Search

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...

In general, a steel beam is assembled with a concrete slab by shear connectors. The connection requires high stiffness and strength to secure the composite effect even in the ultimate state. Facing this need, perfobond shear connectors are attracting a great attention by virtue of its outstanding mechanical performance. However, the connector is subjected to the fully reversed cyclic stress between the compression and tension during an earthquake. Therefore, as presented in the earlier research addressing stud shear connectors, the concrete may originate cracks under the tensile stress; and eventually, the expected composite effect is not possibly performed. To address this concern, this research carried out a total of three fully reversed cyclic loading tests using the component model of perfobond shear connection. The parameters are the presence of reinforcing bars and concrete strength. In conclusion, it was found that perfobond shear connectors exhibit more stable mechanical behavior and capacity than stud shear connectors regardless of stress orientation due to a localized stress transfer mechanism that results in smaller cracks in the slab under a fully reversed cyclic loading.

In this study, numerically and experimentally the dynamic characteristics of graphene-reinforced glass fiber–reinforced polymer hybrid uniform and thickness tapered laminated composite beams were investigated. First, the graphene-epoxy nanocomposite solution without and with 0.25, 0.50, and 0.75 wt.% of graphene reinforcement is prepared by the heat shearing technique and then used for the fabrication of glass fiber–reinforced polymer hybrid uniform and thickness tapered composite beams using the hand lay-up method. The elastic properties of the hybrid beams were evaluated using the impulse excitation of vibration technique (ASTM E1876-15) under elevated temperature. Further, the numerical and experimental modal analysis of the hybrid beams with uniform and tapered configurations were conducted with variation in wt.% of graphene particles under fixed-fixed and fixed–free end supports. The results reveal that the natural frequencies of the glass fiber–reinforced polymer hybrid uniform and tapered configurations with 0.25 wt.% of graphene are greater than those of the glass fiber–reinforced polymer beams without graphene reinforcement and observed lesser for 0.5 and 0.75 wt.% of graphene under fixed-fixed and fixed-free end supports, respectively, due to unavoidable agglomeration effects. Furthermore, the parametric study was performed with the influence of weight fraction of graphene and temperature on the transverse response of the tapered composite beam. Hence, it can be concluded that the use of graphene filler in the glass fiber–reinforced polymer composites in the tapered composite beams improves the bending natural frequencies significantly when the weight fraction of the graphene is used lesser as agglomeration is unavoidable in practical condition. Therefore, the comprehensive numerical and experimental work presented in this study will be useful to the designers while using graphene fillers to improve the bending characteristics of the tapered composite beams.

Post-buckling and dynamic nonlinear stability analyses of a sandwich functionally graded material (FGM) composite beam subject to in-plane compressive static and periodic loading are conducted by implementing a higher-order shear deformation with von Karman kinematics. The dynamic instability region is evaluated using the Mathieu-Hill-type equation in Bolotin’s method. Comparisons of the layered composite beam, FGM sandwich composite beam, shape memory polymer (SMP) composite beam, and SMP-FGM sandwich composite beam with variable in-plane loads $$(N_x^1, N_x^2, N_x^3)$$ are depicted for the first time in the current work. The unstable region of $$N_x^3$$ is lower compared with those of $$N_x^1$$ and $$N_x^2$$ .

Composite materials are age-old materials used to fulfill different needs in different applications. Polymer matrix composites can be laid layer-wise to fabricate laminated composite beams (LCBs). ...

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...

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.

A novel bamboo-concrete composite structure with threaded reinforcement connections is presented. Experimental investigations on the shear behavior of the connectors and the flexural performance of the bamboo-concrete composite beams were carried out. The results indicate that the load-slip behavior of the shear connection with threaded reinforcement exhibits good ductility and that its failure mode is ductile failure. The threaded reinforcement provides an efficient connection before the initial shear failure. The load-displacement curves of the bamboo-concrete composite beams are close to those of the full composite structure, and the midspan displacement is greatly reduced under the same load compared with that of the contrast bamboo beams. The loads PL/250and PL/300, corresponding to the midspan deflections of L/250 and L/300 ( L is the span of the beams) of the composite beams, increase by averages of 3.36 times and 3.71 times, respectively, compared to those of the contrast bamboo beams. The load-bearing performance of the beams in the service state is greatly improved. Based on the equivalent cross-sectional stiffness calculated using the γ-method with a reduction of 0.80, the calculated results of the displacement are in good agreement with the test results.

Modern ambient energy harvesters meet the micropower demands of the industrial sensors and communication hardware. Optimum design of such systems to maximize the power output is, therefore, of vita...

The present study develops computationally efficient meshless model for the first-ply failure analysis and predicts the weakest ply, based on various failure criteria via one-dimensional, higher-or...

The present paper investigates the 3 D free vibration behavior of curved metallic and composite beams via a novel beam theory. The refined beam theory is constructed within the framework of the Car...

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 work examines flexural–torsional coupling for static and stability analysis of thin-walled composite beams having variable stiffness. Variable stiffness composites (VSCs), manufactured with...

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...

In order to understand the mechanical properties and force transfer law of steel-concrete composite beam deck under negative bending moment, and further guide the design. Based on a steel-concrete composite girder cable-stayed bridge, the model test of the mechanical behavior of the steel-concrete composite girder deck under the action of negative moment was carried out. The characteristics of mechanical failure and mechanical properties were analyzed.

In this paper, the size effect in unidirectional (UD) laminated glass-fibre reinforced plastic (GFRP) composites subjected to quasi-static bending loading was investigated: the sensitivity of a specimen’s mechanical behaviour and failure mechanism to its geometry was studied. Composite beams with different numbers of 0° unidirectional plies were tested and their post-deformation structures were analysed microscopically. In the subsequent simulations, the intraply damage was modelled using continuum damage mechanics, implemented as a user-defined VUMAT subroutine in ABAQUS/Explicit, while cohesive zone elements were employed to characterize the delamination between different plies. It was observed that the flexural failure triggered the multiple delaminations; their location was studied. The influence of the size effect on the bending response of the UD composite beams was analysed in depth. The findings of the current study can be used to design modern structures made of composite materials.

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 paper, the aeroelastic behavior of a composite wing is investigated in the compressible flow using the analytical method. The composite wing is simulated as a thin-walled single-cell closed cross-section beam with circumferentially asymmetric stiffness (CAS) configuration. The best layup configuration for the maximum flutter speed is determined by analyzing four layups configuration where the fiber orientation angle varies within the range of 0–90 degrees. Moreover, an included foam layer between composite layers resulted in higher bending stiffness and improved stability characteristics of the wing. It was shown that there is a significant improvement in the flutter speed for [Formula: see text] layup. Numerical results demonstrate the advantages of foam filled model over the model without foam in terms of the flutter speed to the weight ratio.

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.

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.

In this paper, flexural wave in a steel-concrete composite beam with periodically surface-bonded cement-based piezoelectric patches (CPP) is studied. The composite beam is designed using the idea o...

In this article, wave propagation of the sandwich composite beam with tunable electro-rheological (ER) fluid core is investigated. The sandwich composite beam is made of three layers consisting of ...

In recent years, thin-walled, cold-formed steel (CFS) structural members have gained expanding use in building construction and various sorts of structural systems [1,2,3].The utilization Cold-Formed Steel (CFS) structures has become progressively popular in different fields of building technology. The reasons behind the developing popularity of these products include their ease of fabrication, high strength/weight ratio and suitability for a wide range of applications. These advantages can result in more economic designs, as compared with hot-rolled steel, especially in short-span applications. In this project work attempt has been made to use Cold formed steel section as replacement to conventional steel reinforcement bar.

In this article, vibration analysis of a beam-fluid coupled system was performed and then, employing magnetostrictive layers, vibration amplitude of the cantilever beam was controlled according to ...

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...

Ductility and robustness are two of the most important structural properties for the design of a building against extreme load cases, such as earthquakes and column loss scenarios. Various ...

The cost-efficient field design is very important in the civil engineering. Therefore, the cold-formed steel structures (CFS) are preferred for construction. A Sophisticated CFS structure which uses a Cellular Concrete is implemented in this paper. The utilization Cold-Formed Steel (CFS) structures have become increasingly popular in different fields of building technology. The reasons behind the growing popularity of these products include their fabrication ease, high strength/weight ratio and suitability for a wide range of applications. These advantages can result in more economic designs, as compared with hot-rolled steel, especially in short-span applications. In this project work an attempt to use a Cold formed steel section as replacement to conventional steel reinforcement bar has been made.

In this paper, it is aimed to identify flaws in glass fiber reinforced polymer composites by smart skin graphene nano platelet (GNP) spray coating in infrared thermography technique. The initial resistance of GNP was made to 1 kΩ. Characterization of sensor and beam was done with scanning electron microscopy and computed tomography (CT) respectively. The thermo-elastic behaviour was evaluated in uniaxial test. The surface temperature was studied with IR camera and it was observed that the surface coated GNP sensor upon a damage and without the damage specimen retains heat than without coating the sensor. Hereafter testing with 0.1 mm/min, 0.5 mm/min and 1 mm/min, it was found that without damage specimen, the temperature increased to 112.5%, 13.3% and 40% respectively. And temperature increased to 93.2%, 36.7% and 76.4% in the specimen with the damage. Specimen were also tested for spectrum fatigue cyclic load at 0.1 Hz and 1 Hz. Failure peak of laminates has been analyzed with optical microscopy and CT which was correlated with temperature rise. For 0.1 Hz spectrum loading, the specimen with the damage, with and without GNP coated, temperature rose to 2040% after first laminate failure. Similarly, for 0.1 Hz specimen temperature rose to 15,637.5% in case of without damage specimen, with GNP coated than without GNP coated. And in case of 1 Hz spectrum loading with damage specimen, the temperature rose to 105.73% after GNP coated. Similarly, at 1 Hz loading, the temperature rose to 143.07% in case of without damage specimen after GNP coated. GNP skin coated nano-sensor helps in early detection of temperature signals.

The article discusses the study of Vibration Analysis of Generally layered Graphite-Epoxy with lay-up [300 /500 /300 /500 ]. The finite element method is utilized in the study, to analyze the effect of lay-up on the natural frequency and comparing the results with the article[1]. Method: The study is done using Ansys. Graphite-epoxy is considered for the study. The model is prepared from SHELL 281 element which is well-suited for composite shells and sandwiched construction. The accuracy in modeling composite shells is governed by the first-order MindlinReissner shell theory. The element has 8 nodes with 6 degrees of freedom at each node translations in the x, y, and z axes, and rotations about the x, y, and z-axes respectively. Finding: The study concludes that the values of natural frequency decreased when increased the difference between angles of lay-up. Novelty/Applications: Vibration Analysis study has been done in aspects, like sandwiched beam in which different materials are sandhwiched in a layer by layer fashion. Many studies also covers composite material with lay-up in great detail, but there is acute study about the comparision of the different lay-up angles at given boundary condition. These articles cover the same at a greater extent, and conclude that the strength and capacity of composite beams can be enhanced not only by blending composites together, but also giving importance to the arrangement of layers of composite materials.

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.

This paper deals with the shear behaviour of steel stud connectors in composite beams with profiled steel sheeting under static and impact loads. An experimental program including five static and ten impact push-out tests is firstly carried out, and the failure modes, the time history of impact load and slippage displacement, as well as the shear capacity of stud connectors are presented and discussed. Based on the dynamic responses, the influence of the arrangement form of profiled steel sheeting on the shear mechanism of steel stud connectors under impact loading is examined. Moreover, a design proposal developed previously by the authors is verified to reasonably predict the shear capacity of stud connectors with profiled steel sheeting parallel to the steel beam under impact loading. However, it is unsafe to predict the dynamic shear capacity of stud connectors with profiled steel sheeting transverse to the steel beam when the strain rate effect is considered. Additionally, the failure mode of shear connectors with solid slab in this paper is different from that of the previous work, which lead to the lower dynamic shear capacity of the connectors with the solid slab, and some further discussion is also carried out. The testing results can provide an essential data for future analytical and design-oriented study of composite beam with shear stud connectors with profiled steel sheeting under extreme loading conditions.

It has long been recognized that traditional exact methods may encounter numerical instability when analyzing the free vibration of a continuous partial-interaction composite beam, a type of composite beam which considers the interfacial slip. In contrast to the Euler–Bernoulli beam theory, the form of the general solution for the free-vibration governing equations of partial-interaction composite beams based on Timoshenko beam theory will change dramatically when the frequency is sufficiently high, indicating that shear deformation cannot be ignored at high-order frequencies. To tackle this difficulty, this paper presents a numerically stable and theoretically exact method to analyze the dynamic responses of continuous composite beams with partial-interaction. The new method can effectively overcome the problem of numerical instability encountered by traditional theoretical solutions such as the dynamic stiffness matrix method and transfer matrix method, particularly for high-order vibrations or long-span continuous beams. Some numerical examples are provided to demonstrate the performance of the proposed method.

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.

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 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.

An accurate mixed-form global-local higher-order theory including transverse normal thermal deformation is developed for thermo-mechanical analysis of multilayered composite beams. Although transverse normal deformation is considered, the number of displacement parameters is not increased. The proposed mixed-form global-local higher-order theory is derived using the displacement assumptions of global-local higher-order theory in conjunction with the Reissner mixed variational theorem. Moreover, the mixed-form global-local higher-order theory retains a fixed number of displacement variables regardless of the number of layers. In order to obtain the improved transverse shear stresses, the three-dimensional equilibrium equation is used. It is significant that the second-order derivatives of in-plane displacement variables have been eliminated from the transverse shear stress field, such that the finite element implementation is greatly simplified. The benefit of the proposed mixed-form global-local higher-order theory is that no post-processing integration procedure is needed to accurately calculate the transverse shear stresses. The equilibrium equations and analytical solution of the proposed model can be obtained based on the Reissner mixed variational equation. The performance of the proposed model is assessed through different numerical examples, and the results show that the proposed model can better predict the thermo-mechanical responses of multilayered composite beams.