdisciplines were studied and the Multi-disciplinary Design Optimisation (MDO) framework of shafting dynamics was established. Finally, taking the hollowness of the shaft segments and the vertical displacement of bearings as design variables, combined with the optimal algorithm, the MDO of shafting dynamics, considering the coupling effect of the propeller-shafting-hull system, was realised. The results presented in this paper can provide a beneficial reference for improving the design quality of ship shafting. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the spall propagation mechanism in ball bearing raceways using physics-based models. Spalling is one of the most common types of bearing failures that can lead to catastrophic failure. This research takes a step forward toward developing a prognostic tool for ball bearings. It is first necessary to understand the spall progression process in order to formulate a constitutive law of spall deterioration and to estimate the amount of remaining useful life. Fragment formation in the vicinity of the spall edge was found to consist of surface and sub-surface cracks that eventually coalesce, and a fragment is released from the raceway, based on naturally-developed spalls. Here, we describe a physics-based model, integrating a dynamic model with a finite element one to simulate this process. A continuum damage mechanics (CDM) approach and fracture mechanics tools were embedded into the finite element model to simulate the damage propagation. The formation of cracks in the vicinity of the spall (surface and sub-surface cracks) were studied using this effective stress CDM model, and the propagation of the cracks was examined using two approaches: a fracture mechanics approach and an accumulated inelastic hysteresis energy CDM approach. The latter also predicts the overall process of a single fragment release. The simulation results of the spall propagation models are supported by experimental results of spalls from both laboratory experimental bearings and an in-service Sikorsky CH-53 helicopter swashplate bearing. The results obtained show that the impact of the ball on the spall edge affects the crack propagation and the appearance of the surface and sub-surface cracks. Both release the residual stresses and cause crack propagation until a fragment is released. [ABSTRACT FROM AUTHOR]

Since the damage of the bridge structure may cause great disasters, it is necessary to monitor its health status, especially the bridge bearing, the important connecting component of the bridge's upper and lower structures. Nowadays, manual inspection is the main method to get the information of the bridge bearings' work status. However, occasional damage of bridge bearing may not be detected in time, and sometime the installation position of the bearing makes the manual inspection on bridge bearing difficult and even impossible. Therefore, in order to know the work status of the bridge bearings timely, an intelligent remote monitoring system for the bridge bearing is developed. A 32-channel real-time acquisition system is designed by using an AD7768-1 analog-to-digital converter and Xilinx Spartan-6 Field Programmable Gate Array for interface stress continuously acquired in the bridge bearing. To assure the good linearity and low noise performance of the monitoring system, the data acquisition card is meticulously designed to reduce noise from both hardware and software and realize high-precision acquisition. Through the establishment of the monitoring server, the compressive stress data can be displayed synchronously and the overpressure situation can be alarmed in real-time. The experimental results show that the accuracy of the calibrated sensor is within 1.6%, and the detection error of the acquisition board is less than 200 μV. The acquisition system is deemed to have considerable advantages in accuracy and applicability. [ABSTRACT FROM AUTHOR]

Novel binuclear platinum(II) complexes driven by C^N cyclometalated ligands with the general formula [Pt2(C^N)2Cl2(μ-L)], where C^N = 2-phenylpyridine (ppyH) or 2-(2,4-difluorophenyl)pyridine (dfppyH) and L = 1,1′-bis(diphenylphosphino)ferrocene (dppf), 1,1′-bis(diisopropylphosphino)ferrocene (dippf), and 1,1′-bis(dicyclohexylphosphino)ferrocene (dcpf), have been designed, synthesized, and characterized. Single crystal X-ray analysis confirmed the molecular structures of complexes. The electronic absorption spectra of these Pt(II) complexes are examined, and density functional theory (DFT) and time-dependent DFT (TD-DFT) were employed for geometry optimization and electronic structure computations, respectively. To evaluate the potential of these complexes as anticancer agents, the biological activities including cytotoxic activity, DNA interaction and molecular docking were accomplished. The cytotoxic activity of the prepared complexes was assessed against A549, HeLa, and MCF-7 tumor cell lines using the MTT assay. The results demonstrated that 2c and 3c had reasonable cytotoxic activities, while the other complexes revealed less cytotoxic activity. In comparison to cisplatin, 3c showed significantly higher cytotoxicity against A549 cells. Additionally, the SAR results established that the dfppy ligand, which contains fluorine atoms improved the cytotoxic activity of these complexes. To understand the antiproliferative mechanism of 3c, analyses of DNA damage (comet assay) and apoptosis were carried out. In addition to this, the detection of cellular reactive oxygen species (ROS) was evaluated. Moreover, molecular docking simulations suggested reasonable interactions between these complexes and DNA. This study suggests that metal-based drug design can be developed utilizing the scaffold of 3c as a valuable anticancer agent. [ABSTRACT FROM AUTHOR]

This paper describes a study on the responses analyses of a seismically isolated multi-span highway bridge recorded during the 2011 Great East Japan (Tohoku) earthquake and assessment of isolation bearing condition based on the responses. During the earthquake, lateral pounding and locking between the side-stoppers and the upper steel plate of the isolation bearings were observed of several piers. Finite element model was employed to analyze the problem and scenarios of locked bearing on the piers were simulated. The study also presents a wavelet-based technique to detect the presence and location of locked bearing. Instantaneous frequency of continuous wavelet transform of girder and piers accelerations were employed to evaluate isolation bearing condition by identifying the occurrence of high-frequency filtering effect. Afterwards, bearing condition was characterized via statistical clustering technique. Accuracy and efficacy of the technique were verified in simulations using three-dimensional finite element model of the bridge. Results of simulations demonstrate that wavelet-based features can effectively characterize isolation bearings condition directly from seismic responses of girder and piers. [ABSTRACT FROM AUTHOR]

A tie-down rope-spring device (TRD) is proposed to control bearing uplift of cable-stayed bridges under a design earthquake. The mechanical properties of TRD depict a favorable interaction between its horizontal and vertical directions, i.e. the horizontal displacement results in tie-down force. A procedure is proposed to design the TRD for a case cable-stayed bridge under longitudinal seismic excitations. Analytical results validate the effectiveness of TRDs in restricting bearing uplift of the case bridge, showing a large reduction of uplift displacement at deck end, pounding force at bearings and shear force of the crossbeam. [ABSTRACT FROM AUTHOR]

Friction pendulum systems (FPSs) are increasingly being used for bridge seismic isolation, and the isolated response is generally achieved at the expense of inducing large bearing displacements. Setting up a tuned inerter damper (TID) is an approach for improving seismic performance. Nevertheless, the optimization and performance enhancement of multiple TIDs to mitigate the seismic responses of bridges isolated with the FPSs are limited. In this study, the stochastic optimization of multiple TIDs for controlling stochastically excited bridges with FPS bearings was pursued. By describing the hysteretic characteristics of the FPS using the Bouc–Wen model, augmented systems of the bridge model, FPS bearings, and TIDs were formulated and combined with the modeling of stochastic excitation as filtered Gaussian white noise. A stochastic optimization procedure of multiple TIDs for controlling the bridge response considering the nonlinearity of the FPS bearings is proposed and illustrated using examples of continuous bridges. The effects of FPS friction on the optimization and robustness of the TID parameters were identified. A parametric study was performed to determine the mechanism of TID performance enhancement depending on the number of TIDs, multiple modes of tuning, and inertance distribution. Numerical results indicate that the TIDs designed via stationary-stochastic-global (SSG) optimization significantly reduced the responses of the isolated bridge, and the performance was improved by increasing the TID number. Considering the multi-mode contributions to the transversal responses, the performance of spatially distributed TIDs can be substantially enhanced by adding the TID inertance as a design parameter. [ABSTRACT FROM AUTHOR]

Summary: As critical components that transmit internal forces laterally in multigirder bridges, joint degradation can destroy the cooperative working mechanism of a multigirder system and seriously reduce bridge bearing capacity. This research aims to reveal the joint damage effects on lateral internal force transmission and propose a joint damage detection and location method. A spring‐jointed plate model is established to analyze the effects of joint damage, based on which the relationship between the shear forces in the joints and the shear stiffness of the joints can be obtained. Furthermore, a joint damage index is deduced based on the lateral deflection influence lines, and a bridge load testing method is proposed to obtain such influence lines. By using multiple influence lines to jointly solve the damage index, the joint damage in the lateral bridge direction can be accurately detected and located. In addition, by carrying out the damage detection process at several cross sections of the bridge, the joint damage position in the longitudinal bridge direction can also be determined. Finally, a numerical model of an adjacent box girder bridge is illustrated as an example to verify the effectiveness of the damage detection. It can be concluded that the proposed method can effectively identify and locate single or multiple joint damage locations under noise interference, and the joint damage degree can be quantitatively evaluated. This study can provide an effective method to identify the joint damage for adjacent box girder bridges with high accuracy and reliability. [ABSTRACT FROM AUTHOR]

The paper describes the effect of cooling media and temperature on 20 KW axial flux BLDC motor performance using numerical and experimental analysis. The motor is applied in electric car with initially as natural air cooling, and it is modified as liquid cooling. Numerical and experimental analysis shows that cooling temperature has significant effect on power and efficiency of motor. Lower cooling temperatures produce higher motor power and efficiency. Based on experimental investigation, maximum power of water cooled BLDC motor can generate power of 25 kW and 81.0 % efficiency, while air cooled motor produces lower power and efficiency of 19.1 kW and 65.0 % respectively. Comparative analysis of motor performance based on model and experiment were presented as well. Maximum motor power calculated by model is slightly higher than that measured by experiment. It can be explained that in modeling, the friction losses on the bearings are neglected, while in the experiment, the friction loss remains a variable that affects the motor power output. [ABSTRACT FROM AUTHOR]

Single-layer reticulated domes with high capacity and attractive shapes are widely used in many modern facilities, ranging from industrial architecture to large-scale public buildings, including railway stations, sports gymnasiums and exhibition halls. In order to understand the seismic performance of single-layer reticulated dome subjected to three-dimensional seismic motion, a shaking table test on this type of structure was conducted, and the experiment was also simulated using FEA software ABAQUS considering the material damage accumulation. And then, an innovative three-dimensional isolation bearing with the corresponding mechanical model was applied to reduce the dynamic responses of the structure. Furthermore, the seismic performance of single-layer reticulated dome with the isolated bearing was investigated through shaking table test and numerical simulation. The results show that FEA software ABAQUS with a user-defined subroutine (UMAT) to consider material damage accumulation can accurately simulates the structural dynamic behaviour before and after the application of the isolated bearing. Therefore, numerical analysis will be used in the different types of large-span space structure in the further study. At the same time, the design and engineering practice of the three-dimensional isolation bearing is mainly realized by numerical analysis, which is of great support significance for the quantitative research and engineering practice of the isolated large-span space structure. This can also make this new isolation technology quickly popularized, and also has an important role in promoting the subsequent revision of seismic isolation code for large-span space structure. [ABSTRACT FROM AUTHOR]

Multi-span simply supported (MSSS) highway bridges are one of the most common bridge types across the world and have several vulnerable components, including bearings, piers, and abutments. Although several past studies have evaluated the seismic response and fragility of common multi-span simply supported bridges, there is negligible research that explores the influence of bearing types, and non-ductile failure modes of bridge piers on the performance of older non-seismically designed simply supported bridges. Additionally, a better understanding of seismic risk to highway transportation systems necessitates the exploration of design code advances and subsequent impact on the seismic vulnerability of MSSS highway bridges. Consequently, this study also focuses on developing and comparing fragility curves for the older design era non-seismically designed, and modern era seismically designed MSSS bridges. High-fidelity three-dimensional (3-D) analytical models, which account for the nonlinear behavior of different components, including non-ductile failure modes of bridge piers, are developed. Deterministic seismic response assessment reveals a higher seismic demand on bridge pier for MSSS bridges with steel bearings as compared to those with elastomeric bearings. The bridge component and system fragility curves are developed with a suite of ground motions representative of the seismic hazard of the case-study region. Results reveal the significant vulnerability of older non-seismically designed MSSS bridge with steel bearings due to the non-ductile failure of the bridge pier. The vulnerability of the bridge is significantly reduced with the adoption of modern seismic design and detailing practices. [ABSTRACT FROM AUTHOR]