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Steel-concrete composite structures are widely adopted in civil engineering attributed to the large span-to-depth ratio, light weight and rapid construction. However, long-term behavior of these structures attacked by environmental agents has not been fully investigated. This study presents an experimental study on monotonic and fatigue behavior of steel-concrete composite beams subjected to corrosion. Ten specimens were prepared using accelerated artificial corrosion and tested under four-point bending with a special focus on the effect of corroded studs. Different failure modes were observed for the specimens tested by static and fatigue loading. Corrosion was demonstrated detrimental effect on both monotonic load-bearing capacity and fatigue life of the specimens. The residual bending stiffness also decreased with corrosion rates.

A computer-aided engineering (CAE) fatigue life prediction technique is developed in this paper to determine the fatigue strength of bolted shear connectors in composite structures. A relatively ne...

Nowadays, composite beams have found increasing popularity in the structures due to their proper features. Previous studies did not address the effect of structural damping to analyze the vibrations of composite curved beams. Therefore, in this study, semi-analytical and finite element methods are developed to consider the damping effect in vibration analysis. Furthermore, a framework is presented to study the composite curved beams with variable cross-sections considering the effect of different parameters such as geometric parameters, boundary conditions, and fiber orientation which has been compared with commercial software ANSYS. The results show that the present method can well predict the behavior of the beams.

Structural steel and reinforced concrete are the main materials used in civil structures, and each has its own advantages and disadvantages. Nonetheless, when they are combined together to form a composite material, they result in tremendous advancements. There exist different devices to attain the composite action between steel and concrete among which is the shear stud connector that represents one of the most commonly used methods in composite construction, and it is the scope of this study. This monograph examines the degree of shear connection in steel–concrete composite beams depending on the properties of the shear connectors, where mild and rigid shear connectors where studied. It has been concluded via a non-linear numerical analysis backed by experimental testing that the capacity and the deformation of composite beams depend on the configuration and the mechanical properties of the shear connectors. Moreover, a simplified model to predict the degree of shear connection and the capacity of the composite beam was proposed.

A shear deformable hybrid finite element formulation is developed for the lateral-torsional buckling analysis of fibre-reinforced composite thin-walled members with open cross-section. The method is developed by using the Hellinger–Reissner functional. Comparison to the displacement-based formulations the current hybrid formulation has the advantage of incorporating the shear deformation effects easily by using the strain energy of the shear stress field without modifying the basic kinematic assumptions of the thin-walled beam theory. Numerical results are validated through comparisons with results based on other formulations presented in the literature. Examples illustrate the effects of shear deformations and stacking sequence of the composite layers in predicting bucking loads.

This article presents continuous interlaminar shear stress analysis of laminated beams with functionally graded single-walled carbon nanotube reinforced composite (FG-CNTRC) layers based on an exte...

Delamination failure commonly appears in composite structures, especially those with curved regions, where a relatively high through-thickness stress is generally created. This study examined the d...

Flexible links are often part of massive aerospace structures like helicopter or wind turbine blades, satellite bae, airplane wings, and space stations. In the present work, a mixed variational statement based on intrinsic variables is derived for multilinked smart slender structures. Equations involved in the derivation do not involve approximations of kinematical variables to describe the deformation of the reference line or the rotation of the deformed cross-section of the slender links resulting in a geometrically exact formulation. Finite element equations are derived from weak formulation, which can analyze large geometrically non-linear problems. The weakest possible variational statement provides greater flexibility in the choice of shape functions, therefore reducing the associated numerical complexities. The present work focuses on developing a single integrated computational platform which can study multibody, multilink, lightweight composite, structural system built with both embedded actuations, sensing, as well as passive links. Validation of static mechanical and electrical outputs from 3D FE simulation and literature proves the efficacy of the computational platform. Dynamic results will be communicated in future correspondence. The computational platform developed here can be applied for monitoring and active control applications of flexible smart multilink structures like swept wings, multi-bae space structures, and helicopter blades.

Composite elements are generally used for special types of structures owing to their high efficiency. This research presents an experimental and theoretical investigation on the flexural behavior of low steel reinforcement ratio steel plate-reinforced concrete composite beams. The experimental program consists of 14 reinforced concrete specimens. Meanwhile, the theoretical study involves the verification of the experimental work and a parametric study on the behavior of the steel plate-reinforced concrete composite beams using nonlinear finite element software (ANSYS 18.1). The theoretical and experimental variables include the shape and thickness of the steel plates, the concrete compressive strength, the number of shear connectors, and the use of epoxy resin. The experimental test results revealed that the use of mild steel plates as a replacement for high-tensile steel reinforcements inversely affects the load-bearing capacity of the steel plate-reinforced concrete composite beams. However, when high-tensile steel plates were used as additional reinforcements, the nonlinear finite element analysis predicted up to a 40% increase in the values of the ultimate loads for the composite beams.

In this study, a novel method for determining stresses in the torsion problems of laminated composite trimetallic and bimetallic bars was developed and evaluated via experimental and numerical analyses. The objective of this method is to transform a real transversal section of a model for a laminated composite bar into a hypothetical virtual section that is homogenous and isotropic. An analogy with the transformed-section method for solving composite beams under flexion was conducted. The shear stresses (maximum on external surfaces and interfaces) in laminated composite bars were undergoing torsion. Isotropic symmetric and asymmetric laminated composite bars were examined analytically, and the results of their respective experimental and numerical tests were analyzed. The proposed method exhibits differences between 2 % and 12 % compared with the experimental results and between 2 % and 10 % compared with the results obtained using the finite element method.

This paper proposes a steel-wood composite beam with H-shaped steel beam webs glued to the wood. As a new type of composite beam, it combines the advantages of low energy consumption of wood, high permeability, and less pollution and the advantages of light weight and high strength of steel, high degree of assembly, short construction period, and less construction waste generated. Carrying out research is of great significance to improve the mechanical properties of steel-wood composite beams and promote the development of steel-wood composite structures. In this paper, three hot-rolled H-beam-larch composite beams and one pure steel beam were tested for bending capacity. The composite beams are divided into two different combinations of A and B types. The two sides of the web are connected with larch wood by structural glue to form a composite beam. The type B composite beam is a larch wood glued on both sides of the H-shaped steel web and penetrates the bolts at the same time. Through the three-point monotonic static grading loading of the composite beam, the deflection change, failure phenomenon, and form of the specimen during the experiment were observed. Under the circumstances, the ultimate bearing capacity of the test piece was changed to study the combined effect of larch and hot-rolled H-shaped steel. The results show that the overall performance of the H-shaped steel-larch composite beam is good. Bonding wooden boards on both sides of the steel beam web can improve the bearing capacity, and the form of the member is more reasonable and effective; increasing the cross-sectional size of the H-beam in the steel-wood composite beam can further improve the bearing capacity of the composite beam; adding bolt anchorage on the basis of the structural glue used in the composite beam can further improve the bearing capacity of the composite beam. The superposition principle is used to simplify the calculation of the ultimate bearing capacity of H-shaped steel-larch composite beams. Comparing the calculation results with the test results, the data are in good agreement, which can provide a design reference for the practical application of such composite beams.

Shape memory alloys are used in composite structures due to their shape memory effect and phase transformation. The recovery force of the shape memory alloy improves the post-buckling behavior of the structure. In this study, the thermal buckling and post-buckling of Shape Memory Alloy (SMA) hybrid composite laminated beam subjected to uniform temperature distribution is investigated. To this purpose, considering Von-Karman non-linear strain terms for large deformation, the non-linear equations of SMA reinforced beam based on Reddy Bickford theory have been derived. Besides, the recovery stress of the restrained SMA wires during martensitic transformation was calculated based on the one-dimensional constitutive law of the Brinson’s model. A numerical solution using Galerkin’s method has been presented for solving the nonlinear partial differential equations to obtain the critical buckling temperature and transverse deformation of the beam in the post-buckling region in both symmetric and anti-symmetric layups. The effect of SMA volume fraction, pre-strain, the boundary condition of the beam, stacking sequence, and its geometric properties have been studied. The results show that even by adding a small amount of SMA to the composite, the critical buckling temperature increases significantly, and the beam deflection decreases. Besides, using this theory has an evident effect on the anti-symmetric layup, especially for the thick beams.

Delamination between any two plies is an important damage commonly seen in composite structures. It may initiate and grow in the composite laminates for different loading conditions, and it may finally lead to failure of the component under the cyclic loading. Therefore, fatigue life prediction in these structures is important to avoid the effects of delaminations in economic and safety considerations. The usage of artificial neural network (ANN) in estimating fatigue failure in composites with delaminations would be high. In this work, experimental fatigue data were obtained for glass fiber-reinforced composite beams with and without delaminations. The experimental results were used to train and test the neural network. Finally, ANN was found to be accurate tool for fatigue life estimation for composite materials with delaminations as it produces reasonably good fatigue life prediction for delaminated composites.

The free vibration behaviors of the embedded and co-cured perforated damping sandwich composite (ECPDSC) in which the holes are filled with resin are investigated. The displacement field of laminated structure and the equivalent elastic parameters of the heterogeneous damping layer are presented by the combination of the first order shear deformation theory with homogenization method. The dynamic equations of the structure are derived on basis of the equivalent complex modulus theory, and the theoretical results are verified by experimental platform. The relationships of damping area ratio and the thickness of damping layer as well as the elastic modulus of viscoelastic material with the dynamic properties of ECPDSC are theoretically explored further. Results indicate that the modal frequency decreases slowly when the damping area ratio is relatively small, the modal frequency decreases rapidly when the damping area ratio is relatively large, and the trend of loss factor is just opposite. This investigation will lay a foundation for the design and manufacture of composite components with light weight, large damping as well as high stiffness.

Present investigation deals with the snap-through phenomenon in a thermally pre-buckled or post-buckled reinforced composites beam. Composite laminated beam is reinforced with graphene platelets (G...

Recently, composite members had been widely used in construction, where the use of appropriate materials arranged in an optimum geometric configuration providing the required compressive and tensile strength, achieve greater stiffness, material saving, less own weight and better vibration resistance. Unfortunately, the behavior of continuous composite beams supported on other beams is unpredictable and such system requires a more complicated design. Most of the current design codes do not mention the behavior of this system due to the lack of both experimental data and practical experience. Therefore the designer usually ignores the real behavior of such system which acts as a paneled beam system, and considers the secondary beams as simply supported composite beams, or as continuous steel beams leading to either unsafe results or over conservative results, due to the lack of adequate code guidance, Thus, this paper explains the behavior of such system using linear finite element analysis, together with the most important factors affecting it.

Composite structures are used in structural systems to take advantage of concrete and steel, and the role of shear connectors between the two is extremely important. Currently, anchor- and angle-type connectors are mainly used as shear connectors, and the angle type offers several advantages over the anchor type. The angle type can be manufactured as a shape that fits the composite structure with a greater basic strength than that of the anchor type, so it can be installed in wider spaces. Much research has been conducted on the anchor type, but that on the angle type has been insufficient so far. In this study, push-out and yield-strength tests were conducted on various angle-type shear connectors used for filling-type composite beams. The variables included the height, width, and thickness of the angle-type shear connector. The tests were terminated when a strength reduction of 80% of the maximum strength occurred. The slip capacity of the specimen was evaluated by referring to Eurocode. Based on the experimental results, the design equations have been reviewed to determine whether or not they can be used for the shear connection of concrete-filled composite beams. In addition, the strength was assessed by existing design equations. Meanwhile, a new design equation was proposed, including the height of the shear connector, which is not considered in the current design equations. The other strength was calculated by the new design equation.

A total of seven simply supported composite specimens are tested under concentrated load at the mid-span of the beam to investigate the strength of specimens to resist the applied load if web buckling take place. A novel technique of using a corrugated CFRP struts to strengthen the web of the steel girder is presented in this study. This technique provides two layers of CFRP laminate which are from biaxial fabrics to provide a knitted material that can undergo the complex state of stress in the web. The studied specimens are divided into two groups in addition to the control specimen having the same length. There are three specimens in each group, these specimens have different castellation ratios of (33.3%, 43.3% and 54.3%), the first group is identical to the second one except that the second group was strengthened with the proposed CFRP corrugated struts while the first one kept unstrengthen as a reference. Composite beams have a vertical stiffener at the action area above the supports. The reference group showed decrease in deflection of (11.11, 20 and 26.67) % for (33.3, 43.3 and 54.3) castellation ratio while strengthened girders record (13.75, 6.11 and 13.93) % for the same opening depths, compared to the control specimen. In addition, CFRP struts decrease the web buckling from (1.6, 2.9 and 83.33) to (0.8, 0.4 and 0.3) mm for beams with castellation ratio of (33.3, 43.3 and 54.3) respectively.

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.

This study presents dynamic responses of a composite thick beam with a functionally graded porous layer under dynamic sine pulse load. The boundary conditions of the composite beam are considered as viscoelastic supports. Three layers are considered, and face sheet layers have porous functionally graded materials in which the distribution of material gradation through the graded layer is described by the power law function, and the porosity is depicted by three different distributions (i.e., symmetric distribution, X distribution, and ◊ distribution). The layered composite thick beam is modeled as a two-dimensional plane stress problem. The equation of motion is obtained by Lagrange’s equations. In formation of the problem, the finite element method is used with a 12-node 2D plane element. In the solution process of the dynamic problem, a numerical time integration method of the Newmark method is used. In numerical analyses, influences of stiffness and damping coefficients of viscoelastic supports, material gradation index, porosity parameter, and porosity models on the dynamic response of thick functionally graded porous beam are investigated under the pulse load.

Timber-concrete composite beams are a new type of structural element that is environmentally friendly. The structural efficiency of this kind of beam highly depends on the stiffness of the interlayer connection. The structural efficiency of the composite was evaluated by experimental and theoretical investigations performed on the relative horizontal slip and vertical uplift along the interlayer between composite’s timber and concrete slab. Differential equations were established based on a theoretical analysis of combination effects of interlayer slip and vertical uplift, by using deformation theory of elastics. Subsequently, the differential equations were solved and the magnitude of uplift force at the interlayer was obtained. It was concluded that the theoretical calculations were in good agreement with the results of experimentation.

One of the essentials for designing composite structures exposed to heat is the correct choice of reinforcing materials. In the present research work, a comparison is made between the performances of two well-known advanced materials, Shape Memory Alloys (SMAs) and Carbon Nanotubes (CNTs), in thermal bucking behavior of thin composite beams with simply supported boundary conditions. First, the effect of embedding SMA wires on the thermal buckling of laminated composite beams are examined. The stability equations are derived based on Timoshenko Beam Theory (TBT), and the critical buckling temperatures are obtained analytically. The advantages and disadvantages of using SMA wires as well as their proper functional range are studied. Then, in the next step, the influence of CNTs on the thermal buckling response of composite beams is presented. To this end, the results of some experiments such as Dynamic Mechanical Thermal Analysis (DMTA) and Thermo-Mechanical Analysis (TMA) tests are used to obtain thermal properties of CNT-reinforced composite materials. The performance of CNTs is also evaluated in comparison with SMA wires. It is found from the analysis that, depending on the structural conditions, one reinforcing material can outperform the other. Finally, the idea of simultaneous use of both reinforcing materials comes up. The results show that, in some circumstances, the use of only one of the SMAs or CNTs does not have significant effect on the thermal buckling of composite beams, but applying both of these advanced reinforcing materials in the composite medium can extraordinarily enhance the critical buckling temperatures.

The timber board interlayer is applied as the formwork for the pouring of concrete slab in various practical applications of timber–concrete composite structures, with the rehabilitation of timber buildings, in particular. At present, there are few studies performed to study the shear stiffness of inclined screws in timber–concrete composite beams with timber board interlayer. In this article, eight groups of shear tests were carried out to study the shear stiffness of inclined screws in timber–concrete composite beams with timber board interlayer. The key parameters included the embedment depth of the screw connector into timber, screw diameter, the thickness of concrete slab, and concrete strength. As indicated by the test results, the shear stiffness of the inclined screws was improved as the embedment depth of screw into timber and screw diameter increased. When the embedded depth of screw into concrete remained unchanged, the thickness of concrete slab and concrete strength exhibited no significant impact on the shear stiffness of inclined crossing screws. On the basis of the theory of a beam on a two-dimensional elastic foundation, the calculation method for predicting the shear stiffness of inclined screw in timber–concrete composite beams with interlayer was proposed. The comparisons demonstrated that the shear stiffness of inclined screw can be well predicted using the calculation method.

For the studs in the composite beam under bending effect, axiel stress should be taken into account as well as the shear stress. This condition emphasizes the adherence between the studs and the concrete slab. Under the cyclic loading effect, lateral displacement of the stud leads to cavities in the concrete slab. These cavities affect the service life of the composite system. In this study, composite beams with fixed span and section properties are analyzed for different stud layouts. Reference specimens are strengthened with the use of tendon. This strengthening with the tendon has been made in order to limit the stress and deflection demands of the studs. For this purpose, experimental and numerical analyzes are carried out. Ansys Work Bench finite element program has been used for the numerical analysis. From the analysis results, stud count and the layout has been observed to be effective on the system behavior. For the lateral displacement of the system, the double row and the staggered layouts has given better results compared to the single row layout. It has been observed that the tendon added to the system has affected the stud stress distributions and stud lateral displacements positively. In addition, the tendon has contributed to the system capacity and the ductility.

Steel-concrete composite frames with semi-rigid connections can be designed to resist earthquakes in low to moderate seismic zones by ensuring that they have adequate strength, stiffness and ductility. However, the design of semi-rigid composite frames to ensure desirable seismic performance is a complex problem due to several issues such as calculation of flexural stiffness of the composite beam, evaluation of the storey drifts and defining the secant stiffness of the nonlinear connection. In this paper, issues in the design of semi-rigid composite frames are discussed and proposed preliminary design guidelines for semi-rigid steel-concrete composite frames to satisfy the drift limits and give acceptable performance. Seismic performance of frames designed as per the force based design and direct displacement based design is compared and found that direct displacement based design is not promising in low seismic zones in terms of utilisation of material.

The aim of this study was to improve four-point bending performance of foam core sandwich composite beams by applying various core machining configurations. Sandwich composites have been manufactured using perforated and grooved foam cores by vacuum-assisted resin transfer moulding method with vinyl-ester resin system. The influence of grooves and perforations on the mechanical performance of marine sandwich composite beams was investigated under four-point bending test considering the weight gain. Bending strength and effective bending stiffness increased up to 34% and 61%, respectively, in comparison to a control beam without core modification. Analytical equations were utilised for calculating the mid-span deflection, equivalent bending stiffness and ultimate bending strength of the sandwich beams. Finite element analysis was also performed to analyse the flexural response of the specimens taking into account the combined effect of orthotropic linear elasticity of the face sheet and the non-linear behaviour of the foam core. © The Author(s) 2020.

In this paper, the free vibration analysis of composite laminated beams reinforced with parabolic fibers are studied on the basis of the equivalent single layer theory (ESLT) using the isogeomtric ...

Time-dependent behavior is characteristic of adhesively bonded structureswhen put under constant load (creep). In this study, adhesively bonded beam specimens prepared by adhesively bonding two uni...

Most of Russian research about composite structure fire resistance are dedicated to the composite slab behavior. The composite beams fire resistance had been never investigated in enough volume: the temperature evaluation within the scope of the actual Russian design codes leads to the significant reduction in the shear connection strength. Meanwhile, there no correlation between the strength decreasing and type of the shear connection. The article provides an overview of the relevant researches and offers some approaches which could take into account bearing capacity reduction of the shear connectors within composite structures design.

The design of graded laminated composite is proposed to reduce the stress discontinuity in the laminated composite structures. The functionally graded (FG) layer with varying fiber orientation angle is inserted at the interface of cross-plies so that the continuity of the material properties is achieved and also the stiffness of the conventional composite is almost retained. The smooth stress distribution is observed across the thickness of a laminated composite beam subjected to a static/moving load. So, it may be useful in the practical applications of conventional laminated composites.

The work is aimed to facilitate the design of composite beams. The known methods of bending analysis of composite beams for different composite layups are compared in the presented paper. The paper presents the difference between the results of different calculation methods, both analytical and numerical, and the experimental data. Three models of FE analysis and analytical methods are used to identify the dependence of the deflection of the beam on the used method and to show the differences between the calculated results in comparison with the experiment. The classical laminated theory, the FE analysis and some new approaches are used in comparison with an experiment. Specimens made of three different materials stacked into four different layups that are used for the experiment. So it enables us to see the differences of the results from calculation methods in different cases of composite layups and their deviations. The aim of this work is to find an analytical simple tool for computation of the deformation of the composite beams that can be used for initial designs and sizing.

Ductile shear connectors are often applied in timber-concrete composite beams. The relative interface slip of such kind of composite beams will affect the mechanical performance of the composite beams and result in structural nonlinearity. Gamma method which adopts effective bending stiffness to reflect semi-rigid connection is recommended in Eurocode 5. The effective bending stiffness is irrelevant to external loads and calculation points of the composite beam. However, actual bending stiffness distribution along the beam is variable due to that shear connectors are subjected to different shear force. In order to verify the accuracy of gamma method, four-point bending tests of a total of three glulam-concrete composite beams with lag screw connectors and one pure glulam beam were conducted in this article. The failure mode, bearing capacity, and load–deflection relationship were investigated in the experiment. Meanwhile, push-out tests of composite beams were also conducted for determination of the force–displacement relationship of ductile shear connectors. Then, numerical simulation using beam-truss model was established for investigation on the mechanism of composite beams. Finally, theoretical analysis of composite beams considering the effect of interface slip was also presented. Comparing results from gamma method with the presented method, it is shown that both methods can calculate deflection at serviceability limit state with high precision. However, non-uniform distribution of actual bending stiffness cannot be reflected by gamma method.

The research concentrated on the corrosion resistance of reinforced self-consolidating concrete (SCC), lightweight SCC (LWSCC), fiber reinforced LWSCC (FRLWSCC), Engineered cementitious composite (ECC) and composite (ECC-SCC/LWSCC) beams. The performance of corroded beams were analyzed based on current measurements, half-cell potential readings, crack pattern/width, rebar mass loss and diameter reduction from accelerated corrosion tests. Corroded and their companion uncorroded beams were tested to failure under four-point loading to evaluate load-deflection response, crack pattern, 1st flexure/diagonal cracking load, failure load and failure modes. Composite beams with higher ECC layer thickness exhibited superior corrosion resistance than their lower thickness counterparts and full depth SCC or LWSCC counterparts as well as performance of beams with ECC wrap was better than those with layer. Overall, ECC beams can be a superior alternative of their conventional counterparts and ECC can be used as layer or wrapping in conventional/LWSCC beams to enhance corrosion resistance and structural performance

Shear and flexure performances of composite beams with different engineered cementitious composites (ECC) to self-consolidating concrete (SCC) depth ratio were investigated. Shear reinforced composite ECC/SCC beams showed similar behavior compared to their non-shear reinforced counterparts until the formation of diagonal cracks but exhibited higher ultimate shear resistance and ductility. Compared to the full depth SCC and full depth ECC beams, non-shear reinforced composite ECC/SCC beams showed higher ductility and energy absorption capacity. Composite ECC/SCC beams showed higher number of cracks with lower crack width because of fiber bridging and micro-cracking characteristics of ECC. Code based equations and other design specifications were conservative in predicting shear strength of shear/non-shear reinforced composite ECC/SCC beams. Composite ECC/SCC flexure beams showed satisfactory flexural performance compared to their full depth ECC and SCC counterparts.

Externally prestressed steel–concrete composite (EPSCC) beams in their deformed configuration are characterized by changes in the effective depth of external tendons. However, little infor...

Based on the loading features of reinforced timber-concrete composite (TCC) beams, a calculation model of their ultimate flexural capacity is established. To verify calculation results, four TCC beams with different degrees of reinforcement were prepared and tested, and a good agreement between test data and calculations was found to exist.

Although prestressing is a technique usually linked to reinforced concrete structures, composite steel-concrete beams may improve their mechanical behaviour through post-tensioning tendons. A particular feature of composite beams is the possibility of slip or partial interaction between the components as a result of the shear connection flexibility. This paper describes the development, implementation and test of a one-dimensional finite element formulation for the nonlinear analysis of steel-concrete composite beams prestressed by external tendons, fixed at discrete points along the steel component, taking into account the partial interaction between steel and concrete. Physical and geometrical nonlinearities are considered and a consistent derivation of the tangent stiffness matrix for the tendon is introduced. A recently developed procedure for state determination after prestressing operation is adapted for partially connected composite beams prestressed by external tendons. The accuracy and robustness of the finite element formulation is assessed by means of the comparison with a comprehensive series of experimental results.

Experimental investigations of laminated timber-concrete and steel-timber-concrete composite floor or bridge beams show that complex failure modes develop in such members. This paper prese...

In search of an improved compatibility between cold-formed steel profiles and precast floor systems, this study proposes an alternative shear connector for cold-formed steel-concrete composite beams. This connector consists of a steel plate with holes placed longitudinally in the middle of the upper flange of the steel profile, aiming to maximize the support area for precast slabs during the assembly. The proposed solution was experimentally tested on I-beams under bending, composed by two cold-formed steel channels, connected to a reinforced concrete slab by the shear connector. The relative slip between the steel profile and concrete, vertical deflection of the beam, and strains at several locations of the composite section were measured. The results show that the proposed connector assures shear transfer at the interface of the composite section components and shows strength of the same magnitude as other commonly used connectors. Resumo Buscando compatibilizar as estruturas em perfil formado a frio com os sistemas de piso com pré-laje, foi proposta nesse trabalho uma alternativa de conector de cisalhamento para vigas mistas compostas por perfil formado a frio que visa maximizar a área disponível para apoio das pré-lajes durante o processo construtivo. Trata-se de um conector em chapa perfurada disposto longitudinalmente no centro da mesa superior do perfil. Para testar a solução proposta, foi realizado um trabalho experimental em que se submeteu à flexão uma viga de seção I composta por dois perfis U enrijecidos formados a frio conectada a uma laje de concreto armado através dos conectores propostos. Nestes ensaios foram medidos o deslizamento relativo entre o perfil de aço e o concreto, o deslocamento vertical da viga e as deformações em diversos pontos da seção mista. Analisando os resultados obtidos pôde-se concluir que o conector proposto consegue desempenhar a função de transferir o cisalhamento na interface dos componentes da seção mista apresentando resistência da mesma ordem que conectores usuais

It is shown that it is possible to create branchy and shaped composite leaf springs with a constant cross-sectional area and three-fold reduced weight, at a given level of accumulated elastic energy, by choosing an appropriate spring geometry. The advantages of branching in comparison with shaping are the absence of cut fibers, exclusion of fiber disorientation, and the possibility of decreasing the spring size by combining its leafs into a bundle. The use of a unidirectional GFRP makes it possible to multiply reduce the spring weight compared with that of a steel analog with the same strength and stored energy requirements. An efficient use of branchy composite springs is possible for transport systems and, in the future, for space-based constructions due to their low weight and the extremely low energy of their production, and these factors allow one, in principle, to create such springs directly in orbit conditions.

Composite members have been widely used in the construction of medium- and high-rise buildings. The results of the development of a new structural member by experimental investigation of the flexural behavior of hollow composite beams are presented in this paper. This research aims to exploit the properties of composite sections and their strength in developing a new approach for overcoming the problems of service pipes in buildings. A hollow steel section encased fully in concrete is used to form a composite hollow beam. The structural benefit provided by the steel section (composite part) is adopted to increase the stiffness of the member. The hollow part is employed to provide services and economic benefits by reducing the amount of expensive ultra-high-performance concrete (UHPC) used and decreasing the self-weight of the member. The flexural strength of 11 UHPC beams is tested under two-point loads. The variables in this investigation include the type of hollow core mold material and the size, location, and shape of steel hollow sections in the middle and tension zones of the cross-section. Experimental results are compared and discussed. The tested results show that the flexural capacity and stiffness of the UHPC-encased steel hollow beams are 109% and 23.5% higher than those solid beams, respectively.

Composite floor systems rely on shear connection, commonly using headed steel stud anchors, to ensure that the steel beam and concrete slab work together as a unit, but also to transfer load from the diaphragm to the lateral force-resisting system. Under cyclic loading, slip and degradation can occur at the shear connection, affecting the seismic response of the floor and building systems. For composite floors using anchors welded through profiled steel deck, the slip and degradation may be more severe than floors with solid concrete slabs. In this paper, a series of push-out tests were conducted to study the monotonic and cyclic behavior of headed steel stud anchors in composite beams with profiled steel deck. The parameters that were investigated include the profile type, steel deck direction, and loading conditions. The results show both the monotonic and cyclic response are affected by the shape of the profile with newer, closed profiles, performing better than others tested. Additionally, comparisons are made between the test results and several design codes.

A mass timber panel-concrete (MTPC) composite floor system consists of a timber panel in the tensile zone, a concrete layer in the compression zone, and shear connectors between timber and concrete. The notched connections that are cut in timber and connected with concrete by the interlocking effect are often classified as the best type of connection system in terms of stiffness and load-carrying capacity. To study the effect of notch geometry to the performance of notched connections and composite beams, 2D finite element models are built in ABAQUS in this study. The concrete portion is modelled with concrete damaged plasticity model while the timber portion is modelled with Hashin’s failure criteria. The effective bending stiffness and ultimate bending capacity of the composite beam under uniformly distributed load are obtained from the finite element models and are compared with the well-known Gamma method in Eurocode 5 and strut-and-tie model. Good agreement between finite element model in the elastic range and strut-and-tie model was achieved. However, due to the assumptions made in the Gamma method, it was found that this simplified design method is not capable of describing MTPC composite floors with discrete notched connections.

A closed-form analytical solution is developed for analyzing laminated composite beam with asymmetric Z cross-section. The explicit expressions for evaluating sectional properties such as centroid, shear center, equivalent bending/torsional stiffness and warping stiffness are formulated based upon modified lamination theory and taken into consideration of the structural deformation characteristics of beam with narrow section. The ply stresses of flanges and web laminates are computed for composite Z-stiffener under axial, bending, and torsional loads. The present results give excellent agreement with the results from ANSYS™. A parametric study of their centroid and shear center with various layup sequences was performed by using the developed solution. It is found that the sectional properties are not only dependent of structural configuration but also the laminate property. Moreover, these properties are only dependent of structural configuration if the entire Z-stiffener is made of the same family laminates regardless their ply orientation and stacking sequence. It is concluded that the present approach is a viable and efficient method for designing composite Z-stiffener.

The work presented in this article is the outcome of a combined strategy of a mathematical tool for 2D cross-sectional analysis, i.e., Variational Asymptotic Method (VAM) as well as the 1D exact beam analyzer, i.e., the intrinsic mixed variational formulation for modeling and analysis of Piezoelectric-laminated composite beams. This work talks about a novel approach of mixed variational formulation to analyze a two-way electromechanically coupled piezoelectric composite beam. In a classical intrinsic mixed variational approach for a passive structure, the 1D exact beam model deals only with mechanical degrees of freedom. In the present case, an extra 1D electrical degree of freedom has been incorporated. A computational code is developed based on the present theory to solve the two-way coupled electromechanical beam problem. In the present case, we have validated the static results for sensor application. Both linear and nonlinear results have been discussed. Results obtained are very promising and are helpful in building a platform where design, optimization and nonlinear analysis of composite ‘smart’ beams in a multibody framework can be done faster while maintaining acceptable accuracy.

This study presents the impact behaviour of marine sandwich composite beam structures that manufactured by vacuum-assisted resin infusion process (VARIM). The sandwich composite consists of different thicknesses of upper and lower E-glass fibre-reinforced polymer as facesheets and PVC foam as core material. Low velocity impact tests have been conducted to understand the impact response of the sandwich composite by using a drop-weight impact machine with a hemispherical impactor. Square samples with 100 mm X 100 mm side dimensions were subjected to impact machine at five energy levels of 20J, 40J, 60J, 80J and 100J. The impact loadings have been applied to thicker facesheet of the sandwich composite to obtain impact parameters experimentally. Damage type on thicker facesheets and internal parts of PVC foam have been characterized through the contact force - time, contact force - displacement and contact force - energy curves after the tests. Impact failures that occurred on the upper facesheets, core and lower facesheets of the specimens were observed. (C) 2019 The Authors. Published by Elsevier B.V.