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Highlights • Adopted a novel TMDI system to control the undesirable VIV of long-span bridges. • Proposed an optimization method for the TMDI-VIV system. • Validated the efficiency of TMDI prior to TMD in VIV control of long-span bridges. Abstract The undesirable vortex-induced vibration (VIV) may seriously influence the fatigue life and serviceability of bridge structures. It is important to take countermeasures to suppress the adverse VIV of long-span bridges. In the present study, a novel inerter-based system, namely the tuned mass damper inerter (TMDI), is proposed to control the VIV of the main deck of long-span bridges. In this system, an inerter device, which is able to transform the linear motion into the high-speed rotational motion and thus significantly amplifies the physical mass of the system, is incorporated into the conventional tuned mass damper (TMD) system to further improve the performance of TMD. An applicable layout of the TMDI inside the bridge deck is introduced and the governing equations of the structure-TMDI system subjected to VIV are established. The optimization of the TMDI parameters with the consideration of nonlinear aeroelastic effect is derived. The control performance and robustness of the proposed system are investigated through an analytical case study in both the time and frequency domains. It is observed that the TMDI system can obviously reduce the VIV responses of the bridge deck. Moreover, compared to the conventional TMD system, the static stretching of the spring due to gravity and the oscillation amplitude of the mass block in the TMDI system are significantly reduced. These properties make the proposed TMDI system an attractive alternative for the VIV control of long-span bridges. [ABSTRACT FROM AUTHOR]

• A novel lever-arm TMDI is proposed for vibration control of long-span bridges. • The influences of design parameters are systematically investigated. • Empirical design formulas are proposed. • Control performance is validated in both frequency and time domains. In this study, the lever mechanism is incorporated with the tuned mass damper inerter (TMDI) to further promote the practical application of TMDI in long-span bridges. Four potential configurations of the lever-arm tuned mass damper inerter (LTMDI) are first established, and the corresponding governing equations are derived. Then, the optimum configuration of LTMDI is identified by minimizing the peak of non-dimensional displacement frequency response function (FRF). Subsequently, the influences design parameters, such as mass ratio, inertance ratio, lever mass ratio, and spanning distance of the inerter are investigated. Based on the results, empirical design formulas of design parameters are proposed and verified. Finally, a cable-stayed bridge is adopted as a numerical case to further illustrate the performance of LTMDI in terms of response reduction and robustness. The results show that the involving of the lever into TMDI is an effective mechanism for implementing the inerter's spanning in long-span bridges. With this mechanism, it is practically feasible to achieve a high effectiveness, low space requirement and more robustness control device for long-span bridges. The developed design formulas have a high accuracy, which can provide reliable support for the design of the LTMDI in engineering applications. [ABSTRACT FROM AUTHOR]

• Bridge VIV system with different Scruton numbers are simulated in wind tunnel. • Instantaneous properties of aeroelastic damping and stiffness are obtained. • A method to obtain periodic equivalent damping of VIV models is proposed. • Capabilities of commonly used VIV models are examined. The capabilities of some commonly used single-degree-of-freedom (SDOF) VIV models for bridge decks are examined through wind tunnel experiment. The VIV responses of a sectional deck model at different Scruton numbers are measured. An instantaneous identification method is adopted for obtaining the properties of aeroelastic damping and stiffness of the VIV system. The simulated aeroelastic damping by these models as well as the predicted VIV responses of the deck at different Scruton numbers are compared with experiments. The results indicate that the more accurate the simulated aeroelastic damping by an empirical model, the smaller the prediction errors by this model will be. Through directly fitting the aeroelastic damping, the prediction errors by an empirical model can be further reduced. [ABSTRACT FROM AUTHOR]

Highlights • Cyclic tests were carried out based on the first rocking bridge in China. • Buckling-restrained plates were adopted to enhance its seismic performance. • Improved force-displacement model considering the compression depth was proposed. Abstract Seismic resilient structures with low structural damage and self-centering behavior after an earthquake are focus issues of current earthquake engineering. Unbonded pretensioned rocking columns offer advantages for accelerated bridge construction in seismic regions, which utilize column-uplifting mechanisms, high strength post-tensioning, and replaceable energy dissipation devices to enhance seismic performance and resilience. The experiment of three 1:3 scale unbonded, post-tensioned rocking bridge bents with different types of external replaceable energy dissipation devices subjected to quasi-static loading protocols, were carried out according to practical engineering demand in high-intensity earthquake regions. An improved analytical model was proposed for predicting the force-displacement relationship of the post-tensioned rocking bridge bent systems considering the neutral axis depth. Minimal physical damage was observed for the post-tensioned rocking bridge bent systems, which exhibit good energy dissipation and self-centering behavior. Especially, the external replaceable buckling-restrained plates dissipaters can be easily replaced if severely damaged subjected to higher than expected ground motions. The satisfactory analytical and experimental comparisons are presented as a validation of the reliability for the high-performance seismic-resistant bridge bent systems and the modelling techniques in this study. [ABSTRACT FROM AUTHOR]

• A three-dimensional numerical model that can accurately predict the nonlinear behavior of the novel socket joints was developed. • The influence of performance parameters on the mechanical properties of the socket joint were studied. • The modified moment capacity calculation method of the socket joints under different failure modes was verified. • The convenient design process of the socket CFST column-cap beam joint with UHPC grouted connection was proposed. The excellent mechanical properties of concrete-filled steel tube (CFST) make it a competitive alternative to column-cap/foundation cap socket connections in accelerated bridge construction (ABC). To investigate more research parameters and facilitate the seismic design of socket CFST column joints, a detailed numerical analysis model of socket column-cap beam joint was established and verified by experimental data, and the bearing capacity and failure modes of socket joints under the dimensions of the CFST parts and their material properties were investigated as well. It is found that the size of steel tube, the strength of steel tube, the socket depth of CFST, and the type of forming hole have significant effects on the strength and failure modes of column to cap beam socket joints. This study also proposed a moment calculation method for socket joints that can accurately predicts the bearing capacity under different failure modes. Finally, a design process was developed to facilitate the widespread application of this socket CFST column-cap beam joint with Ultra High-Performance Concrete (UHPC) grouted connection. [ABSTRACT FROM AUTHOR]

• A FEM of UHPC grouted RC column-footing socket joints was established. • Influencing parameters of joints performance were analyzed. • An estimation method of moment capacity was proposed. Socket connection is an effective connection method for assembling precast columns and adjacent components in accelerate bridge construction(ABC). In order to further enhance the efficiency of this connection type, an extensive numerical study of reinforced concrete(RC) column-footing socket joints was conducted by experimental data. The force transmission mechanism, the influence of parameters on the strength and failure state of the socket joints are revealed. It was found that the socket depth, longitudinal rebar ratio and axial load ratio have notable effect on the mechanical performance of the socket joints compared with other parameters. Base on the numerical simulation and experimental results, a calculation method for the moment capacity of socket joints was developed, which can accurately predict the moment capacity and failure mode of RC column-footing joints with socket connections. A design method of RC column-footing socket joints was also given for practical engineering. [ABSTRACT FROM AUTHOR]

• Seismic performance of high-strength centrifugally hollow columns was investigated. • A modified hollow pipe column confined concrete constitutive model is proposed. • The influence of neutral axis position on ductility of hollow column is evaluated. The seismic behavior of high-strength centrifugally prefabricated reinforced concrete pipe columns of a practical engineering project is investigated through three 1:2 large-scale quasi-static tests. The influence of axial compression ratio and section form on their performance is evaluated. Based on the confinement effect in the high-strength centrifugally prefabricated RC hollow pipe columns, a modification to one of the most widely used confined concrete models is proposed. It can accurately predict the confined concrete behavior in the hollow pipe columns, and its accuracy is verified by numerical analysis. Finally, the hollow pipe columns are analyzed with the proposed modified confined concrete model and are subjected to different axial compression ratios. The results show that the confinement effect of single-layer transverse reinforcement on the core concrete of centrifugal prefabricated RC hollow pipe columns is not as good as that of solid pipe column, but if the neutral axis is controlled within wall of the hollow pipe columns by changing the axial compression ratio or other design parameters, they can show satisfactory ductility. [ABSTRACT FROM AUTHOR]

The quantification of uncertainty in civil structures poses a significant challenge in contemporary research due to the substantial computational demands involved. This study introduces an innovative approach for updating the finite element model (FEM) and quantifying uncertainties in civil structures through the synergistic use of variational autoencoder (VAE) and polynomial chaos expansion (PCE). Within this framework, the unknown parameters inherent to the structural FEM are represented as latent variables and can be effectively inferred through the VAE. These latent variables are modeled using a multivariate Gaussian distribution. In the proposed methodology, the PCE serves to approximate the log-likelihood function associated with the latent variables, facilitating the derivation of the analytic expression for the variational lower bound. By maximizing this variational lower bound, both the mean and standard deviation can be readily determined. To assess the accuracy and computational efficiency of the proposed technique, numerical analyses are performed on a cantilever beam and a steel pedestrian bridge. Furthermore, the effectiveness of the proposed approach is validated through its application to damage identification within a benchmark model. Significantly, the results indicate that the proposed method offers superior computational efficiency compared to the conventional VAE approach. Notably, the findings reveal that employing a high-order PCE is unnecessary; rather, a low-order PCE suffices for precise parameter identification. Consequently, the proposed methodology necessitates only a limited dataset for training to ascertain the PCE coefficients, thereby enhancing its practical applicability and efficiency. • A new variational inference approach is developed for uncertainty quantification of civil structures. • The posterior distribution of unknown structural parameters are represented by the multivariate Gaussian distribution. • The analytic form of the variational lower bound is derived. • PC expansion is used to represent the log-likelihood function and only low-order PC expansion is required. [ABSTRACT FROM AUTHOR]

In recent years, the rapid development of Internet of Things (IoT) technology has greatly advanced research in the field of structural health monitoring. IoT sensors equipped with microprocessors have the ability to process and analyze the collected data in real time, which reduces the data transmission for structural health monitoring and eases the burden of data analysis and processing in the monitoring system. This study proposes a novel IoT device for cable force monitoring and identification that incorporates 4 G and edge computing technologies. The IoT device is developed and designed based on Raspberry Pi 4B and includes a screen, a 4 G module, an acceleration data acquisition card, and a power supply module. To diagnose the status of the tension cable, the IoT device embeds the frequency domain decomposition (FDD) method and the vibration-based cable force identification method. By collecting and analyzing the acceleration signals of the bridge cable, the health status of the cable can be continuously monitored and evaluated. This paper provides a detailed description of the hardware design of the IoT device, the FDD method and the cable force identification method. The accuracy and feasibility of the IoT cable force identification device is verified through experimental studies conducted in the laboratory. In addition, a comparison is made between the data collected by the traditional acquisition system and the micro-electromechanical system (MEMS) sensor. The experimental results show that the IoT device can accurately identify the cable force with lower cost and higher convenience. • A novel IoT device is proposed for tension force identification and condition monitoring of bridge cable. • The tension force identification method and modal identification method are embedded in the IoT device. • The IoT device is capable of collecting vibration data and identifying the tension forces of bridge cable in real-time. • Two experimental verifications are presented. [ABSTRACT FROM AUTHOR]

• Tuned inerter damper is proposed to control the vibrations of adjacent bridge structures. • The control effectiveness of the proposed damper is compared with the conventional viscous dampers. • Tuned inerter damper can achieve the same control effectiveness with smaller damping coefficient than viscous dampers. • Vibration characteristic differences between adjacent bridges influence the control effectiveness. • Increasing the absolute stiffness of a bridge improves the control efficiency. This paper proposes using a tuned inerter damper (TID) system to mitigate the potential pounding and unseating damages between the adjacent bridge structures under severe earthquakes. The control effectiveness of the proposed method is investigated both in the frequency and time domains. For comparison, the models and responses of the adjacent bridge structures without control and controlled by the traditional viscous dampers that are modelled by a Kelvin system or a Maxwell system are also developed and calculated. The analytical results reveal that the TID system can achieve almost the same or even better control effectiveness compared to the conventional viscous dampers with a much smaller additional damping. The proposed method can provide a good alternative to control the excessive relative motions between the adjacent bridge structures. [ABSTRACT FROM AUTHOR]

• CFST embedded column-cap beam with UHPC grouted connection for high-intensity areas. • Experimental study on reliability and seismic behavior of CFST socket connection. • A model for evaluating the moment capacity of CFST socket connection. The seismic behavior of an embedded concrete-filled steel tubes (CFST) precast column-to-cap beam socket connection of a practical engineering project was investigated through 1:3-scale quasi-static tests. The precast column and cap beam was integrated by ultrahigh-performance concrete (UHPC) grouting to improve the interface bonding behavior and lateral constraint. The influences of embedment depth, socket forming method, and column section size on the cyclic response of the structure were evaluated. The experimental results revealed that when the concrete-filled steel tube (CFST) embedded depth is 1.0 times tube diameter, the specimens can obtain good strength and hysteresis performance. The socket hole formed by a steel pile can further promote the hysteresis performance of the cap beam-column joint, and the ultimate failure of the joint is the fracture of the column longitudinal rebar. A model for evaluating the moment capacity of the CFST socket connection was proposed and verified by the test results, which can be used in the preliminary design the proposed connection. [ABSTRACT FROM AUTHOR]

• Cracking mechanism of sleeve region was investigated. • Shear strength of precast columns with grouted sleeve connection was quantified. • Back-bone cure analysis model of precast columns with grouted sleeve connection was proposed. • The improved model was verified by experimental results. Precast columns are widely adopted in Accelerated Bridge Construction (ABC) due to its fast construction speed, environment amity and little interference to existing traffic. The bending behavior of precast columns with grouted sleeve connections under seismic effect has been widely studied. However, studies on the shear behavior of this kind of columns (for example, short columns under seismic effect) are limited, which restricts the application of ABC in seismic regions. This study proposes an approach for evaluating the shear cracking mechanism of sleeve region and the shear strength of precast columns with grouted sleeve connection. In this approach, the sleeve units and concrete units in the sleeve region are established according to the different stiffness between sleeve and concrete, individually. The cracking angle of membrane element of units is solved based on the Modified Compression Field Theory (MCFT). Thus, the crack developing diagram is drawn in light of the cracking range of units. An improved model for computing the shear strength of precast columns with grouted sleeve connection is presented by the predicted cracking method in this paper. A skeleton curve prediction method based on the principal compressive strain in compression zone has also been proposed and verified. In general, the improved MCFT method given in the paper is effective for predicting shear failure of precast bridge columns with sleeve connection. [ABSTRACT FROM AUTHOR]

• Seismic behavior of 1:3-scale UHPC-filled column-to-footing socket connection. • The difference of the cyclic response between the precast column and CIP column. • A FEM to consider the rotation effect of the column embedded in the footing. Accelerated bridge construction (ABC) has been paid great attention in China for the significant advantages compared with cast-in-place (CIP), such as higher construction speed, less environmental impact and structural members of higher quality. However, the reliability, durability and seismic behavior of the connection between prefabricated bridge column and the rest of the structure are primary factors that limit the application of the ABC in the moderate and high seismic zones. In this study, quasi-static experimental investigation of seismic performance of three 1:3-scale ultra-high performance concrete (UHPC)-filled socket reinforced concrete (RC) column-foundation connection specimens were conducted. A fiber-based finite element model is developed considering the rotation effect of the column embedded in the footing. The seismic behavior of the precast column specimens with UHPC-filled socket connection type was compared with that of CIP specimen. The experimental and numerical results show that the damage evolution, failure modes and hysteretic responses of the precast bridge column are equivalent with those of the CIP bridge column. Numerical analysis also validated that the finite element model(FEM) in this paper is adequate to predict seismic response of the precast column with UHPC-filled socket connection. The UHPC-filled socket connection is a reliable connection type in prefabricated column-foundation connection joint which is suitable for moderate and high seismic regions. [ABSTRACT FROM AUTHOR]

• Proposed a novel type UHPC filled double-column piers system with socket connection. • Carried out experimental investigation on the seismic performance and failure modes of the precast double-column piers. • Developed a 3D numerical model to accurate characterize the nonlinear behavior of socket connections double-column piers. The socket connection has been considered to be an effective connection for accelerated bridge construction (ABC) due to its promising advantages, i.e., higher construction tolerance rate, simpler connection method, easier quality control method, and better seismic performance when the socket depth is sufficient. To further facilitate the promotion of socket connections, a novel double-column piers system with socket connection was proposed, and the prefabricated piers and adjacent elements are connected using Ultra High-Performance Concrete (UHPC) grouting. Three 1:3 scale double-column pier specimens using novel type socket connection, ordinary grouted corrugated duct connection, and cast-in-place connection, respectively, were subjected to pseudo-static tests, aimed to compare the effects of connection methods on the damage development, failure mode, strain distribution, and seismic performance of the double-column pier. The test results indicate that all three double-column piers with three different connection forms exhibit good seismic performance, with the failure mode being the fracture of the longitudinal rebars of the piers. Compared with the piers fabricated with the other two connection forms, the piers with socket connection feature less residual displacement, and the damage is mainly concentrated at the bottom of the pier. Additionally, numerical analysis models were developed and validated for the socket-connected double-column piers to facilitate further research in this area. [ABSTRACT FROM AUTHOR]