Steel Composite Beams Research Articles

Maximum shear strength of concrete-encased steel composite beams: A novel strength model and FE verification

Due to the high load-carrying capacity and rigidity, concrete-encased steel (CES) beams are widely applied as transfer elements in heavily-loaded structures. However, the accurate shear strength prediction method is still under investigation because of the difficulty in the shear contribution decomposition of steel shape and reinforced concrete. Current design codes apply the strength superposition for CES beams, namely that their shear strength can be obtained by directly superimposing the shear strengths of RC and steel shape, which has been proven questionable by existing research. Therefore, it needs to carefully decouple the multiple shear transfer mechanisms in CES beams and explore their roles in a composite structure. In this paper, a novel shear strength model is proposed, in which a CES beam can be divided into a shear web and a composite truss consisting of RC with two steel flanges, and strain compatibility is applied to evaluate the shear contribution of these two parts. After that, an elaborate FE model is established to further quantitatively investigate the shear contribution of the composite truss and the shear web. Finally, the proposed model is verified with 61 existing specimens in the literature, and the comparison between the calculated and test results indicates that the proposed model could predict the shear strength of CES beams accurately.

The behavior of cold‐formed steel geopolimeric composites

AbstractGeopolymer concrete‐filled cold formed steel composite beams can exhibit high durability and adequate strength. The geopolymer concrete is used to manufacture the cold‐formed steel tubular composite beam due to the significant advantages, such as greater in strength resisting capacity, higher‐energy dissipation capacity, and more stiffness than the regular one. This paper reports an experimental investigation on the behavior of rectangular geopolymer concrete‐filled cold‐formed steel composite beams. In order to investigate the mechanical behavior (such as flexural, shear, and torsion) of geopolymer concrete‐filled cold‐formed steel tubular composite beams (GCFTBs), 48 beam samples were tested. The 16‐GCFTBs and another 16‐GCFTBs were tested under flexural and overhanging, respectively, which the 16‐GCFTBs were tested under pure torsion. The relationships for load–displacement, torsional moment‐rotation angle, energy dissipation capacity, ductility, and failure mode were analyzed. The test results showed that the increase in cross‐sectional area and curing temperature had a significant effect on bending, shear and torsion behavior. Although the increase in the cross‐section ratio (height/width) increased the bending moment capacity, it decreased the displacement capacity and caused a decrease in ductility. Curing conditions and cross‐section ratio affected strength, displacement capacity, and experimental modulus of elasticity in both bending and shear tests. Increasing the cross‐section ratio and curing temperature resulted in an increase in ductility. Contrary to bending test and shear test, curing temperature, and cross‐section ratio increased both torsional moment strength and rotation angle in torsional moment tests.

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.

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.

Experimental and analytical comparison of the flexural behaviour of light gauge steel composite beams placed with varied shear connector cross-sections

Experimental and analytical comparison of the flexural behaviour of light gauge steel composite beams placed with varied shear connector cross-sections

Experimental study, finite element simulation and theoretical analysis on failure mechanism of steel–concrete-steel (SCS) composite deep beams with UHPC

Configurations of steel faceplate (SP) and filled concrete (FC) are the main concern issue in steel- ultra-high performance concrete (UHPC) -steel (SUS) composite deep beams, which have important effects on failure modes, mechanical behaviors and interfacial slip. This paper aims to quantify the relationship between failure modes and configurations of SP. Results can be used to explore the failure mechanism and propose the theoretical models of SUS composite deep beams. 6 SUS composite deep beams were measured. Results indicate that SUS composite deep beams with different configurations of SP and FC, exhibit different failure modes, including shear without slip failure, slip failure and flexural without slip failure. Influence mechanism of SP, FC, spacing of shear studs on failure modes, mechanical behaviors and interfacial slip was explored. Failure mechanism was revealed by a modified Strut-and-Tie model. Subsequently, finite element (FE) models of SUS composite deep beams were developed to obtain the width of concrete diagonal strip, and configuration relationship between SP and FC. Based on the test results and FE results, the theoretical models of SUS composite deep beams corresponding to different failure modes were deduced and validated, considering the interfacial slip between SP and FC.

Composite Cold-Formed Steel Beams with Diagonal Rebars for Earthquake-Resistant Buildings.

The construction industry is on the lookout for cost-effective structural members that are also environmentally friendly. Built-up cold-formed steel (CFS) sections with minimal thickness can be used to make beams at a lower cost. Plate buckling in CFS beams with thin webs can be avoided by using thick webs, adding stiffeners, or strengthening the web with diagonal rebars. When CFS beams are designed to carry heavy loads, their depth logically increases, resulting in an increase in building floor height. The experimental and numerical investigation of CFS composite beams reinforced with diagonal web rebars is presented in this paper. A total of twelve built-up CFS beams were used for testing, with the first six designed without web encasement and the remaining six designed with web encasement. The first six were constructed with diagonal rebars in the shear and flexure zones, while the other two with diagonal rebars in the shear zone, and the last two without diagonal rebars. The next set of six beams was constructed in the same manner, but with a concrete encasement of the web, and all the beams were then tested. Fly ash, a pozzolanic waste byproduct of thermal power plants, was used as a 40% replacement for cement in making the test specimens. CFS beam failure characteristics, load-deflection behavior, ductility, load-strain relationship, moment-curvature relationship, and lateral stiffness were all investigated. The results of the experimental tests and the nonlinear finite element analysis performed in ANSYS software were found to be in good agreement. It was discovered that CFS beams with fly ash concrete encased webs have twice the moment resisting capacity of plain CFS beams, resulting in a reduction in building floor height. The results also confirmed that the composite CFS beams have high ductility, making them a reliable choice for earthquake-resistant structures.

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.

Prediction of the Bending Strength of a Composite Steel Beam-Slab Member Filled with Recycled Concrete.

This study investigated the structural behavior of a beam-slab member fabricated using a steel C-Purlins beam carrying a profile steel sheet slab covered by a dry board sheet filled with recycled aggregate concrete, called a CBPDS member. This concept was developed to reduce the cost and self-weight of the composite beam-slab system; it replaces the hot-rolled steel I-beam with a steel C-Purlins section, which is easier to fabricate and weighs less. For this purpose, six full-scale CBPDS specimens were tested under four-point static bending. This study investigated the effect of using double C-Purlins beams face-to-face as connected or separated sections and the effect of using concrete material that contains different recycled aggregates to replace raw aggregates. Test results confirmed that using double C-Purlins beams with a face-to-face configuration achieved better concrete confinement behavior than a separate configuration did; specifically, a higher bending capacity and ductility index by about +10.7% and +15.7%, respectively. Generally, the overall bending behavior of the tested specimens was not significantly affected when the infill concrete's raw aggregates were replaced with 50% and 100% recycled aggregates; however, their bending capacities were reduced, at -8.0% and -11.6%, respectively, compared to the control specimen (0% recycled aggregates). Furthermore, a new theoretical model developed during this study to predict the nominal bending strength of the suggested CBPDS member showed acceptable mean value (0.970) and standard deviation (3.6%) compared with the corresponding test results.

Experimental study on the seismic performance of a cold-formed thin-walled steel–concrete composite column-H steel beam frame

For lightweight steel frame structures consisting of steel H-beams and cold-formed steel columns filled with concrete, seismic performance comparison tests and numerical simulation analyses were performed for bare and infilled frames. The effects of the lightweight wall panels, the axial compression ratio and the wall thickness of the steel sections of the columns on the seismic properties of the structure were investigated. The failure of the bare frame was concentrated in the weld fractures at the beam-column joints. When the wall panels were embedded in the frame, the damage was concentrated at the corners and edges of the wall panels and the connectors. The wall panels significantly improved the initial stiffness of the frame, early energy dissipation and resistance, and the wall panel energy dissipation rate was initially as great as 91%. As the axial compression ratio increased, the resistance of the structure significantly decreased. Under monotonic loading, the resistance on the structure with an axial compression ratio of 0.4 was reduced by nearly 44% compared to the structure without axial compression. Increasing the wall thickness of the steel sections of the columns increased the load-bearing capacity of the structure, but the increase diminished with increasing wall thickness.

ADVANCED ANALYSIS OF STEEL‐CONCRETE COMPOSITE BUILDINGS

AbstractThis paper presents a nonlinear simulation method for composite framing systems constituted from concrete‐filled steel tubular columns (CFST) and composite beam systems. A force‐based fibre beam‐column element in OpenSees was adopted. This element was capable of accurately capturing the local buckling of steel and the confining effect of concrete using the modified stress‐strain relationships of the steel and concrete fibres. A source code for the connection element was also developed in OpenSees to capture the semi‐rigid behaviour of the beam‐to‐column connections of the composite buildings. Through the verification with numerous experiments, the model has shown its capability of accurately simulating composite frames with simplicity and less computational cost. An extensive parametric study was conducted to examine the effect of the bracing systems and the rigidity of the connections on the behaviour and instability of the whole composite buildings.

EVALUATION OF THE PLASTIC DEFORMATION CAPACITY OF COMPOSITE BEAMS THROUGH THE CONNECTION COEFFICIENT

AbstractFor safer structural design, a simple index that describes the plastic deformation capacity of composite beams is needed, similar to the connection coefficient in the case of strength. In this study, the relationships between the plastic deformation capacity and strength under varying material properties and geometric shapes of concrete and steel members were considered through finite element analyses. Based on the obtained results, the plastic deformation factor was defined as the ratio of two rotation angles. The minimum value of the connection coefficient in composite beams corresponding to the ductility factor under severe earthquakes was determined because the plastic deformation factor can be used similar to the ductility factor. In addition, the minimum value of the connection coefficient in bare steel beams that will be safe even if a concrete slab is added was determined; therefore, the design of bare steel beams and composite beams are connected by the connection coefficient.

Mechanical performance of hybrid high-strength steel composite cellular beam under low cyclic loading

This study aimed to compensate for the impairments in structural load-carrying capacity and stiffness caused by conventional reduced web section beams, and to meet the strength design requirements for engineering. A new hybrid high-strength steel composite cellular beam (HHS-CCB) using high-strength steel in the beam flange and ordinary steel in the web was proposed. A composite cellular beam between the rigid joint and inflection point in the frame structure was selected as the research object, and low cyclic loading tests were conducted on one homogeneous ordinary steel composite cellular beam (HOS-CCB) and four HHS-CCB specimens. The effects of the hybrid use of high-strength steel and ordinary steel on the failure modes, load-carrying capacities, strength and stiffness degradation, ductility, and energy-dissipation capacities of the composite cellular beams were investigated. The test results show that with reasonable values for the diameter of the web opening and for the distance from the first opening at the beam end to the column surface (abbreviated as the hole edge distance), the HHS-CCB specimens exhibit local plastic damage at the first opening at the end of the beam but maintain a good ductility, stiffness degradation, strength degradation, and energy dissipation capacity, while significantly improving the structural load-carrying capacity loss owing to the web opening. Compared with HHS-CCB specimens using HHS in both the upper and lower flanges, the HHS-CCB specimens using HHS only in the lower flange show superior mechanical properties. Considering the poor plastic deformation capacity of HSS, the steel plate strength of the flange should not be much higher than that of the web to ensure the full development of plasticity in the cross-section, and Q460 steel or Q550 steel is generally recommended. A nonlinear finite element (FE) model was developed using ABAQUS software to predict the hysteresis behavior of specimens. Numerical simulation shows that the simplified FE model can be used to simulate the hysteresis performance of HOS-CCB and HHS-CCB.

Mitigation of damage in composite steel beams with flexible gel-coated studs

Mitigation of damage in composite steel beams with flexible gel-coated studs

Interface slip of steel–concrete composite beams reinforced with CFRP sheet under creep effect

Under the creep action of composite steel and concrete beams reinforced by carbon-fiber-reinforced polymer (CFRP) sheet, the face of the CFRP sheet, steel beam, and concrete slab beam produce relative slip. This slip affects the interface interaction, reduces the bearing capacity and stiffness of the members, and increases the deformation. In this paper, elastic and energy methods are used to analyze the interface forces between steel beams and concrete slabs reinforced by CFRP sheeting under the action of concrete creep. The calculation formulas for interface slip, axial force, and incremental deformation are established. The influence of design parameters on the mechanical properties of the interface is analyzed. Results show that the increments in interface slip, axial force, and deformation are zero on the 28th day. With increasing age, the increments in interface slip, axial force, and deformation gradually increase, and the increase is large in the first 100 days; it basically remains unchanged during the time interval from 100 to 1028 days. When the load increases by 5 N/mm (5 kN), the slip increments increase by approximately 0.004 mm, 0.002 mm, and 0.002 mm. The increments in axial force are approximately 19.4 kN, 15.9 kN, and 16.1 kN. The deformation increments increase by approximately 1.7 mm, 1.1 mm, and 0.6 mm.

DESIGN OF STEEL STRUCTURE ELEMENTARY SCHOOL BUILDING SDN 05 PAGI IN CIBUBUR

Abstract—The compressive strength of concrete can be used to increase the strength of steel beams, especially in the positive moment region. From the composite action that occurs it is expected to reduce the size of the steel profile to be used. This thesis compiles a plan using Composite Steel Beams and End Plate Connections, using the SAP2000v23 program for static calculations, and calculation of beam and column dimensions as well as connection and base plate planning. To analyze the dimensions of the required WF Steel Profiles for Columns, Composite Beams, beam-column connections, main beams-joists, and floor slabs. From the analysis results, the dimensions for main beams are WF 400x200x8x13 and WF 450x200x9x14, for joists using WF 300x150x8x13, and for columns using WF 350x350x12x19. The design of the connection on the flanged beams uses an End Plate with a plate thickness of 18 mm and the number of bolts is 8 Ø 24 mm. The connection design for the web beam-column connection uses an End Plate with a thickness of 10 mm and a total of 8 Ø 20 mm bolts. The connection design for the main beam-subbeam and the joist beams uses an angled profile of 80x80x8 and the number of bolts is 4 Ø 22 mm. The required base plate size is 550x550x45mm using 8 Ø 19 mm anchors with a length of 800 mm. Keywords : Steel Structure, Composite, SAP2000v23

Neural networks-based formulation for predicting ultimate strength of bolted shear connectors in composite cold-formed steel beams

In recent years, the use of artificial intelligence-based methods in engineering problems has been expanded. In the current study, the method of artificial neural networks (ANN) has been employed to predict the ultimate strength of bolted shear connectors in cold-formed steel (CFS) composite beams. For this purpose, multilayer perceptron (MLP) networks with a hidden layer were used. Three parameters affecting the performance of these networks, including the training algorithm, the activation function in the hidden layer, and the number of neurons in the hidden layer, were examined and the most accurate network was selected. The input and target data for training the network were provided by conducting an extensive numerical study on the behavior of bolted shear connectors in CFS composite beams. Consequently, using ABAQUS software, finite element (FE) models validated with experimental results were first developed. Then, 216 models with different characteristics were analyzed and a reliable database was provided for the development of neural networks. Moreover, in order to prove the high accuracy of the ANN method, the stepwise regression (SR) method was also developed as one of the powerful regression-based methods, and the performances of these two methods were compared. Finally, the most important purpose of this study is to propose an accurate ANN-based formulation in order to predict the ultimate strength of bolted shear connectors in CFS composite beams. Due to the fact that so far no relationship has been proposed to predict the resistance of shear connectors in CFS composite beams, the formula presented in this paper can be helpful in the design process of this type of beams.

A Study on the Influence of Bolt Arrangement Parameters on the Bending Behavior of Timber–Steel Composite (TSC) Beams

The present paper investigates the impact of bolt distance, bolt diameter, and the number of bolt rows on the bending performance of timber–steel composite (TSC) beams. This study aims to facilitate the application of bolt connections in assembled TSC structures. Composite steel I-beams were designed with timber boards connected in the upper section with bolts. Three-point static bending tests were conducted on nine timber–steel composite beams divided into four groups (L1, L2, L3, and L4) with varying bolt arrangements. The destruction mode, ultimate bearing capacity, ductility coefficient, load–midspan deflection curve, and load–midspan strain curve of each specimen were obtained. In addition, the destruction mechanism, the quantitative relationship between the bolt area ratio and interfacial slip, and the ideal bolt area ratio were identified. It was found that when the midspan deflection of the timber–steel composite beam approached the prescribed limit, the main failure mode can be explained as follows: The top surface of the boards of all the specimens had longitudinal local splitting, except L1, which had fewer bolts and no obvious damage. Moreover, due to compression and because the stress at the lower edge of the I-beam entered the flow amplitude stage, some of the specimens were crushed but were not pulled off. The composite beams had high flexural load capacity and ductility coefficient, and the maximum relative slips of the timber–steel interfaces were in the range of 2–6 mm. It was also found that the maximum slip of the interface and the ductility coefficient decreased steadily as the bolt area ratio increased, while the specimen’s flexural bearing capacity increased. The optimal bolt area ratio was determined to be 8 × 10−3. Using the total bolt area, we designed the arrangement of the bolts on the board. For convenience, multiple bolt variables were converted into one bolt variable. The longitudinal distance of the bolts had a greater impact on the slip, and the bolt diameter had a smaller impact. The theoretical values of total relative slip were found to be in good agreement with the experimental results, which were based on the superposition of the relative slip equations with varying bolt distances. The effective bolt area ratio and the formula of the relative slip of each segment can provide instructions for the arrangement of bolts and the control of the relative slip of intersections in engineering practices.

The effect of cross section type on the performance of different sized bolted shear connectors for composite cold-formed steel beams

The effect of cross section type on the performance of different sized bolted shear connectors for composite cold-formed steel beams

Finite element analysis of shear performance of UHPFRC-encased steel composite beams: Parametric study

The shear response of ultra-high performance fiber reinforced concrete (UHPFRC)-encased H-shaped steel section composite beams is simulated using a three-dimensional (3D) non-linear finite element model (FEM) in the present study. The proposed FEM's accuracy is validated against experimental data from previously tested steel and UHPFRC beams available in the literature. Numerical results agreed well with the experimental findings in terms of load–deflection response and failure mode. Before conducting the parametric analysis, the influence of the model mesh size on the ultimate load capacity, as well as the initiation and propagation of cracks along the entire length of H-shaped steel and UHPFRC beams, is considered. The mesh sensitivity analysis, which was performed using three different mesh sizes of 50, 40, and 30 mm, revealed that all mesh sizes successfully predicted the ultimate load of the analyzed beams, while the lowest one (30 mm) was the best in predicting the distribution of shear and flexural cracks along the entire length of the steel and UHPFRC beams. The parametric study investigated the encasement effect as well as the shear-span-to-depth ratio and effective length of the steel beam on the ultimate load capacity, stiffness, ductility, and failure pattern of composite beams. The gain in ultimate load of the composite beam was 448 % and 278 % with respect to the bare steel and UHPFRC beams, respectively. Furthermore, the ultimate load reduction ratios for specimens with shear span-to-depth ratios of 2.1, 2.6, 3.1, and 3.6 were 20, 32, 38, and 41 %, respectively, with respect to the shear span-to-depth ratio of 1.6.