Steel-concrete Composite Box Girder Bridges Research Articles

Effective width of steel-concrete composite box girder bridges: a review and method comparison

Steel-concrete composite girders have non-uniform stress distribution on the slab, presenting maximum stresses next to the webs of the girder. This phenomenon is known as shear lag effect. To understand this effect, there is the effective width concept, in which only a portion of the slab width is considered effective in contributing to the composite element’s resistant capacity. However, in the technical standards, there is no recommendation for calculating the effective width in steel-concrete composite box girder bridges. In view of this situation, the purpose of this paper is to carry out a systematic review on effective width and/or the shear lag effect in steel-concrete composite bridges, in order to raise the main existing recommendations and compare them. Through a bibliometric scan with carefully chosen keywords, it was found that of all research on shear lag or effective width in steel-concrete composite structures, only 31.19 are on bridges and 14.97% are on bridges with box girders. Among the papers, those that have a method for calculating the effective width of steel-concrete composite girder bridges have been compared quantitatively and qualitatively with the procedures of AASHTO and EN 1994-2-2. In these procedures were also identified that the, for the boundary conditions of the present paper, the parameters that most influencing the effective width are, in that order, the span length, the distance between girders, the concrete slab height, the longitudinal position and the type of load.

Vibration Control of the Steel-Concrete Composite Box Girder Bridge with Slip and Shear-Lag Effects by MTMDs under the Train-Bridge Interaction

Steel-concrete composite girder bridges, in essence, are thin-walled structures, the dynamic responses of which will be greater than those of a typical Euler–Bernoulli beam under the train-bridge interaction because of the shear lag and interface slip. Thus, in this study, the dynamic analysis model of a train-composite box girder bridge-multiple tuned mass damper (MTMD) coupling system is proposed, with the derived dynamic equations of this time-varying system. Meanwhile, the program is compiled using the Newmark-β method for the solution, combined with the optimization toolbox to solve the complex optimization design problems of MTMDs involved. Finally, factors affecting the vibration-damping effect are studied, such as the mass ratio of MTMDs, the number of trains, and the slip and shear lag of the composite box girder bridge.

Dynamic Analysis of a Steel–Concrete Composite Box-Girder Bridge–Train Coupling System Considering Slip, Shear-Lag and Time-Dependent Effects

A dynamic computational program considering slip, shear-lag and time-dependent effects of composite box-girder bridge–train coupling system is firstly proposed based on the authors’ previous studies. In the program, the long-term vertical displacement of a composite bridge is firstly calculated. The calculated vertical displacement is then superimposed on the existing uneven track as the new excitation of the composite box-girder bridge–train coupling system to obtain the dynamic responses of the bridge–train coupling system. A 3 × 40 m simply supported steel–concrete composite box-girder bridge is selected to investigate the influence of its time-dependent behavior on its dynamic responses. The results showed that the time-dependent effect will amplify the dynamic characteristics of the composite box-girder bridge and the high-speed train. The maximum vertical displacement and acceleration of the composite bridge increase by 8.82% and 13.64%, and the maximum vertical acceleration of the train body increases by 144.78%. Additionally, the slip and shear-lag effects have an impact on the dynamic responses of the composite box-girder bridge–train coupling system at different operation times. The dynamic responses of the coupling system strengthen with the decrease in shear connection stiffness. The dynamic responses of the system may be underestimated when the shear-lag effect is not neglected. Therefore, these conclusions should be given sufficient attention in the design, construction and operation of high-speed railway composite bridges.

Lateral overturning process and failure mechanism of curved steel-concrete composite box-girder bridges under specific overloading vehicles

Curved steel–concrete composite girders are regularly adopted for use in ramp bridges in urban overpasses. As such, it is important that the lateral overturning stability of girders supported by single-column piers is analyzed. In order to comprehensively evaluate the lateral overturning mechanism of girders, this paper carries out a full-range nonlinear analysis of the lateral overturning process of a three-span curved steel–concrete composite box girder based on the explicit dynamic finite element (FE) method. According to the FE analysis results and actual forces acting on the structure, a new method for analyzing overturning stability considering the corresponding limit state is proposed. The results show that the overturning process can be divided into three stages: (i) small girder rotation; (ii) large girder rotation; and (iii) lateral displacement and overturning. The mechanical behaviors, overturning processes and failure characteristics of curved steel–concrete composite girders are similar to those of typical concrete box girders. However, some distinct characteristics, including the crawling behavior of girders and buckling of bottom plates, only exist in composite girders. The proposed overturning stability checking method is found to be more appropriate for determining the bearing capacity of girders on the ultimate limit state than the current design method described in the specifications (JTG 3362-2018). Some measures – such as setting lateral movement limiting devices, setting pre-eccentricity of supports and increasing the distance between supports which can considerably improve the lateral overturning stability of steel–concrete composite girders – are highlighted.

Temperature Field and Gradient Effect of a Steel-Concrete Composite Box Girder Bridge

To study the effect of the temperature field and gradient of a steel-concrete composite box girder bridge, a 5 × 35 continuous composite box girder bridge is used as the research object. The temperature measuring point is set by selecting a typical cross section, and the temperature change data are measured. The temperature field of the different positions in the composite box girder bridge is studied, the global and local temperature differences are compared, and the law of temperature distribution and the main factors affecting the temperature field are formulated. The most unfavourable expression function of the vertical temperature gradient of the section is simulated using the measured data, the existing standard temperature gradient mode is compared, the finite element model of the bridge is established, and the influence of the actual temperature gradient mode on the stress and deformation of the composite girder is further analysed. The conclusions show that the temperature differences of different azimuth sections and the local temperature differences between the steel and concrete joint parts of the steel-concrete composite box girder bridge are not significant. The temperature gradient heating and cooling model fitted by the measured temperature field can be used as a reference for the structural design of similar local bridges.

Numerical assessment of effective width in steel-concrete composite box girder bridges with partial interaction

This present paper aims to analyze numerically, through the Abaqus® software, the influence of the interaction degree (partial or total) on the effective width of steel-concrete composite box girder bridges. These structures present advantages such as greater torsional rigidity, construction and maintenance benefits, durability and aesthetic appeal. In the case of steel-concrete composite beams for buildings, the use of partial interaction design is a common practice. However, dimensioning of bridges with partial interaction is a less used method and is not even recommended by some regulations. Due to this reason, the influence of the steel-concrete interaction degree is investigated to evaluate the behavior of the composite section with partial interaction, since the dimensioning in such conditions would offer economic advantages. For this purpose, the effective numerical width of 120 models of steel-concrete composite box girder bridges was determined, the study variables being the degree of steel-concrete interaction, configuration of the cross section, height of the concrete slab, length of the longitudinal span and arrangement of elements in the cross section. It was verified that the effective numerical width is directly proportional to the slab height and the longitudinal span’s length. Furthermore, the greater the steel-concrete interaction degree, the higher is the effective width observed. However, in most models, the interaction degree no longer significantly influenced the effective width from the 60% interaction, at which the numerical effective width remained practically constant. Based on the analyses performed, an expression was proposed to calculate an effective width adjustment coefficient depending on the interaction degree in the design of steel-concrete composite box girder bridges with partial interaction, in order to compensate for the non-consideration of the steel-concrete interaction’s degree in the standard procedures and adjust the recommendations of I-girders for box girders.

Numerical evaluation of the slab effective width in steel-concrete composite box girder bridges

ABSTRACT: Bridges are structures built to overcome obstacles and allow continuity of transport routes. In the search for efficient construction systems, steel-concrete composite structures, especially box girder bridges, emerged. The American AASHTO and European EN 1994-2-2 standards present design procedures for this type of bridge, but there are still doubts about which portion of the concrete slab contributes to each web strength in composite section (effective width). The present paper aims to evaluate, by numerical analysis in the Abaqus® software, the concrete slab effective width and to verify whether the expressions for its calculation in composite I-girder bridges are valid for box girder sections. After analyzing the results, it was found that the standards recommendations for composite I-girder cannot be applied directly to box girders. Finally, based on the numerical analysis, an equation was proposed to calculate the effective width of steel-concrete composite box girder bridges.

Numerical assessment of effective width in steel-concrete composite box girder bridges

The present paper aims to determine numerically in the Abaqus® software the parameters that have the greatest influence on the effective width of steel-concrete composite box girder bridges. In the technical standards and in the literature, there is no specific recommendation for calculating the effective width in steel-concrete composite box girder bridge. As an alternative, the existing recommendations for steel-concrete composite I-girders are adopted. Therefore, in the absence of standards recommendations for steel-concrete composite box girder bridges, there is a need for an investigation into the distribution of stresses at the steel-concrete interface, because if the effective width was admitted incorrectly, may result in costly or even unsafe solutions. For this purpose, the effective numerical width of 160 models of steel-concrete composite box girder bridges was determined, in which the study variables were the configuration of the transversal section, the slab height, the span length and the elements arrangement in the cross section. After analyzing the results, it was proposed a recommendation to determine effective width of steel-concrete composite box girder bridges.

Pontes mistas de aço e concreto em seção caixão com protensão externa: procedimentos de cálculo e de projeto

<p class="Normal1">O presente trabalho tem o objetivo de apresentar os procedimentos de projeto e os aspectos construtivos de pontes mistas de aço e concreto em viga caixão com protensão externa. A associação entre aço e concreto tem sido uma solução eficiente para a formação de elementos estruturais mistos, gerando vantagens importantes, como dispensa de fôrmas e escoramentos; redução do peso próprio e do volume da estrutura; aumento da precisão dimensional; redução do consumo de aço estrutural e menor necessidade de proteções contra incêndio e corrosão nos perfis metálicos. Por sua vez, o concreto protendido caracteriza-se pela introdução na estrutura de solicitações opostas às das cargas decorrentes do seu uso, acarretando numa melhoria na resistência e em seu comportamento mecânico. Nesse contexto, as estruturas mistas de aço e concreto com protensão externa configuram uma ótima solução para vencer grandes vãos, atender às limitações arquitetônicas e para reforçar/recuperar estruturas metálicas ou mistas já existentes. Visto isso, e justificando-se na crescente demanda por técnicas construtivas e na necessidade de melhoria de infraestrutura do país, a investigação sobre novas tecnologias intentando-se o seu uso é de grande valia.</p>

Analysis of Shear Connector of Steel–Concrete Composite Box-Girder Bridge Considering Interfacial Bonding and Friction

Steel–concrete composite bridges consist of steel and concrete parts which are connected by shear connector such as the widely-used headed stud. Through the chemistry bonding, interface friction and mechanical action the two different materials parts are combined as a composite structure system. Because of the structural mechanism, longitudinal and lateral relative slip and normal separation between the concrete deck and steel girder flange will inevitably exist during the loading process. Further, the complex interface mechanical behavior causes difficulties with nonlinear numerical analysis. Multiple broken lines mode cohesive zone model considering bonding and friction is used in this paper to describe the tangent slip and normal crack of the interface. A zero thickness cohesive element was implemented via the user-defined element subroutine UEL in ABAQUS. Using this method, numerical simulation analysis of a two span composite continuous box-girder was carried out. Results showed load–displacement curves of the structure, relative displacement between the steel girder and the concrete slab interface, interface stress distribution, and internal force of shear studs. Discontinuous deformation numerical simulation has been realized, and effectiveness of the proposed method and accuracy of the program were verified. Although shear stress was assumed to be transmitted by shear connector in the design stage, interface bonding and friction resistance can affect the force state of the shear connector. Results of this study can be used for detailed analysis and evaluation of the composite box-girder bridge without the need to rely on the constitutive laws of shear connectors obtained from push-out tests.

Influence of local deck vibrations on the evaluation of the maximum acceleration of a steel-concrete composite bridge for a high-speed railway

European design standards have established an upper limit on the deck acceleration of the high-speed railway bridges, however the influence of local vibrations of the deck members is rarely considered when modelling the vibrational responses of bridges. To evaluate how the inclusion of local deck vibrations might influence predictions of the maximum acceleration, detailed measurements were taken from a steel-concrete composite box-girder bridge on the Italian high-speed railway, and a numerical model of the system was developed. Deck vibrations were measured during high-speed train passages at the maximum train speed of 374 km/h, and compared against a numerical model of the vehicle-bridge system. This analysis revealed that the maximum deck acceleration is 1.3 times greater than the acceleration of the bridge girders, because of the sixth- and seventh-order resonance between the deck’s local vibration modes and the structure with a train running at high speeds over 300 km/h. Moreover, when considering local deck vibrations in the numerical model, we found that the interaction between transient local rail deformations and the vehicle travelling on the rails can increase the acceleration of the deck through resonance.

Beam-Truss Model of Steel-Concrete Composite Box-Girder Bridges II: engineering application

This paper firstly presents the field tests of a straight and a curved composite continuous box girder bridges. Elaborate FE model and beam FE model are then built on the basis of achievements of the companion paper. According to the comparison of results among elaborate FE model, beam FE model and field test, testing coefficient of mid-span deflection is 0.5∼0.8, and that of stress is 0.6~0.9 for the elaborate FE model. Also good correlation of the calculation results between elaborate FE model and beam FE model can be observed with the relative errors within the range of ±10%. This and the companion paper propose the beam-truss model of composite box-girder bridges, then accuracy and adaptability are fully verified by amounts of numerical analysis. Conclusions drawn in these papers are helpful for design analysis of steel-concrete composite box-girder bridge.

Beam-Truss Model of Steel-Concrete Composite Box-Girder Bridges I: theory and calculation

In this paper, modeling strategy for member and section level is firstly established based on shear-flexible grillage theory cellular decks. In addition, modal analysis and static analysis under the dead and live load are conducted for composite simply supported and continuous box girder bridges, the alignment of which includes straight and curve. High accuracy and good applicability of beam-truss model of composite box-girder bridge can be verified due to good correlation of numerical results between elaborate and beam FE model. The research in this paper has laid the foundation for the further application of beam-truss models in the design analysis of actual composite box-girder bridge.

Load distribution for composite steel–concrete horizontally curved box girder bridge

A comprehensive numerical investigation is carried out to assess the load distribution mechanism of horizontally curved steel–concrete composite box girder bridges when subjected to loading recommended by Australian Bridge Design Code and American Association of State Highway and Transportation Officials (AASHTO). In this investigation, the effect of various parameters such as curvature ratio, span length, number of loading lanes and number of cells is considered. In addition, a convergence study is carried out to identify the appropriate bracing system so as to retain the maximum torsional rigidity of these structures. The numerical model is first validated with actual test results so that they can be adopted for an extensive parametric study with good confidence. The results obtained from the parametric study are used to determine load distribution factors for moment and shear of horizontally curved box girder bridges. It is observed that these load distribution factors according to AASHTO loads are considerably higher than those obtained from the loading recommended by Australian Bridge Design Code. Hence, it is not reasonable to use load distribution factor based on AASHTO loading guidelines for the design of these curved bridges subjected to Australian Bridge Design loading.

Analysis of Loading Test Research on a Steel-Concrete Composite Box Girder Bridge

In order to understand the overall mechanical characteristics of a steel-concrete composite box girder bridge, static and dynamic tests were carried out. According to the results of tests and calculations, its bearing capacity and working performance were evaluated. The results show that the stress and deformation at control cross-section of the bridge meet design requirements under the static load, the vibration frequency and impact coefficient consistent with the theoretical calculation results under the dynamic load.

Accurate FEM of Steel-Concrete Composite Box Girder Bridge for Damage Identification Based on Dynamical Experimental Study

Based on the results of experiment, this paper discusses about the updating and validation of accurate finite element model for damage identification of the steel-concrete composite box girder bridge. Taking a 5 meters long steel-concrete composite box girder bridge as the research object and the finite element model is established. By means of scale model test the updating of the accurate finite element model has been completed and validation is confirmed.

Composite Box Girder Bridge Behavior During Construction

Steel-concrete composite box girder bridges may have a flexible open box section prior to the placement of the slab. Excessive twist or distortion can arise under construction loading. Bracing systems are usually installed within the girder during construction to increase the torsional and distortional stiffness of the open section. The influence of these bracing systems on open box behavior is discussed using finite strip analysis results and a one-quarter scale girder model test data. Tie and distortional bracing were found effective in preventing distortion, with web stiffening found to be more effective than interior cross bracing. Horizontal bracing at the flange level was considered to reduce twisting of the section. This bracing can take the form of either torsion boxes or top chord bracing, both being effective. A torsion-bending analysis based on a rigid section behavior is discussed.

Bracing for composite box girder bridges

For steel–concrete composite box girder bridges, the steelwork is generally erected first and then the concrete deck cast. During construction the girder may be subjected to a variety of construction loads. If the girder is a flexible open section, and lacks distortional or torsional stiffness, the cross section will deform or twist excessively; such difficulties with box girder construction have been reported. Bracing systems should be installed to increase the torsional and distortional stiffness of the open section during construction. A finite strip analysis of the influence of bracing systems on open section box girders is presented and compared with test results obtained using a one-quarter scale model. With the analysis, the influence of ties, distortional bracing, torsion boxes, and top chord bracing on the behaviour of torsionally open box girders is examined. Simplified design methods are also presented whereby the bracing forces and the stresses arising from the distortion of the section can be computed. Key words: bridges (box girder), bridges (steel), box beams, torsional distortion, bending distortion, bracing, construction safety.

Live load field test on the Muskwa River Bridge

The performance of a steel–concrete composite box-girder bridge is examined through a series of live load field measurements. This paper describes the measurement program and the results obtained, as well as comparisons wherever possible between the observed values and those obtained from beam theory calculations and bridge code equations. It was found that the measured strains were generally much lower than the design values and that for bridges with asymmetrical cross sections, a beam theory calculation using bridge code live load distribution formulas can lead to nonconservative results.