Behavior Of Composite Beams Research Articles

Corrigendum to “Experimental and analytical investigations into flexural behavior of composite beams with UHPC T-section and HRS H-section” [Eng Struct 315 (2024) 118445

Corrigendum to “Experimental and analytical investigations into flexural behavior of composite beams with UHPC T-section and HRS H-section” [Eng Struct 315 (2024) 118445

Experimental study of deconstructable embedded bolted shear connectors in composite beam subjected to cyclic loading

Bolted shear connectors have recently been introduced and studied as a convenient and demountable alternative for shear studs in steel-concrete composite beams. The major problem of welded studs is their undeconstructability. Bolted shear connectors make it possible to deconstruct and reuse the connection after its service life. In this study, the cyclic behavior of embedded bolted shear connectors in steel-concrete composite beams was investigated. The specimens included prefabricated concrete slabs with a square hole, which was filled with grout after assembling the concrete slab and steel section. Eight specimens were fabricated and tested to examine the effect of the bolt's diameter and strength on the cyclic behavior. To determine its behavior characteristics force-slip curves were applied. Ductility, strength degradation, and energy dissipation were the primary parameters investigated in this study. The results showed that the bolt’s diameter and strength significantly influenced the cyclic behavior of composite beams. Increasing the bolt's diameter and strength improved the connection's ductility and energy dissipation. Furthermore, doubling the bolt's cross-section increased the connection's ultimate strength by more than twice.

Flexural behavior and numerical simulation of reinforced concrete beams with a UHPC stay-in-place formwork

To overcome the shortcomings of traditional concrete structures such as long construction cycle, high construction cost and poor durability, seven composite beams with a UHPC stay-in-place formwork (UCB) and one reinforced concrete (RC) beam were designed. An experimental study was conducted to investigate the flexural behavior of composite beams under the static load. The research parameters include formwork thickness, reinforcement rate, and formwork surface treatment. The results revealed that roughening the surface of UHPC formwork has a positive impact on enhancing the integrity of composite beams. The utilization of UHPC stay-in-place formwork can effectively improve the stiffness, cracking load, and peak load of members. Compared with that of the RC beam, the cracking load and peak load of composite beams increased by 63% ~ 103% and 6% ~ 15%, respectively, and the yielding stiffness increased by 23% ~ 41%. Different from the RC beam, new cracks occurred on one side of the initial crack's end and continued to extend upwards rather than along the original crack. The existence of a significant quantity of tiny cracks in composite beams effectively slowed down the increase in the width of pre-existing cracks in the early stage of loading. Due to the multi-crack pattern exhibited by the UHPC formwork, the strain concentration of the steel bars was effectively mitigated. When subjected to the same load level, the strain of the longitudinal steel bars in composite beams was smaller than that of the RC beam. The formula for calculating the flexural bearing capacity of composite beams is established through theoretical analysis. In addition, the numerical model of the composite beam is established by the finite element method (FEM). The influence of the contact method of the UHPC-NC interface on the flexural performance of the composite beam is explored. The supplementary analysis of the parametric study of the reinforcement rate and the UHPC formwork thickness is carried out. When using ABAQUS for the numerical analysis of the composite beam, it is appropriate to adopt the cohesion model or the Tie model for the UHPC-NC interface, and it is not appropriate to use the Coulomb friction model.

Experimental and analytical investigations into flexural behavior of composite beams with UHPC T-section and HRS H-section

This study investigated the flexural behavior of composite beams with ultra-high performance concrete (UHPC) T-section and hot rolled steel (HRS) H-section. First, a four-point bending test on six specimens was conducted. The effects of stud spacing and tensile reinforcement ratio on flexural performance were investigated in terms of crack patterns, failure modes, ultimate load, load-strain response, relative interfacial slip, and ductility. The experimental results indicated that the stud spacing and the presence of tensile reinforcement had a visible effect on the crack patterns of UHPC web. The distribution of group cracks was observed at UHPC web of specimens with unreinforced UHPC bulb. During the failure stage, the whole HRS H-section in the constant moment region yielded. In particular, the partial cross section of HRS entered the strain hardening stage. In addition, an analytical approach verified by six tested specimens was developed to study the moment-curvature response of HRS-UHPC composite beams (HUCBs). The comparison results indicated the good accuracy of the analytical approach. Then, the proposed sectional analysis model was utilized to investigate the effects of the strength of HRS and UHPC, the total depth of cross section, and the depth of HRS H-section on yielding moment, including ultimate moment and ductility. The analytical results revealed that the strength of HRS and the total depth of cross section had a significant impact on the moment-curvature response of HUCBs. The sectional analysis also illustrated that the yielding point was mainly determined by the yielding of HRS H-beam. Compared with UC120, the ultimate moment and ductility coefficient of the composite beam using UC200 increased by 20.6 % and 87.7 %, respectively. However, the tensile strength of UHPC had a slight influence on the yielding and ultimate moment as well as ductility.

Numerical simulation of steel-concrete composite beams and slabs at elevated temperatures

Steel-concrete composite beams with shear studs providing composite action between the concrete slabs and steel beams are widely used in modern steel-framed building construction. Three-dimensional finite element modelling has been a viable option for investigating the fire behaviour of composite beams. Although many finite element models are available in the open literature, most of them are simplified models verified by limited test data. Meanwhile, early test data often did not have all the required information for finite element simulation, and some assumptions need to be made. But more detailed test data are now available in the open literature for steel-concrete composite beams, which can be used to develop a generalised finite element model. In addition, National Institute of Standards and Technology has proposed new stress-strain models for steels at elevated temperatures, which can be compared with the more widely adopted Eurocode 4 steel material models in simulating composite beams. Accordingly, this paper selected 22 specimens, including two reinforced concrete slabs, 12 composite beams with reinforced concrete slabs, two composite slabs with profiled steel sheeting, two steel-concrete composite push test specimens with profiled steel sheeting, and four composite beams with profiled steel sheeting, from nine references to verify the developed finite element model. The proposed finite element model can capture different failure modes of composite beams, such as steel yielding/local buckling, concrete cracking/crushing, debonding of profiled steel sheeting, and stud fracture, which is crucial to comprehend the composite beam behaviour at elevated temperatures.

Comparative analysis of geometric imperfections and residual stresses on the global stability behavior of cantilever composite alveolar beams

Few studies addressed the influence of geometric and structural imperfections of steel alveolar I-sections on the stability behavior of composite beams under hogging moment. Therefore, this paper aims to study the sensitivity to geometric imperfection amplitude and residual stress distribution on their global stability. The research primarily focuses on comparing numerical results with experimental data in detail, which addresses four tests involving cantilever composite beams with castellated and cellular I-sections. It includes applying various residual stress patterns and geometric imperfection values to advanced numerical analyses as documented in the literature. Linear buckling analyses (LBA) and geometrically and materially nonlinear analyses with imperfections (GMNIA) are carried out using the ABAQUS software. Regarding the first positive eigenvalue from LBA analyses, the eigenvectors presented Web-Post Buckling (WPB) with a slight compressed flange lateral curvature, inserted as the initial geometric imperfection in the GMNIA analyses. However, when the residual stresses were implemented in the GMNIA analyses, some finite element models had different failure modes regarding the deformed configurations from LBA analyses, in which the failure modes were characterized by Lateral-Distortional Buckling (LDB), which was in agreement with the test results. As the beams reached LDB in an inelastic regime, residual stresses significantly affected their resistant capacity. This way, the distribution of compressive residual stresses in the flanges had the most critical influence on the global stability behavior of the analyzed beams, as these residual stresses favor the LDB occurrence. Finally, higher geometric imperfection amplitudes did not provide only lower ultimate loads, as when the instability phenomena are reached in an inelastic regime, the effect of global geometric imperfections becomes highly complex.

Experimental investigation on flexural performance of steel-UHPC composite beams with steel shear keys

Test results of steel-ultra high performance concrete (UHPC) composite beams with welded steel shear keys (SSKs) under four-point bending are presented in this paper. The objective of the investigation is to reduce the self-weight and manufacturing cost of large-span structures. The study investigates the effects of strength of concrete slab, type, spacing and size of SSK, and concrete slab height and width on flexural behavior of composite beams. The experimental results demonstrate that enhancing concrete strength, reducing SSK spacing, increasing concrete slab size, and using large-size SSK can all significantly enhance the flexural performance. The composite beams with welded SSK exhibit a maximum relative slip of less than 4 mm, while the counterpart with welded bolts has a maximum relative slip greater than 4 mm. The study shows that the welded SSK is more effective than welded bolts in improving the interface shear performance of composite beams and improving the stiffness and load capacity. Additionally, the study defines four failure modes of steel-UHPC composite beams, and the formulae for flexural capacity is developed based on the reasonable basic assumptions. The calculated results fit well with the tested results. The research findings can be provided as a technical support for the design and application of steel-UHPC composite beams.

A Numerical Study on the Influence of Bolt Corrosion on the Long-Term Behavior of Steel–Concrete Composite Beams

This study establishes a numerical model for beam-type steel–concrete composite specimens considering the corrosion of anchor bolts, with which studies the long-term deformation performance of the components under sustained load. The experimental results were compared with the calculated values obtained by combining the effective modulus method according to the CEB-FIP 1990 code and the ACI 209R code. Then a comparison with the calculation method of shrinkage and creep in standards (Standard Creep Method (SCM)) is made, and it shows that by supplementing the degradation of interface stiffness due to corrosion (using the defined modulus method (DMM)), the simulation results match better with the experimental results, confirming that this approach is suitable for analyzing the long-term load conditions of anchor bolt corrosion. Furthermore, based on the defined modulus method, the long-term behavior of composite beams under different loads and varying corrosion rates is studied.

Experimental analysis of the flexural behaviour of precast concrete composite beams with discontinuous connections

Full-depth precast deck panels hold the potential to enhance constructability and productivity, and reduce the costs associated with highway bridges. This paper investigates the influence of discontinuous shear connections between girders and panels on the flexural behaviour of composite beams. Experimental findings from precast composite beams and direct shear tests are presented, including L-shape push-off tests and double shear tests to determine resistance at rough concrete-to-concrete plain interfaces and shear pocket connections. Composite beams with a full-depth precast slab connected through a shear pocket with shear keys into the upper face of a precast beam exhibit equivalent flexural resistance to monolithic beams when shear pocket spacing remains below the effective depth of the composite beam. However, composite beams with shear pockets featuring plain interfaces show a reduction in flexural resistance of up to 30% compared to monolithic beams. Moreover, composite beams with shear keys demonstrate interface shear stiffness up to four times greater than those with plain interfaces, indicating full interaction. The paper proposes simplified equations to estimate flexural resistance for composite beams with full-depth precast slabs joined by shear pockets, showing a coefficient of variation of only 12% compared to experimental results, offering a reliable method for predicting flexural resistance in composite beams with discontinuous connections.

Free vibration analysis of composite beams and laminated reinforced panels by refined dynamic stiffness method and CUF-based component-wise theory

This paper presents a comprehensive analysis of the free vibration behavior of composite beams and laminated reinforced panels. Employing high-order theories with displacement variables only, the investigation combines dynamic stiffness method (DSM) and the Carrera unified formulation (CUF). The 3D displacement field can be expanded in the framework of CUF as any order of generic unknown variables over the cross-section, in the case of beam theories. Specifically, Lagrange expansions (LE) of cross-sectional displacement variables are considered, enabling the refinement modeling of complex cross-sections with different layers (layer-wise) and components (component-wise). The governing differential equations and natural boundary conditions are derived using the principle of virtual displacements. Subsequently, an exact dynamic stiffness matrix is developed by establishing a relationship between the amplitudes of harmonically varying loads and the corresponding responses. The Wittrick–Williams algorithm is employed to solve the transcendental eigenvalue problem resulting from this approach. The Lagrange-based CUF(LE)-DSM outperforms other polynomials (such as Taylor)-based CUF in analyzing composite structures, enabling detailed analysis with various geometries, lamination schemes and boundary conditions. It delivers accurate results in reinforced panel analysis, requiring only 13% of the DOFs compared to 3D FE models, thereby reducing computational costs significantly, as confirmed by comparative studies and validations.

The behavior of Shear Connectors in Steel-Normal Concrete Composite Structure under Repeated Loads

In today's construction industry, the use of composite beams is becoming more and more important, particularly for long-span bridges that must withstand repeated loads from moving automobiles. This work investigates the behavior of composite beams through experimentation. Six push-out steel-concrete specimens are made and tested with various levels of static and repetitive loading applied. The specimens are made of rolled steel sections that are joined to concrete decks on both sides by stud shear connectors. Two approaches—one static and the other repeating—applied a push-out load to two sets of samples. One has a stud shear connector measuring 16 mm, and the other measures 25 mm. Three specimens were made for each group. To determine the final load, one specimen from each group underwent a static push-out test in the first stage. In the subsequent phase, repeated loads of 0-80% and 25-80% of the maximum static load were applied to the remaining ones. The analysis process measured the variation in slip between the concrete decks and the steel section over several load cycles. It was found that the recorded slip values at the ultimate load increased about four times just before the failure. The recorded values of the residual slip at the end of each load cycle decreased with the increase in load cycle numbers. Also, it was found that the values of the residual slip depend on the values of the lower and upper limits of the load level. Doi: 10.28991/CEJ-2024-010-01-013 Full Text: PDF

Flexural Behavior of Composite Beams with Angle Shear Connectors

Flexural Behavior of Composite Beams with Angle Shear Connectors

Time-dependent response of continuous steel-concrete composite beams under sustained loading

Although the long-term behavior of composite beams raises critical concerns in their application, only a few investigations have been conducted on the time-dependent response of continuous composite beams (CCBs). Herein, long-term tests were conducted on four two-span CCBs with different loading ages. The shear stiffness and time-slip relationship of flexible shear connectors were evaluated by carrying out short-term and long-term push-out tests. The experimental results revealed that loading age substantially affected the development of deflection, interface slip, crack, and internal force redistribution of CCBs under sustained loads. A finite element model (FEM-2) of test specimens was developed, considering the damage evolution, creep and shrinkage of concrete slab, and stiffness degradation of connectors. After the FEM results were verified against the experimental data, the developed FEM-2 model was implemented to further investigate the influences of loading age and loading level on the long-term performance of CCBs.

Experimental study on longitudinal shear behavior of prefabricated steel-concrete composite beams with notched connections

To address the fit-up issues caused by the interference between shear connectors and extended transverse bars, a novel deck-to-girder connection detail, notched connection, is applied to steel-concrete composite bridges with partial-depth deck panel (PDDP) systems. In the novel joint detail, protruding transverse reinforcement is replaced by evenly distributed notches at the ends of precast panels, and tie bars inserted in the notches are anticipated to resist longitudinal shear stress, achieving shear connection between steel girders and precast deck slabs. Considering the discontinuity of bottom transverse reinforcement, a four-point bending test was performed to investigate the longitudinal shear behavior of composite beams incorporating notched connections. Experimental findings indicate that the configuration of transverse reinforcement critically influences the failure modes of composite specimens, which involve crushing of concrete slabs, longitudinal shear cracking and splitting. Notably, tie bars sufficiently anchored in notches function equivalently to extended bars spliced by welding, and the specifically designed U-shaped notches enhance the anchorage performance of tie bars. Transverse reinforcing bars placed in the concrete topping prove more effective in resisting longitudinal shear than those in the bottom layer, and therefore asymmetrically reinforced concrete slabs experience reduced longitudinal shear cracking and splitting. Moreover, interface shear reinforcement effectively ensures the full composite action, while concentrated point loads can induce excessive local longitudinal shear stress. The study also provides design recommendations for notched connections.

Effects of Recycled Concrete on Structural Behavior of Composite Beams with Y-Rib Shear Connectors

This study inspects the structural behavior of composite steel concrete beams connected together by Y-Rib shear connectors using recycled concrete. The main method involves using stud shear connectors with normal concrete. By comparing the structural performance of Y-Rib shear connectors with conventional stud shear connectors, the study aims to determine the benefit of using this type of connector with recycled concrete. Improved results in terms of maximum load-bearing capacity before failure and maintaining structural integrity until failure would indicate a viable solution to the sliding issue seen in traditional composite beams. Regardless of challenges in acquiring traditional shear connectors, the study also explores an alternative: 20mm diameter reinforcing bars. Although this falls outside the primary research scope, the main focus remains on the behavior of composite beams connected by Y-shaped shear connectors with recycled concrete. The investigation encompasses 18 shear connector types, divided into two groups: 9 models with normal coarse aggregate concrete (35.17 MPa) and 9 models with recycled coarse aggregate concrete (33.48 MPa) to determine the benefit of recycled aggregate concrete usage.

A review on long‐term behaviour of steel‐concrete composite structures

AbstractThe exceptional structural performance of steel‐concrete composite structures, which harness the advantages of both steel and concrete, has garnered considerable attention. Following a summary of the fundamental time‐dependent characteristics of concrete, this paper reviews the existing studies about the long‐term behaviour of various steel‐concrete composite components, including slabs, beams, columns and walls. For composite slabs, nonuniform shrinkage occurs along the thickness direction. The long‐term behaviour of composite beams is significantly affected by the degree of shear connection. While the creep and shrinkage effects of composite columns are substantially reduced in comparison to reinforced concrete columns, stress redistribution may cause yielding or buckling of the steel tube. However, there is currently limited research available on the long‐term behaviour of composite walls with profiled steel plates, and no studies have been conducted on composite walls made of double‐skinned flat steel faceplates infilled with concrete. This lack of knowledge may lead to design uncertainties for composite coupled wall‐frame structures. To bridge this gap, the authors are currently conducting a corresponding long‐term experimental program.

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.

Behavioral Evaluation of Strengthened Reinforced Concrete Beams with Ultra-Ductile Fiber-Reinforced Cementitious Composite Layers

In the literature, there is little information available regarding the behavior of composite beams made up of reinforced concrete (RC) and ultra-ductile fiber-reinforced concrete (UDFRC). In this study, UDFRC was examined for its effectiveness in enhancing the strength of RC beams. With a tensile strength of 4.35 MPa and a strain capacity of 2.5%, PVA-based UDFRC was prepared. The performance of 12 medium-sized reinforced concrete (RC) beams was measured under four-point flexural loading. The beams measured 1800 mm long, 150 mm wide, and 200–260 mm deep. The experimental program on beam specimens was divided into two phases. In the first, four 150 × 200 × 1800 mm RC beams with UDFRC layer thicknesses of 0, 30, 60, and 90 mm were tested. Additionally, four concrete and four concrete–UDFRC beams were investigated, measuring 150 × 230 × 1800 mm and 150 × 260 × 1800 mm, respectively. The study focused on medium-sized, slender RC beams under quasi-static loads and room temperature with additional or substituted UDFRC layers. As a result of replacing concrete with UDFRC, the load-carrying capacity at first crack and steel yield significantly increased between 18.4 and 43.1%, but the ultimate load-carrying capacity increased only in the range of 6.3–10.8%. Furthermore, beams with additional UDFRC layers could carry 30–50% more load than their concrete counterparts. An RC-UDFRC beam had a load-carrying capacity 10–15% greater than that of a comparable RC beam. Generally, there is a lower deflection response in UDFRC–concrete composite RC beams than in control concrete beams. The UDFRC layering can potentially improve the load-carrying capacity of RC beams, at least when ductility provisions are considered.

Flexural behavior of U-shaped steel-concrete composite beams under positive bending

The use of cold-formed U-shaped steel and concrete composite beams has increased with the advantage of permanent steel form as a load-resisting element. In this study, a new type of U-shaped steel-concrete composite beam with a bolt connection was proposed. Four-point flexural tests of full-scale specimens were performed to evaluate the flexural behavior of the composite beams under a positive bending moment. The main test parameters were the types of U-shaped steel sections and location of the neutral axis at ultimate strength. The U-shaped composite beams under positive bending behaved similarly to the composite beams with an I-shaped steel section. The strain compatibility method is recommended to evaluate the positive flexural strength of the composite beams. In addition, the effective flexural rigidity was proposed to capture the increasing trend of the flexural stiffness ratio according to the shear span-to-depth ratio.

Analysis of steel–concrete composite beam using Ansys 18.1 Workbench

Composite beams made from more than one material can cover large column-free spaces. Composite construction is faster than cast in-situ concrete as rolled steel and prefabricated components are used. Steel concrete composite beam consists of a steel beam above which a concrete slab with reinforcement is casted using shear connectors. In recent years, steel–concrete composite beams have been employed extensively in structures and on bridges. The concrete act together with steel to create a stiffer, lighter, less expensive structure. The analysis using ANSYS 18.1 Workbench is significant as it provides more accuracy compared to experimental analysis along with being cost efficient and time saving and it uses the principle of finite element analysis. An experimental study was done to study the behavior of composite beam under monotonic load by Bing Wang, Qiao Huang, Xiao ling Liu and Wenxian Li. The study was conducted on eight composite beams with various arrangement of shear connectors to assess their performance under monotonic load and fatigue load. This paper studies the structural behavior of steel concrete composite beam under monotonic load and also compares the experimental results obtained from above mentioned paper with the results obtained for four steel–concrete composite beams analyzed using Ansys 18.1 Workbench. Non-linear static analysis was done on four sets of beams based on the variation in number of studs and stud spacing. SOLID 65 element was used for concrete and LINK180 element for modelling reinforcement. The analysis as per the report generated by the ANSYS software, seems to stop on 156th iteration and the results were then obtained. Load-deformation and ductility index of the beams were obtained from software and were compared with experimental values. Crack pattern was also obtained using linear analysis. The percentage error occurred in terms of ultimate load, total deformation and ductility index is less than 10%. It was found that as the number of shear connector provided was beyond the permissible number there can be crowding which could result in more cracks. Hence, it is advisable to not to use increased number of studs, as that may result in harming the serviceability conditions of structure.