Composite Girder Research Articles

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.

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.

Load Distribution Factors For Horizontally Curved Composite Concrete-Steel Girder Bridges

This paper focuses on Load distribution factors for horizontally curved composite concrete-steel girder bridges. The finite-element analysis software“SAP2000” is used to examine the key parameters that can influence the distribution factors for horizontally curved composite steelgirders. A parametric study is conducted to study the load distribution characteristics of such bridge system due to dead loading and AASHTO truck loading using finite elements method. The key parameters considered in this study are: span-to-radius of curvature ratio, span length, number of girders, girders spacing, number of lanes, and truck loading conditions. The results have shown that the curvature is the most critical factor which plays an important role in the design of curved girders in horizontally curved composite bridges. Span length, number of girders and girder spacing generally affect the values of the moment distribution factors. Moreover, present study reveals that AASHTO Guide criterion to treat curved bridges with limited curvature as straight one is conservative. Based on the data generated from the parametric study, sets of empirical equations are developed for the moment distribution factors for straight and curved steel I-girder bridges when subjected to the AASHTO truck loading and due to dead loading.

Theoretical calculation of bending capacity of a steel beam - ultra high performance concrete slab composite girder

The composite girder, which combines a steel beam with an ultra-high-performance concrete (UHPC) slab, has gained significant attention in recent years as a new type of bridge structure. However, accurately estimating the bending capacity of such girders remains a challenge, as practical methods are limited. In this article, the authors propose a theoretical approach based on the Euler-Bernoulli beam theory to determine the bending capacity of composite girders. This approach considers the assumptions of plane sections remaining plane and infinitesimal strains during bending. By applying this theoretical approach, the authors derive a formula that allows engineers to calculate the bending capacity of the composite girder. The formula takes into account the dimensions and properties of both the steel beam and the UHPC slab. The derived formula serves as a valuable tool for evaluating the structural behavior and performance of composite girders. To validate its accuracy, the authors compare the results obtained from their calculations with numerical simulations of composite girder failures caused by bending. The close agreement between the theoretical calculations and the numerical simulation results confirms the reliability and applicability of the proposed formula. This research significantly contributes to the field of composite girder design by providing a practical and reliable method for estimating the bending capacity of steel beam-UHPC slab composite girders. The proposed theoretical approach, validated through numerical simulations, offers valuable insights for the design and optimization of these composite girders in various engineering applications.

Full-Scale Fatigue Test and Finite Element Analysis on External Inclined Strut Welded Joints of a Wide-Flanged Composite Box Girder Bridge.

For a wide-flanged composite box girder bridge, the risk of fatigue cracking in the external inclined strut welded joint under the fatigue vehicle load is a problem. The main purposes of this research are to verify the safety of the main bridge of the Linyi Yellow River Bridge, a continuous composite box girder bridge, and to propose suggestions for optimization. In this research, a finite element model of one segment of the bridge was established to investigate the influence surface of the external inclined strut, and, using the nominal stress method, it was confirmed that the fatigue cracking of the welded details of the external inclined strut was risky. Subsequently, a full-scale fatigue test of the external inclined strut welded joint was carried out, and the crack propagation law and S-N curve of the welded details were obtained. Finally, a parametric analysis was conducted with the three-dimensional refined finite element models. The results showed that the welded joint in the real bridge has a fatigue life larger than that of the design life, and methods such as increasing the flange thickness of the external inclined strut and the diameter of the welding hole are beneficial to improve its fatigue performance.

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.

Calculation Method for Flexural Bearing Capacity of Composite Girders with CFST Truss Chords

To study the flexural behavior of composite girders with concrete-filled steel tubular (CFST) truss chords under positive and negative bending moments, model tests, and theoretical analysis were carried out to investigate the evolution of their flexural behavior and the flexural bearing capacity. The results showed that the web members and joints of composite girders with CFST truss chords subjected to positive and negative bending moments had high strength and rigidity, which ensured that joint failures did not occur before the failure of the entire cross section. The longitudinal strains along the member axis changed linearly along the cross-sectional height, which confirmed the correctness of the plane-section assumption. The failure mode was due to the yield of the steel tube used in the chord and the rebars in the concrete slab under positive and negative bending moments, respectively. The contributions of the web members to the flexural bearing capacity under positive and negative bending moments were 12.5% and 8.6%, respectively. Calculation methods considering the contributions of the web members to the flexural bearing capacity under positive and negative bending moments were proposed. The deviation between the results of the proposed calculation methods and the test and the results of the finite-element parametric studies was less than 8.1%.

Behavior Analysis of Prestressed Steel Composite Concrete Girder Joint

Recently, studies have been actively conducted for increasing the length of bridges by connecting steel composite and concrete girders. This study proposes a prestressed steel composite concrete girder and analyzes the composite behavior of the proposed steel composite concrete girder joint. The full-size specimen 3000 × 1000 × 1200 mm was fabricated. In the construction stage experiment, the strains of the top flange, vertical steel plate, and web were measured by applying prestressing; moreover, the allowable stress of the connection between the concrete and steel composite girder was analyzed via the finite element analysis. The stress in the connection between the steel girder and concrete girder was found to be within allowable stress at all construction stages. Finite element analysis revealed that the joint of the proposed girder exhibited appropriate structural behavior.

Experimental and theoretical investigation of the shear lag effect in the novel non-prismatic prestressed CSW–UHPC composite box girders

Experimental and theoretical investigation of the shear lag effect in the novel non-prismatic prestressed CSW–UHPC composite box girders

Experiment and Modelling on Effective Width of Single and Twin I-beam Composite Girders

Effective width (beff) has been widely used by designers, and several specifications can be selected. However, insufficient research has been conducted on the beff of single and twin I-beam composite girders. Thus, finite element (FE) models, calibrated by the experiment, were used to study the effects of slab thickness, web position, interaction degree (ID) of shear studs, width-to-span ratio, and their coupling effects on beff. Different loading types and two definitions of beff were elaborated. The FE results were compared with specifications in Eurocode 4 (EC4) and AASHTO LRFD bridge design specifications (AASHTO). The following results were obtained. The modeling agrees with the experiment. The critical steel height-to-slab thickness ratio is around 4. When the ratio deviates from the critical value, beff is reduced with the increase of slab thickness. ID has a slight influence on beff. beff changes within 10% when ID changes within 10%. The maximum beff can be obtained when the web spacing-to-physical width ratio is 1/2. The decrease of web spacing brings a maximum reduction of 14% on beff, whereas increasing web spacing results in a maximum reduction of 70% for twin I-beam. The coupled effect of web position and slab thickness is limited. The maximum difference is 25%. Recommended equations were proposed to evaluate beff for single I-beam and twin I-beam composite girders based on the specifications in EC4 and AASHTO, which can ensure that the negative error is within 10%.

Study on the Dynamic Response of Composite Box Girder Bridges with Corrugated Steel Webs

To more accurately consider the dynamic response of composite box girder bridges with corrugated steel webs under the effect of live loads, based on the theory of vehicle-bridge coupled vibration, a refined finite element model of vehicle-bridge coupled vibration analysis for composite box girders was established. The advanced dynamic response analysis of composite box girders with corrugated steel webs and traditional concrete box girders with 30 m single boxes and single cells, as well as with 50 m single boxes and multiple cells, was carried out. The research revealed that the natural vibration frequency of the composite box girder with corrugated steel webs is lower than that of the corresponding concrete box girder. When the bridge deck condition is poor, the dynamic impact coefficient of the composite box girder is much larger than that of the concrete box girder. When the bridge deck is in poor condition, the dynamic impact response is significantly enhanced, and the difference is significantly compared with that when the bridge deck is in good condition, which is greater than three times and even six times at the maximum. Both the difference in the vehicle model and the change in the vehicle speed influence the dynamic impact coefficient of the composite box girder.

Numerical investigation on strength of CFRST composite truss girder

CFRST composite truss girders consist of a CFRST truss and a concrete slab. The failure mechanism and strength of the girder were observed to be different under various failure modes. To investigate the strength of the girder under different loading conditions and parameter combinations, numerical simulations were carried out and validated against existing experiments. The axial force distribution of the girder was found to be similar to the pin-jointed truss model when the concrete slab and the chord were considered a unified component of the composite top chord. Three distinct failure modes were identified, including composite top chord failure mode, brace and joint failure mode, and bottom chord failure mode. The failure mechanism of each failure mode was analyzed, and a design method for the girder’s strength was proposed. The proposed method was validated through numerical analysis and compared with other existing methods. The results showed that the method can accurately predict the strength of the girder under different failure modes while maintaining reasonable safety margins.

Time-Varying Evolution Behaviors of Steel–Concrete Composite Girders with Differentiated Connectors

To improve the cracking resistance of a concrete slab in the hogging moment region, a new concept called uplift-restricted and slip-permitted (URSP) connection technology has been proposed. Several studies have been conducted on URSP connectors, but investigations into the time-varying evolution behaviors of composite beams with URSP connectors are still lacking. In this paper, three types of elaborate finite element models of composite girders with differentiated connectors and different construction methods were established. Simulation of the concrete shrinkage and creep effect was realized using a user subroutine based on an improved rate-type formulation. The performances of the composite girders in three schemes were analyzed and compared in both the construction and service stages. The results demonstrated that the URSP connection technique can effectively increase the prestressing efficiency and decrease the tensile stress of the concrete induced by dead loads and vehicle loads. With an increasing service time, the concrete shrinkage effect will enhance the advantage of the URSP connection technique, and the creep effect will reduce this advantage. Finally, parametric analyses were conducted, and a value of 0.2 is recommended for the URSP length ratio to promote practical applications.

Shear lag effect of composite cable-stayed bridges under dead and live loads

The modern composite cable-stayed bridge always has a wider deck, and the slab has an obvious shear lag effect. At the operation stage, internal forces distribution of the composite girder under live loads differs from that under dead loads only. It is essential to investigate the shear lag of the main beam under dead and live loads. Then, in-situ tests under truck loads were carried out on Xia Zhang Bridge. Considering the superposition of axial forces, a simplified method is proposed to evaluate the effective width. The finite element models (FEMs) of the full bridge using solid shell elements under dead and live loads were established. The longitudinal distribution of the effective widths for concrete slabs under different loading positions and loading forms was obtained. Furthermore, the full-scale variable parameter analysis considering the effects of span lengths and deck widths was conducted by FEMs. The numerical results show that the composite girder segments at the location of the bridge tower and the loading position need to be concerned for shear lag analysis. A generalised verification for a cable-stayed bridge was made, and compared results show that simplified methods can calculate the normal stresses in slabs more accurately than Eurocode 4.

Experimental Study and Theoretical Analysis of Steel–Concrete Composite Box Girder Bending Moment–Curvature Restoring Force

A steel–concrete composite box girder has good anti-seismic energy dissipation capacity, absorbs seismic energy, and reduces seismic action. It is very suitable for high-rise and super high-rise mega composite structure systems, which is in accordance with the condition of capital construction. In order to accurately study the elastic–plastic seismic response of the composite structure, the restoring force model of the building structure is the primary problem that needs to be solved. Previous research shows that shear connection degree, force ratio, and web height–thickness ratio are the major factors that influence composite box girder bearing capacity and seismic behavior. In this paper, low cycle vertical load tests of four steel–concrete composite box girders were conducted with different shear connection degrees and ratios of web height to thickness. The seismic behavior of a steel–concrete composite box girder was analyzed in depth, such as the hysteresis law, skeleton curve, and stiffness degradation law, etc. The influence of the shear connection degree and ratio of web height to thickness on seismic performance of the steel–concrete composite box girder was investigated. A three-fold line model of the bending moment–curvature skeleton curve of composite box girders was established. On the basis of experimental data and theoretical analysis, the formula of positive and negative stiffness degradation of composite box girders was obtained. Furthermore, the maximum point orientation hysteresis model of the bending moment–curvature of steel–concrete composite box girders was established. The calculated results of the restoring force model agree well with the experimental results. The accuracy of the proposed method is verified. The calculation method of the model is simple and clear, convenient for hand calculation, and suitable for engineering applications.

Multi-span composite girders with composite dowels – Experimental investigations and design approach to account for the beneficial effect of shear force redistribution along the composite interface

The broad use of composite dowels as shear connectors in multi-span steel and concrete composite members is currently hindered by insufficient regulations for hogging moment regions, where the connectors are located in cracked concrete slabs and have reduced shear resistance. This paper reports on the results of three beam tests that illustrate the ability of continuous steel and concrete composite beams with composite dowels to redistribute shear forces from impaired connectors located in hogging bending regions to intact connectors in sagging bending regions. The effect of concrete cracking on the load-bearing behaviour of composite dowels is analysed with regard to their strength, stiffness and ductility by means of three full-scale member tests. This paper proofs the existence of a beneficial shear force redistribution process along the interface of multi-span composite members and quantifies the shear force transfer occurring between connectors in sagging and hogging bending regions. In addition, the paper provides an economical design method for continuous composite girders. Previously developed models regarding the shear resistance of single composite dowels in cracked concrete are refined aiming to provide both safety and ease of use. These models are subsequently extended into a comprehensive design strategy that allows us to consider the beneficial shear force redistribution processes along the interface when designing the shear connection of multi-span composite beams with composite dowels.

Analysis on Mechanical Properties of Bolt Connector under Reinforcement Binding and Welding Conditions Considering Flexural-shear Ratio

In order to study the force transmission mechanism of the connection interface between the corrugated steel web and the concrete diaphragm in the corrugated steel web composite girder bridge, the internal force of the bolt shear connector under the coupling of different flexural-shear ratio was compared, the simple support beams model under different steel rebar arrangements and different loading positions were designed. Based on the force characteristics of the bolt shear connector, taking a Bridge as the engineering background, and using the finite element analysis software ABAQUS to establish a simple support beam model. The analysis compares the stress of steel bar and steel plate under the coupling action of different flexural-shear ratio, the stress of steel bar and steel web under the connection method of binding or welding of steel bar, the stress of bolts and the load-slip curve of bolts were also compared. The analysis results show that the reinforcement arranged in the diaphragm can significantly improve the ultimate bearing capacity of the overall structure by welding with the diaphragm, effectively improve the stress distribution of the bolt, reduce the stress value of the connection between the bolt and the steel plate, and improve the shear resistance of the bolt. With the wide application of corrugated steel webs, more attention should be paid to the force transmission performance of the connection interface between the steel webs and the concrete diaphragm in the engineering design process. The research results can be used for the design calculation of the connection between the corrugated steel web composite beam bridge and the diaphragm in the future, and provide reference for engineering application.

The Multi-Functional Modelling Shear Lag Method for Accurate Calculation of Static Response and Accordion Effect of Improved Composite Box Girders

The composite box girder with corrugated web and steel bottom plate (CW-SBS) is a kind of improved steel-concrete structures. The design of CW-SBS box girders needs the accurate method to calculate the working response and accordion effect in consideration of the self-stress equilibrium condition of shear lag warping stress and shear deformation. This study proposes the multi-functional modelling shear lag (MFMSL) method which adopts the four longitudinal displacement difference functions to model the variation of shear lag in the CW-SBS box girders with different wing slab widths and thicknesses. Therefore, MFMSL is a method to calculate the static response and accordion effect of the CW-SBS composite box girders. Structural differential equations based on the energy-variation principle present that the MFMSL method effectively improves the calculating accuracy of the CW-SBS box girder static response, which can be verified by both experimental and simulative results. Also, the MFMSL method demonstrates that the accordion effect of the CW-SBS box girder is stronger than that of the traditional composite box girder and closely relates to the load distribution. Hence, the proposed method further lays the foundation for the analysis and design of CW-SBS box girders.

Experimental study and analysis for the long-term behavior of the steel–concrete composite girder bridge

Due to the influence of the meteorological factors, the long-term behaviors of steel–concrete composite girders of the real bridge is different from that of indoor laboratory models. In order to address this issue, a long-term field test of 4 years was performed on the simply-supported steel–concrete composite girder bridge to study the temperature, shrinkage and creep effects. The temperature field models (TFM) and mechanical behavior models (MBM) were built in sequence and verified by the test results of the concrete deck and steel girders of 2018 and 2019 since the temperature and strain changed greatly during this period. The temperature calculated by the TFM agreed well with the test results. Although the stress of composite girders obtained by the test is different from that of the MBM, the difference in the whole service stage is small. The test results of the steel cross beam, the steel–concrete interface, the wet joint and the concrete continuous layer were also discussed, and the former three were all under compressive state, while the concrete continuous layer is under tensile state in some time period with the maximum tensile stress 3.12 MPa. Then, the verified models were used to separate the temperature strain from the long-term tested strain, and the remaining tested strain is the shrinkage and creep strain. In summer and winter, the shrinkage and creep stress calculated by the age-adjusted effective modulus method (AEMM) was different from the tested values due to the influence of air humidity, initial load age, stress level and inherent error of the prediction model. Much attention should be paid to the influence of the meteorological factors on the long-term behaviors of steel–concrete composite girder bridges.