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Cable tension is an important parameter for monitoring the health of cable-supported bridges. Live loads cause periodic changes in cable tension. Given the lack of test methods for cyclic cable tension, the resonance-enhanced magnetoelastic (REME) effect was adopted for cable tension monitoring. Combining the magnetoelastic effect and the electromagnetic induction theory, the relationship between cable tension and the REME sensor’s induced voltage was deduced. This relationship indicated the feasibility of using the REME effect to monitor cable tension. According to the variation law of cable tension, a cyclic cable tension monitoring experiment was carried out. Based on the experimental results, a cyclic cable tension monitoring method via the REME effect was proposed. When the tension variation amplitude was less than 100% of the design tension, the monitoring error was less than 5%. The proposed method could be used to accurately monitor the large-amplitude cyclic cable tension. [ABSTRACT FROM AUTHOR]

Shear properties between ultra-high performance concrete (UHPC) and normal strength concrete (NSC) are critical factors influencing the efficiency of UHPC strengthening. However, existing studies primarily focus on the properties of the toughness-improved UHPC-NSC interface under static load, the accumulative fatigue damage induced degradation of shear properties remains inadequately investigated. To address this, the damage evolution and residual performance of the toughness-improved UHPC-NSC interface were explored through fatigue push-off tests. Then, the calculation method for the residual shear resistance of UHPC-NSC interface was established. Results indicate that the lower limit of fatigue stress exhibited a limited effect on the damage evolution of the UHPC-NSC interface. The UHPC-NSC interface specimens experienced two phases of damage evolution under high-stress fatigue loading: crack formation and crack propagation. In phase I, a tiny crack was formed in the center of the interface. Phase II was characterized by slow propagation of the interfacial crack, and this phase exhibited stable fatigue damage evolution comprising more than 80% of the fatigue life. The interface reinforcement ratio and lower limit of fatigue stress exhibited insignificant effects on the secant modulus (Dn). Dn =0.50 and Dn =0.85 can be used to characterize the damage initiation and endurance limit of the UHPC-NSC interface under high-stress fatigue loading. Additionally, the residual shear performance of the UHPC-NSC interface decreased significantly with the opening of the fatigue crack tip, and the residual strength can be predicted based on the degradation model of material property. • Fatigue push-off tests of the toughness-improved UHPC-NC interface were carried out. • The evolution law of interfacial fatigue damage was revealed using the secant modulus. • Residual shear performance and calculation method of the toughness-improved UHPC-NC interface was investigated. [ABSTRACT FROM AUTHOR]

• The magnetic parameter, concrete strain, reinforcement strain and deflection exhibit synchronous growth with high correlation. • The Y and B C curves in the mid-span of the beam effectively divide the beam failure mode into three loading stages. • The quantification of the relationship between mechanical indexes and SMFL intensity reveals linear associations for Y-B C and ε-B C. • A correlation between SMFL intensity, reinforcement stress and beam flexural strength is established. This paper proposes a novel approach for monitoring the bearing capacity of RC beams using the spontaneous magnetic flux leakage (SMFL) effect. Three decommissioned reinforced concrete hollow slab (RCHS) beams underwent bending loading failure experiments to collect data on crack formation, deflection Y , concrete strain ε , steel bar strain ε and SMFL intensity B x/y/z. The mechanical properties of concrete outside the structure and the magnetic properties of steel bars inside the structure during loading are investigated. The force-magnetic coupling effect of HRB400 steel bars is characterized. The SMFL parameter B C closely correlates with Y and ε variations in loading process, the quantitative relationship models between mechanical and magnetic parameters of the beam structures are established. A theoretical model predicted the ultimate bending capacity of RCHS beams. The relationship between beam bending capacity and SMFL intensity is clarified. [ABSTRACT FROM AUTHOR]

Long-span cable-stayed bridge (LCB) with unequal-height towers is being designed and constructed in metro lines due to its better adaptability to environment and terrain conditions compared to traditional cable-stayed bridge with equal-height towers. However, the asymmetrical arrangement of towers leads to obvious nonuniformity of the structural stiffness along the longitudinal direction, which intensifies the wheel-rail coupled vibration behaviour, and affects the running safety of operating trains and ride comfort. Therefore, train-bridge dynamic behaviour of long-span asymmetrical-stiffness cable-stayed bridge is deeply investigated in this work. Primarily, considering the comprehensive index of frequency difference and modal assurance criterion (MAC), a nonlinear model updating technique (NMUT) based on penalty function theory is proposed, which can be used to optimize the bridge numerical model. Secondly, on the basis of the train-track-bridge dynamic interaction theory (TDIT), a train-track-bridge coupled dynamic model (TCDM) is established. Finally, a LCB with unequal-height towers is applied as a case to illustrate the influence of asymmetrical stiffness on the train-track-bridge dynamic characteristics. Results show that the proposed NMUT is efficacious and practical. For the LCB with unequal-height towers, a significant difference between the bridge vibration at low tower location and that at high tower location appears. The vertical displacement difference of the main beam on both sides of the bridge increases with the distance from the observation point to the bridge tower increasing. The variation of acceleration difference on both sides of the bridge is influenced by the speed of the train and the position of the observation point simultaneously. In general, vibrations of the main beam at low tower location are larger than those at high tower location. [ABSTRACT FROM AUTHOR]

The Real Time BeiDou Navigation Satellite System (BDS) has evolved into a reliable technique to detect both the three-dimensional magnitudes and frequencies of displacement of structures. BDS technology is exactly what monitoring needs for the bridge deformation. Also, the oscillations and damage severity can be evaluated and classified according to the dynamic bridge characteristics obtained from BDS. The intention of the present work is to demonstrate the use of BDS to provide data for the assessment of existing structures safety. The raw data were collected continuously over a period of 24 h at a minimum rate of 1 Hz. The collected data include traffic flow (for load estimation) and environment factors (such as wind speed, wind direction, relative humidity and temperature). The vibration frequencies are also measured from BDS data and compared with those given in the literature. The results of all the experiments proved to be very encouraging, and showed that the performance of BDS as it has developed in recent years, and that the BDS is reliably in quantifying both environmental induced bridge vibrations and high-frequency transient motion caused by vehicle loading, in particular changes of mass associated with changes in traffic loading are observed, providing the ability for verification and/or improvement of bridge design and modelling. [ABSTRACT FROM AUTHOR]

The roof sheathing panels of low-rise buildings are generally prone to serious damage during strong winds. This study develops Monte-Carlo Simulation (MCS)-based first- and multi-order methods to estimate the wind damage of roof sheathing panels under various mean recurrence intervals (MRIs) with consideration of directionality effects. Numerical examples are used to illustrate the effectiveness of proposed methods and study influences of both correlations of directional yearly maximum wind speeds and multiple extreme response coefficients in each direction on wind damage. Results showed the proposed first-order method can present the same estimation accuracy and higher estimation efficiency compared with the existing method. The difference between wind damages with smaller MRIs by the first- and multi-order methods is significant only when the wind speed and response coefficient in the dominant direction have large and small variations, respectively. It is pointed out consideration of the correlation associated with wind speeds results in more significant differences (>19%) in the estimation of damage ratios with various MRIs as compared with the differences (<7%) by the correlation associated with response coefficients. Correlation associated with wind speeds reduces the wind damages with lower MRIs (e.g., 10 years) but increases wind damages with larger MRIs (e.g., 50 years). • A more efficient first-order Monte-Carlo simulation method to estimate wind damage of roof sheathing panels is proposed. • A novel multi-order Monte-Carlo simulation method to estimate wind damage of roof sheathing panels is developed. • The performance of the first-order method and comparison of the first- and multi-order methods are addressed. • Influences of both correlations of directional wind speeds and response coefficients on wind damage are addressed. • Some novel conclusions have been given. [ABSTRACT FROM AUTHOR]

• The stress state of bridge rebars is an effective indicator of the safety state of the bridge engineering. • The weak magnetic detection method is introduced into the stress classification evaluation of the rebar. • This study has preliminarily realized the quantitative measurement of the working stress of the rebar. • The modified dimensionless parameter KRMS ecNj is defined and used to evaluate the stress state of rebars. In order to explore an evaluation method for nondestructive testing of the rebar stress, the weak magnetic field test of the rebar stress was carried out in this paper. The evolution characteristics of the magnetic induction component By along the length direction of the rebar under tensile load were analyzed. The value of the root mean square gradient of the axial magnetic induction intensity KRMS e was introduced. The law of linear decline of characteristic parameters with the stress in the elastic stage was revealed. The relationship between the feature parameters and the lift-off value of the sensor was further analyzed, and the lifting effect of the feature parameters was modified. Based on the correction of the lifting effect, the influence of the initial magnetization on the weak magnetic detection of stress was removed through the simulation test. The naive Bayesian classification algorithm is introduced into the stress classification evaluation. The statistical analysis of the relationship between the modified characteristic parameter KRMS ecN and stress is carried out. A stress classification evaluation model is established based on the maximum of posteriori probability. The model can classify the rebar stress in specific ranges with high accuracy. This study provides a new evaluation method for nondestructive testing of the rebar stress state. [ABSTRACT FROM AUTHOR]

For a reinforced concrete beam subjected to fatigue loads, the structural stiffness and bearing capacity will gradually undergo irreversible degeneration, leading to damage. Moreover, there is an inherent relationship between the stiffness and bearing capacity degradation and fatigue damage. In this study, a series of fatigue tests are performed to examine the degradation law of the stiffness and bearing capacity. The results pertaining to the stiffness show that the stiffness degradation of a reinforced concrete beam exhibits a very clear monotonic decreasing "S" curve, i.e., the stiffness of the beam decreases significantly at the start of the fatigue loading, it undergoes a linear decline phase in the middle for a long loading period, and before the failure, the bearing capacity decreases drastically again. The relationship between the residual stiffness and residual bearing capacity is determined based on the assumption that the residual stiffness and residual bearing capacity depend on the same damage state, and then, the bearing capacity degradation model of the reinforced concrete beam is established based on the fatigue stiffness. Through the established model and under the premise of the known residual stiffness degradation law, the degradation law of the bearing capacity is determined by using at least one residual bearing capacity test data, for which the parameters of the stiffness degradation function are considered as material constants. The results of the bearing capacity show that the bearing capacity degradation of the reinforced concrete beam also exhibits a very clear monotonic decreasing "S" curve, which is consistent with the stiffness degradation process and in good agreement with the experiment. In this study, the stiffness and bearing capacity degradation expressions are used to quantitatively describe their occurrence in reinforced concrete beams. In particular, the expression of the bearing capacity degradation can mitigate numerous destructive tests and save cost. The stiffness and bearing capacity degradation expressions for a reinforced concrete beam can be used to predict the deformation and bearing capacity of a structure during the service process and determine the structural fatigue damage and degree of degradation. [ABSTRACT FROM AUTHOR]

Bridges are an essential part of the ground transportation system. Health monitoring is fundamentally important for the safety and service life of bridges. A large amount of structural information is obtained from various sensors using sensing technology, and the data processing has become a challenging issue. To improve the prediction accuracy of bridge structure deformation based on data mining and to accurately evaluate the time-varying characteristics of bridge structure performance evolution, this paper proposes a new method for bridge structure deformation prediction, which integrates the Kalman filter, autoregressive integrated moving average model (ARIMA), and generalized autoregressive conditional heteroskedasticity (GARCH). Firstly, the raw deformation data is directly pre-processed using the Kalman filter to reduce the noise. After that, the linear recursive ARIMA model is established to analyze and predict the structure deformation. Finally, the nonlinear recursive GARCH model is introduced to further improve the accuracy of the prediction. Simulation results based on measured sensor data from the Global Navigation Satellite System (GNSS) deformation monitoring system demonstrated that: (1) the Kalman filter is capable of denoising the bridge deformation monitoring data; (2) the prediction accuracy of the proposed Kalman-ARIMA-GARCH model is satisfactory, where the mean absolute error increases only from 3.402 mm to 5.847 mm with the increment of the prediction step; and (3) in comparision to the Kalman-ARIMA model, the Kalman-ARIMA-GARCH model results in superior prediction accuracy as it includes partial nonlinear characteristics (heteroscedasticity); the mean absolute error of five-step prediction using the proposed model is improved by 10.12%. This paper provides a new way for structural behavior prediction based on data processing, which can lay a foundation for the early warning of bridge health monitoring system based on sensor data using sensing technology. [ABSTRACT FROM AUTHOR]

• The B T/N intensities in different directions on the rebar surface have various force-magnetic coupling characteristics. • The effect of stress strength and initial magnetization intensity on the variation pattern of rebar SMLF intensity is different. • Initial magnetization induces an abrupt change in B T/N curves at the yield strength, effectively distinguishing rebars' elastic and plastic stages. • The initial magnetization state enhances the sensitivity of SMLF intensity to characterize stress variation in rebars. • The tangential SMLF parameter D T has a higher sensitivity to the stress variation in rebars. To investigate the effect of the initial magnetization state on the force-magnetic coupling effect of rebars, magnetic field magnetization experiments and axial tensile experiments of rebars were conducted. The tangential/normal components of spontaneous magnetic leakage field (SMLF) intensity B T/N were collected. The "SMLF intensity distribution parameters" D T/N were introduced to quantify the degree of stress-induced changes in the distribution of the B N/T curves on the rebar surface. The results show that both the stress state and the initial magnetization state affect the variation pattern of SMLF intensity of rebars, and B T/N have different characteristics of the force-magnetic coupling effect. With the increase of tensile stress, B T curves shift downward and B N curves rotate counterclockwise. With the increase of magnetization, the convexity degree of B T curves and the variation range of B N curves enlarge. And both B T/N values change abruptly at the yield strength point. The initial magnetization state drives the force-magnetic coupling effects in the elastic and plastic stages to exhibit differences. The σ-D T/N curves in the elastic stage are linearly monotonically decreasing, where the σ-D T fitted straight line has a large downward slope. D T is more sensitive to stress changes. The D T/N variations in the plastic stage can effectively characterize the stable development region of plastic deformation. The modified J-A magnetomechanical model reveals the contribution of the initial magnetization state to the characterization of the force-magnetic coupling effect. The morphological analysis of the rebar microstructure clarifies the physical reasons for the SMLF variation under different stress states. This research provides a new idea for the non-destructive detection of the rebar stress state. [ABSTRACT FROM AUTHOR]

In conventional buffeting analyses for long-span bridges, the aerodynamic admittance functions (AAF) with respect to the longitudinal (u-) and vertical (w-) turbulence components are usually assumed to be equivalent. This assumption could cause unpredictable errors due to complicated turbulence-structure interactions. This study proposes an experimental method to determine the u- and w- AAFs in the framework of three-dimensional buffeting theory. First, passive wind tunnel test is conducted to measure necessary aerodynamic parameters. Next, the turbulence characterized only by u-velocity fluctuations is generated in a multi-fan active-controlled wind tunnel to reproduce the u-velocity component in the passive wind tunnel test. The aim is to identify the u-AAF separately. Finally, the w-AAF is evaluated by combining the parameters measured in the active and passive wind tunnel tests. For a streamlined bridge girder, results show significant discrepancies between the u-AAF and w-AAF. The derivation degrees depend on the frequency and the angle of attack (AoA). This indicates the inaccuracy of the conventionally invoked assumption. In detail, the w-AAF is higher than the u-AAF at low frequencies, whereas the relationship reverses at higher frequencies. The proposed method is also applicable for other bluff-body structures, it is useful for improving the accuracy of buffeting analyses. [Display omitted] • A theoretical framework is derived to determine the AAFs with respect to u- and w-turbulence components. • The three-dimensional effects of turbulence are considered in the theoretical framework. • The theoretical framework is realized by combining active- and passive-wind tunnel tests. • The u-component in the active-wind tunnel test is adjusted to reproduce that in the passive wind tunnel test. • Comparisons between the u- and w-AAFs of a bridge deck directly indicate the inaccuracy of the equivalent-AAF assumption. [ABSTRACT FROM AUTHOR]

• The self-magnetic flux leakage effect eliminates the need for any processing on the RC beam. • The whole process failure test of RC beams under four-point bending loading was carried out. • The RC beams' stress and crack development over the entire loading process were analyzed. • A dimensionless parameter A σ was defined to quantitatively calculate the reinforcement stress of RC beams. The self-magnetic flux leakage (SMFL) effect has been widely studied because it not only can identify early damage evaluation of ferromagnetic materials but is highly sensitive to the stress state. To promote the application of the SMFL effect in the health detection of reinforced concrete (RC) bridge, the whole process failure experiment of the RC beams under four-point bending loading was carried out and a method for detecting and quantitatively evaluating reinforcement stress in RC beams was established. A three-axis automatic displacement device based on metal magnetic memory was used to collect the magnetic signals of the RC beams under different loads, the magnetic signals under different values (LOVs) and multiple scanning paths were analyzed. Based on the magnetic signals under different stress states, a dimensionless parameter A σ was defined to quantitatively calculate the steel bars stress of RC beams. The experimental results show that in the pure bending section of RC beam, the steel bars stress, and the dimensionless parameter A σ emerged with a linear relationship. Furthermore, the effect of parameter lift-off values (LOV) on the test results was discussed. [ABSTRACT FROM AUTHOR]

• During repetitive tensile loading, the fluctuation period of the tangential leakage intensity Bσ Y can accurately indicate the stress fluctuation of the steel bar. • Repetitive tensile load induces the stabilization of the tensile displacement v of the steel bar. The variation of v is positively correlated with the variation of Bσ Y. • The proportional change in the repetitive tensile load amplitude 2f i is approximately equivalent to the proportional change in the tangential leakage magnetic intensity ΔBσ Yi. • A linear relationship exists between the parameter B N and 2f i. The quantitative measurement of fluctuating stresses can be achieved by detecting the ΔBσ Yi value, combined with the f i expression. For the ambiguous status of force-magnetic effect on bridges under repeated loading, different repetitive loads were applied to HRB400 steel bars. The magnetic leakage intensities of steel bars were detected and the 'magnetic leakage ratio parameter' B N was introduced. The results indicate that the fluctuation of tangential magnetic leakage intensity Bσ Y is consistent with the variation of tensile load. The variation ΔBσ Y is positively correlated with steel bar tensile displacement v and repetitive tensile load amplitude 2f i. At various loading phases, the proportional change of 2f i is equal to the proportional change of ΔBσ Yi. That makes a linear relationship between 2f i and B N , which derives the expression of f i. Tensile loads are effectively calculated, enabling quantitative measurement of fluctuating stresses in steel bars. The measured deviation rate is within 10.0%. The theoretical model verifies the correctness of experimental results. This study provides new ideas for the nondestructive testing of stress. [ABSTRACT FROM AUTHOR]

Concrete fatigue strain evolution plays a very important role in the evaluation of the material properties of concrete. To study fatigue strain and fatigue damage of concrete in reinforced concrete beams under constant amplitude bending fatigue loading, constant amplitude bending fatigue experiments with reinforced concrete beams with rectangular sections were first carried out in the laboratory. Then, by analyzing the shortcomings and limitations of existing fatigue strain evolution equations, the level-S nonlinear evolution model of fatigue strain was constructed, and the physical meaning of the parameters was discussed. Finally, the evolution of fatigue strain and fatigue damage of concrete in the compression zone of the experimental beam was analyzed based on the level-S nonlinear evolution model. The results show that, initially, fatigue strain grows rapidly. In the middle stages, fatigue strain is nearly a linear change. Because the experimental data for the third stage are relatively scarce, the evolution of the strain therefore degenerated into two phases. The model has strong adaptability and high accuracy and can reflect the evolution of fatigue strain. The fatigue damage evolution expression based on fatigue strain shows that fatigue strain and fatigue damage have similar variations, and, with the same load cycles, the greater the load level, the larger the damage, in line with the general rules of damage. [ABSTRACT FROM AUTHOR]

The relationship between velocity, acceleration, and dynamic fracture toughness during rapid crack propagation is difficult to effectively capture. In this study, a novel semi-circular holed disc bend is proposed to achieve a long fracture path. Hopkinson pressure rods with crack growth and strain gauges are used to impact the semi-circular holed disc bend specimens and to monitor the cracking process of a mode-I fracture. The experiments show that the crack growth speed increases to a critical value after crack initiation and then oscillates as a result of the reflected stress wave. The dynamic propagation fracture toughness (K IC d) increases with increasing crack velocity for steady crack propagation; however, this does not apply for unsteady propagation. An experimental–numerical–analytical method is developed to determine the dynamic stress intensity factor, which initially increases with time, then decreases, and ultimately increases again. The acceleration (v ˙) can be used to investigate the unsteady crack propagation process. K IC d values for v ˙ < 0 are greater than those for v ˙ > 0. An energy release rate formula related to v ˙ and the crack propagation velocity (v) is proposed and verified by the experiments. A thorough understanding of v , v ˙ , and K IC d is important to analyze high-speed fault rupture processes. [ABSTRACT FROM AUTHOR]

• The weak magnetic excitation method can reduce the differentiation of the magnetic signal variation in tensile processes of rebars with different initial residual states. • The parametric A W , which can quantify the stress state of the rebar, was proposed and a linear relationship between A W and the tensile load T in the elastic stage was obtained. • An expression of the rebar stress state is obtained, with a deviation rate of under 15% between the calculated and actual stress values. • The lift-off value has an impact on the measured sensitivity, and reducing the lift-off value can improve the effectiveness of the stress state measurement. This paper used weak magnetic detection technology for nondestructive testing of rebar stresses. An applied excitation magnetic field was used to reduce the effect of different initial residual states of the rebar and to strengthen the force-magnetic coupling effect of the static tension process. Five sets of rebar samples were prepared, and magnetic field excitation with different magnitudes was applied. The tangential component of magnetic induction By is analyzed and the 'magnetic signal curve fluctuation parameter' A W is introduced. The results showed that the consistent variation pattern A W -T curves indicated magnetic field excitation could reduce the magnetic differences in various rebars tensile processes. When the excitation magnetic field strength exceeds the geomagnetic field, the A W -T curve in the elastic phase decreases linearly. By extracting the magnetic signals, the stress state in the elastic phase of the rebar is calculated by substituting for the formula, and the control error is within 15%. [ABSTRACT FROM AUTHOR]

• The method is suitable for the steel strands of in-service structures. • The prestress of the inside steel strands could be measured outside the structures. • The resistance-prestress relationship is nearly linear. • The average relative errors are about 10%. • The proposed method is suitable for long prestressed steel strands. To test the prestress of internal prestress steel strands, the relationship between the resistance and the prestress was analyzed. The equivalent electrical models of the testing systems were established. The results of the prestress testing experiments showed that there was a nearly linear relationship between the resistance and the prestress. Steel strands with similar physical properties had similar resistance-stress relationships that were not influenced by the prestress variation. Connecting both ends of the steel strand to the testing circuit, the prestress of the inside steel strands could be measured outside the structures. Both in the structural construction phase and the operation phase, the prestress testing errors were about 10%. When testing long steel strands, the proposed method may have higher sensitivity and smaller errors. [ABSTRACT FROM AUTHOR]

This study proposes a new method for the rapid and non‐contact measurement of cable forces in cable‐stayed bridges, including a cable force calculation method based on measured cable shapes and a batch acquisition method for the true shape of cables. First, a nonlinear regression model for estimating cable forces based on measured cable shapes is established, and a Gauss–Newton‐based cable force solving method is proposed. Furthermore, terrestrial laser scanning technology is used to collect geometric data of the cables. Meanwhile, automatic segmentation, noise reduction, and centerline extraction algorithms for the cable point cloud are proposed to accurately and efficiently obtain the cable shape. The correctness of the proposed cable force calculation method is verified in a well‐designed experiment, with the measurement error of cable forces for 15 test samples being less than 1%. Finally, the proposed point cloud automation processing algorithm and cable force measurement method are fully tested on a cable‐stayed bridge with a span of 460 m. The measurement accuracy of the proposed method for actual bridge cable tension is comparable to that of the frequency method, but the detection efficiency on site is nine times higher than that of the traditional frequency method. Overall, this study provides a new measurement method for construction control, health monitoring, intelligent detection, and other fields of cable‐stayed bridges. [ABSTRACT FROM AUTHOR]

The identification of cross-sectional loss in cables due to corrosion is crucial for evaluating the remaining strength of bridge cables. To accurately determine the cross-sectional loss rate, this paper derived a three-dimensional magnetic dipole model for spatial cable damage. The study employed an independently designed self-magnetic flux leakage (SMFL) sensor array to detect corrosion on a bundle of 37 parallel steel wires. The analysis investigated the correlation between corrosion degrees and SMFL signal features. The results show that the spatial magnetic field inversion collected by the sensor array device is more accurate. The cable damage location can be pinpointed by observing abrupt changes in the Bx and Bz curves. Additionally, this paper introduces five corrosion characterization features, all correlated with the cable cross-sectional loss rate. However, recognition stability using a single characteristic value is insufficient. The cable cross-sectional loss rate identification method, utilizing a back propagation neural network in conjunction with multiple characteristic indicators, demonstrates robust quantitative and adaptive capabilities. The maximum relative error of this method is 7.6%, offering a new perspective for future cable damage detection. [ABSTRACT FROM AUTHOR]

This study introduces a method for identifying tension in suspension rods based on impedance from self-inductive coils, grounded in electromagnetic induction and magnetic elasticity principles. The theoretical feasibility of this method was analysed through a high-frequency inductive coil model. Steel strand tensile tests, utilising self-inductive coil sensors at various frequencies, explored the relationship between resistance, inductance, and capacitance with tension. According to the experimental results, the sensitivity coefficient is used to determine the optimal prediction frequency of each impedance parameter. Within the optimal frequency range, a single impedance parameter regression prediction method based on the impedance difference ratio index was proposed. To improve the accuracy and stability of the predictions, a GA-BP neural network prediction model based on the fusion of multiple impedance parameters was proposed. The results indicate that the GA-BP neural network prediction method, which integrates multiple impedance parameters, achieves higher accuracy in identifying cable forces than the single impedance parameter regression prediction method. Specifically, at a frequency of 5 kHz, the relative error of the GA-BP neural network prediction method, which integrates multiple impedance parameters, was only 3.74%. This research offers a novel approach for future in-service tension identification in bridge suspension rods. [ABSTRACT FROM AUTHOR]

Both corrosion defects and stress can cause magnetic field mutations, so the effect of stress must be considered in the magnetic detection of steel corrosion. This paper focuses on exploring the influence law of tension on magnetic signals of the corroded specimens. Based on the spontaneous magnetic leakage mechanism of steel bar corrosion and the stress magnetization model, the magnetic memory detection of corroded reinforced concrete under tension was carried out. The magnetic characteristics of corroded specimens before and after loading were analyzed. The corrosion positions of the specimens can be determined according to the representative mutation points (RMP) of the Byc(0) curves, and the magnetic index I2 was proposed to roughly determine the corrosion degree of the specimens when the specimens were not subjected to tensions. The experimental results showed that the RMP of Byc(F) curves can still represent corrosion positions when the specimens were under tension. The theoretical derivation showed that the magnetic field change caused by tensile force is limited, and the maximum value of the magnetic field change caused by tensile force can be obtained. Based on this, the corresponding I3-F curves were obtained through the test. The magnetic field change caused by the most unfavorable tensions was calculated to analyze its influence on corrosion magnetic detection. Compared with I2, the relationship between I3 and the corrosion degree was more discrete, indicating that tensile forces affected the quantitative detection of corrosion. Still, the magnetic field caused by corrosion played a leading role. The verification showed that the measured corrosion positions of reinforced concrete specimens were in good agreement with those detected by the magnetic memory method. [ABSTRACT FROM AUTHOR]

• The deterioration of concrete exposed to ESA was studied from pore structures. • Smaller pores were formed in the PSA-induced deterioration on concrete. • The pore structures played a leading role in the resistance to PSA. Sulfate attack-induced deterioration on concrete begins with significant expansive forces generated at the narrow mesoscopic pore-level. However, the corresponding mesoscopic deterioration characteristic of concrete under different types of sulfate exposure remains uncertain. This experimental study devoted to provide a fundamental understanding on the possible alteration of the mesoscopic pore structures in concrete caused by chemical sulfate attack (CSA) and physical sulfate attack (PSA), by using a nondestructive testing technology. Results indicated that at the early stage of sulfate exposure (0–3 months), the sulfate attack reaction products attempted to fill most categories of mesoscopic pore structures (most categories of pores and pore throats) in concrete specimens exposed to CSA, but they preferred to abundantly accumulate in relative larger pores (e.g. Detrimental Pore III, DP-III) in concrete suffered from PSA. At the middle and later stages of exposure (3–9 months), the deterioration of concrete specimens under PSA was characterized by the rapid formation of the smaller pores (DP-I and DP-II) and the smaller pore throats (PT-I and PT-II), while the situation was just the reverse under CSA condition. In addition, suggestion was made that intentional reducing the initial volumes of DP-III (pores with 1–100 µm in diameter) in concrete by appropriate methods may significantly enhance the sulfate resistance of concrete materials suffered from physical attack. [ABSTRACT FROM AUTHOR]

A novel method is considered to evaluate the tensile deformation and stress of hyperelastic material by indentation method, the feasibility of which is on the basis of nonlinearity of hyperelastic materials. Under a tensile deformation, the instantaneous mechanical property shows an anisotropic character such that the contact region is elliptic rather than round. In order to capture the contact image, the traditional indentation device is upgraded with a special optical system. Besides, the spherical indentation experiment is conducted on the uniaxially stretched silica gel sample. The theoretical predictions and the experimental results show a good agreement with the difference from each other by less than 14%, that further validates the reliability of the transparent indentation method in spite of its insensitivity to the initial deformation. The aim of this paper is not only to evaluate the tensile deformation and stress of hyperelastic material but also to explore a new application domain of indentation method. Unlabelled Image • Transparent indentation method is presented to evaluate the tensile deformation and stress. • A special optical system is utilized to capture the contact morphology. • Indentation experiment is conducted to validate the reliability of this method. • This work is an attempt to explore the new application domain of indentation method. [ABSTRACT FROM AUTHOR]

The metal magnetic memory is used to detect the micro damage of structure based on the SMFL (self-magnetic flux leakage) effect, but it lacks an effective comprehensive diagnosis index suitable for the ferromagnetic material. In this paper, steel strand specimens were tensioned at different force levels, and the experimental study on the corrosion detection was carried out. Besides the monitoring analysis of the cable force, the initial structural magnetic field ΔBx0 and the surface SMFL signals Bx(α) induced by corrosion were both analysed. The results show that ΔBx0 curves of steel strand material present the periodic fluctuation. Considering ΔBx0 and measuring distance z, the proposed dimensionless damage analysis index X can be used for the quantitative research of corrosion diagnosis. The small influence of the cable force on index X is also illustrated. Moreover, the strong correlation that exists between the average maximum index X m a x ‾ and the corrosion ratio α is well fitted by the three-order polynomial curves. [ABSTRACT FROM AUTHOR]

• Bending strength of corroded RC beams evaluated via innovative NDT technique SMFL. • SMFL index K for quantitative evaluation was proposed theoretically. • Quantitative correlation between index K and bending strength loss rate β was established. • Bending strength of corroded RC beams was quantitatively evaluated via K based on Bayesian model. The self-magnetic flux leakage (SMFL), a non-destructive testing (NDT) technique, was applied innovatively to the quantitative statistical evaluation of the bending strengths of corroded reinforced concrete (RC) beams. In this study, the variations of the SMFL and bending strength caused by steel bar corrosion were analyzed theoretically and experimentally. Based on theoretical analysis, a SMFL index K that is not affected by the initial magnetization and magnetization history was proposed. The bending strength loss rate β of the corroded RC beams could be evaluated quantitatively using index K. 1775 K data from 18 corroded RC beams with different corrosion degrees were extracted, and the experimental correlation between K and β was established based on the experimental data and a theoretical correction. The results indicated that the magnitudes of K from different beams were similar, which proved that K eliminated the difference between the initial magnetization and magnetization history between different individuals. K and β were approximately exponentially related, and their correlation was not significantly affected by the stirrups. In view of the discreteness of the experimental sample K , β was statistically evaluated via K based on a Bayesian model. The posterior probability distribution of β in different value intervals when K was in a certain value interval was given. Thus, the quantitative classification of β was realized. This work is beneficial for the engineering evaluation of the bending strengths of corroded RC beams and provides an innovative research idea. [ABSTRACT FROM AUTHOR]

In an actual structure, the arrangement of steel bars is complicated, there are many factors affecting the corrosion of steel bars, and these factors affect each other. However, accurately reflecting the corrosion of steel bars in actual engineering through theoretical calculations is difficult. Besides, it is impossible to detect and evaluate steel bars rust completely and accurately. This article is based on spontaneous magnetic leakage detection technology and adopts the method of stage corrosion and scanning along the reinforcing bar. Based on spontaneous magnetic flux leakage detection technology, the linear change rate of the tangential component curve of the magnetic flux leakage signal generated after the corrosion of a steel bar is studied, and a comparison is made between the steel bar coated concrete samples with different steel bar diameters. In this paper, the "origin of magnetic flux leakage signal" is defined as a reference point, which is convenient for effectively comparing the magnetic signal curves under all operating conditions. Besides, the "rust-magnetic fluctuation parameter" is proposed to accurately reflect the sudden change of leakage magnetic field caused by disconnection due to the corrosion of a steel bar. A new data processing method is provided for the non-destructive testing of steel corrosion using the spontaneous magnetic flux leakage effect, which can effectively reduce the influence of steel bar diameter on magnetic flux leakage signal and improve the precision of non-destructive testing technology of steel bar corrosion using the metal magnetic memory effect. [ABSTRACT FROM AUTHOR]

Cable tension monitoring is important to control the structural performance variation of cable-supported structures. Based on the elasto-magnetic effect and the self-induction phenomenon, a new non-destructive evaluation method was proposed for cable tension monitoring. The method was called the elasto-magnetic induction (EMI) method. By analyzing the working mechanism of the EMI method, a set of cable tension monitoring systems was presented. The primary coil and the induction unit of the traditional elasto-magnetic (EM) sensor were simplified into a self-induction coil. A numerical analysis was conducted to prove the validity of the EMI method. Experimental verification of the steel cable specimens was conducted to validate the feasibility of the EMI method. To process the tension monitoring, data processing and tension calculation methods were proposed. The results of the experimental verification indicated that different cables of the same batch can be calibrated by one proper equation. The results of the numerical analysis and the experimental verification demonstrated that the cable tension can be monitored both at the tension-applying stage and the tension-loss stage. The proposed EMI method and the given monitoring system are feasible to monitor the cable tension with high sensitivity, fast response, and easy installation. [ABSTRACT FROM AUTHOR]

Structural dynamic response corrupts frequently due to the sensor malfunction. The loss of dynamic response will hinder the structural condition assessment. In recent years, significant efforts have been devoted to recovering the dynamic response during the linear elastic stage of the structure. However, relevant researches on the response recovery of damaged structures are rarely reported due to its strong nonlinearity. With the growing significance of post-disaster structural maintenance, it is critical to develop effective methods for recovering missing data in damaged structures. To this end, this paper proposes a dynamic response recovery method for damaged structures using residual learning enhanced fully convolutional networks (FCN), which can provide a baseline for the recovery of monitoring data in operational civil infrastructure. Specifically, a FCN incorporating residual learning and skip connections is designed to capture high-dimensional nonlinear relationships between input and output channels, thereby achieving the data recovery for any concerned channel. Then, a time–frequency domain evaluation mode is constructed, in which L2 norm is used to measure the difference of recovery results in the time domain, while instantaneous frequency is employed to evaluate the integrity of the spectral information of recovery results. Finally, a destruction test of an experimental arch was conducted, and the acceleration data under different damaged state were collected to investigate the feasibility of the proposed method. Besides, the recovery effects concerning input channel location and quantity, multi-channel response and cross-state recovery are examined. The results show that even in a severely damaged state, the proposed method effectively recovers the missing data. In addition, improving the correlation between input and output channels and increasing the number of input channels can further enhance the recovery accuracy. [ABSTRACT FROM AUTHOR]

With the continuous service time, long-span track cable-stayed bridges are inevitably affected by material time-varying and fatigue load periodic effects, and permanent down-deflection phenomenon is inevitable. The down-deflection of the main girder would lead to the irregularity of bridge deck, which would directly affect the running comfort and safety of the train. The permanent deformation control value should be set reasonably. In this paper, based on the research and analysis of domestic and foreign codes and standards, the evaluation criteria for the service performance of long-span track cable-stayed bridges was determined, aiming at the problem of deformation classification control in the service stage of the long-span track cable-stayed bridge. The limit of permanent deformation of main girder was analyzed, and the decision processing was put forward and applied to an engineering example. According to the vehicle-bridge coupling vibration analysis, the maximum vertical deformation safety control value in the service stage is L/400, and the pre-warning control value is L/500. With the non-permanent deformation value β deducted, the permanent deformation safety control value is L/400- β, and the pre-warning control value is L/500- β. The rationality of the grading control limit of permanent deformation based on service performance analysis has been verified by application analysis. [ABSTRACT FROM AUTHOR]

To study the wind field characteristics near the ground pulsation in typhoon conditions, wind field conditions in the area affected by Typhoon "Fung-Wong" were monitored using wind field instruments installed in the construction building of Wenzhou University, China. Real-time wind field data were collected during typhoons. Wind characteristic parameters such as mean wind speed, wind direction angle, turbulence intensity, gust factor, peak factor, coherence function, and autocorrelation were analyzed, and the wind field characteristics during the typhoon were summarized. The results indicated that the longitudinal and lateral turbulence intensities decreased with an increase in the mean wind speed, and there was an obvious linear relationship between them. The vertical and horizontal gust factor and peak factor decreased with an increase in mean wind speed, and the trend was more obvious in the horizontal direction. There was a significant correlation between the gust factor and the peak factor. The turbulence intensity and gust factor decreased with time, and the turbulence intensity attenuation speed increased with time. The empirical curve presented by Davenport (1961) can simulate the correlation characteristics of the fluctuating wind speed components of Typhoon Fung-Wong at some measuring points. With an increase in the time difference, the dependence of the instantaneous values at the two time points gradually decreased. [ABSTRACT FROM AUTHOR]

DNA digital storage provides an alternative for information storage with high density and long-term stability. Here, we report the de novo design and synthesis of an artificial chromosome that encodes two pictures and a video clip. The encoding paradigm utilizing the superposition of sparsified error correction codewords and pseudo-random sequences tolerates base insertions/deletions and is well suited to error-prone nanopore sequencing for data retrieval. The entire 254 kb sequence was 95.27% occupied by encoded data. The Transformation-Associated Recombination method was used in the construction of this chromosome from DNA fragments and necessary autonomous replication sequences. The stability was demonstrated by transmitting the data-carrying chromosome to the 100th generation. This study demonstrates a data storage method using encoded artificial chromosomes via in vivo assembly for write-once and stable replication for multiple retrievals, similar to a compact disc, with potential in economically massive data distribution. [ABSTRACT FROM AUTHOR]

Based on the metal magnetic memory effect, this paper proposed a new non-destructive testing method for the internal tensile force detection of steel bars by analyzing the self-magnetic flux leakage (SMFL) signals. The variation of the SMFL signal of the steel bar with the tensile force indicates that the curve of the SMFL signal has a significant extreme point when the tensile force reaches about 65% of the yield tension, of which the first derivative curve has extreme points in the elastic and yielding stages, respectively. To study the variation of SMFL signal with the axial position of the steel bar under different tensile forces, a parameter reflecting the fluctuation of the SMFL signal along the steel bar is proposed. The linear relationship between this parameter and the tensile force can be used to quantitatively calculate the tensile force of steel bar. The method in this paper provides significant application prospects for the internal force detection of steel bar in the actual engineering. [ABSTRACT FROM AUTHOR]

This paper presents a nondestructive test method to evaluate the residual bending strength of corroded reinforced concrete beam by analyzing the self-magnetic flux leakage (SMFL) signals. The automatic scanning device was equipped with a micromagnetic sensor and sensor-based experimental details were introduced. Next, the theoretical formula of the normal component HS(z) of the SMFL signal that originated from the corroded region was derived based on the magnetic dipole model and the experimental results were discussed. The results indicate that the experimental data of HS(z) are consistent with the theoretical calculations, both location and extent of the steel bars corrosion can be qualitatively determined by using HS(z). The gradient K of HS(z) is approximately linearly related to the loss rate, S, of the bending strength, which can be used to evaluate the residual bending strength of the corroded reinforced concrete beam. This work lays the foundation for evaluating the residual bending strength of corroded reinforced concrete beams using the SMFL signal; the micromagnetic sensor is further applied to the civil engineering. [ABSTRACT FROM AUTHOR]

This paper proposed a new computing method to quantitatively and non-destructively determine the corrosion of steel strands by analyzing the self-magnetic flux leakage (SMFL) signals from them. The magnetic dipole model and three growth models (Logistic model, Exponential model, and Linear model) were proposed to theoretically analyze the characteristic value of SMFL. Then, the experimental study on the corrosion detection by the magnetic sensor was carried out. The setup of the magnetic scanning device and signal collection method were also introduced. The results show that the Logistic Growth model is verified as the optimal model for calculating the magnetic field with good fitting effects. Combined with the experimental data analysis, the amplitudes of the calculated values (BxL(x,z) curves) agree with the measured values in general. This method provides significant application prospects for the evaluation of the corrosion and the residual bearing capacity of steel strand. [ABSTRACT FROM AUTHOR]

Summary: Acoustic emission (AE) technology is extensively acknowledged as a promising structural health monitoring (SHM) approach; meanwhile, AE monitoring has long been criticised for a lack of quantitative results. This work revealed a strong correlation between the shear stress distribution and the resulting AE distribution, enabling accurate and real‐time quantification of the shear stress states in concrete beams using only AE measurements. This paper started by introducing the AE phenomenon and the theoretical distribution of the shear stresses on a beam cross section, which revealed that the distributions of the stresses and the resulting emissions inherently correlate to each other. Twelve reinforced concrete beams were then tested, deploying devices including an AE system. The results showed that the AE source intensity distribution strongly correlated with that of the shear stresses in a beam segment when the beam was in both the working stage and the failure phase and that the matching degree of these two distribution curves varied from 79.20% to 94.12%. The correlation revealed in the paper will boost a wide range of significant AE‐based scientific research and engineering applications, including SHM and non‐destructive testing. [ABSTRACT FROM AUTHOR]

• A correlation between bending strength and SMFL of corroded RC beams was explored. • A simplified theoretical model was established. • An SMFL feature was used to estimate the bending strength of corroded RC beams. • The experimental results agreed with those of the theoretical analysis. Measuring the bearing capacity is critical for assessing the safety and durability of civil engineering structures. However, the existing non-destructive testing (NDT) techniques cannot estimate the bending strengths of corroded reinforced concrete (RC) beams easily. Thus, the correlation between self-magnetic flux leakage (SMFL) and bending strength of corroded RC beams was investigated in this study to estimate the bending strength. First, a theoretical model was established based on the physical properties of ferromagnetic materials and engineering mechanics. Preliminary research found that the peak-to-valley differences of the SMFL curves of corroded RC beams were strongly correlated with the bending strength. The normalized peak-to-valley differences NB P (x) and normalized bending strength NBS were defined based on this correlation. NBS of corroded RC beams can be evaluated using NB P (x) of SMFL curves. The data from 18 corroded RC beams and the theoretical model were analyzed and employed to verify the correlation between NB P (x) and NBS. The experimental results were consistent with those predicted by theory and showed the semi-quantitative correlation that NB P (x) was related to NBS exponentially (without stirrups) or approximate linearly (with stirrups). Therefore, the bending strength can be estimated semi-quantitatively via the SMFL curves. In this work, a novel correlation between the SMFL and bending strengths of corroded RC beams was established. The SMFL technique can be regarded as a new effective NDT technique for estimating the bending strength of corroded RC beams. [ABSTRACT FROM AUTHOR]

In this study, the PORO-FSSI-FOAM model is applied to investigate the wave-induced oscillatory soil response during the caisson installation, where the Reynolds averaged Navier-stokes equation is used to simulate the flow motions, and the poro-elastic equation is used to govern the soil dynamic response around the caisson. Unlike previous studies, the caisson installation process is considered when investigating the wave-induced oscillatory soil response in this paper. Firstly, the accuracy of the PORO-FSSI-FOAM model in simulating the wave-seabed interaction is validated. Then, the effects of the submerged depth, the geometrical dimensions and the installation sequence of the caisson on the wave-induced oscillatory pore pressure response are examined, and the momentary soil liquefaction during the caisson installation is explored. Finally, a simple formula that describes the relationship between the maximum soil liquefaction depth and the caisson submerged depth is proposed. Numerical results indicate that the caisson dimensions can greatly influence the wave-induced pore pressure response, and the relationship between the oscillatory pore pressure response and the caisson submerged depth is inconsistent at different locations surrounding the structure. Moreover, the installation sequence can significantly affect the momentary soil liquefaction and the simple formula proposed in this study can provide reference for engineers to assess the seabed stability during the caisson installation. • A three-dimensional numerical model for wave-seabed-caisson interaction was established based on OpenFOAM. • The wave-induced oscillatory pore pressure response during the caisson installation was studied. • The momentary soil liquefaction during the caisson installation was investigated. • A simple method that describes the variation of the maximum soil liquefaction with the submerged depth for different caisson dimensions was proposed. [ABSTRACT FROM AUTHOR]

The self-magnetic flux leakage (SMFL) detection technique has great potential in the corrosion detection of bridge stay cables due to its advantages of small testing equipment, high accuracy, and fast testing rate. However, the vibration effect in the cable's SMFL detection is unclear. To address this, the influence of vibration on the magnetic field distribution of cable structure is analyzed theoretically. According to the theoretical model, the effect of vibration on SMFL detection primarily manifests as displacement changes (displacement-added magnetic field) and defect shape changes (deformation-added magnetic field). SMFL detection experiments are conducted on steel strands. The results demonstrate that the displacement-added magnetic field exhibits statistical characteristics in the form of a normal distribution, fluctuating around the zero value. The impact of the deformation-added magnetic field on SMFL is linearly correlated with the corrosion ratio c. Moreover, a corrosion characterization index A was proposed and has an excellent linear fit with the corrosion ratio c. The index A effectively improves the accuracy of corrosion detection and provides early warning for the maintenance of cable structures. [ABSTRACT FROM AUTHOR]

Changes in loading position have a significant impact on the stress field of each vulnerable area of an orthotropic steel deck (OSD). The arc opening area of the diaphragm and the connecting area between the U-rib and the diaphragm under the moving load are prone to fatigue cracking. By comparing the stress responses under different methods, the hot spot stress (HSS) method is used as the main stress extraction method in fatigue performance evaluation. The control stress of fatigue cracking was analyzed by comparing the direction of the principal stress field with the crack direction in this experiment. According to the stress amplitude deviation under the biaxial stress state, a set of methods for evaluating the effects of in-plane biaxial fatigue was developed. An improved luffing fatigue assessment S–N curve was applied to analyze the fatigue life of the diaphragm's arc opening area. The results show that when the moving load is exactly above the connection of the deck and the web of the U-rib on one side, it is in the most unfavorable position in the transverse direction, and the diaphragm is mainly under the in-plane stress state. The longitudinal range of the stress influence line of the arc opening is approximately twice the diaphragm spacing. Two to three stress cycles are caused by one fatigue load. Fatigue crack control stress is the principal stress tangential to the arc opening's edge in this area. The normal direction of the principal stress in the model test is roughly consistent with the crack initiation direction. The variation in the stress amplitude deviation in this area is caused by changes in the action position of the moving load. When the moving load is at a certain distance from the involved diaphragm, it is reduced to zero, implying that the in-plane fatigue effect is the greatest in this area. [ABSTRACT FROM AUTHOR]

• The vibration effect concept of measuring displacement and defect deformation on the magnetic field is interpreted. • The increment of magnetic field change under vibration mainly depends on Δ B Def. • The quantitative characterization method of the magnetic field considering the vibration effect is proposed. • γ sum can effectively weaken the vibration effect on the magnetic characteristics of cable structure. The self-magnetic flux leakage (SMFL) method has excellent potential in corrosion measurement research of bridge stay cables and suspenders. However, the vibration effect in the cable's SMFL measurement is unclear and short of the systematic experimental analysis. Based on the magnetic field superposition principle, this study interpreted the vibration effect on steel cable structure magnetic field. The effect was innovatively summarized by the magnetic field increment resulting from the measuring displacement (Δ B Dis) and the defect deformation (Δ B Def). Then, the SMFL measurement experiment of the corroded steel strands during the vibration was carried out. The magnetic field distribution law and the influence of the corrosion loss ratio were also analyzed. The results show that Δ B Dis presents a "zero value" distribution law via the statistical histogram. The increment of the magnetic field under vibration mainly depends on Δ B Def , which positively correlates with the structure's corrosion degree and deformation curvature. An excellent linear correlation between the comprehensive characteristic parameter γ sum and the corrosion ratio is obtained. So, the quantitative characterization analysis method under vibration was proposed, and γ sum can weaken the vibration effect on the magnetic characteristics of cable structure. [ABSTRACT FROM AUTHOR]

To accurately evaluate the overall corrosion degree of reinforced concrete (RC) beams, on the basis of the SMFL technology, the overall random corrosion detection experiment of six RC beams was carried out. The relationship between the tangential component By and the normal component Bz of the magnetic induction intensity and corrosion degree was analyzed, and a multidefect magnetic dipole model was established. The correlation between the average corrosion ratio C of the RC beam and the magnetic characteristic index KG was emphatically explored. The results showed that, with the increase in the average corrosion ratio C, the magnetic characteristic index KG showed an increasing trend as a whole. The index KG could weaken the influence of different historical magnetizations, but it had a certain dispersion. On the basis of the correlation and the Naive Bayesian model, the average corrosion ratio C was divided into four grades. The probability of C falling in different value ranges can be quantitatively evaluated using the KG magnetic characteristic index. The reliability is as high as 97.4% and as low as 56.8% so as to realize the quantitative grading evaluation of the corrosion of the rebar in the RC beam. [ABSTRACT FROM AUTHOR]

• The theoretical model of self-magnetic flux leakage for dual defects on bridge cables was derived. • The correlation between the self-magnetic flux leakage signals in three directions and the broken wire defects was explored. • A novel quantification method for the broken wire defects of the parallel steel wire bundle was proposed. • A three-dimensional line graph that can qualitatively determine the depth of broken radial wires was proposed. The wire breakage of bridge cable may result in potential bridge safety and durability problems. Therefore, it is urgent to develop an effective testing method for quantitatively evaluating wire breakage. In this paper, based on magnetic dipole theory, the dual defects magnetic dipole model of bridge cables was established to quantify the width of breakage. Then, the multi-dimensional self-magnetic flux leakage (SMFL) detection experiments were carried out for different wire breakage states of parallel steel wire bundles. The experimental results show that the distribution law of the theoretical model is consistent with the experimental results. Finally, a method was proposed to quantitatively characterize the axial wire breakage width of the cable using the Boltzmann fitting curve. In addition, a three-dimensional (3D) line graph was proposed to qualitatively evaluate the relative magnitude of the radial wire breakage depth. This study provides a theoretical basis for quantitatively evaluating bridge cables using the SMFL signals. [ABSTRACT FROM AUTHOR]

Orthotropic steel deck (OSD) are widely used in steel bridges because of their many advantages, but the structures and stresses of OSD are complex and sensitive to fatigue. Based on the model test, the structural fatigue analysis of OSD is carried out by using the extended finite element method (XFEM) to understand and reveal the causes of fatigue detail cracks and the generation and propagation of fatigue cracks at the welding ends of diaphragms, U-ribs, and diaphragms, which are the main structural fatigue details of the deck. The results show that: the fatigue crack at the diaphragm opening is not caused by a single factor, but the horizontal relative displacement is the root-cause of the fatigue crack; the contribution of out-of-plane displacement to the fatigue crack is more significant than that of vertical displacement or in-plane stress, which often leads to the initiation and propagation of the fatigue crack; the crack-propagation direction is perpendicular to the contour of principal stress, and the crack propagates into the plate along the high-stress area in the horizontal direction, which is in accordance with the basic theory of crack propagation. The research methods can provide technical support for the design of similar structures. [ABSTRACT FROM AUTHOR]

Polymeric graphitic carbon nitride is an efficient visible-light photocatalyst for NO removal which can be prepared by precursors rich in C and N elements, such as melamine, dicyandiamide, urea, and thiourea et al. The method of synthesizing carbon nitride from melamine and dicyandiamide has much higher yield and, whereas the photocatalytic efficiency of the product was lower than that of synthesizing from urea and thiourea. In present work, the photocatalytic performance of carbon nitride prepared from dicyandiamide was significantly improved; melem/g-C 3 N 4 was prepared from dicyandiamide under lower temperature with superior performance on NO purification than pure carbon nitride (g-C 3 N 4 ). Suitable depolymerization ratio and surface protonation status could bring about higher photocatalytic activity through XPS characterizations. Through the SEM images, two kinds of morphology nanorod carbon nitride and bulk carbon nitride cross each other together and the ratio variation are consistent with reaction temperature and time. The different band gap structure between g-C 3 N 4 and melem could drive the photogenerated electron-hole separation due to the offsets and lead to higher NO removal efficiency. This heterojunction consisted of melem and g-C 3 N 4 was developed here just by adjusting reaction temperature and time, which could open up a new possibility for air purification in a low cost way. [ABSTRACT FROM AUTHOR]

Aiming to reduce residual deformation, herein, we propose the design concept of a self-centering buckling-restrained brace (SC-BRB) applied to the structural fuse of arch bridge structures. First, a novel assembled SC-BRB with combined disc springs is proposed. Notably, the hysteretic curve characteristics can be effectively controlled by the ratio of the BRB system load capacity to the SC system preload. The construction and operating mechanism of the novel SC-BRB are described, and a theoretical hysteretic model under cyclic loading is derived. Five SC-BRB specimens with different combinations are designed and fabricated. Through quasi-static tests, the characteristics including residual deformation and hysteretic energy dissipation are analyzed and compared to explore the self-centering effect and damage mode. The test results reveal that the hysteresis curve of the assembled SC-BRB is characterized by an apparent flag-type form and stable hysteretic performance. The combined disc spring significantly reduces the residual deformation of the brace, resulting in an apparent self-centering effect. The theoretical hysteretic model proposed in this paper agrees well with the test results. Finally, a comparative analysis is conducted on the seismic performance of a concrete filled steel-tube (CFST) arch bridge structure with three types of lateral braces: SC-BRB, BRB, and an ordinary brace. The OpenSees analysis results demonstrate that the CFST with the SC-BRB demonstrates better performance in terms of the displacement response and residual deformation compared with the other two CFSTs. • A novel assembled self-centering buckling-restrained brace with combined disc springs (SC-BRB) is proposed. • Five SC-BRB specimens with different combinations are tested under the quasi-static load. • The theoretical hysteretic model is provided and verified. • The feasibility and applicability of SC-BRB applying into CFST arch bridge structure are investigated. [ABSTRACT FROM AUTHOR]

• Analytical solution to water flow into vegetated soil slopes considering hydro-mechanical coupling is proposed. • The proposed analytical solution is combined with limit equilibrium method to assess vegetated slope stability. • Transpiration rate influences the pressure head and the safety factor of vegetated slopes. Developing analytical solutions for water flow in partially saturated soil slopes is a significant issue in practical engineering. In this study, an analytical solution to rainfall seepage into vegetated unsaturated soil slopes considering hydro-mechanical coupling is proposed using Green's function. The proposed analytical solution is compared with the solution of finite element method. Combined with the limit equilibrium method, the proposed analytical solution is used to assess the slope stability. Parametric studies are performed to investigate the effects of slope angle, rain intensity, suction-based elastic modulus, and transpiration rate on pressure head and factor of safety for slopes. The results show that the pressure head and factor of safety (F s) decrease with the increase of slope angle or rain intensity. As the transpiration rate increases, the pressure head and F s increases. The smaller the absolute value of the suction-based elastic modulus, the more obvious the effect of hydro-mechanical coupling on F s. Additionally, the vegetated slope stability varies more greatly than that of bare slopes due to the hydro-mechanical coupling effect. The proposed analytical solution is simple in form and has few input parameters, which can be used as a simple and effective method for analyzing rainfall infiltration in vegetated slopes. [ABSTRACT FROM AUTHOR]

Deflection data provides important information about the mechanical characteristics and structural health condition of bridges. The study presented here pertains to development of a deep learning based approach for structural health monitoring by employing the bridge deflections. The method presented herein uses the long short-term memory (LSTM) framework in detecting the state of damage by tracking the feature changes of time-series deflection and temperature data. Deflection and temperature data of Chongqing Egongyan Rail Transit Suspension Bridge was employed over a period of 15 months to develop the proposed method. The concept of square error index (SE) is introduced as an assessment tool for estimation of the bridge damage level. Results from the present study indicated that the statistical characteristics of SE index are proportional to the level of damage, and are only sensitive to abnormal changes in deflection. Structural health monitoring data over the period of 15 months indicated that the proposed approach has the capability to detect cable damages as low as 0.5%. [ABSTRACT FROM AUTHOR]

• The detection and evaluation of reinforcement elastic stress in RC beams were studied. • The magnetic signal gradient was quantitatively modeled and verified by experiments. • A method based on Bayesian theory was developed to estimate the elastic stress. • This method can be reliably applied for rapid and economic stress detection in RC beams. This study developed a method for detection and quantitative evaluation of the elastic stress of the reinforcement in reinforced concrete (RC) beams. By combining the minimum energy and magnetic dipole theories, a quantitative model of the magnetic signal gradient and magnetization angle was established. The spatial distribution of the magnetic signals and variation of the average gradient with stress in the pure bending section of the RC beams were obtained through four-point bending experiments. The results show that the law of the average gradient with the stress is consistent with that predicted by the theoretical model. Based on the Bayesian theory, a method to evaluate the elastic stress was established, which can be applied for grading the elastic stress of the reinforcement within a certain range of accuracy. [ABSTRACT FROM AUTHOR]

Cyanophages play an important role in regulating the dynamics of cyanobacteria communities in the hydrosphere, representing a promising biological control strategy for cyanobacterial blooms. Nevertheless, most cyanophages are host-specific, making it difficult to control blooming cyanobacteria via single or multiple cyanophages. In order to address the issue, we explore the interaction between cyanophages and their heterologous hosts, with the aim of revealing the principles of designing and constructing an artificial cyanophage genome towards multiple cyanobacterial hosts. In the present study, we use synthetic biological approaches to assess the impact of introducing a fragment of cyanophage genome into a heterologous cyanobacterium under a variety of environmental conditions. Based on a natural cyanophage A-4L genome (41,750 bp), a truncated cyanophage genome Syn-A-4-8 is synthesized and assembled in Saccharomyces cerevisiae. We found that a 351–15,930 bp area of the A-4L genome has a fragment that is lethal to Escherichia coli during the process of attempting to assemble the full-length A-4L genome. Syn-A-4-8 was successfully introduced into E. coli and then transferred into the model cyanobacterium Synechococcus elongatus PCC 7942 (Syn7942) via conjugation. Although no significant phenotypes of Syn7942 carrying Syn-A-4-8 (LS-02) could be observed under normal conditions, its growth exhibited a prolonged lag phase compared to that of the control strain under 290-millimolar NaCl stress. Finally, the mechanisms of altered salt tolerance in LS-02 were revealed through comparative transcriptomics, and ORF25 and ORF26 on Syn-A-4-8 turned out to be the key genes causing the phenotype. Our research represents an important attempt in designing artificial cyanophages towards multiple hosts, and offers new future insights into the control of cyanobacterial blooms. [ABSTRACT FROM AUTHOR]

Since the excessive seismic support uplift force may cause the support failure of long-span cable-stayed bridges, this study focused on the support uplift force at the auxiliary pier for a double-tower cable-stayed bridge with a main span of 1088 m. A shake table test was designed and performed based on the 1/35-scale test model scaled from the prototype bridge. Details of the test model, including the scale factor, structural member configurations, boundary conditions, and the numerical validation were briefly presented. The test results show that although only the longitudinal ground motion was applied, significant seismic support uplift and compression forces would be generated in the bearings at the auxiliary pier, resulting in the bearing uplift. The vertical vibration of the deck contributed by the first vibration mode of the test model was one of the main causes of the bearing uplift, but no rigid-like pounding effect occurred due to the vertical nonlinear mechanical behaviour of the bearing. Furthermore, the effect of the bearing uplift on the main seismic responses of the test model was negligible. • The support uplift force of a long-span cable-stayed bridge under longitudinal ground motions is experimentally studied. • The seismic responses of the tests model related to the support uplfit force are obtained and analyzed. • Significant seismic support uplift force and compression force will be generated, resulting in the bearing uplift. • The vertical vibration of the deck contributed by the first vibration mode is one of the main causes of the bearing uplift. [ABSTRACT FROM AUTHOR]