Bridge System Research Articles

A method for suspenders tension identification of bridges based on the spatio‐temporal correlation between the girder strain and suspenders tension

AbstractIn the actual structural health monitoring system of suspension bridges, only part of suspenders tension can be monitored, but not all the suspenders tension can be obtained. To solve this problem, a method for suspenders tension identification of bridges based on the spatio‐temporal correlation between the girder strain and suspenders tension is proposed. By using actual monitoring data of vehicle loads, a spatio‐temporal correlation model of the girder strain and tension forces of all suspenders is constructed based on the combined application of stacked denoising autoencoder and convolutional neural networks‐long short‐term memory model, so as to realize the preliminary identification of suspenders tension. On this basis, by using the actual monitoring data of suspenders tension and the strain monitoring data obtained through the distributed optical fiber sensors, the delicate identification of tension forces of all suspenders is realized based on the error interpolation of preliminary identification results. The results of the example bridge show that the method in this paper can effectively identify tension forces of all suspenders of the suspension bridge, and identification results are more accurate than the method using only the monitoring data of suspenders.

Modeling and vibration suppression based on Nussbaum function for beam bridge with unknown control directions and unknown nonlinear time-varying actuator faults

In this paper, the modeling of the beam bridge system with in-domain control and the vibration suppression under unknown control directions, unknown nonlinear time-varying actuator faults and external disturbances are studied. The beam bridge with fixed ends can be regarded as Euler Bernoulli beam, which is a typical distributed parameter system. Firstly, the partial differential equation (PDE) model of the beam bridge is established according to Hamilton principle. Then, an adaptive in-domain control scheme based on Nussbaum function is designed on the PDE model to eliminate the vibration of the beam bridge. It is proved theoretically that all closed-loop signals are uniformly bounded under this control law, and the vibration of the system asymptotically converges to zero. The simulation results also prove the effectiveness of the proposed control scheme. What’ more, the modeling and control scheme presented in this paper can be applied to a class of systems similar to beam bridges, such as vibration suppression of the main beam of an overhead crane bridge.

Effect of Ground Motion Time–Frequency Non-Stationarity on Seismic Response of High-Speed Railway Simply Supported Bridge Based on Wavelet Packet Transform

Time–frequency non-stationarity is a ground motion characteristic which is frequently neglected in current seismic design and research. This paper studies its impact on the seismic response of high-speed railway simply supported bridge (HSRSSB). A method for generating time–frequency stationary earthquakes (TFSEs) and time–frequency non-stationary earthquakes (TFNSEs) using wavelet packet transform is proposed. A finite element model of a three-span HSRSSB is established using OpenSees. The seismic response is obtained through non-linear dynamic time history analysis, and the fragility curves of bridge components and system are calculated through incremental dynamic analysis. Finally, the reasons for the differences are analyzed by comparing the differences in seismic response of bridge, component fragility and system fragility under two groups of ground motion. The results show that the time–frequency non-stationarity of ground motion has an effect on the bridge response and fragility under strong earthquakes. TFNSE will lead to larger ground motion response, and the damage probability of bridge components and systems is higher. The reason is related to the damage and period extension of bridges under ground motion. Structures with prolonged period anti-seismic measures need to pay attention to this effect.

Damage mechanism and assessment of precast double-column bridge piers under blast impact

This paper aims to investigate the damage mechanism of precast double-column bridge piers under blast impact and propose a new damage evaluation method. The three-dimensional solid separation model of a pier column under explosion actions is established using ANSYS/LS-DYNA, and the accuracy of the numerical simulation method is verified by the existing experimental results. Subsequently, numerical experiments of the double-column bridge piers under explosions are carried out. The damage accumulation process and local failure mechanism are investigated with the analyses of the propagation of stress waves in concrete. In addition, the criteria containing residual bearing capacity and local damage are introduced in the damage assessment, aiming to evaluate the explosion damage degree of bridge piers comprehensively. The P-I (pressure-impulse) curves of precast double-column piers are established, based on the overpressure-impulse damage assessment method by Henrych’s empirical formula. The general evaluation process and method of double-column bridge piers under blast impacts are proposed and verified. The research results provide important insights and references for the anti-blast design of precast double-column piers and their bridge systems.

Impact of Variable Parameters of Expansion Joints and Bearing Supports on the Vehicle-Induced Vibration of Curved Girder Bridges

To study how varying the parameters of expansion joints and bearing supports (E-B parameters) affects the dynamic response of a coupled vehicle–bridge system for curved girder bridges, a dynamic response analysis method for the coupled vehicle–joint (bearing)–bridge system, which takes into account centrifugal forces, was proposed and verified. Subsequently, taking a continuous curved box girder bridge as the prototype, the influence of the E-B parameters on the vehicle-induced dynamic response of the curved girder bridge was explored. The results showed that the dynamic amplification factor (DAF) of the middle beam of the expansion joint (DAF-EJ) and the main girder of the curved bridge (DAF-MG) were both significantly influenced by the E-B parameters. When there were height differences between the middle beam and side beam in the EJ, the DAF-EJ obviously varied, and the DAF-MG increased. When the EJ was damaged, the impact effect of the vehicle on the bearing support increased. The DAF-EJ and DAF-MG both increased with the decrease of the vertical support stiffness of the bearing support. The DAF-EJ was greatly affected by the single-support void at the near-slit end of the lane. The DAF-MGs at the beam end, the 1/4 point and 1/2 point of the first span, and the 1/2 point of the second span, were significantly affected by the single-support void near the measuring point. Compared with the single-support void, the DAF-EJ and DAF-MG more significantly increased under the double-support void. Variation in the height difference of the EJ had a more significant effect on the DAF-EJ and DAF-MG at the beam end, while a vertical stiffness reduction in the bearing support had a more significant effect on the DAF-MG.

Monoterpenoid indole alkaloids from Alstonia scholaris and their Toxoplasma gondii inhibitory activity

Nine previously unreported various types of monoterpenoid indole alkaloids, together with seven known analogues were isolated from the stem barks of Alstonia scholaris through a silica gel free methodology. The structures of 1–9 were elucidated by spectroscopic data analysis, electronic circular dichroism calculations, and single-crystal X-ray diffraction. Compound 1 is a modified echitamine-type alkaloid with a novel 6/5/5/7/6/6 hetero hexacyclic bridged ring system, and 8 and 9 exist as a zwitterion and trifluoroacetate salt, respectively. The anti-Toxoplasma activity of all isolates on infected Vero cells were evaluated, which revealed that compound 14 at 0.24 μM displayed potent activity. This study expanded the structural diversity of alkaloids of A. scholaris, and presented their potential application in anti-Toxoplasma drug development.

A novel 3D train–bridge interaction model for monorail system considering nonlinear wheel-track slipping behavior

Variable speed operation of the train cause easily the wheel-track slipping phenomenon, inducing strong nonlinear dynamic behavior of the suspended monorail train and bridge system (SMTBS), especially under an insufficient wheel-track friction coefficient. To investigate the coupled vibration features of the SMTBS under variable speed conditions, a novel 3D train–bridge interaction model for the monorail system considering nonlinear wheel-track slipping behavior is developed. Firstly, based on the D’Alembert principle, the vibration equations of the vehicle subsystem are derived by adequately considering the nonlinear interactive behavior among the vehicle components. Then, a high-efficiency modeling method for the large-scale bridge subsystem is proposed based on the component mode synthesis (CMS) method. The vehicle and bridge subsystems are coupled with a spatial wheel-track interaction model considering the nonlinear wheel-track sliding behavior. Furtherly, by a comprehensive comparison with the field test data, the effectiveness of the proposed method is verified, as well as the reasonable modal truncation frequencies of the bridge subsystem are determined. On this basis, the dynamics performances of the SMTBS are evaluated under different initial braking speeds and wheel-track interfacial adhesion conditions; besides, the nonlinear wheel-track slipping characteristics and their influences on the vehicle–bridge interaction are also revealed. The analysis results indicate that the proposed model is reliable for investigating the time-varying dynamic features of SMTBS under variable train speeds. Both the axle load transfer phenomenon and longitudinal slip of the driving tire would be easy to appear under the braking condition, which would significantly increase the longitudinal vehicle–bridge dynamic responses. To ensure a good vehicle–bridge dynamics performance, it is suggested that the wheel-track interfacial friction coefficient is larger than 0.35.

Enhancing Seismic Damage Detection and Assessment in Highway Bridge Systems: A Pattern Recognition Approach with Bayesian Optimization.

Highway bridges stand as paramount elements within transportation infrastructure systems. The ability to ensure swift recovery after extreme events, such as earthquakes, is a fundamental trait of resilient communities. Consequently, expediting the recovery process necessitates near real-time diagnosis of structural damage to provide dependable information. In this study, a data-driven approach for damage detection and assessment is investigated, focusing on bridge columns-the pivotal supporting elements of bridge systems-based on simulations derived from nonlinear time history analysis. This research introduces a set of cumulative intensity-based damage features, whose efficacy is demonstrated through unsupervised learning techniques. Leveraging the support vector machine, a prominent pattern recognition algorithm in supervised learning, alongside Bayesian optimization with a Gaussian process, seismic damage detection and assessment are explored. Encouragingly, the methodology yields high estimation accuracies for both binary outcomes (indicating the presence of damage or the occurrence of collapse) and multi-class classifications (indicating the severity of damage). This breakthrough opens avenues for the practical implementation of on-board sensor computing, enabling near real-time damage detection and assessment in bridge structures.

A non-linear static analysis for the seismic design of single-span integral abutment bridges

Integral abutment bridges are characterised by a monolithic connection between the deck and the abutments. Because of this connection, the seismic behaviour of the entire structure tends to be controlled by its interaction with the surrounding soil, and especially with the approach embankments. To date, methods for the seismic design of this type of bridges are still characterised by substantial uncertainties, mostly because of insufficient understanding of the dynamic response of the soil–structure system. This paper provides a contribution to the interpretation of the seismic behaviour of integral abutment bridges, focusing on a single-span structural scheme that has been receiving significant attention in recent years. The dynamic interaction between the bridge and the soil is studied with global numerical models of the soil–bridge system developed in OpenSees and subjected to a variety of ground motions. The results of the dynamic simulations, interpreted also with the aid of a modal analysis of the system, are used to develop and finally validate a simplified design procedure. This procedure is based on the capacity spectrum method, aimed at evaluating the maximum deformation and internal forces in the structure produced by the longitudinal component of the seismic motion that typically dominates the design of integral bridges.

Shape memory alloy-reinforced UHPC tube confined bridge piers for enhancing the seismic resistance of highway bridges

Multi-span continuous highway bridges supported with reinforced concrete (RC) bridge piers may experience large permanent deformation after strong earthquakes. To overcome the limitations, an innovative UHPC tube-confined SMA reinforced bridge pier, i.e., shape memory alloy (SMA) replacing the steel rebars at the plastic hinge region and a prefabricated UHPC tube substituting the cover concrete, is proposed. To fully utilize the tensile strength of UHPC, the UHPC tube is embedded into the foundation. A performance-based seismic design procedure considering target residual drift as engineering demand parameter (EDP) is proposed to design this novel UHPC-SMA pier. The seismic responses of novel bridge systems supported by UHPC piers (Bridge II) and UHPC-SMA piers (Bridge III) are investigated and compared with reference bridge (Bridge I) having RC piers. The results indicate that both UHPC piers and UHPC-SMA piers are efficient in improving the seismic resistance of highway bridges. Compared with Bridge I, the prefabricated UHPC tube significantly decreases the residual deformation of Bridge II piers by 22.9 % as a result of the bridging effect of steel fibers. Due to the excellent self-centering property of SMA, the residual deformation of Bridge III piers decreases further by 57.8 % in comparison to reference bridge. The UHPC tube increases the low stiffness of bridge piers caused by SMA rebars at the plastic hinge region. The combination of UHPC tube and SMA can effectively prevent core concrete from severe damage with less dissipated energy of bridge piers.

Orthopalladated imidazolones and thiazolones: synthesis, photophysical properties and photochemical reactivity.

The reaction of Pd(OAc)2 with (Z)-5-arylidene-4-(4H)-imidazolones (2a-e) and (Z)-4-arylidene-5(4H)-thiazolones (3a-e) in trifluoroacetic acid results in the corresponding orthopalladated dinuclear complexes (4a-e, imidazolones; 11a-d, thiazolones) with trifluoroacetate bridges through regioselective C-H activation at the ortho position of the 4-arylidene group. Compound 4e, which contains an imidazolone substituted at 2- and 4-positions of the arylidene ring with methoxide groups and exhibits strong push-pull charge transfer, is an excellent precursor for the synthesis of fluorescent complexes with green yellowish emission and remarkable quantum yields. Breaking the bridging system with pyridine yields the mononuclear complex 5e (ΦF = 5%), while metathesis of trifluoroacetate ligands with chloride leads to the dinuclear complex 6e, also a precursor of fluorescent complexes by breaking the chloride bridging system with pyridine (7e, ΦF = 7%), or by substitution of chloride ligands with pyridine (8e, ΦF = 15%) or acetylacetonate (9e, ΦF = 2%). In addition to notable photophysical properties, dinuclear complexes 4 and 11 also exhibit significant photochemical reactivity. Thus, irradiation of orthopalladates 4a-c and 11a-c in CH2Cl2 with blue light (465 nm) proceeds via [2 + 2] photocycloaddition of the CC double bonds of imidazolone and thiazolone ligands, yielding the corresponding cyclobutane-bridging diaminotruxillic derivatives 10a-c and 12a-c, respectively.

Seismic performance of tunnel-building-urban bridge systems in soft clays

Seismic performance of tunnel-building-urban bridge systems in soft clays

Current Research Status of Cable Beam Anchorage System for Cable-Stayed Bridges

Current Research Status of Cable Beam Anchorage System for Cable-Stayed Bridges

Structural monitoring of a historic masonry bridge

Structural Health Monitoring (SHM) aims to develop autonomous integrated systems allowing inspection and detection of damage with minimal human intervention. It thus represents a process of implementing a damage identification strategy through which, by periodic observation of the structure, it is possible to arrive at an assessment of certain characteristics of the system, as well as to define its current state of health. The case study under consideration describes a new static and dynamic monitoring system of a five-arch masonry railway bridge, realized by a network of sensors installed according to a placement strategy. The general objective of monitoring is the acquisition of all the information concerning the current condition of the bridge and thus the structural behaviour under static and dynamic actions to ensure an adequate level of public safety. Any change in the dynamic characteristics over time is indeed an indicator of ongoing degradation in the structure, due for instance to material damage phenomena, or geometrical. The collected data are visualized in real time with the help of the Web Platform where various operating parameters including sampling rates, resolution, trigger thresholds, alarm thresholds, etc. can be set. The data are finally analysed following a scheduled plan or upon reaching pre-established alarm thresholds.

Digital Twin and Asset Management for Italian highways decision support towards scheduled maintenance, repair and rehab

This paper describes Sina’s current inventory and inspection system (SIOS) development with BIM (Building Information Modelling) applications and BMS (Bridge Management System) strategies towards an Asset Management system implementation. Procedures and data flows using Sina databases SIOS (Sistema Ispettivo Opere Sina inventory and inspection data, seismic vulnerability analysis database, etc.) as inputs supporting BIM modelling are described. Starting from a first project, which is currently being applied to an entire highway agency and which also envisages a later integration of tunnels, a BIM modelling procedure was developed to reach information models for an “inspection” “BIM USE”. Such information models, populated with the information necessary for bridge management system processing, have been connected to Business Intelligence tools to create dashboards supporting decision-making criteria based on management and maintenance approaches (Bridge and Asset Management System). In addition, for Asset Management development, the approach of decision-making tools, integrated with a multi-level approach of Italian Guidelines For The Classification And Management Of Risk, The Assessment Of Safety And The Monitoring Of Existing Bridges, can convey information flows to support criteria planning to choose routine and extraordinary maintenance and restoring interventions. The project illustrated in this paper shows how integrating technologies, methodologies, experience and knowledge must be supported by consistent information management towards companies’ digital transformation and asset management development as a decision-making tool based on enabling technologies.

New advanced monitoring systems of Bridges with Actionable Real Time Sensor Data

The reliability of structures and the preservation of the built environment are issues with a decisive role in the field of civil engineering as well as in the public eye. The existing heritage surrounding human beings is varied and fragile because of its inherent characteristics and the environment in which it is inscribed. These elements are found and emphasized when dealing with special facilities, by constitution and by public utility. This case study analyzes innovative approaches and IoT tools for defining an operational procedure for the proper Life-Cycle management of infrastructure works through a Digital Twin approach. This methodology provides key elements for the proper planning of structural rehabilitation and reinforcement strategies and techniques with innovative interventions and methods, starting with a careful investigation/monitoring campaign to assess its safety condition. This monitoring activity involves the assessment of the real robustness and safety of large structures by acquiring the general principles of signal analysis and the traditional technologies currently available for diagnostics and monitoring (accelerometers, inclinometers, deformometers, strain gauges, etc.). The case study under consideration monitoring activities go through a static type of monitoring that involves the acquisition of absolute and relative displacements, and through a dynamic structural monitoring that is based on the analysis of natural and traffic- induced vibrations using triaxial accelerometer transducers. The latter case of structural monitoring makes it possible to derive the dynamic properties of the structure and ensure the reliability of the finite element model; in addition, the variation in dynamic characteristics over time is an indicator of ongoing degradation in the structure due to damage phenomena. By means of a dense network of sensors (IoT devices) operating completely wirelessly that are able to communicate in real time through a LoRaWAN telecommunication technology, it is possible to create a digital, living and interactive copy in constant update of the physical object. In addition, the system includes implementation of a Real Time notification system called "recognized call," which consists of automatically making a phone call, to numbers specified by the managing body of the work, whose content includes indication of the location, type of alarm threshold, actions to be taken. The objective of this study is to investigate the possibility of using Digital Twin-based systems associated with structural health monitoring of infrastructure works through real-time data analysis.

Laboratory testing and model calibration of a crushed stone backfill in a geosynthetic reinforced soil wall

The objective of this study was to understand the effect of the choice of backfill constitutive models on the numerical simulation of a geosynthetic reinforced soil-integrated bridge system (GRS-IBS). The #89 material, a crushed angular granite stone, characterized by maximum particle sizes of 9 mm, was used for the reinforced backfill for the retaining wall. Consolidated drained triaxial tests were conducted at confining stresses of 48 kPa, 83 kPa, and 117 kPa. The average friction angle was 42 degrees. Two soil models (the linear-elastic perfectly-plastic and the Hardening Soil) were calibrated using the laboratory test results. The calibrated soil models were then used to model the reinforced backfill material in finite element simulations of the abutment. Results of the calculated vertical stresses at the instrument position showed reasonable agreement with the field measurement. The non-linear model predicted about twice the deformation (lateral displacement and bridge seat settlement) compared to the linear-elastic perfectly plastic model. Settlement results showed maximum values corresponding to 0.22% and 0.45% of the abutment height for linear-elastic perfectly-plastic model and Hardening-Soil model, respectively, which are less than 0.5% limit recommended by US FHWA, while the lateral displacements were 0.22% and 0.44% of the abutment height for linear-elastic perfectly-plastic model and Hardening Soil model, respectively, both less than the 1% limit recommended by the US FHWA.

Physics-informed artificial intelligence models for the seismic response prediction of rocking structures

Abstract The seismic response of a wide variety of structures, from small but irreplaceable museum exhibits to large bridge systems, is characterized by rocking. In addition, rocking motion is increasingly being used as a seismic protective strategy to limit the amount of seismic actions (moments) developed at the base of structures. However, rocking is a highly nonlinear phenomenon governed by non-smooth dynamic phases that make its prediction difficult. This study presents an alternative approach to rocking estimation based on a physics-informed convolutional neural network (PICNN). By training a group of PICNNs using limited datasets obtained from numerical simulations and encoding the known physics into the PICNNs, important predictive benefits are obtained relieving difficulties associated with over-fitting and minimizing the requirement for a large training database. Two models are created depending on the validation of the deep PICNN: the first model assumes that state variables including rotations and angular velocities are available, while the second model is useful when only acceleration measurements are known. The analysis is initiated by implementing K-means clustering. This is followed by a detailed statistical assessment and a comparative analysis of the response-histories of a rocking block. It is observed that the deep PICNN is capable of effectively estimating the seismic rocking response history when the rigid block does not overturn.

Effect of Water Immersion on the Seismic Isolation Performance of Castable Polyurethane Bearing

This study performs a 120-day water aging simulation on castable polyurethane (CPUE) bearings and tests them at 30-day intervals for vertical load-bearing performance and 100% horizontal shear performance. The results indicated that the CPUE bearings achieved full water aging after 120 days of water immersion. Besides, the vertical stiffness, horizontal shear stiffness, and equivalent damping ratio decreased by 10.3%, 16.8%, and 10.0%, respectively. Moreover, the study investigates the hydrolysis mechanism of CPUE bearings using Atomic force microscopy (AFM) and cross-linking density (NMR) tests. Subsequently, it develops models for unaged CPUE bearings (CPUE-un) and fully water-aged bearings (CPUE-aged), selecting unaged test results for CPUE-un and the test results from 120 days of water immersion for CPUE-aged. Within the study context, a representative high-pier continuous girder bridge serves as the basis for evaluating the effects of seismic conditions on the CPUE-un and CPUE-aged bearing bridge systems. The findings demonstrate that water-aged CPUE experiences significant material softening, with bearing deformations increasing by 14.99%, 34.06%, and 46.65% at 0.3, 0.6, and 0.9 g peak ground acceleration (PGA), respectively. The likelihood of damage to water-aged bearings increased under seismic influence, while the impact on piers was less pronounced. This research provides a valuable reference for the application of CPUE bearings in humid environments.

Calculation of pre-stressed cable-stayed steel bridge with intersecting cable stays/Berechnung einer vorgespannten Schrägseilbrücke aus Stahl mit sich kreuzenden Schrägseilen

Compared to other structural systems, cable-stayed bridges are marked by their exceptional architectural appeal. However, these bridges have several disadvantages – their deformability under asymmetrical or local loads the relatively significant mass of stiffening girder and the pylons. A successful way of stabilizing the bridge’s initial form could be using additional stay cables and additional pylons. The article discusses the calculation method of an innovative cable-stayed steel bridge system consisting of intersecting cables and additional intermediate pylons. The system’s behavior is analyzed under symmetrical and asymmetrical loading. The calculation method results are compared to the numerical analysis using the FEM software.