Resistance Bridge Research Articles

An approach to the selection of target reliability index of Cable-stayed bridge's main girder based on optimal structural parameter ratio from cost-benefit analysis

A reasonable value of target reliability index is vital for long-span cable-stayed bridges. However, there are few methods to determine the reasonable target reliability index for long-span cable-stayed bridges. In this work, an original approach to solve this problem is developed. In this approach, a concept of optimal structural parameter ratio is presented from the perspective of cost-benefit. Determination of structural target reliability index should meet the requirements of safety and economy. This approach includes two parts. First, based on the statistical parameters of load and resistance of the cable-stayed bridge’s main girder and the most unfavourable bending moments obtained by finite element analysis, the structural reliability index was calculated by the JC method. Second, the reliability indexes with different structural parameter ratios were calculated, and the relational expression between the reliability index and structural parameter ratio was obtained by data fitting. Then the optimal structural parameter ratio was calculated from the perspective of cost-benefit. Finally, by substituting the optimal structural parameter ratio into the relational expression between the reliability index and structural parameter ratio, the optimal reliability index can be obtained. The optimal reliability index corresponding to the optimal structural parameter ratio can be regarded as the target reliability index.

Wind characteristics of a bridge site and wind-resistance key technology in complex mountains

The random variability of mountainous area terrain and the mutual aerodynamic interference between different terrain features make the wind field in bridge sites extremely complicated, which results in considerable challenges to the wind resistance of large-span bridges. In this study, the wind characteristics of a bridge site in a typical mountainous area were determined by field measurements. The design reference wind speed was derived from historical statistics, numerical wind tunnel simulations, field measurements, etc. According to the wind characteristics of the mountainous area, the flutter performances of a bridge under non-uniform and non-stationary inflow were analyzed, and the effects of common aerodynamic measures on flutter stability were analyzed at large angles of attack. The results showed that the integrated wind speed standard in complex mountainous terrains can derived in various ways, which is significantly different from a conventional plain area. The non-uniform, large angle of attack, and non-stationary inflow has a significant impact on the flutter performance of a bridge.

Correction of nonlinearities in series structure-based resistance thermometry readouts.

Series structure-based resistance thermometry readouts offer several advantages for multi-point temperature measurements. However, because of the diversity of nonlinear error sources and differences among channels in such readouts, existing nonlinear error correction methods are ineffective. In view of this situation, a nonlinear error correction method based on error source analysis is proposed. The proposed method first determines the impacts of error sources by analyzing the circuit architecture. The contributions of the common-mode rejection ratio and the mismatch between positive and opposite exciting currents are then eliminated using resistance bridge calibrators. Finally, the residuals are fitted to various polynomial functions. The results of experiments show that correction based on the proposed method results in a maximum nonlinear readout error of 1.87 × 10-5, compared with 4.01 × 10-5 using the classical method. Thus, the proposed method of nonlinear error correction is effective for series structure-based resistance thermometry readout.

Probabilistic seismic vulnerability and loss assessment of a seismic resistance bridge system with post-tensioning precast segmental ultra-high performance concrete bridge columns

Precast segmental ultra-high performance concrete (UHPC) columns with post-tensioned (PT) tendons can effectively protect the compression toe from damage and enhance energy dissipation (ED) capacity of column compared to conventional segmental concrete columns. Extensive experiments and numerical studies have been carried out to explore the cyclic response of segmental UHPC columns in the existing literature; however, the effect of such novel columns on the seismic safety of bridge structures has not been thoroughly understood. This study aims to numerically assess the seismic fragility and seismic life-cycle loss of bridge structures supported by the precast segmental UHPC columns. For comparison, the seismic performance of the same bridge with monolithic reinforced concrete (RC) piers are also evaluated. Here, three-dimensional (3D) numerical models are generated to simulate these two bridge types. A performance-based earthquake engineering (PBEE) framework is used to evaluate and compare their seismic performance. The segmental UHPC column model is validated with the previous experimental studies. The validated model is combined into the whole bridge. Numerical results showed that the precast segmental UHPC bridge experiences similar peak acceleration and larger peak displacement in comparison to the monolithic RC bridge. The segmental UHPC bridge pier experiencing lower residual deformation can effectively reduce the damage probability and life-cycle loss of a bridge compared to the conventional monolithic RC pier. Under the design event (2475-year return period) and maximum considered event (5000-year return period), the expected losses of the segmental bridge in the lifetime were approximate 92% and 84% of that of the monolithic bridge, respectively. The segmental UHPC bridge has a noticeable economic benefit when such a bridge is constructed in regions of high seismicity.

A Resistance Bridge Based on a Cryogenic Current Comparator Achieving Sub-10⁻⁹ Measurement Uncertainties

A new resistance bridge has been built at the Laboratoire national de m\'etrologie et d'essais (LNE) to improve the ohm realization in the $Syst\`eme International$ (SI) of units from the quantum Hall effect. We describe the instrument, the performance of which relies on two synchronized and noise-filtered current sources, an accurate and stable current divider and a cryogenic current comparator (CCC) having a low noise of $\mathrm{80~pA.t/Hz^{1/2}}$. The uncertainty budget for the measurement of the 100 $\Omega/(R_\mathrm{K}/2)$ ratio, where $R_\mathrm{K}$ is the von Klitzing constant, amounts to a few parts in $10^{10}$ only.

A stochastic process model for resistance deterioration of aging bridges

The serviceability and safety level of bridges often deteriorates due to the environmental or operational conditions. A stochastic deterioration model is of essential importance for describing the time-variation of bridge performance (e.g., stiffness and strength), and for use in the estimate of bridge reliability under a probabilistic framework. In this context, the Gamma process has been widely used to model the resistance deterioration of aging bridges, yet suffers from the deficiency that the statistical characteristics of the process (namely mean value, variance and autocorrelation) are not mutually independent. This paper presents a new stochastic model for bridge resistance deterioration. As a modified version of the Gamma process-based one, the proposed model includes a new parameter that can release the dependence of the process autocorrelation and variance on the mean value. The impact of the new deterioration model on the time-dependent reliability of aging bridges is studied.

Effects of Redecking from RC Deck to Orthotropic Steel Deck on Seismic Resistance of Elevated Girder Bridges

Due to the rapid deterioration of reinforced concrete decks (RCD) under the combined effects of deck overloads, weather and salts, the orthotropic steel decks (OSD) that are light weight and require less construction time are being used increasingly to replace old deteriorated decks. In this paper, a numerical investigation was carried out to study the effect of reduction in superstructure weight on the earthquake resistance of elevated girder bridges when an existing RCD was being replaced by an OSD. Firstly, an eigenvalue analysis was carried out to study the effect of superstructure weight on the global vibrational characteristics of the bridge and then, the evaluation of seismic performances of both the bridge models were carried out by performing a series of non-linear dynamic analysis with input earthquake data in the longitudinal and transverse directions separately and simultaneously. The behavior of the pier bases was examined by monitoring the displacement responses and plastic strains during earthquakes. It was found that the bridge model with OSD exhibits a shorter period of vibrations and a huge improvement in the seismic performance of the bridge was observed by replacing the existing RCD with the OSD. The analysis results could be useful in finding a solution for seismic retrofit of existing girder bridges.

Metrological Self-Monitoring Method of Piezoresistive Pressure Sensors

This study considers existing metrological self-monitoring methods of sensors used in technological industries for measuring temperature and pressure. Furthermore, metrological self-monitoring methods of piezoresistive pressure sensors are analyzed. Then, a new metrological self-monitoring method is proposed on the basis of the supply voltage on the measuring diagonal of the bridge. The temperature of the piezoresistive bridge is determined using a semiconductor thermistor installed near the bridge. In this manner, the change in bridge resistance can be adjusted depending on the change in bridge temperature. With aging and exposure to external conditions, a change in the overall resistance of the piezoresistive bridge can be used to judge the error of the sensor. An experimental model of a piezoresistive pressure sensor is then developed. In the sample, the failure of the piezoresistive bridge is simulated by connecting an additional resistor in parallel with one of the arms of the bridge. The experimental studies show that the proposed technical method can assess the effect of changes in the total bridge resistance on the error of the sensor.

Impact of the diaphragm structure on the linearity and temperature sensitivity of low-pressure piezo-resistive MEMS pressure sensors

This paper presents result of a detailed simulation study aimed at optimizing the different diaphragm structures of silicon micro machined MEMS pressure sensor for operation and measurement of the low-pressure ranges(600mbar). We first show that the conventional arrangement of the Wheatstone bridge resistors realized using the “Flat diaphragms” give rise to large temperature dependence of the offset voltage which affects the sensitivity and linearity of the pressure sensors during operation in the temperatures ranging from-40°Cto+80°C, thus making the temperature compensation of the sensor output voltage rather tedious and impossible in certain instances. We further demonstrate that, this issue can be circumvented and excellent linearity with minimum dependence of the offset-voltage, sensitivity and linearity can be achieved by using “sculptured diaphragms” with optimized diaphragm dimensions. Towards this goal, in this paper, we present a set of simulation studies involving optimization of the pressure sensor diaphragm dimensions and structures with single and multiple boss structures to achieve better sensitivity, linearity, and at the same time minimize temperature drift, and to achieve better repeatability.

Seismic performance evaluation of existing light poles on elevated highway bridges

Damages on light poles and utility poles mounted on elevated highway or railway bridges were observed in the past several large earthquakes. They were mostly due to excessive pole deformation, bending failure caused by yielding, buckling of the pole and falling of the mast. The damages did not only affect functionalities but also impeded the traffic and further complicated post-earthquake recovery of affected area. While seismic resistance of elevated highway bridges has been evaluated and upgraded in the seismic codes, most light and utility poles were designed for wind loading and not for earthquake, so their seismic performances were rarely evaluated. In this research, seismic performance of a typical light pole mounted on elevated highway bridges is investigated. The study includes experimental modal analysis of existing light pole, finite element simulation, and case study of the light pole on existing elevated highway bridge. The results of finite element simulations show that response amplification occurs when the bridge’s natural frequency is within a close range of the light pole’s fundamental frequency. Due to inherently low structural damping, the light pole experiences large amplification at the resonance, and this leads to bending failure when the maximum stress exceeds the yield stress limit.

A Power-Efficient Bridge Readout Circuit for Implantable, Wearable, and IoT Applications.

A power-efficient bridge-to-digital sensing interface is proposed, which also offers immunity against power supply noise. The interface utilizes duty-cycling to reduce the static power consumption of resistive bridge sensors, which are commonly used in implantable, wearable, and internet of things (IoT) applications, such as intracranial pressure (ICP) sensing and blood pressure (BP) monitoring. The proposed interface uses a revised version of the pseudo-pseudo differential (PPD) topology with the ping-pong technique to reduce the complexity of traditional fully-differential counterparts. A proof-of-concept prototype has been fabricated in 0.35-μm CMOS and occupies an active area of 0.48 mm2. It achieves 9.13 effective number of bits (ENOB) at 3.72 kHz sampling rate and improvement of more than 50 dB in the power supply rejection ratio (PSRR) by employing the ping-pong technique. It reduces the power consumption of a 5-kΩ Wheatstone bridge by 99.6% compared to a traditional interface, down to 2.53 μw at 1.8 V supply. The functionality of the system has also been demonstrated in an experimental setup in conjunction with an embedded resistive bridge pressure sensor.

A Packaged 0.01–26-GHz Single-Chip SiGe Reflectometer for Two-Port Vector Network Analyzers

This article presents a packaged SiGe BiCMOS reflectometer for 0.01–26-GHz two-port vector network analyzers (VNAs). The reflectometer chip is composed of a resistive bridge coupler and two wideband heterodyne receivers for coherent magnitude and phase detection. In addition, a high-linearity receiver channel is designed to accommodate ~20 dBm of RF input power to the reflectometer. External sources are used to provide stimulus over the entire bandwidth, and a high-linearity shunt 50- $\Omega $ switch is placed at the input of each reflectometer chip to provide a matched condition for better measurement accuracy. The measured dynamic range (DR) of the heterodyne receiver is 129±3 dB at 0.01–26 GHz at an IF resolution bandwidth (RBW) of 10 Hz. The reflectometer chip is packaged on a low-cost printed circuit board (PCB) and connectorized for repeatable measurements. Several passive and active device-under-test (DUTs), such as filters and amplifiers, are measured in single- and dual-port complex $S$ -parameter setup at 0.01–26 GHz. The single-chip reflectometer results in excellent agreement with commercially available test equipment and with minimal magnitude and phase difference. Several definitions (mean deviation and error vector) are used to quantify the measurement accuracy. A measured $S_{21}$ of −80 dB is obtained using high-rejection filters. An in-depth DR analysis of possible limiting factors in the measurement setup is also presented. This article shows that silicon-based highly integrated reflectometers can be used in low-cost VNAs with excellent DR and accuracy.

Synthesis and fabrication of self-sustainable triboelectric energy case for powering smart electronic devices

In recent times, Triboelectric Nanogenerators (TENG) have attained the focus of the scientific community due to its potential as a medium to harvest mechanical energy from the ambient environment. Human motion has been attributed as a source of mechanical energy to drive electronic devices and sensors through TENG. Based on the principles of single electrode TENG, we have developed a Triboelectricity based Stepping and Tapping Energy Case (TESTEC) which magnifies the prospect to power touch electronic devices by utilizing finger tapping and stepping motion. This novel case was constructed with two single electrode TENG operating through the triboelectric mechanism between human skin and Polyethylene terephthalate (PET) film on the front part and Nitrile Butadiene Rubber (NBR) and PET film on the back part. This cost effective device was further tested by attaching with a cell phone at variable load frequency, airgap and finger combinations where the output response increased with the increased frequencies (60–240 BPM) and air gap (1 cm–5 cm). Maximum output voltages of 14.8 V and 50.8 V were obtained for the front and back parts, respectively. Besides, maximum output powers were observed to be 3.78 W/m 2 at 0.46 MΩ and 6.21 W/m 2 at 1.02 MΩ, respectively. Also, the device was tested by integrating with conventional electronic components including capacitors, bridge rectifiers and 15 LEDs. Based on the results, a electrical circuit has been proposed to power touch cell phones. The device was further modified using Silver (Ag) nanoparticles in the front part. The modified TESTEC provided higher output response compared to the primary TESTEC. The TESTEC can be a self sustainable way to power touch electronic devices which can reudce the necessity to charge electronics devices in the conventional way. In this work, A cost-effective and self-sustainable energy case containing two single electrodes triboelectric nanogenerators has been designed and fabricated to power smart electronic devices by utilizing the mechanical energy generated while using the device or carrying the device. The device was thoroughly tested with real life parameters such as airgaps, load frequencies and finger combinations. Also, it was tested with bridge rectifiers, resistors, capacitors and LEDs to verify its compatibility with conventional electronic components and ability to power smart electronic devices. • PET and NBR based single electrode Triboelectric Nanogenerators have been developed. • Self-sustainable energy case to power smart electronics through tapping and stepping motion. • The output of the energy case was tested for variable load frequency, airgap and finger combination. • The maximum output voltage was recorded to be ~51 for the back part. • The device was further modified and tested using silver nanoparticles.

Simulation of the In Situ Spatially Varying Ground Motions and Nonlinear Seismic Response Analysis of the Cable-Stayed Bridge

To study the nonlinear seismic behavior and seismic resistance of the long-span cable-stayed bridges subjected to earthquakes, the multidimensional and multisupported artificial ground motions are synthesized first based on the in situ site conditions of the bridge considering the coherent and traveling wave effects. Then, considering the material nonlinearity of the cable-stayed bridge, a 3D finite element model is established based on the OpenSees platform, and the nonlinear seismic response analysis of the bridge is carried out under the synthetic artificial ground motions. The nonlinear seismic response of main bridge components such as piers, towers, bearings, and cables is analyzed, and key conclusions and observations are drawn.

Realization of 5he2 with graphene quantum Hall resistance array

We report on the realization of 10 quantum Hall devices in series fabricated using epitaxial graphene on silicon carbide. Precision measurements with a resistance bridge indicate that the quantized Hall resistance across an array at a filling factor of 2 is equivalent to 5he2 within the measurement uncertainty of approximately 4 × 10−8. A quantum Hall phase diagram for the array shows that a metrological quantization of 5he2 can be achieved at the magnetic field of 6 T and a temperature of 4 K. This experiment demonstrates the possibility of timely unchangeable resistance reference in various ranges in relaxed experimental conditions.

Resistance Assessment of Service-Proven Aging Bridges Incorporating Deterioration-Load Dependency

The historical vehicles passed through an existing bridge can be regarded as proof-loading tests for the bridge, and, as a result, are evident of the bridge’s performance. Such service history information has been utilized to update the estimate of bridge resistance in previous studies with the help of a Bayesian method, where the resistance deterioration process was assumed to be independent of the vehicle load process. This assumption is, however, untenable in many cases where the deterioration stochastic process is statistically correlated with the load process (e.g., a greater load intensity may affect/accelerate the deterioration of structural resistance and the accumulation of structural fragility). With this regard, this paper investigates the effect of correlation between the resistance deterioration and load processes on updating the resistance of aging bridges with prior service load information. The copula function is employed to model the joint distribution of the correlated deterioration and load processes, with which the correlation is measured by the Kendall’s tau. A new method is developed in this paper to assess the updated bridge resistance taking into consideration the deterioration-load dependency in an explicit form. The applicability of the proposed method is illustrated using an existing RC beam bridge. The sensitivity analysis is conducted to examine how the deterioration-load dependency affects the updated resistance of service-proven aging bridges.

Performance‐Based Seismic Fragility and Residual Seismic Resistance Study of a Long‐Span Suspension Bridge

Earthquakes can cause serious damage to traffic infrastructure and even induce the collapse of bridges, which is even worse. At the same time, earthquakes are key factors to the overall service capacity of the traffic network. Therefore, mastering the failure mechanism and evaluating accurate residual seismic resistance of a bridge under earthquakes are of great significance to the rapid recovery of traffic network function. For this reason, a performance‐based methodology for the evaluation of the residual seismic resistance of a suspension bridge is proposed. In this paper, we provide the fragility curves of the key sections of the pier by incremental dynamic analysis (IDA), mathematical statistical analysis, and the damage law and obtained the failure state of the structure and the overall seismic capacity residual ratio and the stage seismic capacity residual ratio of the structure. Then, based on the research results of IDA, the reserve seismic capacity is analyzed as well. The research results explore a new method to accurately estimate the residual seismic capacity for resilience assessment.

Reliability Assessment and Residual Life Estimation of Concrete Girder Bridges Strengthened by Carbon Fiber during the Service Stage

In recent decades, carbon fiber reinforced plastics (CFRP) have been widely used to repair and maintain concrete structures around the world. Since the parameter uncertainties of load and resistance are very important for the reliability assessment of RC bridge strengthened by CFRP, this paper presents a method to estimate the reliability and residual life of RC bridges strengthened by CFRP. In the proposed method, uncertainties of material properties, geometry parameters, load model, and time‐dependent resistance model are taken into account. The proposed method combines the inverse reliability method and the calculation method of load and resistance of RC bridge strengthened by CFRP and is illustrated by an example RC bridge strengthened by CFRP during the service stage. The results indicate that the proposed approach can provide valid information regarding parameter uncertainties for the reliability of RC bridge strengthened by CFRP during the service stage. Additionally, the effects of parameter uncertainty of the reliability and residual life of RC bridge strengthened by CFRP during the service stage are analyzed and discussed. The proposed method is more robust and reliable than the traditional method.

A 2.18-pJ/conversion, 1656-μm² Temperature Sensor With a 0.61-pJ·K² FoM and 52-pW Stand-By Power

This letter describes a miniature, ultra low power, all-dynamic temperature sensor based on a duty-cycled resistive transducer bridge and a 9-bit asynchronous SAR ADC in 65-nm CMOS. It features a novel floating bridge technique and automatic power gating to achieve the lowest reported power consumption. It consumes 2.18 pJ per conversion and has an RMS resolution of 0.53 K, leading to an FoM of 0.61 pJ·K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . A standby power of 52 pW allows a high power-efficiency, even at low sample rates. It occupies 36×46 μm of chip area and has a sensing range from -20 °C to 120 °C.

Method of metrological self-checking of a strain gauge pressure sensor

Existing methods of metrological self-monitoring of measuring sensors for temperature and pressure of technological industries are considered. The analysis of methods of metrological self-checking of strain gauge pressure sensors is carried out. Method is proposed based on measuring the supply voltage and voltage on the measuring diagonal of the bridge. The temperature of the strain gauge bridge is determined using a semiconductor thermistor installed near the bridge. This allows you to adjust the measured value of the total resistance of the bridge from the temperature of the bridge. With aging and exposure to external conditions, a change in the overall resistance of the bridge can be used to judge the error of the sensor. An experimental sample of the sensor was made. The failure of the strain gage bridge is simulated by parallel connection of an additional resistor to one of the shoulders of the bridge. Experimental studies have shown that modern technical means make it possible to assess the effect of changes in the total bridge resistance on the sensor error.