Analysis Of Bridge Structures Research Articles

Prediction of bridge structure deformation and strain based on dynamic testing and intelligent algorithms

The field load test is a direct and effective method for evaluating the performance of bridge structures. However, existing bridge field static load tests are costly and inefficient; moreover, they obstruct traffic and cause unavoidable damage to the bridge structure. As an alternative the the static load test, a random model update method based on bridge dynamic load tests and the Bayesian inference is proposed in this paper. The bridge static load test results were predicted with a high accuracy. To speed up the Bayesian method to infer the posterior probability density of the updated parameters, the Gaussian process was used in place of the finite element model, and the Bayesian inference used the Markov chain Monte Carlo method based on the delayed rejection adaptive Metropolis algorithm. First, the parameters to be modified for the bridge structure analysis model were determined based on the global sensitivity analysis method. Second, a uniform design sampling method was used to establish the Gaussian process optimization model to update the random model of the bridge structure. Finally, a reinforced concrete truss arch bridge was used to verify the correctness of the static load results of the bridge predicted by the random model update method based on dynamic load testing and Bayesian inference. The research results reveal that the prediction results of the bridge static load test based on the dynamic load test and Bayesian inference method agree with the actual test results.

Thermal Stress Analysis and Fatigue Life Assessment of Bridge Structures under Multi-Physical Field Coupling

Thermal Stress Analysis and Fatigue Life Assessment of Bridge Structures under Multi-Physical Field Coupling

Static Mechanics and Dynamic Analysis and Control of Bridge Structures Under Multi-Load Coupling Effects

With the rapid development and wide application of large-span bridges, the problem of dynamics and safety control of bridge structures under multiple loads is becoming more and more prominent. To realize the dynamic analysis and mechanical control of the girder structure, this paper designs a new type of magnetorheological (MR) mechanical damper based on the mechanistic analytical method and establishes a coupled dynamics model of the vehicle-rail-MR mechanical damper. The simulation and validation results show that the error between the semi-analytical method and the finite element theory calculation results is only 1.0%, while the kinetic simulation is consistent with the measured frequency domain trend. The analytical results show that: After applying MR mechanical damper for mechanical control, the moment live load and shear values of side spans were reduced by 27.68% and 10.79%, respectively; and the maximum moment and shear values generated at the center pivot were reduced by 28.19% and 10.81%, respectively. After applying the mechanical damper, the stress distribution of the cable-stayed bridge is more balanced, and the maximum diagonal stress of the overall structure is reduced from 3.8 MPa to 2.9 MPa. After safety control, the root-mean-square (RMS) value of the mid-span displacement amplitude was reduced by 59.32% and the maximum value was reduced by 11.46%, which improved the stability of the girder dynamics. After mechanical control, the dynamic acceleration response of the beam within the span decreased between 2 and 8 seconds and increased between 8 and 10 seconds. The overall response fluctuated around −5 m/s2 with a relatively smooth trend.

Finite Element Analysis of Steel Truss Bridge Structure Based on ANSYS

With the rapid development of bridge engineering in China, steel truss bridge is widely used with many advantages such as clear force of the structure itself, easy to analyze, and low requirement for foundation. In this paper, the finite element analysis method is adopted to analyze the stress and deformation distribution of steel truss bridge on the platform of ANSYS, a large-scale finite element analysis software. In the static analysis, by applying the vehicle load, the operation mode of the structure is simulated, and the cloud diagrams of its displacement and stress are derived. The dangerous areas of the bridge are identified to provide a reference basis for the design of steel truss bridges.

Static Behavior Prediction of Concrete Truss Arch Bridge Based on Dynamic Test Data and Bayesian Inference

The field load test is a direct and effective method for evaluating the performance of bridge structures. However, the existing bridge static load tests on site are costly, inefficient, and obstruct traffic; moreover, improper loading may also cause some damage to the bridge structure. This paper proposes a random model update method based on bridge dynamic load tests and the Bayesian inference as an alternative to the static load test. The Gaussian process model was used instead of the finite element model to reduce the cost of model calculation. Furthermore, choose the Markov Chain Monte Carlo (MCMC) method based on delay rejection adaptive Metropolis algorithm for Bayesian inference to improve the speed of the Bayesian method inferring the posterior probability density of updated parameters. First, the parameters to be updated for the bridge structure analysis model were determined based on the global sensitivity analysis method. Second, a uniform design sampling method was used to establish the Gaussian process optimization model to update the random model of the bridge structure. Finally, a reinforced concrete truss arch bridge was used to verify the correctness of the static load results of the bridge predicted by the random model update method based on dynamic load testing and Bayesian inference. The results show that the predicted results of the bridge static load test based on the dynamic load test and Bayesian reasoning method have an excellent agreement with the measured results, and this method can effectively overcome the adverse effects of the existing bridge static load test.

Structural Stability Analysis of Bridge Structure Using FEA

In the current research, the dynamic analysis of bridge structure is conducted to determine the natural frequency and mode shape. The dynamic analysis is conducted using ANSYS FEA simulation package. The critical regions of high deformation and energy states are determined. The analysis revealed the presence of several dominant vibration modes, each associated with distinct deformation patterns and nodal patterns. These findings shed light on potential vulnerability zones and areas of concern that may be susceptible to resonance and excessive vibrations during bridge operation. Understanding these critical modes is vital for designing appropriate damping and vibration control measures to ensure the bridge's long-term stability and safety.

Numerical simulation analysis of load-bearing capacity at joints of symmetrical cantilever-assembled bridges based on the logistic regression model

Abstract Bridge joint bearing capacity analysis is difficult to fit the requirements of the era of big data. The traditional way of bridge-bearing capacity numerical analysis exists in the wave of digital development of big data information, the Internet of Things, and artificial intelligence technology like a wild development. The traditional way of under the problem: is efficiency, engineering analysis is not accurate, data information paper, work responsibility is not in place, technical equipment, etc. This paper revolves around the numerical simulation analysis of the load-bearing capacity at the joints of symmetrical cantilever-assembled bridges based on the logistic regression model by finding literature to understand the concept and algorithm of the logistic regression model, construct logistic regression model based on dichotomous dependent variable logistic regression algorithm, logistic regression model parameter estimation, logistic regression. The three aspects of the model evaluation index are studied. The numerical simulation analysis of the load-bearing capacity at the symmetrical cantilever joint based on the logistic regression model, the shear strength calculation at the bridge joint, and the bridge longitudinal bar slip deformation are calculated, respectively, and then the actual value of the bridge load bearing capacity is derived. Simulation in the bridge bearing capacity at 0kN, 5kN, 10kN, 15kN, 20kN, 25kN, and 30kN, the model algorithm evaluation index under the three indicators of prediction rate, accuracy, deviation of the verification analysis. The results show that the prediction rate of the logistic regression model algorithm based on the load carrying capacity up to 30kN is 84%, the accuracy rate is 94%, and the deviation is 11%, and the three index values have better performance compared with the one-dimensional linear regression model algorithm and the multiple linear regression model algorithms. This study is beneficial to extend the bridge structural analysis function and make the bridge load capacity assessment more automatic; it can facilitate the comparison of historical data of bridge tests, longitudinal change of indicators at different testing time points, and grasp the current situation and change trend of bridges. Thus it is of great historical significance to the development of the Chinese bridge infrastructure industry.

Normalising flow-based vehicle load modeling for bridges

Accurate vehicle load modeling is critical to the maintenance, reliability analysis and safety assessment of bridge structures. The weigh-in-motion (WIM) system is usually used to archive actual vehicle load by recording vehicle load variables including the number of axles, axle weight, total weight, vehicle length, inter-axle spacing, and vehicle speed. However, modeling multidimensional vehicle load variables considering their correlations remains a challenge. Normalising flow, as a probability estimation method based on deep learning, models vehicle load variables as a multivariate distribution so that not only their marginal distributions but also their correlation structure can be captured accurately. This article proposed a normalising flow-based method to model the vehicle load for bridges. The normalising flow-based vehicle load model learns from the actual vehicle load variables by maximising their log-likelihood and generates new samples of vehicle load. With the proposed vehicle load model and headway information, stochastic vehicle flow can be established. The results of the WIM data from an actual bridge show that the proposed method can model the vehicle load variables accurately and the stochastic vehicle flow based on the proposed method can accurately reflect the actual vehicle flow.

Probabilistic Seismic Sensitivity Analyses of High-Speed Railway Extradosed Cable-Stayed Bridges

It is known that the extradosed cable-stayed bridge, a hybrid bridge, possesses the virtues of both classic cable-stayed bridges and girder bridges in mechanical behaviors. In this paper, the sensitivity of seismic fragility demand parameters (SFDP) of a high-speed railway extradosed cable-stayed bridge is studied systematically along with the consideration of structural parameter uncertainty. Based on the probability distribution and correlation of random parameters, the Latin hypercube sampling method is adopted herein. The dynamic 3D finite element model of the employed bridge is established by using powerful and attractive OpenSEES nonlinear software. A nonlinear incremental dynamic analysis is performed to consider the randomness of structural parameters using sampling analysis. Some important conclusions are drawn indicating that the structural design parameter uncertainty predominantly has influence on the SFDP for fragility analysis of bridge structures. The design parameters of extradosed cable-stayed bridges are categorized and identified as primary, secondary and insensitive parameters. The high sensitivity parameters of extradosed cable-stayed bridges for fragility analysis include friction coefficient of bearing, concrete bulk density, damping ratio, peak compressive strength of confined concrete, component size and peak strain of confined concrete. Additionally, the strength and strain of unconfined concrete cannot be ignored. Furthermore, the uncertainty of structural design parameters fails to be responsible for the cable force responses due to larger girder stiffness. The structural design parameter uncertainty has a significant influence on the responses of extradosed cable-stayed bridges for seismic fragility analysis.

Viaduct and Bridge Structural Analysis and Inspection through an App for Immersive Remote Learning

Until now, in the design phase of infrastructures there has been a general tendency to “economize” the resources allocated to them. This modus operandi did not consider the installation of monitoring and control systems as an integral part of the infrastructure itself, not considering the high post-intervention costs. This work aims to show how the integration of immersive technologies, including Virtual/Augmented/Mixed Reality, combined with geomatics, survey and structural monitoring techniques can ensure a better visualization and understanding of the different contexts in which the managing bodies are required to guarantee maintenance interventions. In particular, the potential of an application, developed by the authors in Unity 3D, to help the managing institution is described. The app permits the user to explore infrastructures under inspection in a virtual environment. This makes all the information related to the infrastructure available and accessible through the 3D analysis (which is manageable in the app after a mesh edge reduction phase) exploiting the full potential of Mixed/Virtual Reality. The main ability of our application derives from the chance to easily use and integrate different techniques (3D models, information models for construction, VR/AR) allowing for the choice of different 3D models testing and performing their simplification and dimensional reduction. This makes the loading phase of the application faster and the user experience easier and better. The experimentation of the proposed methodology was conducted on a viaduct located in Reggio Calabria.

Study on the Basic Performance Deterioration Law and the Application of Lead Rubber Bearings under the Alternation of Aging and Seawater Erosion

Lead rubber isolation bearings are well-recognized as a common and effective means to mitigate the seismic responses of bridges. However, rubber isolation bearings used in offshore bridges are extremely vulnerable to the action of the alternation of aging and seawater erosion caused by weather conditions, wind, waves, and other factors. Meanwhile, the deterioration law and application of lead rubber bearings subject to the effect of aging and seawater erosion cycles are not clear. Thus, aging and seawater erosion cycles testing on both lead rubber isolation bearings (LRB) and rubber materials were carried out. The parameters for the Mooney–Rivlin model of the rubber material used in LRBs were determined and the time-varying law of basic performance of LRBs was obtained based on test results of LRBs and their rubber material. Then, the determined rubber material parameters were applied into the finite-element model of LRBs to verify the basic performance degradation law of the LRBs. Finally, the obtained basic performance degradation law of LRBs was substituted into the finite model of offshore bridges to investigate the impact of the property degradation of LRBs on their seismic performance. The time-varying law of seismic performance of offshore bridge structures was also studied based on finite element analysis. The results show that both the horizontal and vertical stiffness of LRBs increase with the alternating of aging and seawater erosion time, and the horizontal and vertical stiffness increase by 16.1% and 24.3%, respectively, during the 120-year service period. Additionally, the Mooney–Rivlin model parameters of the LRB rubber material are also significantly affected by the alternating of aging and seawater erosion. Additionally, the results also indicate the deterioration of LRBs has a great influence on the anti-seismic performance of offshore bridge structures. After 120 years of service of offshore bridge isolation bearings under the alternating of aging and seawater erosion, the maximum displacement of the pier top of the offshore bridges, the maximum bending moment at the pier bottom, and the maximum displacement of the rubber bearing increased by 14.2%, 6.6%, and 9.1%, respectively. The findings of this paper play an important role in the seismic behavior study and the life-cycle performance analysis of offshore traffic projects such as sea-crossing bridges in marine environments. At the same time, they also lay a theoretical foundation for the performance analysis of rubber isolation bearings and offshore bridge structures under the alternation of aging and seawater erosion cycles.

Potential bias of conventional structural seismic fragility for bridge structures under pulse-like ground motions: Bias evaluation and strategy improvement

Previous studies have highlighted the serious biases that may happen in probabilistic structural fragility analysis (PSFA) due to the ignorance of the effect of pulse period under pulse-like excitations. However, the distribution characteristics of the bias associated with structure-pulse damage parameters are less quantitatively investigated. This paper, therefore, focuses on the influence mechanism of the structure-pulse coupled period (defined by pulse period normalized by structural fundamental period) in PSFA and quantitatively describes the bias that occurred in different damage states. Meanwhile, the PSFA of ductile columns conditioned on two different groups of intensity measures are systematically presented and compared based on Artificial Neural Network prediction. Results reveal that the bias of PSFA, with the variation of the normalized period, can be divided into three different stages, including two ranges of normalized period overestimating structural damage probability and one interval indicating the underestimated condition. Additionally, significant biases (larger than 50%) have been frequently observed in the PSFA of structures with different fundamental periods under various damage states. Moreover, the formulas for quickly obtaining the interval that dangerously underestimates structural damage probability and bias modification factor are correspondingly proposed, which can provide a quite useful method and tool for fragility, risk, and resilience analysis of bridge structures in near-field regions.

Bridge Structure and Material Stability Analysis Using Monte Carlo and COMSOL 3D modeling

The reinforced concrete structure has the advantages of strong stability, small shrinkage and creep, but there are still some hidden structural dangers in reality. This study introduces the background of stability analysis, takes a truss bridge as an example, uses Monte Carlo simulation and COMSOL Multiphysics software to analyze structural stability, and finds out the relevant factors affecting the stability of the truss. Through calculations and comparison of hundred thousand simulations, the stability of the bridge is one of the most critical elements of a bridge and meets the criteria for bridge performance. In particular, the strength and elasticity of the concrete and steel reinforcement at high temperatures were analyzed. Results show that aggregate type, mixing ratio, curing conditions, heating parameters, and cooling state all contribute subtly to the properties of concrete. High temperature causes the concrete and steel strength decreasing, but normal living temperatures do not pose any threat to bridge structures. For elongation, the effect of temperature on the reinforcement is not obvioust.

Review on Comparative Analysis of PSC Box Girder Bridge and PSC Precast I Girder Bridge Structure

Abstract: Bridge is the structure that provide passage over an obstacle. There are different types of bridge structure base on material & geometric parameters, from which prestress concrete I girder bridge and box girder bridge are widely used for medium to long span rang. Box girder bridge are the bridge where the main beam consist of girder in hollow shape, where as in I girder bridge main beam consist of I-shape girder are used as main girder beam. In this review article study about dynamic analysis of PSC precast I-girder bridge and PSC box girder bridge for different parametric variation and different span range have been studied by various researchers. The parameters are geometric parameters, span range, mending moment, shear force, displacement, base shear, base moment, time period, natural frequency, and method of analysis based on different codes. On the above parameters base reaction, base moment, time period, natural frequency, absolute displacement and girder forces of bridge is essential and major concern for the analysis of bridge structure

Validation of the fault rupture-response spectrum analysis method for ordinary and seismically isolated bridges crossing strike-slip fault rupture zones

The fault rupture-response spectrum analysis (FR-RSA) method approximates the peak response of bridge structures crossing strike-slip faults by superposing the peak quasi-static and dynamic responses in the fault-normal and fault-parallel directions. The first part of this article aims to further validate the accuracy of the FR-RSA method for estimating the peak response of ordinary bridges crossing strike-slip faults. This is achieved by comparing results obtained from the FR-RSA method against nonlinear response history analysis (NLRHA) for two ordinary straight bridges under different fault crossing conditions. The effects of modal combination rule and number of modes on the peak response of the considered ordinary bridges are also examined. The second part of the article investigates the adequacy of the FR-RSA method for estimating the peak response of seismically isolated bridges crossing strike-slip faults. This is achieved by considering two seismically isolated bridges along with different fault crossing angles, fault crossing locations, and input ground motions and by comparing results obtained from the FR-RSA method against NLRHA. This investigation involves examining the effects of modal combination rule, number of modes, damping ratio, and mode type on the peak response of the considered seismically isolated bridges. The analysis results indicate that the peak responses of ordinary and seismically isolated bridges computed from the FR-RSA method are in good agreement with those obtained from NLRHA, thus demonstrating the adequacy of the FR-RSA method for the analysis of bridge structures crossing strike-slip faults.

Dynamic analysis of bridge structures under combined earthquakes and wave loadings based on a simplified nonlinear Morison equation considering limit wave steepness

Utilizing the traditional Morison equation to calculate wave forces in cylindrical structures is cumbersome, and there are currently few studies regarding the high-order nonlinear Morison equation. In this study, the traditional Morison equation is simplified, and the simplified second-order nonlinear Morison equation based on the Stokes second-order wave is derived. The correctness of the simplified Morison equation is verified, and the use of the stability point method to solve the second-order nonlinear wave force is proposed. Based on the simplified second-order nonlinear Morison equation, the nonlinear dynamics of bridge structures under the combined loadings of earthquakes and second-order nonlinear waves are investigated. The results indicate that the displacement and stress responses of the second-order nonlinear wave to the bridge structure are significantly greater than those of the linear wave. When under second-order nonlinear waves and earthquake loadings combined within bridge structures, earthquakes will significantly affect these bridge structures. The formula for the breaking wave force based on second-order nonlinear waves is proposed. The breaking wave force based on second-order nonlinear waves has a large load on the bridge structures, and it will induce a weak high-frequency effect. When under combined the second-order nonlinear breaking wave and earthquake loadings on the bridge structure, earthquakes will still play a major role.

Modal Analysis of a Steel Truss Girder Cable-Stayed Bridge with Single Tower and Single Cable Plane

The dynamic characteristics of bridge structures are important in wind stability analysis, seismic design, fatigue assessment, health inspection, and maintenance of bridge structures; however, the mechanical and dynamic properties of different bridge types are different. A long-span cable-stayed bridge has the advantages of large flexibility, long natural vibration period, low natural frequency, dense spectrum, and denser modal than those of general structures. In this paper, the dynamic characteristics of a cable-stayed bridge with single pylon and single cable plane in the maximum cantilever stage and the complete bridge are analyzed. The single-tower cable-stayed bridge has some unique characteristics, such as lower cost, and a more beautiful appearance, but its torsional rigidity is lower, which increases the risk of wind damage and earthquake damage. Therefore, a finite element analysis of this bridge in the maximum cantilever state is carried out, and the influences of the main components’ rigidity, the inclination angles of the stayed cables, the supporting conditions, and the locations of the auxiliary piers are analyzed for the sustainability of this type of cable-stayed bridge. The analysis results show that a cable-stayed bridge with single pylon and single cable plane has more flexibility, and that the lateral rigidity and torsional rigidity are smaller. Structure rigidity, dip angles of the stayed cables, and positions of the auxiliary piers all have significant influences on the dynamic characteristics of cable-stayed bridges.

Расчет мостовых конструкций из алюминиевых сплавов на выносливость

Introduction. The author has developed a method for the fatigue resistance analysis of bridge structures made of aluminum alloys subjected to polycyclic loading. The author suggests that this method should be introduced into the currently enhanced regulatory documentation focused on the analysis of highway bridges made of aluminum alloys. Materials and methods. The method is based on the results of integrated laboratory testing of a number of aluminum alloys 1915T, AD35 T1, 1565hM, EN AW-6082 T6 that have good prospects in terms of the production of bridge structures. Physical-mechanical and fatigue characteristics were identified in the course of the static testing of specimens of these alloys before the fatigue cracking at different values of the cycle asymmetry coefficient. The theoretical fundamentals of the method stem from the domestic research on the fatigue resistance analysis of steel structures and foreign regulatory materials on the fatigue resistance analysis of bridge structures made of aluminum alloys. Results. The reliability of the new method was verified in the course of static and fatigue testing of a full-scale pedestrian bridge made of 1915T alloy and orthotropic plates made of EN AW-6082 T6 alloy, designed by NRU MGSU and manufactured by the Russian plants GS-Reserve, KraMZ and Sespel using advanced innovative technologies of extrusion and friction stir welding. Discrepancies between the experimental findings and the results of the analysis, made pursuant to the proposed methodology, are within 5–20 %. Conclusions. The proposed method can also be applied to other types of structures made of aluminum alloys, such as tanks, pipelines, high-rise structures, and other items that are subject to multiple cyclic effects.

Data-driven structural condition assessment for high-speed railway bridges using multi-band FIR filtering and clustering

The monitoring data makes it feasible to inspect and assess the structural condition of bridges in real time. Among the diverse in situ data of high-speed railway bridges under varying operational environments, dynamic responses caused by passing trains can offer insight into the mechanical properties of the bridge structure. Based on the train-induced response features of influence line (IL) and dynamic load factors (DLF) extracted from raw measured data, a comprehensive data-driven approach is developed for structural condition assessment of high-speed railway bridges, which is applied to a long-span steel-truss bridge as a validation. Considering the sparsity of the train-induced static response in the frequency domain, the multi-band finite impulse response (MFIR) filtering is used to extract the train-induced response features. The features are clustered via the Gaussian mixture model (GMM), and the two-level objective for structural condition evaluation and degradation warning of bridges can be achieved through the dynamically updated clustering results and probabilistic models. The results demonstrate that (1) MFIR filtering can effectively reject abnormal or interfering data and accurately extract the train-induced response features, and (2) the intrinsic nature and laws of features can be revealed by GMM clustering, which provides a statistical premise for the reliability analysis of bridge structures.

Study on the Time-dependent Reliability of Corroded Reinforced Concrete Bridge Structures due to Ship Impact

The cumulative damage caused by chloride ion erosion to coastal bridge structures reduces the ship impact resistance of channel bridge structures and leads to changes in reliability of bridge structures on ship impact. It is of great theoretical and practical significance to study the performance degradation change law of corroded bridge structures and to evaluate the ship impact time-dependent reliability of in-service corrosion-damaged bridge structures. Based on the durability decay model of reinforced concrete structures in a chloride ion erosion environment, the time-dependent resistance analysis of bridge structures is carried out considering the reduction of yield strength of longitudinal reinforcement and hoop reinforcement in pile sections and the decay of compressive strength of protective layer concrete. Based on the study of the probabilistic model and parameters of random variables affecting the time-dependent reliability of ship-bridge collision, the typical damage modes of bridge structures under ship impact are analyzed, the time-dependent reliability analysis model of bridge structures under ship impact is established based on the structural damage criterion, the ship-bridge crash limit state functional function is given, and the time-dependent reliability analysis of ship-bridge collision is carried out based on the response surface method.