Finite Element Model Of Bridge Research Articles

Vehicle-induced fatigue damage prognosis of orthotropic steel decks of cable-stayed bridges

Orthotropic steel deck (OSD) in a long-span cable-stayed bridge is vulnerable to fatigue damage at the deck-to-rib (DTR) joints due to excessive vehicle-induced dynamic stresses. A framework for fatigue damage prognosis of OSD in long-span cable-stayed bridges is thus presented in this paper. The main features of the framework include hourly traffic loading simulation and prediction, multi-scale finite element bridge model, coupled vehicle-bridge system, mesh-insensitive equivalent stress responses at a DTR joint, response surface models for equivalent stress responses, OSD and pavement interaction, asphalt pavement temperature effect, fatigue test-generated S-N curve, and fatigue damage prognosis. To evaluate the feasibility of the proposed framework and to manifest the effects of pavement roughness, asphalt temperature, and vehicle transverse locations on fatigue damage accumulation, a real long span cable-stayed bridge is investigated as a case study. The results indicate that the developed framework is applicable and that the fatigue damage of a DTR joint is underestimated if the time-variant temperature of asphalt pavement and road surface condition are not considered but the fatigue damage is overestimated without consideration of variable transverse locations of vehicles.

Force analysis and research on bridge inverted siphon project in operating period

In order to study the stress and deformation distribution of the inverted siphon bridge project. The finite element method is used to analyse the force of the bridge inverted siphon in operating period, the finite element model of bridge inverted siphon structure is established according to the actual engineering conditions. The results show that, the stress change in the inverted siphon is mainly caused by internal water pressure, water pressure is an important load of inverted siphon structure design, the stress value of inverted siphon pipe inner surface is greater than that of outer surface, there was obvious stress concentration at the support of the inverted siphon, local reinforcement should be used in design.

Nonlinear flutter control of a long-span closed-box girder bridge with vertical stabilizers subjected to various turbulence flows

This study investigated the influence of different heights of upward vertical central stabilizers (UVCS) in flutter performance of long-span suspension bridges through developing nonlinear three-dimensional Finite Element (FE) bridge model using large-deformation beam elements with 14 degrees of freedom (DOFs). Using Runyang Yangtze River Bridge as a case study, the developed FE model firstly incorporates a nonlinear aerodynamic force model of the 2D closed-box girder with various UVCS, and the model predicted critical flutter wind velocities of the bridges were validated using wind tunnel testing results. A series of parametric studies were then carried out to study the aerodynamic performance of the bridge under different vertical intensities of incoming turbulence flow (Iw) by developing multi-variable non-stationary stochastic wind fields. The numerical results show that the installation of UVCS could not only modify from first-order to second-order symmetrical vertical oscillation configuration, but also change the coupled oscillation from the stable condition to the unstable limit cycle of flutter divergence. Furthermore, UVCS mainly governs the vertical DOF partication in the coupled bending-torsional oscillation of the bridge, while the increase of the height of UVCS results in a higher critical flutter wind velocity but a lower torsional frequency, particularly for the 1.1 m UVCS when Iw is over 2.84%.

Reconstitution of Static Deflections of Suspension Bridge Based on Inclinometer Data

Bridge deflection is a significant index reflecting the rigidity, overall stability, carrying capacity, and seismic performance of bridge structures. However, it is difficult to measure accurately, particularly for large-span bridges with complex deflection curves. Inclinometers are tentatively used in the deflection measurements of highway and railway bridges, and they have been found to be potential high-precision deflection measurement instruments. An effective inclinometer monitoring scheme was designed and used to monitor the static deflections of bridge, and an improved data processing method was proposed through using individual analytical solutions in this study. Based on that, analysis was done to explain why the “5 inclinometers” suggested by previous research is the best choice for the deflection test of the simple supported and the continuous beam bridge, which has not explicitly explained in the previous literature. Through the comparative study of the deflection calculation results of the bridge finite element model, inclinometer is applied to measuring the static deflection of a large-span suspension bridge for the first time, and it is found when the number of the instruments is enough and arrangement of the instrument is reasonable, the deflection of suspension bridge can be tested using inclinometer method. In order to reduce the number of test points and improve the deflection measurement precision, semi-span arrangement scheme of test points is proposed, which is applied in the static deflection test of the Jiangyin Yangtze River Bridge, and the error of static deflections is only 1.13% compared to GPS observations.

Structural Reliability Estimation with Participatory Sensing and Mobile Cyber-Physical Structural Health Monitoring Systems

With the help of community participants, smartphones can become useful wireless sensor network (WSN) components, form a self-governing structural health monitoring (SHM) system, and merge structural mechanics with participatory sensing and server computing. This paper presents a methodology and framework of such a cyber-physical system (CPS) that generates a bridge finite element model (FEM) integrated with vibration measurements from smartphone WSNs and centralized/distributed computational facilities, then assesses structural reliability based on updated FEMs. Structural vibration data obtained from smartphones are processed on a server to identify modal frequencies of an existing bridge. Without design drawings and supportive documentation but field measurements and observations, FEM of the bridge is drafted with uncertainties in the structural mass, stiffness, and boundary conditions (BCs). Then, 2700 FEMs are autonomously generated, and the baseline FEM is updated by minimizing the error between the crowdsourcing-based modal identification results and the FEM analysis. Furthermore, using 151 strong ground motion records from databases, the bridge response time history simulations are conducted to obtain displacement demand distribution. Finally, based on reference performance criteria, structural reliability of the bridge is estimated. Integrating the cyber (FEM analysis) and the physical (the bridge structure and measured vibration characteristics) worlds, this crowdsourcing-based CPS can provide a powerful tool for supporting rapid, remote, autonomous, and objective infrastructure-related decision-making. This study presents a new example of the emerging fourth industrial revolution from structural engineering and SHM perspective.

Structural Health Monitoring of the Scaffolding Dismantling Process of a Long‐Span Steel Box Girder Viaduct Based on BOTDA Technology

In this study, a distributed optical fiber sensing technique based on Brillouin optical time‐domain analysis (BOTDA) is used to construct a complete bridge health monitoring system by continuously laying distributed sensing fiber lines in a steel box girder. The bridge scaffolding dismantling process is monitored to study the variation of the strain distribution. Additionally, a bridge finite element model is built to simulate the bridge scaffolding removed condition, and the strain distribution of the long‐span steel box girder viaduct after scaffolding dismantling is compared with the measured values. This study provides a reference for monitoring the scaffolding dismantling process based on BOTDA technology.

Wind‐Induced Vibration Response of an Inspection Vehicle for Main Cables Based on Computer Simulation

This paper presents a simulation approach based on the finite element method (FEM) to analyze the wind‐induced vibration response of an inspection vehicle for main cables. First, two finite element (FE) models of a suspension bridge and a main cable‐inspection vehicle coupled system are established using MIDAS Civil software and ANSYS software, respectively. Second, the mean wind speed distribution characteristics at a bridge site are analyzed, and the wind field is simulated based on the spectral representation method (SRM). Third, a modal analysis and a wind‐induced vibration response transient analysis of the suspension bridge FE model are completed. Fourth, the vibration characteristics of the inspection vehicle are analyzed by applying fluctuating wind conditions and main cable vibration displacements in the main cable‐inspection vehicle coupled FE model. Finally, based on the ISO2631‐1‐1997 standard, a vehicle ride comfort evaluation is performed. The results of the suspension bridge FE modal analysis are in good accordance with those of the experimental modal test. The effects of the working height, number of nonworking compressing wheels, and number of nonworking driving wheels during driving are discussed. When the average wind speed is less than 13.3 m/s, the maximum total weighted root mean square acceleration (av) is 0.1646 m/s2 and the vehicle ride comfort level is classified as “not uncomfortable.” This approach provides a foundation for the design and application of inspection vehicles.

Wind-induced nonlinear behaviors of twin-box girder bridges with various aerodynamic shapes

Wind-induced nonlinear oscillations of twin-box girder bridges are very sensitive to the aerodynamic shape of the deck (i.e., slot width ratio (SWR) and wind fairing shape) due to the complicated flow characteristics around the bridge deck. This paper presents a fully integrated finite element (FE) model in time domain, involving a nonlinear aerodynamic force model and a bridge FE model, to allow the investigation of nonlinear oscillation behaviors of long-span twin-box girder bridges with various SWRs and wind fairing shapes. The parameters in integrated FE model were firstly identified by using CFD simulation, and then, the proposed model was validated by conducting wind tunnel testing using sectional models and full-bridge aeroelastic models. It demonstrates that the developed integrated model has the capability of simulating the nonlinear flutter behaviors of twin-box girder bridges with various aerodynamic shapes. Furthermore, the prediction results show that the wind fairing shape has significant impact on the degree of freedom participation in coupled oscillation and failure modes, as well as flutter performance of the bridges. In addition, there is an increase in amplitudes of the limit cycle oscillations with the increase in the SWR of the twin-box girder bridges, and the relationships between the bending-torsional coupled oscillation, failure modes, and SWR of the bridges with anti-symmetric wind fairings are opposite to those with symmetric wind fairings.

Research on extending the fatigue life of railway steel bridges by using intelligent control

This paper investigates the potential of a vibration control-inspired method towards extending the fatigue life of railway steel bridges. Based on coupled thermal-mechanical and vehicle-track analysis, both the residual stresses from welding and these from traffic on the bridge are obtained. Subsequently, a multi-scale approach with a shell Finite Element (FE) model of the whole bridge and a solid FE model of its critical joints is put forward. The equation of motion is established for the controlled bridge, equipped with a Magnetorheological-Tuned Mass Damper (MR-TMD) system, while the combination of excitation, welding and control effects is practiced through own-developed packages and commercial software sub-model routines. The framework is showcased for the study of the Poyang Lake Railway Bridge in China. After obtaining the controlled stress states at the critical welded joint, the fatigue crack initial life is evaluated by using the critical plane method and the linear cumulative damage theory. Simulation results indicate that the multi-scale modelling approach followed, meets the accuracy needs for capturing the cracking process of the welded joint with high computational efficiency. The MR-TMD system, even when moderately reducing the critical joint stress amplitudes, can improve substantially the overall bridge fatigue resistance over the uncontrolled structure.

Benchmark model correction of monitoring system based on Dynamic Load Test of Bridge

Structural health monitoring (SHM) is a field of research in the area, and it’s designed to achieve bridge safety and reliability assessment, which needs to be carried out on the basis of the accurate simulation of the finite element model. Bridge finite element model is simplified of the structural section form, support conditions, material properties and boundary condition, which is based on the design and construction drawings, and it gets the calculation models and the results.But according to the design and specification requirements established finite element model due to its cannot fully reflect the true state of the bridge, so need to modify the finite element model to obtain the more accurate finite element model. Based on Da-guan river crossing of Ma - Zhao highway in Yunnan province as the background to do the dynamic load test test, we find that the impact coefficient of the theoretical model of the bridge is very different from the coefficient of the actual test, and the change is different; according to the actual situation, the calculation model is adjusted to get the correct frequency of the bridge, the revised impact coefficient found that the modified finite element model is closer to the real state, and provides the basis for the correction of the finite model.

Aeroelastic Response from Indicial Functions with a Finite Element Model of a Suspension Bridge

The present paper describes a comprehensive analysis of the aeroelastic bridge response in time-domain, with a finite element model of the structure. The main focus is on the analysis of flutter instability, accounting for the wind forces generated by the bridge motion, including twisting as well as vertical and horizontal translation, i.e. all three global degrees of freedom. The solution is obtained by direct integration of the equations of motion for the bridge-wind system, with motion-dependent forces approximated from flutter derivatives in terms of rational functions. For the streamlined bridge box-girder investigated, the motion dependent wind forces related to the along-wind response are found to have a limited influence on the flutter velocity. The flutter mode shapes in the time-domain and the frequency domain are consistent, and composed of the three lowest symmetrical vertical modes coupled with the first torsional symmetric mode. The method applied in this study provides detailed response estimates and contributes to an increased understanding of the complex aeroelastic behaviour of long-span bridges.

Monitoring Bridge Dynamic Responses Using Fiber Bragg Grating Tiltmeters.

In bridge health monitoring, tiltmeters have been used for measuring rotation and curvature; however, their application in dynamic parameter identification has been lacking. This study installed fiber Bragg grating (FBG) tiltmeters on the bearings of a bridge and monitored the dynamic rotational angle. The dynamic features, including natural frequencies and mode shapes, have been identified successfully. The innovation presented in this paper is the first-time use of FBG tiltmeter readings to identify the natural frequencies of a long-span steel girder bridge. The identified results have been verified using a bridge finite element model. This paper introduces a new method for the dynamic monitoring of a bridge using FBG tiltmeters. Limitations and future research directions are also discussed in the conclusion.

Failure modes of a seismically isolated continuous girder bridge

Abstract Reliable estimates of the failure modes of basic facilities, especially the seismically isolated bridge, are required for almost any form of analysis used for the seismic design and retrofit of bridge. The Hong Kong-Zhuhai-Macau (HZM) Bridge (HZMB), a seismically isolated continuous girder bridge with six spans, is a sea-crossing bridge, which is now under construction and will connect the Mainland China, Hong Kong, and Macau. Because the bridge is located in a highly active seismic zone, it is essential to evaluate the seismic performance of this bridge, in particular of its failure modes. Based on this practical engineering, this paper investigated the failure modes of isolated continuous girder bridge subjected to strong ground motions by developed weighted rank sum ratio method, in combination with developed 3D finite element bridge models. Firstly, three-dimensional finite element bridge models are developed and assessed using the incremental dynamic analysis method. Due to the flexibility of seismic isolation, both bending and rotational stiffness of isolation bearings are taken into account in the analysis. In addition, the rotational angle of bearings is found to be sensitive to seismic analytical results of isolated continuous girder bridges. Then, it conducted the nonlinear dynamic analysis on the HZM Bridge under sixteen strong earthquake records. Further, statistically significant failure modes and the weakest failure mode of this bridge are identified through the weighted rank sum ratio method. It resulted that, the final failure modes of this isolated continuous girder bridge are presented at the isolation bearings on a part of middle piers, at the isolation bearings on the abutments, at the isolation bearings at a side pier, and at the bottoms of side piers, respectively. The results of the failure mode analysis would greatly assist engineers to establish effective strategies for performance enhancement and seismic retrofit of bridge in the future.

Nonlinear FE model updating of seismic isolated bridge instrumented during the 2010 Mw 8.8 Maule-Chile Earthquake

In this paper, nonlinear finite element model updating (FEMU) is performed to study the prediction accuracy of a state-of-the-art finite element (FE) model of a seismic isolated bridge (SIB). The seismic isolator model parameters are updated in two phases: using component-wise and system-wise FEMU. The isolator model parameter values estimated from 23 isolator component tests show a large scatter, and a poor goodness-of-fit (GOF) of the bridge response to the 2010 Maule Earthquake is obtained when most of those parameter sets are used for the isolator elements of the bridge FE model. In contrast, good agreement between the FE predicted and measured bridge response is obtained when the isolator model parameters are calibrated using the bridge response data recorded during the 2010 Mw 8.8 Maule, Chile Earthquake. The updated FE model is then used to reconstruct response quantities not recorded to gain more insight into the effects of seismic isolation during a strong earthquake.

A Case Study of Dynamic Response Analysis and Safety Assessment for a Suspended Monorail System.

A suspended monorail transit system is a category of urban rail transit, which is effective in alleviating traffic pressure and injury prevention. Meanwhile, with the advantages of low cost and short construction time, suspended monorail transit systems show vast potential for future development. However, the suspended monorail has not been systematically studied in China, and there is a lack of relevant knowledge and analytical methods. To ensure the health and reliability of a suspended monorail transit system, the driving safety of vehicles and structure dynamic behaviors when vehicles are running on the bridge should be analyzed and evaluated. Based on the method of vehicle-bridge coupling vibration theory, the finite element method (FEM) software ANSYS and multi-body dynamics software SIMPACK are adopted respectively to establish the finite element model for bridge and the multi-body vehicle. A co-simulation method is employed to investigate the vehicle-bridge coupling vibration for the transit system. The traffic operation factors, including train formation, track irregularity and tire stiffness, are incorporated into the models separately to analyze the bridge and vehicle responses. The results show that the coupling of dynamic effects of the suspended monorail system between vehicle and bridge are significant in the case studied, and it is strongly suggested to take necessary measures for vibration suppression. The simulation of track irregularity is a critical factor for its vibration safety, and the track irregularity of A-level road roughness negatively influences the system vibration safety.

Towards an efficient method of predicting vehicle-induced response of bridge

PurposeThe purpose of this paper is to present a practical and efficient iterative method for predicting vehicle-induced response of bridge.Design/methodology/approachThe vehicle-bridge interaction (VBI) problem is generalized mathematically and a computational algorithm for VBI is proposed. This method rests on an iterative procedure, which utilizes the whole interaction process for iteration. By this means, vehicle and bridge become totally uncoupled and are only linked by the contact force history. This method provides flexibility to choose simplified or refined vehicle and bridge models for the VBI problem, as well as open options for different commercial FEM software without specialized codes.FindingsThe method is verified through two numerical examples. The first example uses a simple 1D beam bridge model, which illustrates the procedure of this method and demonstrates its fast convergence in several iterations. The second example employs a realistic full 3D finite element bridge model, which shows that the method easily connects complex FEM bridge models in ABAQUS with a calibrated vehicle model in Matlab. The dynamic response of the bridge is reliably calculated within only a few iterations.Originality/valueThe proposed iterative method separates vehicle and bridge into independent subsystems in the computational process, thus providing more flexibility to utilize commercial FEM softwares. Its efficiency is realized through choosing the whole interaction force process for iteration, which considerably reduces the iteration steps.

Dynamic assessment of partially damaged historic masonry bridges under blast-induced ground motion using multi-point shock spectrum method

We studied the partial damage effects on historic masonry bridges exposed to blast-induced ground motion. For this purpose, a historic masonry bridge in Turkey was selected to estimate its shock spectral behaviour. In order to determine these results, first, various damage was created on the restored bridge finite element model. This damage was generally selected by searching for damaged historic masonry bridges in the literature. Various critical regions on an example bridge were detected and corresponding regions were removed from the restored finite element model. Thus, partially damaged historic masonry bridge models were obtained. Dynamic calculations of the bridge are presented by using the multi-point shock response spectrum method obtained from ground motions due to a blast load. Acceleration time histories of blast-induced ground motions are obtained depending on a deterministic shape function and a stationary process. Shock response spectra determined from ground shock time histories are simulated using a MATLAB-based BlastGM computer program developed by us. The frequency-varying shock response spectra are applied to each support of the two-span historic masonry bridge. The influences of various charge weights and distances from the charge centre are also investigated in the analyses. The results from the analyses demonstrate the importance of partial damage on the historic masonry bridge, blast-induced ground motion effects, and charge weight and distance from the blast centre.

Consideration of time-evolving capacity distributions and improved degradation models for seismic fragility assessment of aging highway bridges

This paper presents a methodology to develop seismic fragility curves for deteriorating highway bridges by uniquely accounting for realistic pitting corrosion deterioration and time-dependent capacity distributions for reinforced concrete columns under chloride attacks. The proposed framework offers distinct improvements over state-of-the-art procedures for fragility assessment of degrading bridges which typically assume simplified uniform corrosion deterioration model and pristine limit state capacities. Depending on the time in service life and deterioration mechanism, this study finds that capacity limit states for deteriorating bridge columns follow either lognormal distribution or generalized extreme value distributions (particularly for pitting corrosion). Impact of column degradation mechanism on seismic response and fragility of bridge components and system is assessed using nonlinear time history analysis of three-dimensional finite element bridge models reflecting the uncertainties across structural modeling parameters, deterioration parameters and ground motion. Comparisons are drawn between the proposed methodology and traditional approaches to develop aging bridge fragility curves. Results indicate considerable underestimations of system level fragility across different damage states using the traditional approach compared to the proposed realistic pitting model for chloride induced corrosion. Time-dependent predictive functions are provided to interpolate logistic regression coefficients for continuous seismic reliability evaluation along the service life with reasonable accuracy.

Minimizing noise effect in curvature-based damage detection

Damage detection is essential for condition assessment of serviceability and safety of bridges. Different methods have been developed for damage detection based on static or dynamic response of bridges, among which curvature-based method attracted more and more attention as it shed light on accurate detection of damage location. Although there are many investigations contributed to this method, few of them considered the effect of measurement noise and approaches to minimize noise effect. In this paper, effect of measurement noise is investigated in the curvature-based damage detection. An approach is proposed to minimize noise effect for practical application on realistic cases. To verify its reliability and efficacy, laboratory experiment is conducted on a beam specimen, and the measured displacement is used to identify damage with the proposed approach. To illustrate the applicability for realistic bridges, this method was applied to a detailed Finite Element bridge model which also considers effects of measurement noise. The results indicate the feasibility of this method in practical application on girder bridges.

A novel finite element model updating method based on substructure and response surface model

Combining the substructure finite element model updating method with the response surface model updating method, one novelty finite element model updating method of bridge structure is proposed for updating the finite element model of a certain combined cable-stayed suspension model bridge. In light of specific configurations and mechanical features for combined cable-stayed suspension bridge, substructures are partitioned and the updating design parameters which need to be updated are preselected. On the basis of the variance analysis, the updating parameters are determined by the parameter significance test. Samples of updating parameters are obtained by the homogeneous design method, and the corresponding structural responses are obtained by finite element analysis, finally the response surface model for each updating parameter is fitted and verified. The jointed objective function with the linear combination of fitness functions based on the natural frequency and the static displacement are introduced, and experimental data of the static and dynamic testing for the model bridge is adopted to update the design parameters by the genetic algorithm, then the minimization of the discrepancies between the measurements and the finite element model updating results are achieved. The experimental results show that the updated parameters obtained from the proposed method are reasonable and having a clear physical meaning, and the finite element model of bridge structure can be updated effectively by the proposed finite element model updating method.