Structural Behavior Of Bridge Research Articles

Bridge finite element model updating using stochastic vehicle-induced static response monitoring data

Finite element model updating (FEMU) is a frequent method for minimizing the differences between actual and predicted bridge structural behavior. However, static model updating for long-span bridges usually requires load tests to obtain the response under known static loads, which is costly due to long traffic interruptions. To offset this disadvantage, a static FEMU method based on long-term monitoring data is proposed to update the model in real-time by taking stochastic traffic loads with certain statistical characteristics as known static loads. First, the theoretical relationship between stochastic traffic flow statistical characteristics, static response statistical characteristics, and structural stiffness parameters is established. An objective function based on the probability characteristics of the long-term vehicle-induced response is constructed. Then, the FEMU process based on monitoring data is introduced, including the acquisition of the finite element model vehicle-induced response, the extraction of the actual vehicle-induced response based on the monitoring data, the selection of model updating parameters, and the application of the global-local parameter updating optimization method. Finally, the effectiveness of the proposed method is verified by applying numerical examples and real bridge examples to a long-span suspension bridge. It can be concluded that the proposed method can achieve FEMU based on long-term monitoring data, avoiding the inconvenience and large cost caused by load tests. The accuracy and efficiency of the model updating can meet the engineering requirements well through comparison with the result of the traditional load test method.

Transfer learning based bridge damage detection: Leveraging time-frequency features

Bridges are a crucial part of the transport infrastructure network, and their safety and operational conditions need to be ensured. An early warning of damage is valuable for condition-based maintenance to avoid costly consequence including structural collapse. Dynamic behaviour of bridge structures can be used as indicators for their health status. Machine Learning techniques allow high-dimensional connections between the structures’ vibrational responses and their state of health. In this research, a novel transfer learning-based approach is presented for identifying the location of damage in concrete bridges utilising the time–frequency characteristics from dynamic responses of the bridge under moving vehicles. Convolutional neural networks (CNNs) are used to extract discriminative features from the time-varying input data of vehicle-bridge interaction. Pre-trained CNNs are then fine-tuned for multiple damage classification tasks. The performance of the proposed method is evaluated by comparing it with a variety of pre-trained networks and optimized classification algorithms. Effects of the noise level, vehicle speed, and sensor location on the predicted results are also studied. The numerical results show that the proposed method can precisely locate the damage on concrete bridges using only a single sensor on the bridge deck. The method has valuable potential for practical application for localising the bridge structural damage with further fine-tuning using the field measurement data.

Identification of Nonlinear Behavior of Bridge Structures Using Time Series Analysis of Vibration Signals

ABSTRACT One of the most widely used linear techniques for solving damage identification problems and prediction of the system dynamic behavior is modal testing and analysis. However, most of real structures exhibit nonlinear behavior during their lifetime caused by a number of various reasons. The presence of nonlinearity in a structural system changes its dynamic characteristics; hence, the use of linear techniques is improper for prediction of the system behavior. In this paper, a vibration-based nonlinearity identification technique was proposed to identify early changes in a dynamic system prior to significant damages. This technique combines the time series Autoregressive Moving Average with Exogenous Inputs (ARMAX) modelling, probability theory, and Fuzzy C-Means (FCM) clustering algorithm to categorize the linear and nonlinear dynamic behaviors of a dynamic system. The technique aims to categorize the linear and nonlinear behaviors of a structure, when it is subjected to various levels of excitation source. To show the validity of the proposed method, a series of shake table tests was performed on a six-span steel truss bridge model. The bridge model was excited using different amplitudes of ground motion to control the nonlinearity degree of rubber-based supports. It can be concluded from the analysis results that the new vibration-based nonlinearity identification technique was able to identify nonlinear behavior of the bridge model once it was subjected to different levels of earthquake excitations. This algorithm was able to categorize the linear and nonlinear behaviors of the bridge model and define a specific threshold for different excitation sources.

Visual Multimedia Intelligent Computing System for Seismic Performance of Bridge Structure Based on Object-Oriented Technology.

In order to further promote the standardization of seismic performance design of bridge structures, one must ensure the quality of bridge design and improve design efficiency. First, based on the basic principle of the probabilistic pushover method, the randomness of the structural pushover curve is attributed to the randomness of plastic hinges. Second, the visualization of seismic performance of bridge structures based on the object-oriented technology is adopted. So that the randomness of seismic action can be considered in the analysis of seismic performance. Finally, the limit state equation of the seismic performance of the structure is used to evaluate the reliability of the seismic performance of the bridge in each limit state conveniently. The results show that the failure probability of the structure in each limit state is less than 0.5 under different basic accelerations from 0 to 0.4 g. The software method is simple in calculation and has a strong adaptability, avoiding the difficulty of seismic reliability analysis caused by large-scale simulation and large amount of calculation of traditional structures. Therefore, this method can be easily applied to the probabilistic analysis of seismic behavior of bridge structures under large earthquakes without evaporative deformation failure criterion.

Generalized Beam Theory deformation modes for steel–concrete composite bridge decks including shear connection flexibility

This paper proposes a procedure to calculate cross-section deformation modes for steel–concrete composite bridge cross-sections, including shear connection flexibility, within the framework of the Generalized Beam Theory (GBT). The proposed procedure is computationally efficient and makes it possible to (i) handle arbitrary (flat-walled) composite cross-sections, including complex configurations with several closed cells, (ii) consider the geometric offset between the steel and concrete mid-lines, which is essential in steel–concrete composite members, and (iii) automatically identify, separate, and hierarchize the deformation modes into physically meaningful sets, including a set of shear connection slip deformation modes. For illustrative purposes, the various deformation mode sets are determined for two representative cross-sections, namely a twin-girder and a box-girder with closed longitudinal stiffeners. These deformation modes are then employed to perform the structural analysis of simply supported decks, showing that very accurate results are obtained with a small number of deformation modes and that the modal decomposition of the solution provides in-depth insight regarding the bridge structural behavior.

Ground motion selection and modification evaluation for highway bridges subjected to Bi-directional horizontal excitation

Reinforced concrete (RC) highway bridges are primary lifeline infrastructures where accurate seismic structural analysis is essential to ensure the safety of bridges. The nonlinear seismic behavior of bridge structures generally exhibits distinct differences in the longitudinal and transverse directions, and thus studies on bi-directional ground motion excitation are needed. Performance-based earthquake engineering (PBEE) methodology explicitly takes into account uncertainties in hazard, structural response, damage, and loss estimation such that enables a comprehensive understanding of the structural performance in a probabilistic manner. For a given large ground motion scenario, this study takes advantage of the PBEE methodology (the first two stages of hazard and structural response) to develop a benchmark probability distribution of the seismic demands (PDSD) for a given bridge structure considering different assumed intercept angles of the input ground motions with the bridge longitudinal axis. The accuracy and reliability of the PDSD estimates from various ground motion selection and modification procedures for the purpose of future bridge designs are evaluated against this reference benchmark PDSD. Such an evaluation is conducted for several engineering demand parameters of three representative RC bridges in California.

Ensuring the reliability of the results of computer modeling of the behavior of bridge structures

It is noted that structural mechanics is developing in the direction of improving design schemes, allowing more correctly assess the stress-strain state of structures. One of the topical areas of improvement is the consideration of nonlinear behavior and spatial work of structures. Constructive and genetic nonlinearities are added to the geometric and physical. Attention is drawn to the problem of checking the correctness of design decisions, which are not always based on existing standards, but are justified by calculations of more correct, but also more complex calculation schemes, performed using powerful software systems. To solve this problem, the Glavgosexpertiza recommended making calculations for at least two certified, independently developed and tested in practice software systems, and conducting a comparative analysis of the results. The question that arose about which software systems to use, it is proposed to solve with the help of MIDAS/CIVIL (South Korea) and SOFISTIK (Germany) complexes that have proven themselves quite well in bridge organizations. The article provides a comparative analysis of the MIDAS/CIVIL and SOFISTIK software packages using the spatial calculation of a bridge structure as an example, and the results are also compared with the calculation using the standard methodology. For analysis, the span structure of the railway bridge was adopted, consisting of two main split trusses with a bottom ride, reinforced with longitudinal and transverse beams in the level of movement of the railway load, longitudinal and transverse ties combining the upper and lower truss belts. The main trusses of the diagonal system are reinforced with vertical struts and suspensions. In general, analysis of the calculation results shows that both software systems give fairly close values of the calculated values of forces and stresses, and the differences for individual elements do not exceed 13.90 %. The normative calculation method provides mainly overestimated in comparison with SOFISTIK PC results, and the excess can reach 53.73 % for longitudinal forces and 49.71 % for normal stresses. This difference is a consequence of the use of a flat design scheme in the regulatory methodology, which leads to an increase in the level of the acting longitudinal forces, transverse forces and bending moments. That is, the normative calculation for a number of elements of a bridge structure is, as it were, a margin of safety. In conclusion, the requirements are formulated for specialists involved in the calculation analysis and examination of project documentation.

Experimental verification of real behavior of bridge structures using proof-load tests

The aim of the paper is to point out the inevitability of the proof-load tests for the real and correct behavior of bridge structures in ultimate limit state and maximum allowable deformations in s...

Bi-axial Seismic Behaviour of a Bridge Structure with a Shape Optimized Metallic Damper

This study performs a structural analysis to determine seismic behaviour of bridge structures with optimally designed metallic damper absorbing earthquake energy. Since the metallic damper utilizes the plastic deformation of steel to reduce vibration of the structures, this optimized metallic damper can be more economic, reliable and sustainable than the conventional bridge dampers such as friction or viscous dampers. The considered earthquake loads applied to the structure is assumed to work on two-dimensional directions. Also, the shape optimization of metallic damper is purposed to perform ideally under those bi-axial earthquake excitations. The optimizing process is based on the calculation of dissipated energy by the damper through finite element analysis of ABAQUS and the SQP algorithm by MATLAB. The MATALB algorithm controls the alteration of the damper’s shape to maximize the amount of energy dissipation under the constraint of total mass of the damper. To evaluate the effect of the developed metallic damper using this optimized shape, this study applied the damper into a three-span bridge model and conducted earthquake analysis through SAP2000.

Structural behaviour of an all-composite road bridge

Fibre reinforced polymer composites have become an integral part of the bridge industry because of their versatility, high strength-to-weight ratio and enhanced durability. The novel idea of an all-composite structural system for road bridges has been proposed for the first time in Poland. The FRP bridge is a simply supported structure with 10.0 m long span and 7.66 m wide deck. The superstructure consists of four U-shaped girders bonded with sandwich deck slab, fabricated by means of a vacuum infusion. The bridge configuration, a finite element model developed for design and the proof test results are described in this paper. The test has shown that an all-composite bridge can meet the relevant strength and deflection design criteria. To develop an understanding of the long-term performance of the FRP bridge, a monitoring scheme utilizing distributed fibre-optic sensors was implemented to assess any changes in the bridge structural behaviour.

Experimental and finite element investigation of temperature distributions in concrete-encased steel girders

Summary The structural performance of bridge structures is temporal and is mainly controlled by the types of the applied loads. To continuously observe the structural performance of bridges, structural health monitoring sensors that include among many temperature sensors are used. The impact of nonuniform temperature distributions in bridge girders due to the environment thermal loads has been recognized by former researchers and bridge design codes. To evaluate these and other effects on the structural behavior of bridge structures, many field and experimental structural health monitoring studies were carried out. However, more researches are required to investigate the temperature distributions in other girder configurations. This work is directed to investigate the impact of air temperature and solar radiation on temperature gradient distributions in concrete-encased composite girders. For this purpose, an experimental concrete-encased steel girder segment was instrumented with thermocouples and other sensors. The experimental data recording continued for 6 months during the hot and cold seasons. Furthermore, a thermal finite element (FE) parametric study was conducted to investigate the effect of the girder size. The test results showed that the vertical and lateral temperature gradient distributions and the variation of the temperature gradients with time are controlled by the amount and location of the received solar radiations. The FE analysis showed that the daily temperature variations are higher in smaller girders, whereas the temperature gradients are smaller than in larger girders. Moreover, the FE results showed that the thickness of the girder's concrete members has an important impact on temperature gradients and temperature distributions.

Modal Analysis of Bridge Structure Using Finite Element Analysis

The objective of the research study is to model a bridge with four different material using ANSYS software and to perform a modal analysis of bridge problem. For all four materials eight node solid element is selected and meshing is done individually for each modal. The material property of each material is selected as per literature database in ANSYS software. The modal analysis in ANSYS is performed to obtain the natural frequency and mode shapes of bridge to avoid the resonance of the bridge. Broquet et al. (2004) describe in a paper the dynamic behavior of deck slabs of concrete road bridge. This research interesting in dynamic analyses of bridges. The finite element method was used to study the local dynamic effects of traffic actions on the deck slabs. Advanced numerical models were described and the results of a parametric study presented. The bridge was represented by a shell element model and the vehicle by lumped masses, assembled in a nonlinear damped system. Important parameters that influence bridge vehicle interaction were taken into account, to investigate characteristic properties of the dynamic behavior of the bridge deck slabs of concrete bridges and to deduce the distribution of dynamic amplification factors throughout the deck slab. The vehicle was excited by irregularities of the road surface, generated by using power spectral density function. Experimental studies (Wolek 1992) have indicated that present methods of analysis underestimate impact and, thus, the dynamic effect for many structures. Since so many variables play a significant role in the generation and control of the total response, it is essential that bridge designers develop a better understanding of the dynamic behavior of bridge structures and the physical characteristics and parameters that affect response. II. Material Properties The dynamic material properties for the road-bridge as well as for the adjacent ground are vital information for the study of the road-bridge. Parameters concerning the soil characteristics are taken from the database that was formed during previous studies which were aimed of ensuring adequate vibration levels. By choosing the parameters according to that database it was easier to equate the results with research made previously. The database enclosing material data for the studies also contains information about suitable parameters for concrete and other materials such as asphalt.In Table 2.1 the material parameters which are used in the modelling are displayed. The quantities displayed in Table 2.1 are the materials density ρ (kg/m3), Young's modulus E (MPa), Poisson's ratio v (−).

Structural behavior of non-symmetrical steel cable-stayed bridges

Despite of the growing number of built examples, the analysis of non-symmetrical cable-stayed bridges has not received considerable attention from the researchers. In fact, the effects of the main design parameters in the structural behavior of these bridges are not addressed in detail in the literature. To fill this gap, this paper studies the structural response of a number of non-symmetrical cable-stayed bridges. With this aim, a parametric analysis is performed to evaluate the effect of each of the main design parameters (the ratio between the main and the back span length, the pylon, the deck and backstay stiffnesses, the pylon inclination, and the stay configuration) of this kind of bridges. Furthermore, the role of the geometrical nonlinearity and the steel consumption in stays are evaluated.

Defects and Failures Influencing the Mechanical Performance of Bridge Structures

In the paper the most common defects and failures influencing the mechanical behaviour of bridge structures are analysed. Basic damage types are indicated and classified as well as some corresponding case studies are presented. The whole problem of the defect's development is described: starting from the most common threats to bridges, through damage cases representing some real, complete and often complex situations (usually including a number of basic defects), process of selected damage formation or failure occurrence up to possible post-failure behaviour scenarios and the final consequences of initial defects.The second part of the study concentrates on representation of the defects and failures in numerical models of bridge structures. A method of damage quantification and numerical description is given what enables its useful implementation in the models. Four basic parameters defining location, extent, intensity and degradation level of defects represent a sufficient set of data for description of a single damage type. A specific difference between various defects related to possible damage development scenarios is indicated. Several examples of damage cases represented in Finite Element models are shown and thoroughly commented. A special attention is paid to importance of history of each defect that usually raises a need to apply nonlinear type and appropriate initial conditions of the numerical analysis. Final conclusions on defects’ influence on the mechanical behaviour of bridge structures are given and effectiveness of numerical models’ application in representation of such an effect is evaluated.

Measurements of bridges' vibration characteristics using a mobile phone

ABSTRACTThis research presents an alternative way to perform a bridge inspection, which considers the dynamics parameters from the structure. It shows an experimental phase with use of a mobile phone to extract the accelerations answers from two concrete bridges, from those records is feasible to obtain natural frequencies using the Fast Fourier Transform (FFT).Numerical models with uses finite element model (FEM) allow to determine the natural frequencies from the two concrete bridges and compare with the experimental phase of each one. The final results shows it's possible to use mobiles phones to extract vibration answers from concrete bridges and define the structural behavior of bridges from natural frequencies, this procedure could be used to evaluate bridges with lower costs.

Seismic Analysis (Non-linear Static Analysis (Pushover) and Nonlinear Dynamic) on Cable - Stayed Bridge

Pushover analysis application development is greatly increased in recent years and numerous advanced methods to evaluate the seismic pushover are provided. Because these methods have been proposed mainly for building structures and given the fundamental differences between the behavior of bridge structures and buildings using pushover methods on the bridge structure with the uncertainties faced. 1. First, the effect of non-linear pushover results (time history) 2. Choose a target displacement due to the finite element model should be examined in order to understand the prediction of the seismic capacity. Thus a pushover analysis is presented for evaluation of seismic bridge pylons and deck where the effects of displacement and deformation of the plastic joints, structural changes in the modal characteristics of change used plastic forms and effects of higher modes can be seen clearly. The method is able to accurately approximate the dynamic response of the nonlinear analysis. Ultimately this method compared with analysis time history.

Detailed FE and DE Modelling of Stone Masonry Arch Bridges for the Assessment of Load-carrying Capacity

This paper reports on numerical modelling strategies for assessment of the load capacity of stone arch bridges based on realistic knowledge of the constituent material properties. Detailed micro-models based on FEM and DEM with suitable nonlinear behaviour of the bridge materials are used to evaluate the bridge structural behaviour under incremental static loading. Simplified modelling strategies based on rigid blocks analysis is also used for comparative purposes. Results of laboratory testing performed to characterize the deformability and strength parameters of the bridge materials (masonry and infill) are used to support the structural analysis. The study comprised four existing road bridges located in the North of Portugal. Experimental modal identification of the bridge cases has also been included in the study with the aim of updating and validating the bridge models.

Determination of structural behavior of Bosporus suspension bridge considering construction stages and different soil conditions

In this paper, it is aimed to determine the structural behavior of suspension bridges considering construction stages and different soil conditions. Bosporus Suspension Bridge connecting the Europe and Asia in Istanbul is selected as an example. Finite element model of the bridge is constituted using SAP2000 program considering existing drawings. Geometric nonlinearities are taken into consideration in the analysis using P-Delta large displacement criterion. The time dependent material strength of steel and concrete and geometric variations is included in the analysis. Time dependent material properties are considered as compressive strength, aging, shrinkage and creep for concrete, and relaxation for steel. To emphases the soil condition effect on the structural behavior of suspension bridges, each of hard, medium and soft soils are considered in the analysis. The structural behavior of the bridge at different construction stages and different soil conditions has been examined. Two different finite element analyses with and without construction stages are carried out and results are compared with each other. At the end of the analyses, variation of the displacement and internal forces such as bending moment, axial forces and shear forces for bridge deck and towers are given in detail. Also, displacement and stresses for bridge foundation are given with detail. It can be seen from the analyses that there are some differences between both analyses (with and without construction stages) and the results obtained from the construction stages are bigger. It can be stated that the analysis without construction stages cannot give the reliable solutions. In addition, soil condition have effect on the structural behavior of the bridge. So, it is thought that construction stage analysis using time dependent material properties, geometric nonlinearity and soil conditions effects should be considered in order to obtain more realistic structural behavior of suspension bridges.

Comparison and calibration of numerical models from monitoring data of a reinforced concrete highway bridge

The last four decades were important for the Brazilian highway system. Financial investments were made so it could expand and many structural solutions for bridges and viaducts were developed. In parallel, there was a significant raise of pathologies in these structures, due to lack of maintenance procedures. Thus, this paper main purpose is to create a short-term monitoring plan in order to check the structural behavior of a curved highway concrete bridge in current use. A bridge was chosen as a case study. A hierarchy of six numerical models is shown, so it can validate the bridge's structural behaviour. The acquired data from the monitoring was compared with the finest models so a calibration could be made.

교각일체형 연속 PSC 거더교의 동적거동 특성 연구

건설환경의 지속적인 변화로 인하여 교량 건설비용의 최소화뿐만 아니라 공용기간중의 유지관리를 포함한 전체 비용의 최소화 및 최적화의 요구가 증가하고 있다. 이러한 이유로 교량의 상부구조에서 하부구조로 힘을 전달하기 위해 사용되는 교량받침 대신에 스터드나 연결철근 등과 같은 연결재를 사용하여 교량의 상부구조와 하부구조를 라멘식으로 일체화 시킨 교량형식이 제시되고 있다. 이 논문은 교량의 상부구조 형식을 연속 UD PSC 거더로 하여 철근콘크리트 교각과 일체화 시킨 교각일체형 연속 UD PSC 거더교를 대상으로 한다. 교각일체형 연속 UD PSC 거더교는 라멘교 형식과 거더교 형식을 결합한 교량으로 일반 받침형식의 교량과 상이한 거동특성을 나타낸다. 하지만 거동 특성에 대해 명확히 규명되어 있지 않다. 따라서 본 논문에서는 해석적 방법을 이용하여 교각일체형 연속 UD PSC 거더교의 동적거동 특성을 분석하고 2, 3경간 교각일체형 연속 UD PSC 거더교에 적용할 수 있는 충격계수 산정식을 제시하였다. Recently, the construction industry has been changed in such a way that the cost for bridge construction should be optimized or reduced. Therefore, bridges are required be cost-effective in terms of initial construction as well as in the maintenance during service stage. In order to reduce the cost for bridge construction, the Rahmen typed structure, in which the bridge components from superstructure to substructure are integral, has many advantages to reduce the size of structural members including girders, since the loadings from superstructure may be transferred to substructure through the connecting rebars such as stud, etc. This paper studied on the continuous Up and Down Prestressed Concrete (UD PSC) girder bridge in which the reinforced concrete pier cap is integral with the part of girders in superstructure. In previous studies, it is known that the structural behavior of continuous UD PSC girder bridge is quite different compared to the one of the bridges with conventional bearings or shoes to support the loading from girders. Nevertheless, it has hardly been studied about the structural behavior of bridge with UD PSC girder. Therefore, in this study, various dynamic behaviors of continuous UD PSC girder bridge with integral pier cap have been analyzed using numerical method. Furthermore, an equation to evaluate the impact factor is suggested for the UD PSC girder bridge which has two to three continuous spans.