Steel Composite Beams Research Articles

Shear–slip failure in steel–concrete–steel composite beams with bidirectional webs

Steel–concrete–steel composite structures with bidirectional thin-walled webs (SCSBWs) are used to build large-scale structures. The presence of steel webs causes notable differences in shear behavior compared to other types of steel–concrete–steel (SCS) composite structures. In this paper, the shear–slip behavior of SCSBWs is studied through experiments and numerical simulations. Particularly, the numerical simulations cover a wide range of variations in the structural parameters to explore the effect of each parameter on the shear–slip behavior. A theoretical model to describe shear–slip​ in SCSBWs is proposed chiefly by introducing a slip reduction factor. The experimental and numerical data verified the proposed model, which also demonstrated acceptable accuracy and efficiency.

Push-out tests on bolted shear connectors in composite cold-formed steel beams

Composite beams comprised of steel sections and concrete slabs, are one of the most widely used beams due to their advantages such as improving stiffness and strength compared to bare steel or reinforced concrete beams. Moreover, another important advantage of such beams is to prevent buckling of steel section by placing it under tension, which is especially important for low-thickness steel sections such as cold-formed steel (CFS) sections. Although the use of CFS sections in combination with concrete slabs can increase the efficiency of such sections, their low thickness makes it difficult to weld traditional studs as shear connectors on their top flanges. The current paper presents an experimental investigation about the behavior of bolted shear connectors in the composite cold-formed steel beams as a suitable alternative to welded shear studs. To do so, three main parameters including thickness of CFS sections, and size and strength of bolts were taken into account. Fifteen full-scale push-out specimens were constructed and tested. The ultimate load, ductility, stiffness and failure mode of all specimens were then assessed; and their results were reported and precisely discussed. Based on the results, depending on the size and strength of bolts, the ultimate load per shear connector for 1 mm thick CFS sections’ specimens is found between 6.2 and 8.6 KN, while this value for specimens by 2 mm thick CFS sections, is found between 15.6 and 26.8 KN. Moreover, based on EC4, the ductility of shear connectors was examined; the results indicate that all bolted shear connectors in this study can be assumed ductile and can be used in partial shear connections.

Numerical Simulation of Composite Beam Subjected to Harmonic Force Vibration

Simply supported steel and concrete composite beams connected by a number of headed stud shear connectors were adopted considering the existence of interface slip under the effect of forced vibration. ANSYS software is used to carry out the finite element simulation. Static load was applied first then different load cases of harmonic loadings were applied. The comparison between available experimental data and the obtained results from the numerical analysis proves the reliability of the developed model. The analysis results confirm that the shear connection degrees are a significant index related to the longitudinal shear ability and the overall flexure stiffness of the composite beam. The increase of average slip and mid-span deflection are mostly affected by the static load and with a little significant under dynamic load, whereas, the slip amplitude is mostly affected by the dynamic loading amplitude. The magnitudes of deflection rely on the frequency range and amplitude of loads and the value of frequency reflects the magnitude of applied load that make the deflection vary with the applied loads.

Negative bending behavior of novel U-shaped steel and concrete composite beams

The negative bending behavior of the reinforcement stiffened cold-formed U-shaped steel and concrete composite beams (RCUCBs) is discussed in this paper. The negative bending experiment on 10 specimens were conducted and the damage process and corresponding static behavior in each stage are defined. Two distinct failure modes were found depending on whether the inverted U-shaped reinforcement (IUR) is installed or not: ductile plastic failure mode (when installed) and sudden elastic failure mode (when not installed). The IUR was observed to keep the integral action and improve the bending capacity and ductility of a RCUCB. The closed steel U-section stiffened by the reinforcement truss provides significant confinement to the encased concrete and even maintains its integrity after concrete cracking. The study results show that the plastic hinging of the framed RCUCB under vertical loads spreads to about L0/6 and suggest that the effective slab width in the negative moment zone is Be = L0/3 + b, similar to the positive moment case. Lastly, a negative bending design method was proposed, giving good calculations compared to the test results. The slab reinforcement, steel U-section, encased concrete, and bottom reinforcement contribute 53%, 30%, 11%, and 6% respectively to the negative bending capacity on average.

Development of cross laminated timber-cold-formed steel composite beam for floor system to sustainable modular building construction

Cold-formed steel (CFS) and cross-laminated timber (CLT) structural components are widely employed in low- to mid-rise and modular building constructions. These two materials have individually shown to be lightweight, and possess relatively higher strength characteristics. Owing to these benefits, composite CLT-CFS sections can be used as structural elements and possibly be employed in modular buildings with enhanced structural performances. This paper presents the development of CLT-CFS composite beam for the floor system in modular buildings and investigates the structural performances through finite element (FE) analyses. Initially, the FE models of CFS beam and CLT panel were developed and validated with experimental results. Validated models were used to develop the FE model of CLT-CFS composite beam for the floor system. Results of FE analyses of the CLT-CFS composite floor systems showed that considerable benefits in terms of structural response can be achieved due to the mobilisation of composite action. For the CLT-CFS system investigated in this research, about 20% of enhancement in moment capacity was found. The presented study leads a path to highlight the gains in the structural performance of CLT-CFS composite beams floor system and it is a prospective option to be employed in sustainable modular building construction.

Efficiency of Vierendeel Girder, Post-tensioned Girders and Steel Beams for Long Cantilevers in Buildings

Cantilevers are a part of our life, they are everywhere: bridg–es, building’s balconies, traffic signs, car parking shades even the aircraft’s wings. The long cantilevers of the buildings always present as a big challenge to structural engineers in their practice life. The structural behavior of these cantilevers depends on a several factors, such as rigidity of the slab, rigidity of columns or walls, span continuity... etc. But the real dilemma lies in the economical choice. This paper focused on the cantilever’s structural analysis according to the used structural. Moreover, it shows a comparison between three structural system choices: Vierendeel Girder, Post - Tensioned Girders and Steel Composite Beam in a graph. The objective of this paper is to give a guideline to the structural engineers to choose the optimum system of the building cantilevers according to the factors mentioned earlier. At the end, the paper illustrated the Vierendeel girder is the most efficient system for cantilevers. Accordingly, recommendations result on that up to 4.0 m cantilever length steel beams will be enough, for more than 4.0 and less than or equal to 6.0 m post-tension is recommended, and for more than 6.0 m cantilever we should use Vierendeel girder.

A displacement/damage controlled seismic design method for MRFs with concrete-filled steel tubular columns and composite beams

A displacement/damage controlled (DDC) seismic design method for composite (steel/concrete) frames, consisting of circular concrete-filled steel tube (CFT) columns and composite beams (steel beams connected with concrete floor slabs) is developed in this study. The proposed seismic design method controls displacement and damage in a direct way for all seismic performance levels including the one near collapse. Through empirical expressions this method can estimate the inter-storey drift ratio (IDR) of a designed structure and evaluate the damage index (DI) of critical members for a given seismic intensity. A reduced number of design iterations is achieved while the computationally demanding non-linear time-history analysis can be avoided. The necessary empirical expressions of the design method are derived by means of statistical and sensitivity analysis of a large response databank consists of IDR and DI that cover all the way from elastic behavior to final global dynamic instability. This response databank is created by performing extensive parametric incremental dynamic analyses of many composite framed structures of the kind considered here under many seismic motions and different soil types. Design examples reveal that the DDC design method successfully estimates the targeted IDR for the desired seismic performance level as well as controls the DI in critical beam-to-column joints in order to avoid a soft-storey failure mechanism or partial loss of structure. Compared to all steel framed structures, the composite frames considered here exhibit a better seismic performance with beams and columns exhibiting a lower DI. The low-damage performance of composite frames is mainly emphasized as the number of storeys increases, while both the IDR and DI tend to fall within lower performance levels than those of the corresponding all steel frames for the same seismic intensity.

Optimum Cross Section and Longitudinal Profile for Unstiffened Fully Composite Steel Beams

Composite steel beam is commonly used element in multistory steel buildings today. The composite action between the concrete deck and the steel beam reduces both steel weight and deflection, accordingly, enhance floor economy and serviceability. Many earlier researches were carried out to optimize the design of the composite steel beams under both static loading and dynamic behavior. None of these researches was concerned in optimizing the cross section or the longitudinal profile of built-up composite steel beams. The aim of this research is to develop simple and practical equations to determine the optimum cross section dimensions and optimum longitudinal profile for both shored and un-shored simply supported built-up fully composite steel beams. These equations were developed using (GRG) solving technique considering residential buildings loads and (ASD) design method. Also, the research presented an example for utilizing the developed equations

Composite steel beam is commonly used element in multistory steel buildings today. The composite action between the concrete deck and the steel beam reduces both steel weight and deflection, accordingly, enhance floor economy and serviceability. Many earlier researches were carried out to optimize the design of the composite steel beams under both static loading and dynamic behavior. None of these

In many situations, it is necessary to have a beam web opening in the plastic hinge location. However, very limited studies investigated the behavior of reinforced concrete (RC) beam-column joints with nearby beam web openings. A previous study was conducted for investigating the behavior of beam-column joints with unreinforced nearby web opening. In this study, the effect of adding additional reinforcing around a nearby web opening on the seismic behavior of RC exterior Beam-Column joints is being investigated. Nine full-scale beam-column joints were tested, four joints had an unreinforced opening, while five joints had reinforced opening. The behavior of the beam-column joints is described in terms of maximum resisting load, deflection, energy dissipated, and stiffness degradation. The behavior was significantly affected by the nearby opening. The increase in opening width and the reduction in the distance between the opening and the column resulted in decreasing the strength and ductility of the RC beam-column joint. However, adding additional reinforcement improved the behavior. Thus, it is recommended to provide additional reinforcement all around the opening.

Resistant bending moment to lateral-torsional buckling of continuous steel and concrete composite beams with transverse stiffeners

Abstract In this paper, a numerical analysis using the finite element method, employing the commercial code Ansys, is performed to evaluate the influence of transverse stiffeners welded to the web of the steel profile on the lateral stiffness and resistant bending moment of continuous steel and concrete composite beams subjected to lateral-torsional buckling (LTB). The developed numerical model was validated by comparison with the results of tests performed by another researcher. Subsequently, a parametric analysis was carried out for beams with two and three spans, varying the spacing between the stiffeners. Finally, based on the analysis performed, it was concluded that the transverse stiffeners can significantly increase the lateral stiffness and the resistant moment of continuous composite beams. A calculation procedure to obtain this moment is proposed, having as reference the prescriptions of the Brazilian standard ABNT NBR 8800:2008.

Thermal analysis of steel and concrete composite beams cross sections in fire situations

ABSTRACT: The fire poses a considerable risk to human safety and, therefore, fire protection is a solution that should be incorporated into the construction system of a building. Composite beams, when subjected to fire, lose strength and stiffness due to the degradation of the mechanical properties of their materials. This paper aims to perform the thermal analysis of steel and concrete composite beams in fire situation. The software ABAQUS Version 6.14 [1] was used to develop numerical methods, whose results were analyzed and compared with the values obtained by the simplified calculation method prescribed in ABNT NBR 14323:2013 [2]. Thereby, the thermal behavior of the composite cross-section and the influence of the material and the type of fire protection were analyzed. The results showed that, for a certain type of protection and size of the metallic profile, the temperatures given by the Brazilian Standard may differ substantially from those obtained by numerical simulation.

Simulation analysis of mechanical properties of shear connectors of steel-concrete composite beams

In order to further study the mechanical properties and development distribution of shear connectors of steel-composite beam under the influence of concrete shrinkage and creep. In this paper, on the basis of the existing experimental research, ABAQUS software is used to establish the steel-composite beam model. The structural forms of the model include simply supported beam and continuous beam, and the shear connectors of steel-composite beam include three types: stud connectors, PBL connectors and composite connectors. The time development and spatial distribution of vertical displacement, connector shear force and slip at interface of each composite beam with concrete creep are calculated by finite element software, and some calculated results are in good agreement with the existing test results. By comprehensively comparing the calculation results of the key sections of each composite beam at some time points, the mechanical properties and their respective applications of the shear connectors of the steel-composite beam are analyzed and summarized, and the research results can guide the design and engineering application of the shear connectors of the steel-composite beam.

Calculation method steel reinforced concrete continuous bridge spans with two reinforced concrete slabs on the effect of concrete shrinkage

The article is considered calculation method steel reinforced concrete continuous bridge spans with two reinforced concrete slabs on the effect of concrete shrinkage. For long-term processes that must be considered when calculating the span structures of bridges, besides creep, concrete shrinkage applies. Object of study: composite steel and concrete span beam bridge with two reinforced concrete slabs. Purpose: to develop a calculation method the cross section steel reinforced concrete bridges with two reinforced concrete slabs on the effect of concrete shrinkage considering concrete creep. Continuous spans of steel reinforced concrete bridges with two reinforced concrete slabs over intermediate supports much more economically, in terms of metal consumption, compared to steel reinforced concrete bridges with one concrete slab. Cross section of a reinforced reinforced concrete beam consists of a steel part that combined with two reinforced concrete slabs. The article presents the results of the calculation of continuous steel-concrete superstructure of a road bridge with two reinforced concrete slabs by the above method.

Design and nonlinear time history analysis of a multi-story building with concrete filled composite columns and steel beams

Design and nonlinear time history analysis of a multi-story building with concrete filled composite columns and steel beams

Experimental and numerical studies on the shear connectors in steel-concrete composite beams at fire and post fire exposures

Shear connectors are required to build composite (concrete and steel) beams. They are placed at the interface of concrete and steel to transfer shear and normal forces between two structural components. Such composite beams are sensitive to provide structural integrity when exposed to fire as they loss strength, stiffness, and ductility at elevated temperature. The present study is designed to investigate the shear resistance and the failure modes of the headed stud shear connectors at fire exposure and post-fire exposure. The study includes ordinary concrete and concrete with carbon nanotubes (CNTs) to build composite (concrete-steel) beams with structural steel. Experimental push tests were conducted on composite beams at ambient and elevated temperatures, such as 200, 400 & 600C. Moreover, push tests were performed on the composite beams after being exposed to 200, 400 & 600C. Push test results illustrated the reduction of ultimate shear capacity and stiffness of headed stud shear connectors as the temperature increased. Although similar values of ultimate shear were obtained for the headed stud connectors in both ordinary and CNT concrete, the CNT modified concrete reduced the concrete spalling and cracking compared to ordinary concrete and was observed to be effective at temperatures greater than 400C. All specimens showed a lower shear resistance at fire exposures compared to the corresponding post-fire exposures. Moreover, numerical simulation by Finite Element (FE) analyses were carried out at ambient temperature and at fire conditions. The FE analysis results show a good agreement with the experimental results. In the experimental studies, failure of all specimens occurred due to shear failure of headed stud, which was later validated by FE analyses using ABAQUS.

Bearing Capacity of Composite Joints of U-shaped Steel Composite Beams and Concrete-filled Square Steel Tubular Columns Based on Channel Steel Connection

Bearing Capacity of Composite Joints of U-shaped Steel Composite Beams and Concrete-filled Square Steel Tubular Columns Based on Channel Steel Connection

Seismic Behavior of Hybrid Frame Joints between Composite Columns and Steel Beams

This study presents experimental and numerical study on cyclic behavior of SRC composite columns-steel beam joints. The pseudostatic experiments were carried out on four samples with different axial loads. X-shaped shear reinforcement was added in the sample no. 4 in order to investigate its effect on the crack resistance in the joint core area. Low-frequency cyclic load was applied at beam ends to simulate the earthquake action. The failure characteristics, hysteretic behavior, stiffness degradation, shear resistance, and displacement ductility were investigated. Experimental results indicated that the failure mode of the joints was mainly shear failure, and the composite joints showed excellent seismic behavior with higher capacity and good ductility and energy dissipation ability. X-shaped shear reinforcement performed well to increase the concrete crack resistance. Shear forces from both experimental test and theoretical analysis were compared, and suggestions were given on modification of theoretical formulas. Simulation using the ABAQUS model showed good results that agreed well with the test results. Steel stress distribution and damage development were analyzed in the model. More parameters of web thickness, stiffener thickness, concrete strength, and stirrups and their influence on shear resistance were studied.

Fire Resistance of Steel Composite Beams without Fire Protection

In this study, the fire resistance of steel composite beams typically used in building structures was investigated through standard fire and loading tests. For the tests, fire-exposure conditions depending on the steel section shape and load ratio applied to the beams were considered as the test parameters. Based on the test results, the applicability of fire design methods for composite beams recommended in current domestic and overseas fire design codes was analyzed. The results indicate that the current temperature-based design method and reduced flexural capacity method specified by the American Institute of Steel Construction may lead to the conservative fire design of steel composite beams owing to the underestimation of the effects of the fire-exposure conditions and load ratios.

Assessment of Seismic Behavior Factor of Code-Designed Steel–Concrete Composite Buildings

In this study, the seismic behavior factor of steel–concrete composite buildings was examined. For this purpose, 5-, 10-, 15- and 20-story composite moment-resisting frame (CMRF) buildings having concrete-filled steel tube columns and composite beams were designed at medium ductility (DCM) and high ductility (DCH) levels as per the regulations of Eurocode 8. Examined DCM structures were designed for a PGA of 0.2 g while DCH structures were designed for a PGA of 0.4 g. SeismoStruct software was utilized in the design and performance assessment of the case study structures. Nonlinear static pushover and incremental dynamic analyses were used. In the pushover analysis, the uniform and triangular load distributions were adopted while 12 earthquake ground motions were employed in the dynamic analysis. The effect of ductility levels and number of stories on the seismic behavior of CMRFs was studied using the results of the nonlinear analysis. To this, the variation in the lateral response, global yielding value, code-based behavior factor and component, and dynamic behavior factor were presented for CMRF structures with DCM and DCH. It was observed that the behavior factor of all CMRFs exhibited well above the design assumptions, especially DCM class CMRFs.

Flexural Study on UHPC–Steel Composite Beams with Joints under Negative Bending Moment

Abstract This research aims to experimentally investigate the flexural behavior of ultra-high-performance concrete (UHPC)–steel composite beams with joints under a negative bending moment in order ...