Resistance Bridge Research Articles

A numerical solution for seismic response prediction of bridge piers with high damping rubber bearings

The motion equation of a one-degree-of-freedom system when subjected to earthquakes is usually not solved by analytic methods. This problem can only be solved through the time step method, when integrating differential equations. This paper is devoted to presenting a numerical solution for a seismic analysis problem of a highway bridge pier with high damping rubber bearings under earthquakes. Based on time-stepping Newmark’s method, a numerical solution is developed to predict the seismic responses of the piers. The iteration Newton-Raphson method is also applied in the problem for static analysis of this nonlinear system. The ground acceleration in the analysis is the type- II earthquake in JRA 2004 (Japan Road Association). Further-more, high damping rubber bearings are modeled by the two models: the bilinear design model and the rheology model proposed by authors. After that, the stress responses and the displacement responses of the pier are obtained by a program that is implemented in Matlab software. The comparison results obtained from the two models show that the seismic responses of the pier strongly depend on the modeling of the rubber bearings. This is the important note for engineers to design the earthquake resistance of bridges with high damping rubber bearings. The solution is also a useful tool for engineers to predict the seismic responses of bridge piers in the design procedure.

Electrical breakdown of a dielectric for the formation of a superconducting nanocontact

Electrical breakdown of the dielectric nanolayer between film electrodes of niobium and an alloy of 50% indium and 50% tin forms a bridge of this alloy between the electrodes. The bridge resistance depends on the breakdown current. The length of the bridge is equal to the thickness of the dielectric (30 nm), and its diameter is 25 nm. The calculated coherence length of the alloy at 2 K is close to the length of the bridge. The calculated critical current of a bridge with a resistance of 1 Ω at a temperature of 0 K is 1 mA. It is concluded that such a bridge should have the properties of a Josephson contact at a temperature lower than the critical temperature of the alloy (6.5 K).

Evaluation of a commercial high resistance bridge and methods to improve its precision

Evaluation of a commercial high resistance bridge and methods to improve its precision

The Influence of Lateral Restraining Stiffness on the Box-Girder Superstructure under Unbroken Solitary Waves

At present, box-girder superstructures are commonly used in coastal bridges, and their hydrodynamic performance under extreme waves such as tsunamis has attracted a lot of attention. There is a lack of research focusing on the effect of lateral restraining stiffness on box-girder superstructures under the extreme wave condition. In this paper, a two-dimensional numerical model based on the RANS equation and SST k-ω turbulence model is established. Combined with the dynamic mesh updating technique, the effect of lateral restraining stiffness on the superstructure of a box-girder and the dynamic characteristics of the movable box-girder under the solitary waves were investigated. To ensure the mesh quality, the numerical computational domain is divided into several regions that correspond to specific types of body motion. The numerical model is verified by comparing it with other numerical simulation results and experimental results. The dynamic characteristics and the wave forces of the box-girder superstructure under the effect of lateral restraining stiffness under the unbroken solitary waves are discussed. The results show that the horizontal and vertical forces on the box-girder superstructure under the action of unbroken solitary waves can be reduced by reducing the lateral restraining stiffness. However, with the decrease in lateral restraining stiffness, the lateral displacement of the box-girder superstructure would increase. Therefore, the lateral restraining stiffness and lateral displacement limit of the box-girder superstructure should be fully considered in practical engineering, and the appropriate lateral restraining stiffness should be selected to reduce the wave forces on the box-girder superstructure under extreme wave action, so as to improve the safety of the coastal box-girder superstructure. It is of great importance to study the interaction between the box-girder superstructure and unbroken solitary waves, which will help to have a deeper understanding to improve the disaster resistance of bridges.

Theory for nonlinear section model tests in the wind tunnel for cable-supported bridges

Wind tunnel tests for cable-supported bridges have been utilized extensively to achieve stable and wind resistant bridge designs over the past decades. Section model tests are by far the most common tests carried out. This is mainly due to their simplicity and their cost effectiveness. However, in order to reach this level of simplicity, some generalizations are required. One of them is the assumption that the bridge structure behaves linearly. For most bridges, this seems reasonable, but for very long spans, the cable system plays a dominant role in providing the vertical and torsional stiffnesses. Hence, as the cable system behaves nonlinearly, very long spans show a stronger nonlinear behavior, especially for suspension bridges. Furthermore, the theoretical demonstrations that have been made with regard to structural dynamic instabilities associated with geometric nonlinearities in suspension bridges confirm the need for a better understanding of the possible interaction between nonlinear structural effects and aeroelastic effects. Therefore, this paper presents the theoretical developments for a new type of section model test for bridges that accounts for geometric nonlinearities of the bridge structure. This theory for nonlinear section model tests starts from two-mode nonlinear generalized stiffness parameters obtained using nonlinear pushover analysis, which need to be scaled using a specifically developed procedure. Using eleven numerical models of cable-supported bridges, the assumptions made in the theory for nonlinear tests are then validated. The proposed scaling procedure is also tested.

Structural Design Tuak River Pedestrian Suspension Bridge Anchor Block Type Rigid Symmetric with LISA

Anchor blocks are one of the components and elements that are very risky for suspension bridge construction, because almost The ability The Suspension bridge resistance rests on the cables held in place by the anchor block. This anchor block behavior study is to find out the major stress information occurring in the anchor block elements. In this research, the researcher refers to the Circular Letter of Design Criteria for Rigid Symmetrical Pedestrian Suspension Bridge, and conducts structural modeling using the finite element method-LISA program on anchor blocks. Condition of the anchor block after receiving the appropriate tensile force from the round table at a span of 96 meters, the tensile force of the suspension bridge cable is 664.6 kN, resulting in a stress of 6.184 N/mm2 on the concrete surface of the anchor block using the concrete grade is fc 30 MPa, in the suspension cable of the bridge there is a tension of 22.26 N/mm2 at the point of work. The results of the analysis of the anchor block used on the Tuak River Suspension Bridge with a span of 96 m can meet the required criteria, namely the axial load-bearing capacity, which is greater than the maximum axial force that occurs in the Borpile configuration. In the analysis of the finite element method using the LISA FEA device, a significant stress occurs in the anchor block section with the suspension bridge cable as shown in Figure 9, this occurs because of the large tensile force on the suspension bridge cable and the ability of the anchor block to remain in a stable condition is known.

Bridge’s Overall Structural Scheme Analysis in High Seismic Risk Permafrost Regions

The mechanism of pile-soil reaction in frozen ground is not clear at present, but it is obvious that the reduction of dead weight will be beneficial to the seismic resistance of bridges. In view of the limited bridge engineering practice in high seismic risk permafrost regions, the paper addressed the structural performance of the superstructure and its effect on piles in these special regions. Four superstructures with different dead weights were compared, and bored piles were designed. Numerical simulations were implemented to investigate the refreezing time of the bored pile foundation. The concrete pile cooled rapidly in the first two days. The refreezing times of the GFRP, prestressed concrete T-girder, integrated composite girder, and MVFT girder were 15d, 37d, 39d, and 179d, respectively. The refreezing time of a pile in the same soil layer is mainly affected by the pile’s diameter, and it is significantly correlated to the square of the pile diameter. It reflects that the selection of bridge superstructures in the permafrost region is very important, which has been ignored in previous studies. The pile length and pile diameter of the lighter superstructure can be shorter and smaller to reduce the refreezing time and alleviate the thermal disturbance. Doi: 10.28991/CEJ-2022-08-07-01 Full Text: PDF

Vehicles Loads Influence on Box Girder Bridges

Abstract Box girders bridges are widely used in modern highway systems because of their efficiency and attractive appearance. Vehicles loads represent one of the mainly factors that influence the structure reliability of the box girders bridges. Calculation of bridge resistance with different stress due to vehicles loads as close as possible to the real ones constitute the premise of a correct design of the structure. The goal of this study is to realize a description regarding the behavior of box girders bridges analyzed under different vehicles loads conditions. Nowadays the finite element methods (FEM) are highly used because of their capacity to simulate and evaluate the structure efficiency of bridges. By highlighting where the maximum stress values appear we will help the constructor to avoid dangerous sections. Based on this study, we will outline future research directions, aiming to identify and improve the mechanical and strength characteristics of box girders bridges.

Improving the accuracy of insulation resistance measurements of a single arm unbalanced bridge using a parameter matching design and filtering algorithm for battery packs used in electric ships

In the DC system of electric ships, insulation drops and grounding will pose a threat to stable ship operation and personal safety. Therefore, it is necessary to monitor the insulation status of the battery pack between high voltage and ground in real time. However, traditional measurement methods have problems such as low accuracy, long measurement time, and poor reliability. In this paper, an insulation detection method based on an unbalanced bridge was proposed and the principle of insulation resistance detection was analyzed. The influence of different resistance values of insulation detection circuits on the measurement error of insulation resistance was studied by simulation analysis and experimental tests to obtain the optimal set of bridge resistance matching designs. Digital filter and Kalman filter were used to filter out noise in the voltage signal. The results show that measurement error of insulation resistance after optimization was less than 3% and drops to approximately 0.46% after processing by the Kalman filter algorithm, which proves that the insulation detection method designed in this paper has high measurement accuracy.

Seismic vulnerability of simply-supported bridges considering link-slabs in the continuous deck and pounding

Earthquake-induced poundings have been identified as a critical factor influencing bridge seismic behavior. However, most previous studies on this topic did not consider link-slabs in the continuous deck, which would influence the pounding occurrence and thus the subsequent seismic response. This paper uses a probabilistic method to evaluate the seismic vulnerability of a simply-supported bridge considering pounding and link-slabs. The damage states of girder ends due to poundings are proposed according to the cumulative damage. To analyze the seismic vulnerability of the whole bridge, both the joint probabilistic seismic demand model considering multiple engineering demand parameters and the joint damage state model considering the capability of each bridge component are established. Based on these models, the fragility curve of the whole bridge is obtained using the Monte Carlo method. The effects of gap sizes between pounding components and pier heights on the bridge seismic vulnerability are also investigated. The result reveals that the fragility of the whole bridge system is higher than that of any individual component. Ignoring the contribution of damage to each component to the whole system will lead to an overestimation of the seismic resistance of the overall bridge, which is detrimental to structural safety.

Structural configuration-radiation stability relationship in the degradation of dumbbelled POSSs

The stability of the inorganic filler, polyhedral oligomeric sisesquioxane (POSS) powders modified as dumbbelled structures is analyzed. This study was conducted by γ-irradiation at four γ-doses, when the degradation of compounds was accomplished. The radiochemical stability was investigated by nonisothermal chemiluminescence. This procedure allowed to establish the sequence of radiation resistance as a characteristic feature in their applications as hybrid filler. The activation energies required for the delaying oxidation in the minor component were calculated. The consequences of defined molecular structure are discussed in the relation of the initiation of the material ageing in the formulation they would be included. The shown stabilization property is closely related to the activation energies that is required for the oxidation. The radiochemical modification occurred in dumbbell POSSs is characterized by the resistance of internal bridges rather than the degradation strength of spatial polyhedral configuration. The degradation profiles resulting from nonisothermal CL measurements are conditioned by the structural reasons and the diffusion of fed oxygen which maintains the spontaneous ageing of polymers, where these fillers would be added. The present results are appropriate proofs for the utilization of dumbbelled POSSs as suitable stabilizers for polymer materials subjected to radiation sterilization.

Assessment of time-dependent structural resistance of RC bridges in Barak Valley, Assam, India

Reinforced concrete (RC) bridges deteriorate due to strength loss induced by aging of the structure, extreme weathering conditions and unplanned increased service loads. These load variations and aging factors can compromise structural reliability and reduce the service life for continuous satisfactory operation of service bridges in the future. Accurate prediction of bridge functionality relies on reasonable models of bridge strength and applied loads, and time-dependent reliability assessments can be used to gain a reliable understanding of bridge conditions so that appropriate solutions can be found. In this work, the reliability of bridges under harsh conditions was studied using time-variant and time-invariant reliability models in which both load and resistance are considered as time-dependent parameters. Combinations of the condition rating and time-dependent load were used to gain accurate insights into the degradation of the structural resistance of existing bridges. The results of this study showed the significant impact of aging and the influence of traffic loads on the service life of both national highway bridges and rural road service bridges. These observations could be used to devise appropriate planning strategies and plan rational decisions to ensure bridge safety in the future.

Performance Evaluation of Thermal Bridge Reduction Method for Balcony in Apartment Buildings

Most apartment buildings in South Korea use internal insulation systems to reduce building energy demand. However, thermal bridges such as balcony slabs in apartment buildings still lead to significant heat loss in winter, because the internal insulation system is not continuous in the balcony slab structure, and floor heating systems are commonly used in residential buildings. Therefore, this study investigates two types of thermal break elements, namely thermal break (TB) and thermal break-fiber glass reinforced polymer (TB-GFRP), to improve the thermal resistance of a balcony thermal bridge. To understand the effects of balcony thermal bridges with and without thermal break elements, the linear thermal transmittances of different balcony thermal bridges were analyzed using Physibel simulations. Then, the heating demand of a model apartment under varying thermal bridge conditions was evaluated using TRNSYS simulations. To understand the effect of insulation systems on heat loss through a balcony thermal bridge, apartments with internal and external insulation systems were studied. Whether the apartment was heating was also considered in the thermal transmittance analysis. Thus, the linear thermal transmittance of the thermal bridges with thermal break elements was reduced by more than 60%, and the heating energy demands were reduced by more than 8%.

Low-Noise Resistive Bridge Sensor Analog Front-End Using Chopper-Stabilized Multipath Current Feedback Instrumentation Amplifier and Automatic Offset Cancellation Loop

Resistive bridge sensors are used in many application areas to measure changes in physical parameters. To amplify the resistive changes from sensing elements with high precision, various offset contributors in the resistive bridge and amplifiers should be minimized. This study proposes a low-noise resistive bridge sensor analog front-end (AFE) using a chopper-stabilized multipath current feedback instrumentation amplifier (CFIA) and an automatic offset cancellation loop. The proposed circuit exploits a multipath chopper-stabilized architecture for obtaining low noise performance and wide bandwidth characteristics. This circuit can minimize the offsets in the bridge and the high frequency and low frequency amplifiers, while achieving high precision resistive signal acquisition. The high frequency path of the multipath amplifier uses the CFIA topology with class-AB output stage. The offset in the high frequency path is stabilized by the low frequency path amplifier with a high gain and low noise chopper amplifier. The up-modulated offset in the low frequency chopper amplifier path is reduced by the AC-coupled ripple reduction loop (RRL). An automatic offset calibration loop (AOCL) circuit was designed to calibrate the offset due to the bridge mismatch. The AOCL reduces the bridge offset using a successive approximation register (SAR)-based binary-search algorithm. The gain of the proposed circuit is adjustable from 15.56 dB to 44.14 dB. The AFE is implemented in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18~ \boldsymbol {\mu } \text{m}$ </tex-math></inline-formula> CMOS process and draws <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$123~ \boldsymbol {\mu } \text{A}$ </tex-math></inline-formula> current from a 3.3 V supply. The input referred noise and noise efficiency factor (NEF) are 14.6 nV/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\surd } $ </tex-math></inline-formula> Hz and 6.1, respectively.

VGA With Voltage Feedback, Constant Bandwidth and a High Degree of Independence Between Amplifier and Gain Controller

The following paper is devoted to an amplifier with gain control (Variable Gain Amplifier). The role of amplification and gain control is addressed separately from the very beginning, to achieve the greatest possible independence of the required parameters both for the amplifier itself (gain size, bandwidth, noise figure) and for the gain controller (energy consumption control, distortion). The core of the amplifier consists of an operational amplifier with voltage feedback (VFB) in an inverting circuit, to the feedback of which a gain regulator executed with a diode bridge is connected in parallel. The analysis of the simplified circuit model shows that it is possible to obtain a variable-gain amplifier that maintains its bandwidth. The control of the gain is continuous and only one element, the variable resistance, is sufficient for its control. This resistance can be achieved by a number of components, either by a rheostat, by the resistance of the FET transistor channel (the FET control is related to GND, which is advantageous), or by the resulting dynamic resistance of the diode bridge. Continuous control with one element preserving the bandwidth of an operational amplifier with VFB is unique and the authors are unaware of any other similar solution. If maximum gain is required, the diode bridge is disconnected and does not contribute to the resulting noise of the VGA amplifier. Because the diode bridge is connected between the output of the operational amplifier and its inverting input, and because the inverting input is current controlled, the diode bridge processes only a portion of the output voltage of the amplifier, thus preventing more noticeable distortion. The distortion is further suppressed due to the simultaneous action of four diodes in the bridge, whose characteristics are reciprocal for the signal path. The presented construction is relatively simple and can be a topic not only for other microelectronic structures, but also for applications from discrete components. The achieved parameters of the presented connection are as follows: gain change 0 to 20 dB, constant bandwidth 7 MHz, distance III. harmonics min. 30 dB at an output voltage of 0.5 V, maximum power spectral density at the output 25 ∙10-15 V2Hz-1.

Life-cycle connectivity-based maintenance strategy for bridge networks subjected to corrosion considering correlation of bridge resistances

The safety of road networks is crucial for the well-being of the society. Corrosion is a common problem facing bridges. Traditionally, the reliability analysis is performed on individual bridges and maintenance strategies are laid out based on the reliability profiles resulting from this analysis. This paper aims to investigate how to allocate maintenance resources for a group of bridges in a transportation network. Performance indicators associated with connectivity between different nodes in the bridge network are selected as the objectives of the optimization associated with this allocation. Correlation profiles associated with resistances of bridges subjected to corrosion are taken into account in the optimization process. Two approaches to determine life-cycle maintenance strategies are considered: (a) ranking the importance of bridges in terms of their contribution to connectivity; (b) performing optimization to obtain optimal maintenance strategies associated with objectives related to connectivity and maintenance cost. For each approach, the strategies associated with different O (origin)-D (destination) pairs as well as a performance indicator illustrating the overall connectivity within the bridge network are investigated. The results show that different O-D pairs may have different optimal maintenance strategies under the same maintenance budget to maximize the probability of network connectivity. The correlation of bridge resistances has a significant influence on the probability of network connectivity, and as a result, needs to be accounted for.

Dynamic Characteristics of a Double-Pylon Cable-Stayed Bridge with Steel Truss Girder and Single-Cable Plane

The dynamic characteristics are closely linked to the seismic stability and wind-resistant of the bridge. But different bridge types have different dynamic characteristics. In order to study the dynamic characteristics of a double-pylon cable-stayed bridge with a single-cable plane and steel truss girder whose main span is the longest in the world, the dynamic load test was done, and the finite element and the subspace iteration methods were used to analyze the vibration mode of the bridge. The influence of different structural parameters on the dynamic characteristics of the bridge was analyzed. The changed structural parameters are cable layout, stiffness of steel truss girder, stiffness of stayed cables, stiffness of pylons, the concentration of dead load, number and location of auxiliary piers, and structural system. The results show that the bending and torsion resistance of the double-pylon cable-stayed bridge with a single-cable plane and steel truss girder is weak. The torsional stiffness of the cable-stayed bridge with a double-cable plane is stronger than that of the cable-stayed bridge with a single-cable plane. The seismic stability and wind-resistant of the bridge can be improved by using light dead load, improving the stiffness of pylon and girder, and adding auxiliary piers scientifically. However, the change of cable stiffness has a complex influence on the dynamic characteristics of the bridge. The conclusion can offer references for the construction, maintenance, and design of the same type of bridges.

The Precise Temperature Measurement System with Compensation of Measuring Cable Influence

The article presents an active bridge system that enables the solution of a significant problem consisting in ensuring correct indications of temperature values in a wide measuring range for a Pt100 temperature sensor with properties defined by the standard (EN-60751 + A2). The presented active bridge system combines the properties of the measuring amplifier with the stabilization of the current value in the branch in which the Pt100 sensor was placed. The article focuses on the comparison of the temperature measurement in a typical resistance bridge and the measurement made in the developed active bridge, which has also become the subject of a patent. For the performed tests, in which the correctness of the temperature measurement system operation was verified, and on the basis of the obtained results, the quality of temperature measurements was compared in a wide range of changes.

Mitigation of track buckling in transition zones of steel bridges by geotextile reinforcement of the ballast layer

Track thermal buckling is one of the primary safety issues of continuously welded rail tracks. It has been shown that transition zones of open deck steel bridges are more prone to track buckling, as the thermal loads from the bridge and lower track lateral resistance in this region can destabilize the track in the lateral plane. The aim of this paper is to assess the possibility of reinforcing the ballast layer with geotextiles to mitigate the track buckling problem in the transition zones. To do so, a number of laboratory experiments are performed using one and two layers of geogrids and various depths of ballast layer. Single tie push tests are performed on the track and force-displacement curves are derived for the sleepers. It is shown that adding the geotextile layer to the ballast layer can increase its lateral resistance by up to 41%. The results are then introduced in the numerical model of a track developed in Abaqus finite element software for track buckling analysis. It is shown that adding the geogrid layer can increase the track buckling temperature by up to 11.33 °C, an increase of almost 21%, compared to that of an unreinforced track.

State-of-the-art and annual progress of bridge engineering in 2020

Bridge construction is one of the cores of traffic infrastructure construction. To better develop relevant bridge science, this paper introduces the main research progress in China and abroad in 2020 from 16 aspects. The content consists of four major categories in 16 aspects. The first part is about the bridge structure, including concrete bridge and high-performance materials, steel bridges, composite girders. The second part is about the bridge disaster prevention and mitigation, including bridge seismic resistance, wind resistance of bridge, train-bridge coupling vibration research, bridge hydrodynamics, the durability of the concrete bridges, fatigue of steel bridge, temperature field and temperature effect of bridge; The third part is about the bridge analyses, including numerical simulation of bridge structure, box girder and cable-stayed bridge analysis theories. The last part is concerning the bridge emerging technologies, including bridge informatization and intelligent bridge, the technology in bridge structure test, bridge assessment and reinforcement, prefabricated concrete bridge structure.