Composite Girder Research Articles

Numerical Modeling of Steel‐Concrete Composite Girders Exposed to Web Shear Buckling

AbstractAssessment of the structural behaviour of steel and steel‐concrete composite plate girders exposed to web shear buckling is essential when it comes to their implementation involving heavy loads and/or long spans. In this paper, numerical model of a benchmark steel‐concrete composite girder capable of capturing this phenomenon has been developed using the ABAQUS software. The developed finite element model, based on a series of large‐scale girders planned to be tested in the future, has been evaluated and elaborated on. That includes the implementation of appropriate analysis procedures, element types and contact behaviour in the study of the post‐critical buckling behaviour of steel and steel‐concrete composite plate girders. The advantages and disadvantages as well as recommendations for the future use of the investigated modelling strategies have been scrutinized. In the end, this study demonstrates the parameters with the most significant influence on the structural behaviour of composite girders exposed to shear loading.

Bearing capacity of headed studs under combined tension and shear loading in composite beams with large web openings

AbstractThe use of steel‐concrete composite structures with a high installation grade is becoming increasingly popular in building and industrial construction. To reduce construction height building services are routed through web openings in the girders. However, these openings represent local points of interference where, in the case of composite girders, parts of the acting shear forces are transferred from the web of the steel profile into the concrete slab. This results in additional, local stresses in the remaining steel girder and in the concrete chord, which must be considered in the design of the floor girders and shear connectors. Web openings in composite girders are not addressed in the current European design standard for steel‐concrete composite construction (EC 4). Only with the introduction of the second generation of Eurocodes in the coming years this case will be normatively regulated. During the preparation of the standard further questions about the load‐bearing behaviour arose, as the existing design approaches usually only consider a selection of possible failure scenarios or neglect essential verification steps. A joint research project between the University of Kaiserslautern‐Landau and RWTH Aachen University aims to develop a suitable design concept for composite girders with web openings. Model and beam tests accompanied by numerical simulations will provide further information on the complex local and global load‐bearing behaviour of the composite girders.This paper presents the results of experimental investigations and numerical simulations on the influence of large web openings on the global load‐bearing behaviour of the shear connectors in the composite joint. Based on 60 pull‐out tests and numerical simulations, the load‐bearing behavior of head bolt anchors under combined shear and tensile loading was researched and evaluated.

System redundancy of steel I‐girder bridges and proposal of a system factor for load rating

Abstract3D nonlinear FE analyses of existing plate‐girder bridges were carried out to investigate system redundancy. A comparison of the ultimate live load factors between a whole bridge system (WBS) model and a single girder (SG) model shows that WBS's ultimate live load factor is larger than SG's factor. This difference in the ultimate load factors is interpreted as the system redundancy effect. A system factor to quantify the system redundancy has been proposed based on the nonlinear FE analysis results. The proposed system factor is defined as a factor to convert the ultimate live load factor and rating factor for load rating based on linear analysis into those based on nonlinear analysis. A case study to calculate the system factor for three existing bridges shows dependency of the system factor on the number of girders, composite/non‐composite girders, simple span/continuous span.

COMPARATIVE STUDY ON THE GIRDER ERECTION SCHEME FOR THE CHIBI YANGTZE RIVER HIGHWAY BRIDGE

The construction process of composite cable-stayed bridges varies, and it closely affects the finished bridge. This study takes the Chibi Yangtze River Highway Bridge, which is the world's largest-span composite cable-stayed bridge, as an example in determining the optimal scheme of girder erection during the construction of the composite cable-stayed bridge. Six girder construction schemes were proposed for comparison and analysis. On the basis of satisfying the objective principles of the finished bridge, the stress safety principle, and the economic principle, qualitative and quantitative methods were used to analyze the girder erection schemes. The refined model of the composite girder segment was established by the finite element software ABAQUS to examine the local stress of the bridge. Subsequently, the optimal scheme of girder erection was determined. Then, the key calculation results of the optimal scheme of girder erection during the construction stages and for the finished bridge were given, which proved the feasibility, safety, economy, and controllability of the proposed optimal scheme. Results show that the measured data of the girder line shapes and the cable forces of the finished bridge agree well with the theoretical values. This agreement verifies the correctness of the determination and demonstration of the proposed optimal scheme. This study provides a certain reference for the determination of the girder erection scheme of composite cable-stayed bridges. Keywords: Composite girder; cable-stayed bridge; steel girder erection; single segment one cycle; two segments one cycle; construction process;

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

Part 2: proposed buckling factor for columns in braced and unbraced frames with composite girders

Part 2: proposed buckling factor for columns in braced and unbraced frames with composite girders

Thermo-mechanical behavior of composite beams with corrugated steel webs exposed to localized fire

In this study, a one-way coupling methodology combining fire simulation based computational fluid dynamics (CFD) with finite element (FE) analysis is proposed to investigate the thermo-mechanical behaviors of composite beams with corrugated steel webs (CSWs) under localized fire exposure. Fire Dynamics Simulator (FDS) is used to simulate the local fire environment, and the adiabatic surface temperature (AST) data obtained in FDS are imported into the FE models in ABAQUS by the fds2ascii coupling tool. The validations of FDS models and the CFD-FE coupling method are verified by a localized fire test on a steel beam conducted by the National Institute of Standards and Technology (NIST). Then, the CFD-FE coupling method is applied to analyze the thermo-mechanical behaviors of composite beams with concrete flanges and CSWs exposed to localized fire. As the fire exposure time increases, the composite beam appears significant variation of the temperature gradient at elevated temperature, and induce the dynamic, uneven temperature field in the structural members. Due to the influences of the temperature gradient field, the traditional design assumptions for composite beams with CSWs are not valid when the structures suffered a localized fire. It found that the shear stress on the CSWs is no longer evenly distributed along the depth at elevated temperatures, and the concrete flange resists a considerable part of the sectional shear force, particularly of the fire-affect zone. This study hopes to provide a basis for the fire resistance design of composite girder bridges with CSWs.

The Effect of Interior Stiffeners on the Flexural Behavior of Concrete-Filled Steel Tube Composite Box Girders

The composite box girder is a structural element with high torsional stiffness and resistance against flexural loads. A new form of bridge construction is the Concrete-Filled Steel Tubes (CFSTs) linked to composite slabs by steel trusses. In this study, four different kinds of composite box girders linked to steel tubes filled with concrete were analyzed experimentally and numerically while being subjected to flexural loads. The specimens were evaluated when subjected to a focused load at the mid-span. The first model is a concrete-filled tube without stiffeners and was considered the control specimen, the second model is a concrete-filled tube with internal I–shaped stiffeners welded inside the steel tube, the third was filled with T-shaped stiffeners, and the fourth with V-shaped stiffeners. The test results showed that the CFST sections with interior stiffeners gave higher strength capacity and less deflection than the control specimen. The best shape of the stiffeners was the T-shape. The numerical analysis results were in accordance with the test results.

Analytical study on flexural behavior of steel composite girder using truss element for shear connectors with different types and layouts

The key to improve the accuracy of behavior analysis of the steel composite girder lies in the reasonable modelling the intergration between the reinforced concrete slab and the steel girder. Based on design requirements and construction methods, the type and layout of the shear connectors between the concrete slab and the steel girder are different, significantly affecting the behavior of the composite girder. This study is conducted to (i) investigate the applicability of a truss element available in the popular simulation software Abaqus in modelling the shear connectors of composite girders, (ii) compare the flexural behavior of composite girders with different types and layouts of shear connectors. Two types of shear connectors considered in the study are headed studs and perfobond strips, and their layout corresponds to the construction methods using the cast-in-place and precast concrete slabs. The study results show that a truss element can be used to simulate the shear connector behavior through reasonable assignment of its shear force-slip relationship. With the design principle that the total shear capacity of the shear connector per unit length remains constant, the nonlinear behavior of the composite girder is significantly affected by the type and layout of the shear connectors.

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.

Research on Reasonable Construction Plan for Cast-in-Place UHPC Bridge Deck Plate of Cable-Stayed Bridge

This article takes a single-tower cable-stayed bridge with a steel-UHPC composite deck steel box girder as the research object and develops different casting plans for the UHPC layer on the bridge deck. It analyzes the influence of factors such as the block casting sequence of the UHPC layer on the bridge deck, whether or not to set up a post-casting section, whether or not to set up bridge deck counterweights and the range of it on the additional deformation and stress of the formed UHPC bridge deck during the construction stage, exploring the impact of various factors on the structural target bridge’s completion status (cable force, bridge completion linearity, bridge deck and steel box girder stress) under different pouring schemes. Research has shown that under the constant initial tension of stay cables, adjusting the pouring sequence of UHPC bridge decks and setting post-pouring sections is not significant in reducing the tensile stress of UHPC bridge decks. The more effective technical measure is to use bridge deck counterweight pouring during construction; the closer the counterweight is to the later stage constant load loading value, the more significant the decrease in UHPC tensile stress is. When factors such as on-site construction conditions, construction period, and labor costs are limited, local weight balancing on the bridge deck can be used.

Experimental Study on the Flexural Behaviors of Prestressed Segmental Ultra–High–Performance Concrete Channels and Reinforced Conventional Concrete Deck Composite Girders

Flexural testing on two prestressed segmental ultra–high–performance concrete channels and reinforced conventional concrete deck composite girders (PSUC–RCCD) was carried out. One was made up of four segments with dry joints, and the other was formed of one channel beam without a dry joint. Both of them poured a conventional concrete deck slab on site. The mechanical behaviors of the girders, including the whole loading process, the crack pattern, and the failure mode were investigated and compared. The effect of the number of segments and the steel fiber volume fraction of UHPC on the bending behavior of the PSUC–RCCD girder was explored using the finite element method. This study showed that the loading process of semi-segmental and integral girders is similar; the whole loading process of the girders can be divided into the elastic phase, crack development, and the failure phase. The only notable difference between the two girders was the stage of crack development; specifically, after cracking, the stiffness of the semi-segmental girder reduced rapidly, while the “bridging effect” of the steel fibers in the integrated girder caused a slow reduction in rigidity. The flexural cracks in the semi-segmental girder were significantly less than those in the integral girder in terms of the number of cracks, and were present only at the joints. The finite element analysis showed that the number of segments had little influence on the flexural capacity of the girders, but the girders with even numbers of segments cracked earlier than those with odd segments. Increasing the steel fiber volume fraction in UHPC (ultra–high–performance concrete) had a small effect on the cracking load of the semi-segmental girders but enhanced its ultimate flexural capacity. Based on this experiment, a calculated method for estimating the flexural capacity of semi-sectional girders was proposed. The calculated values were in good agreement with the experimental and finite element values. In the preliminary design, the flexural capacity of the semi-segmental section could be estimated by multiplying the flexural capacity of the integral section by a resistance factor of 0.95.

Experimental Study on the Flexural Behavior of a Novel Nonprismatic Prestressed UHPC Composite Box Girder with Corrugated Steel Webs

Experimental Study on the Flexural Behavior of a Novel Nonprismatic Prestressed UHPC Composite Box Girder with Corrugated Steel Webs

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.

A comparative study of vehicle-bridge interaction dynamics with 2D and 3D vehicle models

The dynamics of vehicle-bridge interaction (VBI) involve the adoption of two-dimensional (2D) and three-dimensional (3D) vehicle models in simulations. It is worth noting that the 2D vehicle model lacks several crucial degrees of freedom and a complete road roughness compared to the 3D vehicle model. Despite the common usage of the 2D vehicle model in VBI simulations, the difference between the two models has not received sufficient attention in previous studies. Therefore, this study aims to quantitatively assess the differences in bridge response between the 2D and 3D vehicle models. To achieve this goal, the study employs a VBI modeling method based entirely on general finite element software first. Then, a series of comparisons between the 2D and 3D vehicle models are implemented through a steel composite girder bridge and a cable-stayed bridge. The results indicate that road roughness significantly contributes to the observed differences. Specifically, the 2D vehicle model generates larger bridge responses than the 3D vehicle model, primarily due to the absence of rolling and vibration cancellation effects. Furthermore, the differences between the two models increase as the road surface roughness worsens, with a maximum difference of 25.07 % in the cable-stayed bridge’s mid-span acceleration. Notably, the discrepancies in bridge acceleration are more significant than those in displacement or cable stress. Adopting the 2D vehicle model in VBI simulations may lead to more conservative engineering recommendations, resulting in higher economic costs and greater consumption of building materials. Thus, this study emphasizes the importance of considering the 3D vehicle model in VBI simulations, particularly for bridges with poor road conditions.

Seismic Vulnerability Analysis of Long-Span Prestressed Concrete Composite Box Girder Bridge with Corrugated Steel Webs under Construction

In order to address the difficulty in determining the seismic damage probability of continuous girder bridges under construction, the seismic vulnerability analysis method of the construction state is proposed in this study. Firstly, taking a long-span prestressed concrete composite box girder bridge with corrugated steel webs (OSW) as an example, the finite element models (FEMs) of dynamic calculation in different phases of cantilever construction are simulated by OpenSEES. Secondly, by selecting reasonable seismic waves and seismic intensity measures, the non-linear time-history analysis is carried out, followed by the demand parameters and damage indexes suitable for the construction state proposed. Finally, the probabilistic seismic demand model (PSDA) of the continuous box girder bridge during the construction stage is constructed by using the “cloud method”, and the seismic vulnerability curves of the piers and temporary bearings are established to evaluate the seismic performance during the construction stage. The results indicate that the damage probability of piers and temporary bearings increases with the progress of construction. The initial formation of the cantilever structure and the sudden change in the size of the construction segmental girder correspond to a high probability of damage, and seismic protection measures should be strengthened during this construction state. Moreover, significantly higher damage probability of the components under construction compared to the completed bridge after it is built.

End diaphragm and interior cross frame modeling in steel tub girder superstructures

Composite steel tub girders are proven to be an economical choice for long span bridges. However, detailed analysis of such superstructures requires extensive Finite Element (FE) modeling that includes many internal and external diaphragms. This paper is an attempt to study diaphragms and interior cross frames in tub girders and present simplified FE modeling details for the tub girder superstructures under gravity and seismic loadings incorporating accurate end diaphragm and interior cross frame stiffness equations. The simplified model is applicable to design of new tub girder bridges as well as load rating, health monitoring and retrofitting of existing bridges which require more sophisticated models. To this end, first a parametric study using 18 different FE models was carried out to better understand the behavior of tub girder superstructure and its components such as end diaphragms, the composite concrete deck and interior cross frames. Second, the stiffness equations for the end diaphragms and interior cross frames were derived analytically. These were associated with equivalent beam elements, which were used in combination with girder/deck elements to arrive at the simplified model. The resultant FE modeling was validated against detailed 3D FE models under gravity and seismic loads as well as the fundamental modes of vibration. Results indicated that the modeling approach is able to efficiently simulate different component behaviors and estimate the static and dynamic demands on the girders with remarkable accuracy.

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.

Structural Performance of Prefabricated Composite Girders for Railway Bridges along with Girder-to-Deck Interface Connections for Mechanical Injection

Recently, to resolve a growing need for durable and resilient railway bridge construction/reconstruction systems, a great amount of research has been carried out in many countries. As a part of such studies, prefabricated composite girders with an innovative girder-to-deck connection have been proposed that facilitate construction by eliminating interference during on-site processes. In this study, a railway bridge prototype of prefabricated composite girders with girder-to-deck connections was designed to facilitate future application enhancement of off-site construction. Then, prefabricated composite girders were developed by deploying different girder-to-deck connections through geometric detailing of reinforcement, headed stud connectors, and precast decks. Based on the calculation theory of interface shear transfer, the detailed design of different girder-to-deck connections was carried out, in particular the reinforcement spacing. Furthermore, finite element analysis of prefabricated composite girders was conducted to determine the flexural moment strength of prefabricated composite girders. Parametric studies were carried out to consider the factors affecting the detailed design of the connection, ensuring that the connection is correctly designed, thereby ensuring the structural performance of prefabricated composite girders. From the results, conclusions were drawn. The developed cases satisfied the interface shear criteria according to both conventional and plastic approaches. There was no significant difference in flexural moment strength between the developed cases since all cases were designed with the full shear connection. In all cases, the flexural performance was ensured and can be used for railway bridges. The most optimum case of prefabricated composite girders is selected in specific design situations.

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.