Concrete Composite Girders Research Articles

Overlap of Splitting in Slabs with Closely Spaced Intermediate Anchorages

Abstract Slab splitting, resulting from the dispersion of a number of intermediate loads arranged in a line, is a common problem in such engineering structures as steel–concrete composite girders a...

Experimental Research of the Time-Dependent Effects of Steel–Concrete Composite Girder Bridges during Construction and Operation Periods

The present work aimed to study the effects of temperature changes and concrete creep on I-shaped steel–concrete composite continuous girder bridges during construction and operation processes. This study combined structural health monitoring data, an ANSYS finite element simulation, and the age-adjusted effective modulus method to obtain the variation laws of temperature and internal force in composite girders. Moreover, a temperature gradient model was proposed that is suitable for bridges in Hebei, China. In addition, a concrete creep experiment under unidirectional axial compression was performed using concrete specimens prepared from the concrete batch used to create the composite girder. The long-term evolution laws of the deflection and internal force of the composite girder were obtained by predicting the concrete creep effect. The measured data showed that the temperature variation trends of the steel beam and concrete slab were characterized by a sinusoidal curve without a temperature lag. The heating rate of the concrete slab was higher than the cooling rate. The prediction results showed that the internal force changes in the composite girder were characterized by three stages. The stress changes in the composite girder during the first 10 days were significant and the stress charge rate of the concrete slab, the steel girder and the shear stud can reach 5%–28%. The stress change rate decreased continuously during 10–90 days. The stress changed slowly and smoothly after 90 days. This research can provide feedback and reference for structural health monitoring and service safety control of similar I-shaped steel–concrete composite bridges.

Seismic Performance of Steel-Concrete Composite Rigid-Frame Bridge: Shake Table Test and Numerical Simulation

Abstract The composite rigid-frame bridge presented in this study is a new type of structural solution that combines the steel–concrete composite box girder and the concrete-filled double-skin stee...

Research on temperature action and cracking risk of steel–concrete composite girder during the hydration process

Temperature changes due to hydration heat often cause cracks in the early-age concrete deck of steel–concrete composite girder bridges, even before opening to traffic. However, no available methods are provided in current specifications for the thermal effect calculation. To fill this gap, large-scale temperature measurements and fine finite-element model (FEM) analysis were performed on an actual composite girder bridge. Based on the fully validated FEM, a comprehensive parametric study was carried out to establish the spatio-temporal pattern of hydration-caused temperature, including a vertical pattern and an evolutionary pattern. Finally, a simplified method was presented for the thermal stress calculation of composite girders, and a case study was also provided. Measurements showed that temperature differences of concrete deck varied below 5 °C, much smaller than the entire composite section. FEM analysis then suggested that the influence of solar radiation can be basically ignored compared with hydration heat. The spatio-temporal pattern in the form of the coefficient of temperature rise was proposed based on the above findings and parametric study, and the reliability was properly verified with experimental or FEM results. For the final simplified method, the case study demonstrated that it can effectively facilitate the thermal stress calculation of composite girders during hydration process by adopting the proposed spatio-temporal pattern. As such, preliminary curing schemes can be easily selected to control the concrete cracking risk before casting.

Utility of steel-concrete composite construction technique in the development of infrastructure Engineering perspective

Steel-concrete composite construction technique is being used in developed nations for last few decades. For obtaining accelerated growth in fast emerging Indian economy, it is becoming necessary to adopt best construction techniques and practices. On one side there is considerable construction of new roads, bridges, flyovers and buildings taking place on daily basis, on the other side we can foresee the effect of such activities on our limited resources and environment. Therefore, it is vital task for all designers, engineers and policy makers. It must be ensured and all the possible way that the best constructional techniques must be adopted to protect both, our depleting resources and environment. Steel-concrete composite construction technique comprises of synergetic bonding between steel girder and reinforced concrete slab using mechanical connectors. In this technical paper stud type shear connectors have been used. In the market, various shapes and sizes are available. The main advantages of this construction method are lightweight foundation structure, faster constructing method, ease in construction and above all the quicker recovery of investments towards development. In the present technical paper, various internal mechanisms and processes are explained. The results of the experiments conducted by authors have also been briefly discussed. The special attention is given to understand internal force resistance mechanics and also the failure patterns due to excess loads than maximum capacity of steel concrete composite girders. Based on experimental results and available literature it has been obtained that we can easily obtain about 30% saving in total investment by adopting composite construction technique.

Numerical study on the deformation behavior of steel concrete composite girders considering partial shear interaction

The present paper focuses on the study of deformation behavior of steel concrete composite (SCC) girders with partial shear interaction. The main objective of this work is to bring out the relative significance of the partial shear interaction with respect to full interaction, which has been addressed with the help of parametric study considering various influencing parameters such as, degree of shear connection, span length, type of loading, distribution of shear stud connectors, geometry of steel girder, yield strength of structural steel and concrete grade. The parametric study has been carried out using a simplified numerical modelling technique with the help of commercially available finite element software SAP2000. The numerical modelling involves simulation of composite action between the concrete deck and the steel girder in the SCC girder, which has been carried out by using various elements such as, beam elements, rigid link elements and spring elements. Further, a comparative study has been carried out to study the accuracy of numerical model with the available analytical models. The results of the numerical model are also compared with the results of the equations given in several national codes to calculate deflections, to study the efficacy of the codal provisions. It is seen that the various aforementioned parameters have considerable influence on the deformations of SCC girders. It is also seen that the change in distribution type of shear stud connectors considerably reduce their number without significantly affecting the deformations of SCC girder.

Mechanical Performance Analysis of Prestressed Concrete Composite Box Girder Bridge with Corrugated Steel Webs under RW Cantilever Construction

As a new type of steel-concrete composite bridge, PC composite box Girder Bridge with corrugated steel webs has been rapidly developed in China in recent years. With the deepening of research, a new type of construction technology - RW cantilever construction began to be applied to the construction of such bridges. This paper first introduces the general steps of RW cantilever construction and the advantages compared with traditional cantilever construction. Then, take a continuous rigid frame bridge with corrugated steel webs under RW cantilever construction as an example, and build its finite element model. The crack resistance and compressive stress of the concrete and the shear stress of the corrugated steel web were checked to meet the requirements of the specification, and the feasibility of the construction method was verified.

Investigation on the Collapse Behavior of Diagonal Stiffened Composite Plate Girders Subjected to Shear Loading

In this study, a new analytical method is presented to estimate the shear capacity of diagonally stiffened steel–concrete composite plate girders. This method is formulated based on tension field action in steel girder web and failure mechanism of concrete slab deck. To validate the accuracy of the proposed method, the obtained results are compared with three-dimensional finite element analysis of composite plate girders with different configuration of stiffeners. The results of analytical and numerical investigations indicate that the proposed method can accurately estimate the ultimate shear capacity of composite plate girders. In addition, it is shown that the diagonal stiffeners on one hand can reduce the buckling effects of shear panel of girders and on the other hand can increase the strength of elastic shear buckling and ultimate shear capacity of girders well in comparison with the unstiffened thin steel plate girders.

Experimental Study on Basic Performances of Reinforced UHPC Bridge Deck with Coarse Aggregates

In order to reduce the self-weight of conventional steel-concrete composite girders and to improve the crack-resisting behavior of normal strength concrete (NC) bridge decks for long-span cable-stayed bridges, an innovative steel–ultrahigh performance concrete (UHPC) composite girder was proposed. Coarse aggregates (CA) were added to UHPC to control shrinkage and cost. On the basis of the Fifth Nanjing Yangtze River Bridge (FNYRB), a 2 × 600 m cable-stayed bridge in China, a series of experimental tests was conducted. The studies aimed to reveal the material properties of UHPC with and without CA and the static and fatigue flexural performances of the reinforced UHPC deck with CA. The test results implied that the UHPC with CA had compressive strength and flexural strength comparable to UHPC without CA, but the former exhibited much lower shrinkage strains under the natural curing condition. The static bending test results showed that the steel fibers and steel reinforcement bars could effectively control the propagation of cracks in UHPC. The average nominal cracking strength of the UHPC bridge deck specimens was 13.8 MPa, about 1.97 times the maximum tensile stress in the design requirement of the FNYRB under serviceable design loads. Further, the fatigue bending test results demonstrated that the cracks in UHPC propagated very slowly under cyclic tensile stresses, and the residual flexural loads were only 7.2% and 10.9% lower than the ultimate loads obtained for specimens free from the fatigue loading processes. Thus, the current study verified the safety of applying UHPC with CA to long-span cable-stayed bridges.

Overhanging Tests of Steel–Concrete Composite Girders with Different Connectors

This study investigated two overhanging 3-span composite girders to simulate the behavior of a suspension bridge. A new uplift-restricted and slip-permitted T-shape (URSP-T) connector is proposed to decrease the concrete slab tensile stress in composite girders. URSP-T connectors installed on one side of the specimen were compared with studs installed on the other side. Various elastic working conditions, ultimate sagging moment conditions, and ultimate hogging moment conditions were employed to investigate the behavior of composite girders with different connectors. The test results showed that the use of URSP-T connectors decreased the tensile stress of the concrete slab and prevented separation of the concrete slab from the steel beam. A hanger system was used to simulate hangers for suspension bridges, and it is demonstrated that girder displacement is predominantly due to cable deflection. The influence of URSP-T connectors on the mechanical properties of composite girders was investigated and design suggestions proposed. The results show that the use of URSP-T connectors increased the slippage of the interface and decreased the bending rigidity of the composite girder. Therefore, the thickness of the foamed plastics should meet the requirement of interface slippage and careful consideration of the buckling behavior of steel girders is required when URSP-T connectors are used.

합성거더 부모멘트부 철근콘크리트 바닥판의 균열폭

연속합성형교량의 부모멘트가 작용하는 내부지점부에서는 슬래브에 설계하중 및 건조수축 영향으로 인장력이 작용하게 되며 사용하중상태에서 횡방향 균열이 쉽게 발생하게 된다. 이러한 균열은 교량 바닥판에 철근 부식 및 콘크리트 열화를 촉진시켜 내구성을 감소시키는 결과를 초래하게 된다. 따라서 연속강합성교량의 슬래브 균열폭은 설계단계에서 허용치 이내로 억제되도록 할 필요가 있다. 현행 도로교설계기준에서는 강합성거더에서의 균열폭 평가와 관련된 직접적인 규정은 없으며, 단순히 인장력이 작용하는 바닥판에 대해 최소철근비 1.5 %만을 제시하고 있다. 이 연구에서는 슬래브 철근비 변화에 따른 합성거더의 균열폭 및 균열간격 조사를 위해 수행되었던 5개의 합성거더에 대한 부모멘트 실험결과를 이용하여 Eurocode에 따른 균열폭 및 균열간격의 평가치와 비교하였다. Eurocode에 따른 균열폭 및 균열간격의 평가치는 각 실험체에 대하여 대체로 안전측의 결과를 보여 Eurocode에 따른 균열폭 평가방법이 강합성교량 설계에 있어서 적절한 것으로 판단할 수 있다.

Design and construction of a launched cable-stayed bridge in China

Zhengbei Bridge is a key structure on the new Nongye Road in Zhengzhou, central China. Completed in 2019, it crosses the city’s north railway marshalling yard, the biggest in Asia. The main bridge is a cable-stayed structure with a single pylon and two 221 m spans. This paper describes the design and construction of the bridge, including the incremental launching of the steel–concrete composite main girder over temporary trestles between the railway tracks. To avoid disrupting rail operations the trestles were up to 92 m apart, so the 56 m launch nose was supplemented with a kingpost and cables.

A Semi-Empirical Deflection-Based Method for Crack Width Prediction in Accelerated Construction of Steel Fibrous High-Performance Composite Small Box Girder.

Accelerated construction in the form of steel–concrete composite beams is among the most efficient methods to construct highway bridges. One of the main problems with this type of composite structures, which has not yet been fully clarified in the case of continuous beam, is the crack zone initiation that gradually expands through the beam width. In the current study, a semi-empirical model was proposed to predict the size of cracks in terms of small box girder deflection and intensity of load applied on the structure. To this end, a set of steel–concrete composite small box girders were constructed by the use of steel fibrous concrete and experimentally tested under different caseloads. The results were then used to create a dataset of the box girder response in terms of beam deflection and crack width. The obtained dataset was then utilized to develop a simplified formula providing the maximum width of cracks. The results showed that the cracks initiated in the hogging moment region when the load exceeded 80 kN. Additionally, it was observed that the maximum cracked zone occurred in the center of the beam due to the maximum negative moment. Moreover, the crack width of the box girder at different loading cases was compared with the test results obtained from the literature. A good agreement has been found between the proposed model and experiment results.

Resistance of Steel – Concrete Composite Girders with Corrugated Web

The paper discusses the analysis of shear resistance of girders with corrugated web, combined with a concrete slab in a way that allows creation of a composite structure according to the definition of Eurocode 4. The results of the authors’ experimental tests of girders with a corrugated web connected to a concrete slab, and the results of tests on girders without a concrete slab were used. Experimental investigations concerned the effectiveness of SIN girder (i.e. with sinusoidal corrugation) WTA 500 / 300x15 strengthening with a concrete slab for shear resistance of the whole steel-concrete element and shear buckling resistance of the web. Load – displacements paths LDPs P(y) as well as the results of tensometric strain measurements of the web were analysed. The results of the composite girder tests were compared with the results of tests of SIN girder without a concrete slab with a similar static diagram and a similar failure mode due to the loss of the web stability. In addition, the first buckling load and slab contribution to shear force transferring were analysed. Based on the analysis of experimental results and available analytical models, the solution for estimating design shear buckling resistance in girders with corrugated web strengthened with a concrete slab was proposed. Using the proposed formula, the contribution of the web and concrete slab to the transfer of shear load for the whole series of girders with web heights hw = 500 mm to 1500 mm and thickness tw = 2 mm, 2.5 mm and 3 mm was shown. The proposed formula takes into account the mutual interaction between the local and global mode of shear stability of the web, which leads to the reduction in design shear buckling resistance. Additionally, improvement in the web boundary conditions as an effect of increased flange stiffness due to joining it to the concrete slab was taken into account. This paper also uses the results of tests concerning SIN girders without a concrete slab, with other web heights and thicknesses than in WTA 500/300x15.

Steel–concrete hybrid bridge decks: rational design models for connection regions

Steel–concrete hybrid bridge decks have been used in several bridges for their added benefit in constructive operations and cost. They usually adopt reinforced concrete side-spans and all-steel or steel–concrete composite girders as main spans, typically with monolithic connections between them. Design codes address separately the design of the steel and concrete regions of the connection. However, a rational design, with an efficient transfer of stresses between the steel and the concrete parts, should be based on a global understanding of the connection region structural behaviour. Therefore, a rational model for the design of the connection region is proposed, which is based on web shear buckling models developed over recent decades for steel panels and stress field models for structural concrete elements. A hybrid bridge deck connection region is presented as the case study. Several solutions for the connection are introduced and shear resistances are evaluated based on the proposed models.

Research on the Modal Experiment of Large-span Cable-stayed Bridge with Steel Concrete Composite Girder During Cantilever Assembling and Finished Stage

The vibration characteristic parameter of large-span cable-stayed bridge with steel concrete composite girder during cantilever assembling and finished stage (vibration frequency, vibration mode and damping ratio) is one of the determinants of the dynamic performance of the bridge and also a representation of the overall state of the structure. The structural system problems, wind resistance and seismic performance of cable-stayed bridge are closely related to the dynamic characteristics of the bridge structure. This paper uses Midas Civil structure analysis software to establish the three-dimensional finite element model of steel box girder cable-stayed bridge of Qihe Yellow River bridge. Dynamic characteristics are analyzed in the construction stage and finished bridge stage. The finite element analysis results are compared with bridge modal experiment results, which provides a reference for the same type of bridge design and construction.

A softened membrane model for prestressed concrete composite box girders with corrugated steel webs under pure torsion

Torsion can be regarded as a principal factor in some cases, such as in curved girders and eccentrically loaded girders, when conducting the structural analysis of prestressed concrete composite box girders with corrugated steel webs. Recently, a rational model, called the softened membrane model for torsion, was proposed for the torsional analysis of reinforced concrete members; thereafter, this model was extended to prestressed concrete members under pure torsion and called softened membrane model for torsion prestressed concrete. This article presents a modified model, the softened membrane model for torsion prestressed concrete for prestressed concrete composite box girders with corrugated steel webs, to analyze full torsional behavior. To build the model, the softened membrane model for torsion in reinforced concrete members is first extended to perform the torsional analysis of prestressed concrete composite box girders with corrugated steel webs by incorporating the torsional contribution of corrugated steel webs. Afterward, the initial stresses and strains due to prestressing are considered to extend the softened membrane model for torsion to softened membrane model for torsion prestressed concrete for prestressed concrete composite box girders with corrugated steel webs by modifying the equilibrium equations, convergence criteria, and constitutive laws of materials. The modified model is validated by experimental data and is proven to be capable of predicting the overall torque–twist curve, especially the precracked branch and postcracked ascending branch. In addition, a comparison between the softened membrane model for torsion and softened membrane model for torsion prestressed concrete indicates that the torque values before and after concrete cracking will be overestimated and underestimated, respectively, without considering the effect of the initial stresses and strains. Finally, another comparison shows that the softened membrane model for torsion prestressed concrete is superior to the rotating-angle truss model for torsion in its ability to predict the precracked branch of the torque–twist curve.

Effect of intermediate diaphragms on the load – carrying capacity of steel – concrete composite box girder bridges

Intermediate diaphragms are used in box girders not only to prevent premature distortion under eccentric loading conditions but also to improve the distribution of live loads. This paper reports an investigation into the effect of intermediate diaphragms on the load - carrying capacity of a Steel – Concrete Composite Box (SCCB) girder bridge with open steel box section. In the current study, a three - dimensional finite element (FE) model of the SCCB girder is developed and analyzed using ABAQUS software. The nonlinear inelastic analysis is invoked in order to accurately capture the actual behavior of the girder. The numerical model is verified with experimental results to ensure the accuracy of the FE modeling method. A parametric analysis is implemented to study the effect of intermediate diaphragms on the load – carrying capacity of an SCCB girder with a 30–60m span length. Based on parametric studies, the number of intermediate diaphragms (N) is recommended for practical design of the girder, which satisfies the requirement stated in the provisions of the AASHTO LRFD standard.

Effect of Partial Shear Interaction in Steel Concrete Composite Girders

Steel concrete composite (SCC) structural system has been commonly used both in the buildings and in the bridges because of the advantages it associates when compared to its counterparts such as RC and steel structures. A typical SCC girder consists of a concrete element placed over a steel element. The effectiveness of this composite system is characterized by the type of connection that exists between the two connecting elements. More commonly shear stud connectors are used to connect the two elements. If the shear studs are infinitely rigid, then it brings about full composite action, on the contrary there is no composite action if the studs are not used, between the two connecting elements. It has been observed that generally the composite action exists somewhere between the full composite action and the no composite action, and is called the partial composite action or the partial interaction. More often the partial composite action is overlooked during the design of SCC girders, and the girder is designed assuming that there exists full composite action, because of the complexities in the analysis incorporating the partial composite action. This might lead to the serviceability issues in the SCC girders. Keeping this in mind the present work has been carried out to understand the significance of the partial interaction in SCC girders. In the present work, a comparative study has been made between the available analytical model and the numerical model. Numerical modeling is performed by using commercially available tool such as SAP2000. The main objective of this work is to bring out the relative significance of the partial interaction with respect to the full composite action, with the help of parametric study. Here, the parametric study has been carried by considering various design parameters, such as, span length, degree of shear connection, cross section geometry of steel girder and concrete slab. It is observed that there is significant increase in deformations of the SCC girder, on account of the partial interaction. The results of the numerical model and the analytical model are in good agreement.

08.02: Experimental research of multiple perfobond connectors for composite girders

ABSTRACTExtensive research has been carried out in recent years focusing on the behaviour of innovative connectors for steel and concrete composite girders. Those elements exhibit large resistance and adequate behaviour under different load types, and at the same time are easy to fabricate and to erect on site. Among these types, the Perfobond connector or Perfobond rib, consisting of a perforated steel plate welded to the steel beam flange, has been extensively studied by numerous authors, due to its particularly convenient efficiency, behaviour and ductility characteristics.Although many connector types have been studied in the past, few studies focused on the behaviour of groups of special connectors, a typical arrangement used in conventional headed stud connectors.This paper focuses on the behaviour of multiple Perfobond connectors placed side‐by‐side on a steel girder and immersed in the reinforced concrete slab. This quite innovative arrangement enhances the resistance from a single connector classic layout, but the proximity to other connectors may significantly change the behaviour of individual connectors that interact with each other.Fourteen push‐out tests on groups of Perfobond connectors were carried out at the Civil Engineering Department of the University of Coimbra, Portugal, while this paper reports and discuss the results.The investigated variables were: the number of connectors, ranging from one (the basic arrangement) to three; the spacing between connectors; the transverse reinforcement within the connector's holes; and the concrete strength. The results are presented and discussed concentrating on the connector's structural response for shear transfer capacity, ductility and collapse modes. A comparative assessment of these properties focusing on the number of connectors and its spacing is presented and discussed, aiming at establishing preliminary conclusions about the behaviour of Perfobond groups. In addition, a brief comparison of the experimental results with existing analytical models for Perfobond connectors is also presented to establish the most convenient model for this particular geometry. Finally, some adapted models referred in the literature to cope with Perfobond groups are applied to the tested geometries and the analytical and experimental tests are compared and discussed.