Steel-concrete Composite Research Articles

Investigation on Vibro-acoustic Characteristics of High-speed Railway Steel-concrete Composite Bridge Based on the Combined FE-BE-SEA Method

This paper presents a combined finite element-boundary element-statistical energy analysis (FE-BE-SEA) method to predict the vibro-acoustic characteristics of high-speed railway steel-concrete composite (SCC) bridge. The train-track coupling model is firstly introduced to accurately determine the forces transmitted to bridge, which are then imported into the established FE-BE model and SEA model. Among them, the former is adopted to calculate the vibration response in full frequency band and acoustic response at 20∼200 Hz, while for the noise part at 200∼2000 Hz, the latter is utilized for calculation. The on-site testing is carried out simultaneously to collect the measured results, which are compared with the predicted ones, validating the reliability and accuracy of the proposed method. Finally, a thorough discussion is conducted on the acoustic contribution and parametric analysis. The results indicate that the dominant frequency bands of deck and web radiated noise are below and above 200 Hz, respectively, ranking first and second in terms of overall acoustic contribution, followed by the diaphragm and flange. Reducing train speed, installing elastic fasteners, as well as increasing web thickness can significantly mitigate the vibro-acoustic responses from SCC bridge, but the effective frequency ranges for vibration and noise reduction are slightly different.

Advances in Steel and Composite Steel—Concrete Bridges and Buildings

Construction steel has widely been used worldwide for developing infrastructure, e [...]

Study on Vibration and Noise of Railway Steel–Concrete Composite Box Girder Bridge Considering Vehicle–Bridge Coupling Effect

A steel–concrete composite beam bridge fully exploits the mechanical advantages of the concrete structure and steel structure, and has the advantages of a fast construction speed and large stiffness. It is of certain research value to explore the application of this bridge type in the field of railway bridges. However, with the rapid development of domestic high-speed railway construction, the problem of vibration and noise radiation of high-speed railway bridges caused by train loads is becoming more and more serious. A steel–concrete composite beam bridge combines the tensile characteristics of steel and the compressive characteristics of concrete perfectly. At the same time, it also has the characteristics of a steel bridge and concrete bridge in terms of vibration and noise radiation. This feature makes the study of the vibration and noise of the bridge type more complicated. Therefore, in this paper, the characteristics of vibration and noise radiation of a high-speed railway steel–concrete composite box girder bridge are studied in detail from two aspects: the theoretical basis and a numerical simulation. The main results obtained are as follows: Relying on the idea of vehicle–rail–bridge coupling dynamics, a structural dynamics analysis model of a steel–concrete combined girder bridge for a high-speed railroad was established, and numerical program simulation of the vibration of the vehicle–rail–bridge coupling system was carried out based on the parametric design language of ANSYS 18.0 and the language of MATLAB R2021a, and the structural vibration results were analyzed in both the time domain and frequency domain. By using different time-step loading for the vehicle–rail–bridge coupling vibration analysis, the computational efficiency can be effectively improved under the condition of guaranteeing the accuracy of the result analysis within 100 Hz. Based on the power flow equilibrium equation, a statistical energy method of calculating the high-frequency noise radiation is theoretically derived. Based on the theoretical basis of the statistical energy method, the high-frequency noise in the structure is numerically simulated in the VAONE 2021 software, and the average contribution of the concrete roof plate to the three acoustic field points constructed in this paper is as high as 50%, which is of great significance in the study of noise reduction in steel–concrete composite girders.

Innovative design and construction of a closure joint for inland-river immersed tunnels via dry-land construction methods: A case study of the Yuliangzhou tunnel in China

Closure joints constructed to fill the spaces between immersed tunnel elements or between the tunnel elements and adjacent cut-and-cover tunnels are crucial for the longitudinal stability of immersed tunnels and affect the overall cost and duration of tunnel construction. To avoid the obstruction of navigation and reduce the difficulty of constructing closure joints, dry-land construction methods have been widely applied to construct closure joints for inland-river immersed tunnels, in particular using procedures involving axial dry docks. However, the traditional dry-land construction method has many inherent drawbacks. For example, the construction of underwater large-scale reinforced concrete antiretreat structures involves many underwater works, complicated construction processes, long operation time spans and high costs. Based on the Yuliangzhou immersed tunnel in China, a new dry-land construction method for closure joints of inland-river immersed tunnels based on tunnel–soil interface friction was developed to address the abovementioned problems. Considering the adverse influences of back-silting sediment on tunnel–soil interface friction, large-scale laboratory and onsite shear tests were carried out to derive the interface friction coefficients between the tunnel element base slabs and prelaid pebble foundation beds. A composite concrete steel sandwich (CCSS) water-retaining system was designed and assembled to separate the water in the dry dock from the river course. A simplified analysis method based on numerical simulations for the determination of the equivalent horizontal thrust P applied to element ES caused by the dewatering of the axial dry dock was proposed. Based on horizontal antisliding stability analyses of the tunnel elements during the axial dry dock dewatering stage, equations for the key design parameters of the new dry-land construction method were established. Through examination of the static equilibrium of the tunnel elements in the tunnel longitudinal direction, temporary longitudinal displacement constraint (LDC) structures at the immersion joints were designed. Furthermore, the following key construction techniques for the new dry-land construction method were systematically designed: installation of a CCSS water-retaining system at the entrance of the axial dry dock, water sealing at contact gaps, installation of finish-rolled screw-thread (FRST) steel bars as the LDC structures at the immersion joints, and construction of rigid connections between tunnel element ES and the cut-and-cover tunnel. Finally, onsite observation of the deformation states of Gina gaskets and monitoring of the tensile forces of FRST steel bars at the immersion joints verified the successful implementation of the new dry-land construction method, supporting the use of these techniques in closure joint design and construction for inland-river immersed tunnels.

Optimized analysis and reinforcement design model for RC/SCC box-section bridges using developed advanced design framework

In recent years, there has been a significant rise in the construction of reinforced concrete (RC) and steel-concrete composite (SCC) box-section bridges. However, design codes do not provide specific design methods for the RC plates of such bridges where the plates experience both intricate forces and moments. The current design approaches are primarily based on conventional one-dimensional beam element theory, which neglects the complex spatial force characteristics of the structural elements, potentially leading to unsafe design. Therefore, it is imperative to address this issue. To bridge this gap, a comprehensive analysis and reinforcement design procedure named as the developed advanced design framework (DADF) is proposed in this study. The spatial analysis of bridges was performed using a refined numerical model, called the spatial grid model (SGM), to consider the structural spatial effects with limited model scales. Subsequently, the internal force corresponding matrix (IFCM) was implemented through Python scripts to determine the most critical internal force combination for an RC plate element. Additionally, the three-layered sandwich model (T-LSM) was employed with limit analysis to automatically design reinforcement for all elements, serving as a practical tool for design. This research demonstrates that the implementation of the DADF can significantly reduce steel reinforcement in the RC plates of such bridges by up to 48 %, and 23 % in total, showcasing the efficiency of the developed framework. Overall, the findings emphasize that the proposed DADF offers a robust procedure for steel reinforcement design of RC/SCC box-section bridges.

Seismic Performance of Cross-Shaped Partially Encased Steel–Concrete Composite Columns: Experimental and Numerical Investigations

Special-shaped partially encased steel–concrete composite (PEC) columns could not only improve the aesthetic effect and room space use efficiency, but also exhibit good mechanical performance under static load when used in multi-story residential and office buildings. However, research on the seismic performance of special-shaped PEC columns is insufficient and urgently needed. To investigate the seismic performance of cross-shaped partially encased steel–concrete composite (CPEC) columns, three CPEC columns were designed and tested under combined constant axial load and lateral cyclic load. The test results show that the CPEC columns had good load capacity and ductility, and that the columns failed because of concrete crushing and steel flange buckling after the yielding of the steel flange. The plump hysteresis loops indicated that the CPEC column also had good energy dissipation capacity. Due to the constraint of hydraulic jacks, increasing the load ratio would decrease the effective length, thereby increasing the load capacity of the CPEC column and decreasing the ductility. A finite element model was also established to simulate the response of the CPEC columns, and the simulated results agree well with the experimental results. Thereafter, an extensive parametric analysis was performed to study the influences of different parameters on the seismic performance of CPEC columns. For the CPEC column with an ideal hinged boundary condition at the top, its lateral load capacity gradually decreases with the growth of the load ratio and link spacing and increases with the rise of the steel yield strength, concrete compressive strength, flange and web thickness, and sectional aspect ratio. This research could provide a basis for future theoretical analyses and engineering application.

Primary Energy and Carbon Impacts of Structural Frames with Equivalent Design Criteria: Influence of Different Materials and Levels of Prefabrication

This study aims to analyze the life-cycle primary energy and climate impacts of structural frames, paying particular attention to the design and prefabrication of different structural materials. The study considers an existing single-story office building with a composite concrete–steel structure and compares it with two functionally equivalent structures, i.e., a conventional reinforced concrete structure and a conventional steel structure. The existing building is located in San Felice sul Panaro, Italy. This study integrates dynamic structural analysis and life-cycle assessment (LCA). The study finds that the use of different materials can reduce the life-cycle primary energy use and CO2-eq emissions by up to 12%. Furthermore, the benefits derived from the recovery and recycling of materials can reduce the primary energy use and CO2-eq emissions by up to 47% and 36%, respectively. The prefabrication of structural elements can also reduce the primary energy use and CO2-eq emissions in the construction stage. A sensitivity analysis considers changes in the electricity supply system and shows that the primary energy and CO2-eq emissions due to prefabrication decrease when assuming marginal electricity based on renewable energies. This analysis supports the development of sustainable structural design to meet the standards concerning the whole-life-cycle carbon emissions of buildings.

INVESTIGATION OF STEEL ANGLE AND PLATE CONFINEMENT ON CONCRETE UNDER AXIAL LOAD USING DIFFERENT AGGREGATE

Steel and concrete are frequently used to construct composite structures, making steel-concrete composites the most common choice. This research aims to compare the confinement effects observed in stone aggregate, brick aggregate, and recycled brick concrete. This analysis evaluates the impact of various thicknesses of steel angles (3mm and 4mm) and steel plates (3mm and 4mm) on the confinement effect. Each aggregate is studied using 18 cube specimens: six with 3mm steel angle confinement, six with 4mm steel angle confinement, and six without steel angle and plate confinement. This study employed Portland Composite Cement and coarse sand at 1:2:4 and 0.45 water-cement ratios. The concrete is carefully built to meet specifications and retain the slump value. Compressive strength testing is conducted on the concrete specimens at the 28-day and 60-day intervals. Simultaneously, the composite cubes are assessed for their suitability for confinement and vertical displacement. The findings reveal that stone aggregate with steel plate confinement demonstrates the highest compressive strength. Specifically, the compressive strength in stone aggregate with steel plate confinement is 3.04 and 3.52 times greater after 28 days and 60 days, respectively, compared to specimens without confinement.

INVESTIGATION OF STEEL ANGLE AND PLATE CONFINEMENT ON CONCRETE UNDER AXIAL LOAD USING DIFFERENT AGGREGATE

Steel and concrete are frequently used to construct composite structures, making steel-concrete composites the most common choice. This research aims to compare the confinement effects observed in stone aggregate, brick aggregate, and recycled brick concrete. This analysis evaluates the impact of various thicknesses of steel angles (3mm and 4mm) and steel plates (3mm and 4mm) on the confinement effect. Each aggregate is studied using 18 cube specimens: six with 3mm steel angle confinement, six with 4mm steel angle confinement, and six without steel angle and plate confinement. This study employed Portland Composite Cement and coarse sand at 1:2:4 and 0.45 water-cement ratios. The concrete is carefully built to meet specifications and retain the slump value. Compressive strength testing is conducted on the concrete specimens at the 28-day and 60-day intervals. Simultaneously, the composite cubes are assessed for their suitability for confinement and vertical displacement. The findings reveal that stone aggregate with steel plate confinement demonstrates the highest compressive strength. Specifically, the compressive strength in stone aggregate with steel plate confinement is 3.04 and 3.52 times greater after 28 days and 60 days, respectively, compared to specimens without confinement.

The Effect of Connection Ductility on Composite Steel–Concrete Bridges

Connection behavior significantly influences the design efficiency of steel–concrete composite bridges. This study investigates the impact of shear connectors, specifically headed stud connectors, on the structural response of symmetric and skewed composite steel–concrete bridges. Utilizing bilinear or trilinear slip–shear strength laws for studs, in line with the existing literature and code provisions, a finite element (FE) model is developed. This FE model is applied to a case study for composite deck analysis, incorporating variations in connection strength and ductility for nonlinear analyses. The study assesses ductility demands in connections for symmetric and skewed bridges of varying lengths and angles, considering both ductile and elastic designs. Results emphasize the importance of stud capacity, ductility, and strength on the overall bridge response, analyzing slip and shear trends at the interface. Skewed bridges, crucial for non-orthogonal crossings of roads, are integral to modern transportation infrastructure. However, skewness angles exceeding 20° can result in undesirable effects on stresses in the deck due to vertical loads. The results indicate that shear distribution in studs changes significantly as the skew angle increases, contributing valuable insights into optimizing bridge design. Thus, this research provides a comprehensive analysis of principles, design methodologies, and practical applications for both symmetric and skewed steel–concrete composite bridges, considering various parameters.

Stress-strain models and numerical simulations of steel headed studs at low temperatures

Headed studs are commonly used in steel–concrete composite (SCC) structures. To promote the application of SCC structures in cold regions, this study first developed prediction equations for key indexes in temperatures ranging from 20 to −80 °C. Then, full-range stress–strain (σ–ε) models of headed studs considering low temperatures were proposed. Validations against 56 tensile test results confirmed that the developed constitutive models accurately estimated the stress–strain behaviour of headed studs at low temperatures. Subsequently, finite element models along with the continuum damage plasticity model (CDM) and proposed σ–ε models were developed for headed studs at varying temperatures. Using the test results combined with finite element analyses, the true stress–strain curve and stress-modified critical strain model were calibrated for headed studs at low temperatures. Finally, the reliability of the developed CDM and σ–ε models were validated by applying them to finite element models of six pull-out and eight push-out specimens.

Wave propagation analysis for three typical box girders: Dominant wave modes and their applications

Because of the prevalent application of bridges in transportation, problems such as vibration and noise of bridges, especially in densely populated urban areas, are increasingly arousing concerns. The vibro-acoustic behaviors of bridges are important for vibration and noise control. Although these vibro-acoustic behaviors have been reported and discussed in several studies in terms of modal analysis, this study focuses on the probe into the vibration properties of three typical box girders (BGs) from the wave motion perspective: concrete, steel–concrete composite, and steel BGs. The dispersion characteristics and mode shapes of waves propagating in BGs are identified using the wave finite element method (WFEM). This calculation method combines the finite element method (FEM) with the Bloch–Floquet theorem, and it is validated by the existing literature and FEM. The wave propagation characteristics of the three typical BGs are then compared to analyze their similarities and differences in vibration. Furthermore, the contribution of each wave mode to the whole vibration and the local vibration of BGs is determined; consequently, the important vibration mechanism can be identified and ranked in different frequency bands. Lastly, some feasible application of vibration control for BGs is given in the light of the vibration mechanism. The study results provide theoretical and practicable foundation of vibration control for BG bridges in urban rail trafficsystems

Flexural behavior of externally prestressed continuous steel-concrete composite beams

To investigate the flexural behavior of continuous externally prestressed steel–concrete composite (EPSCC) beams, flexural tests were conducted on two two-span continuous beams with a total length of 9.8 m. The test parameter focused on the number of deviators in each span. With the aid of detailed measurement of deviator displacement, slip distribution on the steel-slab interface and strain along shear connectors, the shear mechanism of headed studs and the second-order effect in continuous EPSCC beams were evaluated. The test results indicated that both beams underwent concrete cracking over their interior supports, followed by the formation of a plastic hinge in the hogging moment zone, the subsequent formation of a plastic hinge in the sagging moment zone, and ultimately the crushing of concrete slabs in the sagging moment zone. Prior to failure, full plasticity was developed at both the mid-span section and interior support section of each beam. The local moment acting on the shear studs reached its maximum hogging values at the shank root, while its maximum sagging value was attained at approximately the mid-height of the shank. Due to the second-order effect, the removal of deviators at midspans resulted in a 7.1% decrease in the sagging moment of the beam. At the ultimate limit state, the measured degree of moment redistribution values for hogging moment ranged between 52% and 58%, which were higher than the specified limits in current design guidelines. The predictions of the ultimate hogging and sagging moment calculated from plastic theory were consistent with experimental results.

Moment curvature response of composite UHPC filled hollow structural steel cross-sections

A mechanics based analytical method for obtaining the complete moment–curvature response of composite hollow structural steel (HSS) and ultra high performance concrete (UHPC) cross-sections is presented. Flexural response at the cross-sectional level is traced past the local buckling of the steel elements and up to the exhaustion of UHPC and steel material capacity. The proposed method is validated using experimental data from seven flexural tests on composite HSS-UHPC beams. Flexural failure mode is classified as either a UHPC compression-controlled failure, UHPC fiber tension-controlled failure, or a balanced failure. Behavioral differences between the cross-sections that fall into these three categories are discussed in terms of flexural capacity, curvature ductility, and relative contributions of HSS and UHPC to flexural capacity. Flexural response of the composite HSS-UHPC cross-section is compared to that of the bare HSS cross-section. The enhancement in flexural capacity and curvature ductility, for UHPC fiber tension-controlled sections compared to the bare HSS cross-section, was 52% and 79%, respectively. For composite cross-sections that feature a balanced failure, the increase in flexural capacity and curvature ductility, compared to the bare HSS cross-section, was 37% and 35%, respectively. Closed form formulations are proposed to identify the flexural failure mode and predict flexural capacity. The influence of various parameters, such as HSS material grade, size of cross-section, and UHPC material characteristics on the complete flexural response of the cross-section is investigated. The average ratio and corresponding coefficient of variation (COV) of tested to computed flexural strength obtained using the proposed procedure was 1.06 and 21.28%, respectively. Similarly, the average ratio and COV of tested to calculated flexural strength obtained using the proposed closed form formulations was 1.07 and 22.18%, respectively.

Advances in Methodology for Fatigue Assessment of Composite Steel–Concrete Highway Bridges Based on the Vehicle–Bridge Dynamic Interaction and Pavement Deterioration Model

Fatigue cracking is one of the most prominent causes of mechanical failure limiting the service life of existing steel and composite steel–concrete bridges and is among the central concerns of structural and bridge engineers. In this context, the current work presents some recent advancements in an existing methodology for fatigue analysis developed by the authors throughout the years. The methodology is specifically devoted to the fatigue assessment of composite steel–concrete bridges employing the local hot-spot S-N approach and a coupled vehicle–pavement–bridge system considering progressive pavement deterioration with stochastically generated roughness profiles. Two different methodologies were used to solve the dynamic equilibrium equations: the modal superposition method to solve the bridge dynamic equations and a direct integration method to solve the vehicle dynamic equations. From a computational point of view, the present approach is more efficient and detailed than previous versions, as it allows a significant reduction in the analysis time and the use of complex bridge and vehicle finite element models. In this regard, a case study of a highway composite steel–concrete bridge spanning 40 m was selected in order to demonstrate the usefulness of the presented improved methodology by carrying out a fatigue analysis. The results of this investigation (displacements and stresses) are presented, aiming to verify the factors that directly influence the structural response and, consequently, the service life of steel–concrete composite highway bridges.

Interfacial performance and bond-slip constitutive model between steel and modified polyurethane concrete composites

In recent years, ecology conservation optimization (ECO) modified polyurethane concrete is becoming popular in steel deck pavement areas. However, it is reported that the interface performance between steel and ECO concrete suffers a significant degradation caused by diurnal and seasonal thermal cycling. In this paper, the interfacial performance of steel and ECO concrete composites at different temperatures was investigated through four groups of oblique tests at the temperature of −10 °C, 15 °C, 40 °C and 60 °C. The digital image correlation (DIC) technique is used to measure the strain distribution. The results show that the interfacial shear strength and stiffness of the specimens decrease with the growth of temperature, while the ultimate relative slip increases. Based on regression analysis, the formulas for calculating the interfacial shear strength, shear stiffness, and ultimate relative slip of steel and ECO concrete composites at different temperatures were established. A temperature dependent bond-slip constitutive model was proposed then by considering the temperature dependency of model parameters, which shows great accuracy in describing the bond-slip behavior between the steel and ECO concrete. Furthermore, a finite element analysis (FEA) model was established based on cohesive behavior, which agrees well with experimental results. Our research results can provide guidance for engineering applications of ECO concrete.

Behaviour and design of coupled steel-concrete composite wall-frame structures

This paper explores the lateral load-carrying behaviour of coupled steel-concrete composite (SCC) wall-frame structures, which comprise concrete-filled steel tubular (CFST) columns, composite beams and composite walls. Both experimental and numerical studies were conducted. The experimental programme includes one single-storey bare frame structure and three single-storey coupled SCC wall-frame structures. The experimental results showed that applying the composite wall can significantly increase the lateral load-carrying capacity of the entire structure. It was also evident that increasing the wall width and lowering the structural height can effectively enhance the lateral load-carrying capacity. The modelling approaches in ABAQUS and OpenSees were proposed to conduct the finite element (FE) analysis. In particular, ABAQUS was used to build single-storey coupled SCC wall-frame structures to assess the effects of several parameters, such as beam stiffness, the thickness of steel tubes and wall faceplates, wall width, concrete grade, steel grade and axial load ratio. It was found that increasing the thickness of steel tubes and wall faceplates as well as wall width can effectively increase the lateral performance of the structure but increasing the steel beam stiffness only results in limited improvement. Increasing the steel grade can improve the lateral performance of the structure much more significantly than the concrete grade. When the axial load ratio reaches 0.6, the lateral strength of the structure is greatly reduced owing to the P-Δ effect. Moreover, one multi-storey bare frame structure and three multi-storey coupled SCC wall-frame structures were constructed in OpenSees as a case study. The multi-storey coupled SCC wall-frame structures display extraordinary lateral load-carrying capacity by analysing the curves of base shear force versus roof drift ratio. Besides that, instead of the nominal inter-storey drift ratio, the destructive inter-storey drift ratio together with the roof drift ratio are recommended to assess the multi-storey coupled SCC wall-frame structures in order to avoid overconservative design.

Three-Dimensional Numerical Simulation for Lateral Distortional Buckling Behaviour of Steel-Concrete Composite Beams

Lateral Distortional Buckling (LDB) is a mode of instability in Steel-Concrete Composite (SCC) beams that is yet to be fully understood by the structural engineering research and design community. This work investigated numerical methods to understand the LDB behavior of SCC beams under negative moments that exhibit nonlinear behavior. Focus of the study was to develop and validate 3-Dimensional finite element (FE) models which capture the LDB behavior of SCC beams precisely. Detailed 3-Dimensional FE models of the SCC beams were developed using ABAQUS. For modeling concrete, a nonlinear damage plasticity model was considered. A quad-linear curve was used to describe the stress-stain relationship for the steel beam. The stress-stain relationship for the rebar was described using a bi-linear curve while an elastic perfectly plastic model was assigned to the headed stud shear connectors. Steel hardening behavior was simulated using an isotropic hardening model. The interaction between the concrete slab, steel beam, and studs was described using appropriate interface elements combined under suitable constraints. The FE model’s accuracy was validated by results obtained from previous experiments found in literature together with a brief description of the experiments done by previous researchers to ensure completeness. Validation of the model was done by comparing Moment-Rotation curves obtained from the experimental tests, lateral displacements of the bottom flange along the axial direction and comparison of the failure modes between the numerical model and experimental test specimens. It was observed that the maximum relative error for the ultimate moment capacity of the composite beams from FE analysis and the experimental tests was less than 2% which shows that the FE model was in strong agreement with the experimental results. Accordingly, the numerical model developed herein proves to be capable of accurately representing the LDB phenomenon.

Modeling and Testing of a Composite Steel-Concrete Joint for Hybrid Girder Bridges.

A hybrid girder bridge adopts a steel segment at the mid-span of the main span of a continuous concrete girder bridge. The critical point of the hybrid solution is the transition zone, connecting the steel and concrete segments of the beam. Although many girder tests revealing the structural behavior of hybrid girders have been conducted by previous studies, few specimens took the full section of a steel-concrete joint due to the large size of prototype hybrid bridges. In this study, a static load test on a composite segment to bridge the joint between the concrete and steel parts of a hybrid bridge with full section was conducted. A finite element model replicating the tested specimen results was established through Abaqus, while parametric studies were also conducted. The test and numerical results revealed that the concrete filling in the composite solution prevented the steel flange from extensive buckling, which significantly improved the load-carrying capacity of the steel-concrete joint. Meanwhile, strengthening the interaction between the steel and concrete helps to prevent the interlayer slip and simultaneously contributes to a higher flexural stiffness. These results are an important basis for establishing a rational design scheme for the steel-concrete joint of hybrid girder bridges.

Fatigue Behaviors of Joints between Steel Girders with Corrugated Webs and Top RC Slabs under Transverse Bending Moments

Steel-concrete composite box beams are widely used in bridge engineering, which might bear transverse and longitudinal bending moments simultaneously under vehicle loads. To investigate the fatigue performance of joints between the steel girders and the top reinforced concrete (RC) slabs under transverse bending moments, a reduced scale joint between the weathering steel girder with the corrugated steel web (CSW) and the top RC slab was designed and tested under constant amplitude fatigue loads. Test results show that the joint initially cracked in the weld metal connecting the CSW with the bottom girder flange during the fatigue loading process. The initial crack propagated from the longitudinal fold to the adjacent inclined folds after the specimen was subjected to 7.63 × 105 loading cycles and caused the final fatigue failure. Compared with the calculated fatigue lives in the methods recommended by EC3 and AASHTO, the fatigue performance of the details involved in the joint satisfied the demands of fatigue design. Meanwhile, finite element (FE) models of joints with different parameters were established to determine their effect on the stress ranges at the hot spot regions of the joints. Numerical results show that improving the bending radius or the thickness of the CSW helps to reduce the stress ranges in the hot spot regions, which is beneficial to enhance the fatigue resistance of the investigated fatigue details accordingly.