Steel-concrete Composite Girder Research Articles

Temperature field characteristics of railway steel-concrete composite girger with different pavement layers

The temperature distribution in steel-concrete composite girders is complex, existing specifications and studies for temperature gradients in such girders are inadequate as they fail to fully account for the influence of track slabs and ballast. Therefore, this study takes into consideration the effects of laying track slabs and ballast and conducts temperature field experiments on steel-concrete composite girders. A finite element thermal analysis model was established and validated by the experimental data, and the effects of track slabs, ballast thickness, and wind velocities on the temperature field is analyzed. Results show that ballast and track slabs with a thickness of 40 mm exert similar effects on temperature field of girder. Compared to an uncovered composite girder, they change the temperature distribution of the concrete slab from a reverse "C" curve to a top-to-bottom decreasing trend under cooling and from a top-to-bottom decreasing trend to uniform distribution during heating, increasing vertical temperature difference in concrete slab by 4 °C when cooling 15 °C. Interestingly, the steel-concrete interface exhibits temperature differences during all test conditions. The temperature gradient curve observed in the steel-concrete composite girders with railway pavement layers in this study reveals substantial deviations from the temperature gradient curve stipulated by existing bridge design codes. Parameter analysis reveals that, as wind velocities increase, the maximum vertical temperature difference decreases, and the thickness variation of the railway pavement layer within the range of 30–50 mm was found to have no discernible effect on the temperature gradient of composite girder. This study provides reference for research on temperature gradients in railway steel-concrete composite girders.

Push-Out Analysis on the Shear Performance of a New Type of Bellow-Sleeved Stud

For continuous steel–concrete composite girder bridges based on the post-combined method, the conventional rectangular group studs contribute to the isolation of the steel girder and the concrete slab before prestressing, leading to the majority of prestress forces being introduced to the concrete slab. However, rectangular-group stud holes cause the prestress forces to be unevenly distributed. In this study, a new type of bellow-sleeved stud (BSS) was developed to mitigate the weakening effects of rectangular group stud holes on the slab. A steel corrugated sleeve with a diameter of 60 mm was employed to cover the stud, which served as an internal formwork to prevent the concrete from bonding with the root of the stud. After prestressing was complete, the steel sleeve was filled with ultra-high-performance concrete (UHPC) to create a reliable combination between the concrete slab and the steel girder. To investigate the shear performance of this new type of connection, eight push-out test specimens were designed, and finite-element models were built. This study drew a comparison between the BSS and the ordinary headed stud (OHS). The research findings suggested that the BSS is subjected to less bending–shear coupling and offers a 4.5% increase in shear strength and a 31.9% increase in shear stiffness compared with the OHS. The study also analyzed the structural parameters influencing the shear performance of the BSS. It is found that the steel sleeve of the BSS has a negative effect on shear performance, but this can be mitigated by infusing high-strength material into the sleeve. Furthermore, the study examined the effect of construction quality on shear performance and suggested that sleeve deviation and grout leakage considerably reduced the shear performance of the BSS. Accordingly, strict control over the construction quality of the BSS is necessary.

Fatigue performance of stud connectors in joints between top slabs and steel girders with corrugated webs subjected to transverse bending moments

Steel-concrete composite box girders with corrugated steel webs (CSWs) are broadly used in bridge engineering, in which the joints between top RC slabs and steel girders with CSWs are usually subjected to transverse bending moments caused by off-center vehicle loads. Stud connectors arranged in the joints usually bear repeated pull-out forces in this case and are prone to fatigue failure. Therefore, two reduced scale joints between top slabs and weathering steel girders with CSWs were designed and tested, on which variable amplitude fatigue loads were applied to investigate the fatigue performance of studs incorporated in the joints. The two joints presented similar fatigue behavior, i.e., cracks of not more than 0.26 mm in width appeared on the surface of the top slab during the fatigue loading, and the separation of the top RC slabs and the top girder flanges was observed; meanwhile, minute cracks developed along the welds connecting the CSW with the bottom girder flange, and the stiffness of the joints gradually decreased due to the accumulation of fatigue damage. The two joints underwent 2,650,000 and 2,103,600 load cycles respectively before fatigue failure occurred. After partially demolishing the RC slabs, several welded head studs in the joints were observed fractured at the roots and detached from the top girder flange. Whereafter, finite element (FE) models referring to the test joints were developed and analyzed, and the effect of the wave height (WH) of the CSW and the transverse row spacing (TRS) of studs on the distribution of pull-out forces among studs was investigated. It showed that the pull-out force bore by each stud in the joint was distributed unevenly even in the same row. Then, a modification factor α was introduced to revise the pull-out forces of studs calculated in the theoretical method. An equation to determine the factor was fitted, considering the effect of the WH of the CSW and the TRS of studs. Finally, the detail category for studs bearing pull-out forces in the joints was discussed based on the experimental results and the collected test data, and it was preliminarily recommended studs subjected to pull-out forces can be classified into detail category 45 specified by Eurocode 3 in fatigue design.

Investigation of the Mechanical Features of Steel–Concrete Composite Girder Rigid Frame Bridges with V-Shaped Piers during Construction Stages

Steel–concrete composite girder rigid frame bridges with V-shaped piers are a new type of bridge structure. Based on the traditional composite continuous beam bridge, part or all of the vertical piers are changed into V-shaped piers. This special structure makes them have the mechanical characteristics of both composite continuous beams and V-shaped piers. In this paper, the finite element model of the first steel–concrete composite continuous beam V-pier rigid frame bridge in China is established by simulation software, the construction process of the bridge is simulated, and the stress and deflection of the bridge in each construction stage are studied. At the same time, the stress of the completed bridge model considering the construction stage is compared with that of the completed bridge model without considering the construction stage. It is found that the stress difference between the two concrete slabs is as high as 2.7 MPa. The results show that the stress state of the bridge is greatly affected by the construction process. This study can provide guidance for the design and construction of such bridges, which is of great significance.

Numerical simulation analysis of wind load on an integral bridge with steel-concrete composite girder based on cloud platform

The integral bridge with steel-concrete composite girder will be affected by wind load in the natural environment, so the buffeting effect of wind on the integral bridge with steel-concrete composite girder cannot be ignored. In order to solve the above problems, the numerical simulation analysis on the wind load on integral bridge with steel-concrete composite girder based on cloud platform is carried out. Before the buffeting analysis of the bridge, the wind environment condition should be calculated. Taking the integral bridge with steel-concrete composite girder as an example, based on empirical formula, the influence of girder size change on static wind load and static wind load under different wind speeds are calculated and analyzed. With the help of Davenport fluctuating wind’s power spectrum, the fluctuating wind field of integral bridge with steel-concrete composite girder under certain wind speed is simulated by harmonic synthesis method, the wind load value of integral bridge with steel-concrete composite girder is simulated, and the structural design of bridge is carried out, in order to ensure the scientificity and safety of bridge design. The numerical simulation can correctly react the test law, and can predict the wind resistance of the structure with the existing model.

Investigation on cracking performance of UHPC overlaid concrete deck at hogging moment zone of steel-concrete composite girders

Investigation on cracking performance of UHPC overlaid concrete deck at hogging moment zone of steel-concrete composite girders

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.

Structural Behavior of Steel-Concrete Composite Girders Composed of Demountable Shear Connectors

Structural Behavior of Steel-Concrete Composite Girders Composed of Demountable Shear Connectors

A multi-scale model-order reduction strategy for vibration analysis of coupled structures with local inhomogeneities

Although the wave finite-element method (WFEM) is an efficient numerical technique to analyze wave propagation characteristics and forced response of waveguides at medium and high frequencies, its application to large-scale and complex structures is still a challenge. In this paper, we introduce a model-order reduction (MOR) strategy for the WFEM to rapidly investigate the dynamics of coupled elastic systems involving one-dimensional waveguides with local inhomogeneities, such as steel bridges, fuselages and pipeline systems. The proposed method combines the advantages of mode-based component mode synthesis (CMS) and wave-based WFEM. A reduced modal basis is first established to describe the internal degrees of freedom using CMS. Subsequently, a reduced solution subspace considering the contribution of propagating and evanescent waves is constructed by the duality of Bloch’s formulations for the waveguide part, while wave scattering characteristics of the coupled element are used to quantify the influence of fixed-interface modes determined by CMS. Structural dynamic response can be then efficiently calculated using a dynamic stiffness matrix method. The performance of the MOR method in dispersion analysis and forced-response calculation is elaborately illustrated via an example of a steel beam with a diaphragm. The influence of the diaphragm on structural dynamic response is explained from the perspective of wave-propagation characteristics. Finally, the method is applied to a real steel–concrete composite girder, and the effects of the number and thickness of diaphragms on the vibration of each plate of the girder are discussed to provide some suggestions on vibration control.

Aerodynamic interference mechanism of vertical vortex-induced vibration of a ∏-shaped girder paralleled with a truss girder

In this study, the aerodynamic interference characteristics and mechanism of vertical vortex-induced vibration (VIV) of a ∏-shaped steel–concrete composite girder of a highway cable-stayed bridge and a steel truss girder of a railway cable-stayed bridge are investigated via experimental and numerical simulation methods, respectively. To this end, firstly, wind tunnel tests are conducted on section models with a geometry scale of 1:60, consisting of the ∏-shaped girder paralleled with truss girders to investigate their aerodynamic interference behaviors. Moreover, the fluid–structure interaction (FSI) approach based on dynamic mesh and user defined functions (UDF) is applied to study the wind-induced vibrations (WIV) of the single ∏-shaped girder and two parallel main decks for wind attack angle of 0°, respectively. Furthermore, the characteristics of vorticity, surface pressure, and vortex-induced force (VIF) distributions of the ∏-shaped girder and the truss girder are analyzed to investigate the aerodynamic interference mechanism. The results reveal that, the significant vertical vortex-induced vibrations (VIV) of the single ∏-shaped girder are observed, however, no obvious vertical VIV occurs for the single truss girder. Moreover, when the truss girder locates in the windward of the ∏-shaped girder, no obvious vertical VIV responses are observed. However, the ∏-shaped girder and the truss girder both exhibit significant vertical VIV responses for wind from the ∏-shaped girder side, and the maximum vertical VIV amplitude of the ∏-shaped girder is amplified by 32% compared with the single ∏-shaped girder. The vortices shed from the truss girder section disrupt the regular vortex shedding of the ∏-shaped girder section, thus suppressing the VIV of the ∏-shaped girder section. The WIV of the truss girder section is due to the forced vibration caused by the vortex impact of the dominant vortices shed from the ∏-shaped girder section. As the downstream flow field is blocked by the truss girder section, the scale and intensity of the dominant vortices is increased, leading to an amplification of the VIF and the VIV amplitude of the ∏-shaped girder section.

Numerical simulation on behavior of damaged composite girders repaired using CFRP sheets

This study investigated the behavior of corrosion damage-repaired steel–concrete composite girders with CFRP sheets using finite element (FE) analysis. The corrosion-induced damage in the girder was simulated by removing a cross-sectional area of 1480 mm × 4.5 mm from the top surface of the bottom steel flange at the midspan. Afterward, six-layer CFRP sheets were bonded to the underside of the lower flange with epoxy resin as a repair method. A reference model without damage was also considered. FE models of these specimens were established, and a nonlinear FE analysis was conducted. The FE models were validated using experimental results and then used to perform a parametric study considering the limited number of parameters: number of layers and elastic modulus of CFRP sheets. Comparison between experimental and numerical results revealed that the FE simulation could accurately capture the failure orders and predict the comprehensive behavior of CFRP-repaired steel concrete composite girders. Furthermore, an equation was proposed to predict the carrying load-carrying capacity of the CFRP-repaired steel-concrete composite girder. The proposed equation was used to calculate the targeted load-carrying capacity and showed closer values to the numerical results. However, more parameters are required to include in the equation for the rational design method.

Cracking control technique for continuous steel-concrete composite girders under negative bending moment

Cracking control technique for continuous steel-concrete composite girders under negative bending moment

Residual shear behaviour of steel-concrete composite girders after fire exposure: Experimental and numerical study

Steel-concrete composite girders are widely used for their superior mechanical performance. However, research on the shear behaviour of composite girders after fire exposure is limited. This study attempts to reveal the effects of high temperatures and cooling methods on the shear behaviour of composite girders. With heating temperatures (200 °C, 400 °C and 600 °C) and cooling methods (natural cooling and water cooling) as variables, 7 composite girders were designed. First, the composite girders were placed in the fire furnace and heated to simulate fire exposure. Subsequently, the residual shear performance of the cooled composite girders was tested and discussed. The test results show that there is a significant temperature gradient along the height of the girders during heating. High temperatures of no more than 600 °C have a more pronounced effect on the properties of concrete than steel, resulting in a progressive deterioration in the synergistic working property of the concrete slab and steel beam as the temperature increases. The deterioration of the shear performance of composite girders with natural cooling is similar to those with water cooling, probably due to the neutralization of the positive effect of water on the hydration reaction of concrete and the negative effect of the rapid reduction in temperature of the structure caused by water cooling. Further, finite element models of the composite girders were developed and thermal-mechanical coupling analysis was performed to simulate the effects of fire exposure. The parametric analysis conducted show that the steel beam web thickness is highly effective in enhancing the residual shear performance of the composite girders after fire, while the effect of the concrete slab width is relatively minor.

A Case Study Based Analysis for the Behaviour and Optimum Design of Steel Concrete Composite Bridge Girders

A Case Study Based Analysis for the Behaviour and Optimum Design of Steel Concrete Composite Bridge Girders

Post critical characteristics of a side-box steel concrete composite girder: Experimental investigation and mechanism analysis

The present study is aimed to investigate the post-critical behavior of a side-box steel-concrete composite girder under varying wind angles of attack, by conducting a series of section model testing with single-degree and two-degrees of freedom. The essence of flutter, as well as the adverse impact of vortex shedding lock-in on exacerbating post-critical flutter responses, was revealed in detail. The results indicate that the coupled motion of flutter for the prototype composite girder can be characterized as a supercritical Hopf bifurcation with significant phase shifting between motions. The circular character of the limit cycle oscillation (LCO) expressed in the phase diagram is altered to a non-circular form due to the apparent aerodynamic stiffness nonlinearity within a wide range of wind speeds. Interestingly, the coupling vibration between vortex-induced vibrations (VIV) and flutter, i.e., VIV-flutter coupling vibration is observed for the prototype girder, due to the evolution of total damping ratio concave shape with wind speed. Two mitigation countermeasures, i.e., a L-shaped skirt plate and a sharpened wind fairing, were proposed to improve the aeroelastic stability, caused by a significant increase in uncoupled positive aerodynamic damping and alternation of VIV-flutter coupling. In addition, the specific effects of structural damping on the VIV-flutter coupling were discussed in detail.

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.

Shear behaviours of steel-HSFRC welded stud and perfobond rib connectors under static push-out experiments

In this study, high-strength fibre-reinforced concrete (HSFRC) was introduced into steel–concrete composite girders owing to its high strength, good cracking, and impact resistance. Sixteen push-out specimens were tested to study the shear behaviours of the welded stud and perfobond rib connectors used in steel-HSFRC composite girders. The failure modes, load–slip curves, and shear behaviours of the push-out specimens were analysed and compared. The experimental results indicate that the shear capacity and stiffness of these two types of connectors are improved when they are used in steel-HSFRC composite girders, whereas the ductility of the welded stud and one-hole perfobond rib connectors decreases. The stud diameter has a significant effect on the shear behaviour of welded studs, unlike the stud length. The shear capacity of perfobond rib connectors increases with an increase in the perforating rebar diameter and hole number. The initial stiffness and ductility of perfobond rib connectors were larger than those of welded stud connectors with similar shear capacities. Finally, shear capacity prediction equations for welded studs and perfobond rib connectors embedded in HSFRC are proposed and verified to have good accuracy and applicability.

Serviceability Performance of Externally Prestressed Steel-Concrete Composite Girders

The behavior of externally prestressed composite beams under short term loading has been studied. A computer program developed originally by Oukaili to evaluate curvature is modified to evaluate the deflection of prestressed composite beam under flexural load. The analysis model based on the deformation compatibility of entire structure that allows to determine the full history of strain and stress distribution along cross section depth, deflection and stress increment in the external tendons .The evaluation of curvatures for the composite beam involves iterations for computing the strains vectors at each node at any loading stage. The stress increment determined using equations depended on the member deflection at points of connection. The stress increment determined using equations depended on the member deflection at points of connection. The proposed model results for load –deflection response are compared with experimental data taken from Auyyb's beams. For beams with straight tendon profile the average discrepancy reached 5.77%, 8.48% and 5.23% corresponding to the 0.25, 0.5 and 0.75 of the maximum load, respectively. For beams with the draped tendon profile, the average discrepancy of the analytical deflections values reached 15.5%, 5.8% and 6.45% corresponding to the 0.25, 0.5 and 0.75 of maximum load, respectively.

Fatigue test study of weathering steel-concrete composite beam under corrosive environment

In this paper, two sets of comparative fatigue tests on weathering steel-concrete composite girders were carried out in the context of steel-concrete composite girder bridges. The load-deflection relationship of the weathering steel-concrete composite girders under fatigue loading in different environments was investigated contrastively. The experimental results show that under the coupled effect of corrosive environment and fatigue load, the weathering steel still shows obvious corrosion; the simple fatigue load has no significant effect on the stiffness and fatigue modulus of the weathering steel-concrete composite beam, while the coupled effect of corrosive environment and fatigue has a significant weakening effect on the stiffness of the beam, and the weakening of concrete is apparently greater than that of steel beam.

Optimization of Construction Process and Determination of Intermediate Cable Forces for Composite Beam Cable-Stayed Bridge

This paper presents a comprehensive study of the Xiangsizhou Bridge, a double-tower double-cable steel–concrete composite girder cable-stayed bridge located in Pingnan, Guangxi, China. A finite element model of the full-bridge spatial truss system was established using a dual main beam simulation of the steel–concrete composite girder. To obtain the initial reasonable bridge state, the minimum bending energy method was employed, followed by optimization of the state using the unknown load coefficient method to attain the final reasonable completion state. This paper proposes an innovative construction scheme for the erection of the main girders, which is designed to address the issue of excessive tensile stresses in the bridge deck slabs that can arise in conventional construction schemes. This scheme can save about 4 months of construction time and shorten the construction cycle of main beam erection by 60%. Furthermore, the study derived and verified a formula for the intermediate cable force during the construction process, which demonstrated its effectiveness. This study provides practical value for the design and construction of similar bridges.