Design Of Composite Beams Research Articles

Large web openings in steel and composite beams

AbstractThis paper presents the basis for the design of steel and composite beams with large web openings. The main design requirements are the transfer of shear by Vierendeel bending and the control of web buckling next to and between the openings. Cellular beams with regular circular openings are a common example of highly perforated beams and their flange areas are often highly asymmetric. For these beams, web‐post moments may be generated to develop the full shear resistance of the cross‐section.Tests on beams with circular, elongated circular and rectangular openings are presented which are used to verify the design methodology. In addition, the openings cause local displacements due to shear and bending, which add to the overall deflection of perforated beams. Simplified formulae are presented to determine the additional deflection relative to the equivalent solid‐web beams.

Design of single‐span beams for SLS and ULS using semi‐continuous beam‐to‐column joints

AbstractThe objective of this article is to facilitate the use of semi‐continuous joints by providing ready‐to‐use tables and charts for design, which also permit the benefits accruing from the use of semi‐continuous composite beams to be directly identified. The relevant features for the design of composite beams, such as bending moment distribution, maximum deflection and natural frequency, are derived analytically. The influence of semi‐continuous steel joints on the performance of single‐span composite beams is analysed. The article concludes with an example of the use of a new slim‐floor beam type – the composite slim‐floor beam (CoSFB). The tables and charts derived are applied in this example with the intention of demonstrating the advantages of using semi‐continuous joints in combination with composite beams. The present article extends the design of semi‐continuous steel beams presented in the previous article on this subject [1].

An Improved Ant Colony Model for Cost Optimization of Composite Beams

ABSTRACTThis paper focused on the application and evaluation of an improved ant colony search method for the cost optimization of composite beams. The design was based on the American Institute of Steel Construction load and resistance factor design specifications and plastic design concepts. The objective function for composite beam was the cost function. This function included the cost of concrete, steel beam, and shear connectors. In order to validate the proposed model in optimizing composite beam design, two design examples taken from the literature were studied, and the results were compared to the original ant colony optimization and other meta-heuristic algorithms. The results showed that the improved ant colony method was able to find better solutions and had higher convergence speed than other meta-heuristic algorithms. Moreover, a parametric study was conducted to investigate the effects of beam spans and loadings on the cost optimization of composite beams.

Effect of Partial Shear Connection on Strengthened Composite Beams with Externally Post-Tension Tendons

Composite steel-concrete beams are used widely in bridges and buildings construction as the main structural elements in flexure. These structures have a design life and this may be reduced if loads are increased or environmental degradation could happen. These changes may reduce the design life and strength of such members and thus replacement or retrofitting may need to be considered. The present study focuses on evaluating the effect of partial shear connection on strengthen composite beams with externally post-tension tendons. Using three dimensional F.E. modeling it’s able to simulate the overall flexural behavior of composite beams which are strengthen with many shapes of tendons profiles. A fundamental point for the structural behavior and design of composite beams is the level of connection and interaction between the steel section and the concrete slab. The use of partial connection provides the opportunity to achieve a better match of applied and resisting moment and some economy in the provision of connectors, taking into account the demonstrated advantages of externally post tension system like: Increase in ultimate moment capacity of structure, Enlarge the range of elastic behavior before yielding for the structure with the introduction of internal stresses.

Behaviour and design of composite beams with composite slabs at elevated temperatures

This article presents an extensive experimental and numerical study aimed at the evaluation of the thermo-structural response of composite beams with composite slabs. Two full-scale fire tests were carried out on simply supported composite steel-concrete beams with steel sheeting perpendicular and parallel to the steel joist, respectively. Both specimens were observed to fail by developing large displacements. Concrete crushing at the mid-span, debonding of the profiled sheeting and spalling of the fire protection were observed during both tests. A three-dimensional finite element model was developed in ABAQUS, and its accuracy was validated against the experimental measurements collected as part of this study. The model was then used to perform a parametric study to determine the influence of the degree of shear connection, load ratio and design fire rate on the structural response of composite beams at elevated temperatures. These results, together with experimental data available in the literature, were used to evaluate the ability of European guidelines to predict the critical temperature of composite beams. It was shown that predictions from Eurocode 4 were safe and provided conservative estimates for most cases.

Experimental and analytical investigation into the stiffness of composite steel-reinforced timber beams with flexible shear connectors

Most of the current research on the design of timber composite beams involves either complex mathematical models which are not checked with experimental testing, or is purely based on experimental work with no attempt to model the behaviour. In a literature review the authors failed to find a practical way of designing composite timber beams, other than in the Eurocode 5. The equations in Eurocode 5 are unfortunately limited in their application. This paper looks at stiffening timber beams, with a known stiffness distribution, by screwing or nailing a steel strip to the underside of the beam. The modelled behaviour is compared with experimental test results and recommendations for the analysis and design of such members are given. The experimental work involved determining the stiffness of twenty-four South African pine beams reinforced with metal strips. The spacing of the connectors was varied to ascertain the increase in stiffness of the composite with a reduction in the connector spacing. The analytical methods used were the Eurocode 5 method, as well as two finite element modelling methods, which may be used to determine the composite stiffness. The results of the three methods used show a remarkably good fit with the lower-bound experimental results.

Design and Analysis of Sandwich Composite Beam

Design and Analysis of Sandwich Composite Beam

Elastic Buckling Moment of Continuous Composite Beams

Lateral-torsional buckling is one of the criteria in the design of steel and composite beams in ultimate limit state. This paper deals with lateral-torsional buckling of double-span continuous composite beams subjected to two different loadings. The main objective of the paper is the comparison of the elastic buckling moment values of composite continuous beams performed according to approximation formulas of Mcr,A from codes [2] and different sources [3] to more exact values Mcr,E obtained by computer programs based on finite element method [1P]. The results will be presented in the form of elastic buckling moment ratios Mcr,A / Mcr,E.

Optimal design of composite thin-walled beams using simulated annealing

In this paper, a problem formulation and solution methodology for optimal design of thin-walled composite beams is presented. The aim is to maximize the buckling load capacity and minimize the weight of the beam. For this purpose, a theoretical model is developed for the analysis of thin-walled composite beams under a state of arbitrary initial stresses. In order to find the optimal solution, Simulated Annealing method is implemented. Design variables are taken as the stacking sequences of laminate and the dimensions of the cross-section. The space of feasible solutions is constrained by strength, displacements, global and local buckling and geometric conditions.

Surface effects on the bending, buckling and free vibration analysis of magneto-electro-elastic beams

Surface effects are responsible for the size dependence and should be taken into account for dielectric structures at nanoscale dimensions. By incorporating the effects of surface stress, surface piezoelectricity, surface elasticity and surface piezomagneticity, this paper investigates the bending, buckling and free vibration of magneto-electro-elastic (MEE) beams based on the Euler–Bernoulli beam theory. The governing differential equation and its corresponding boundary conditions are derived by Hamilton’s principle. The analytical solutions for the magneto-electro-elastic bending deflection, buckling magnetic potentials and frequency equations of MEE beams are obtained. In contrast to the previously published works, the positive surface stress is found to stiffen the MEE beams, as evidenced by the decrease in the deflections, the increase in the buckling magnet potentials and the increase in the resonant frequencies. Numerical studies show the importance of the surface effects, the electric and magnetic potentials and boundary conditions on the static and dynamic behavior of MEE beams. This work may be of special interest in the design and application of smart composite MEE beams.

Exact sensitivity analysis of stresses and lightweight design of Timoshenko composite beams

The paper describes the novel optimization techniques for lightweight design of composite beams. The optimization model is to find width and depth of composite beams to minimize the mass of beams under the stiffness, strength and delamination failure constraints. The exact formulae for displacements, stresses and their sensitivities with respect to width and depth are derived using Timoshenko continuous beam theory. The analytical stiffness, strength and delamination failure functions, and their gradients are obtained using the exact expressions of displacements and stresses, and their sensitivities. The mass and its gradient are also expressed analytically. The standard gradient-based nonlinear programming algorithms are employed to solve lightweight design problems of composite beams. The lightweight designs of composite beams are performed using the proposed optimization techniques. Three standard gradient-based optimization methods (SQP, interior-point and active-set) using exact derivatives converge to the same lightweight design. However, gradient-based algorithms using finite difference sensitivities may not lead to optimal lightweight designs. It is necessary to develop exact sensitivity analysis method instead of the difference methods for gradient-based algorithms.

Combined Structural and Control Optimum Design of Fuzzy Composite Structures

In most practical applications, the structural and material parameters of composite structures vary considerably and are subject to uncertainties, mainly due to the uncontrollable aspects associated with the manufacturing of composite materials. In many cases, the loads acting on a composite structure may not be known precisely. Fuzzy composite structures involve fuzzy uncertainties, which means that the structural and material parameters and the loads, as well as the model of the composite structure, are fuzzy. In these cases, fuzzy set theories, fuzzy finite element analysis, and fuzzy control theory can be used to model, analyze, and control complex fuzzy composite structures. Because the design of efficient and high-performance structural systems is of fundamental interest to engineers, systematic methodologies are to be used for the combined structural and active control system synthesis in many applications. To satisfy any desired structural and control performance characteristics of fuzzy laminated composite structures, the optimum design of the fuzzy system subject to specific structural and control constraints is to be considered as described in this work. The combined structural and control optimum design of both composite beams and composite plates are explored in this work and two numerical applications are presented to demonstrate the feasibility and applicability of the methodology presented.

Behaviour and design of composite beams subjected to flexure and axial load

Composite steel-concrete beams are used frequently in situations where axial forces are introduced. Some examples include the use in cable-stayed bridges or inclined members in stadia and bridge approach spans. In these situations, the beam may be subjected to any combination of flexure and axial load. However, modern steel and composite construction codes currently do not address the effects of these combined actions. This study presents an analysis of composite beams subjected to combined loadings. An analytical model is developed based on a cross-sectional analysis method using a strategy of successive iterations. Results derived from the model show an excellent agreement with existing experimental results. A parametric study is conducted to investigate the effect of axial load on the flexural strength of composite beams. The parametric study is then extended to a number of section sizes and employs various degrees of shear connection. Design models are proposed for estimating the flexural strength of an axially loaded member with full and partial shear connection.

A novel topology optimization method for composite beams

A new topology optimization design method for aircraft composite beam under various loads is proposed. The cross-sectional stiffness characteristics of composite beam with arbitrary geometry are obtained using finite element method. Both of the warping and shear deformation are considered. To obtain better beam cross section, a multi-material optimization model including anisotropic and isotropic materials is employed. The density of candidate material at each element is designated as the design variables and updated with Sequence Linear Programming (SLP) of accurate gradient-based sensitivity. To avoid checkerboard problem, sensitivity filtering approach is used. Topology design of composite beam cross section with weight constraint is presented for square and airfoil cross section under various loads. The results show that the proposed method is suitable for the optimization design of composite beam, and innovative structures could be given. The external loads have great influence on the final topology shape of beam cross section.

Analyses of the loadbearing behaviour of deep‐embedded concrete dowels, CoSFB

AbstractThe development of the “CoSFB‐Betondübel” is presented in this paper. The “CoSFB‐Betondübel” is a deep‐embedded concrete dowel connecting in situ concrete with a steel section to assure composite action and thus allow for composite beam design. The loadbearing behaviour and parameters influencing this behaviour were determined through experimental tests. Special focus was given to the influence of the ratio of the resistance of the concrete dowel to the concrete compression class. The evaluation of the results concluded in a National Technical Approval [1]. Further investigations were performed via FE analysis in ABAQUS. Further, 3D models with non‐linear material and geometry were prepared and validation undertaken. In addition, a real application example of CoSFB is shown.

Topology design of composite rotor beam with gradient-based algorithms

Purpose – The purpose of this paper is to get the topology shape and material distribution of composite rotor beam under the requirement of cross-sectional characteristics. Design/methodology/approach – A new multi-material topology optimization method is given. Designated shear center (SC) position and stiffness terms are combined as the objective function. Multi-material model including isotropic and anisotropic materials are employed. Sensitivity analysis is given based on gradient-based algorithm, and density filtering scheme is adopted to avoid checkerboard problem. Findings – The topology design method of composite rotor beam provides innovative cross-sectional shape and material distribution method. The final topology shape like “ > ” is given for different material types and cross-sectional shape under SC position requirement. The coefficient of stiffness components has great influence on the cross-sectional final topology shape. Research limitations/implications – The proposed method is just to g...

Optimum design of thin-walled composite beams for flexural–torsional buckling problem

The objective of this research is to present formulation and solution methodology for optimum design of thin-walled composite beams. The geometric parameters and the fiber orientation of beams are treated as design variables simultaneously. The objective function of optimization problem is to maximize the critical flexural–torsional buckling loads of axially loaded beams which are calculated by a displacement-based one-dimensional finite element model. The analysis of beam is based on the classical laminated beam theory and applied for arbitrary laminate stacking sequence configuration. A micro genetic algorithm (micro-GA) is employed as a tool for obtaining optimal solutions. It offers faster convergence to the optimal results with smaller number of populations than the conventional GA. Several types of lay-up schemes as well as different beam lengths and boundary conditions are investigated in optimization problems of I-section composite beams. Obtained numerical results show more sensitivity of geometric parameters on the critical flexural–torsional buckling loads than that of fiber angle.

Behaviour and Design of Composite Beams with Stiffened and Unstiffened Web Openings

This paper presents an investigation on behaviour and design of composite beams with stiffened and unstiffened web openings. The composite beams were simply supported and had profiled steel sheeting oriented transversely to the steel beams. Nonlinear 3-D finite element models were developed to analyse the inelastic behaviour of composite beam components comprising the steel beam, concrete slab, profiled steel sheeting, headed stud shear connectors, reinforcement bars as well as interfaces among these components. In addition, the load-slip characteristic of the headed stud shear connectors in composite slabs with profiled steel sheeting were carefully incorporated into the finite element models. The finite element models of the composite beams have been validated against published experimental results. The composite beams had different moment-to-shear (M/V) ratios at the openings, stiffened and unstiffened web opening sizes, web opening locations, profiled steel sheeting, shear connections, beam lengths, concrete slab strengths and steel beam strengths. The ultimate loads of the composite beams, load-deflection relationships and modes of failure of the beams were predicted from the finite element analysis and compared well against the test results. Furthermore, the variables that influence the composite beam behaviour and ultimate load comprising different stiffened and unstiffened web opening sizes, M/V ratios at openings, web opening locations, beam lengths, concrete strengths and steel beam strengths, were also investigated in an extensive parametric study. It is shown that the ultimate loads of composite beams with stiffened web openings with horizontal stiffeners located above and below the openings, having an opening height equal to 0.6 the steel beam depth, can be considerably increased compared with that of unstiffened openings. It is also shown that the increase in structural steel strength has a remarkable effect on the composite beam ultimate loads. In addition, the ultimate loads of the composite beams with stiffened and unstiffened web openings predicted from the finite element analysis were compared with the design ultimate loads calculated using the Eurocode 4 and technical report SCI P355 published by the Steel Construction Institute for composite beams with profiled steel sheeting and rectangular stiffened and unstiffened web openings. Generally, it is shown that the design ultimate loads accurately predicted the ultimate loads of the composite beams within an average of 6% difference from the ultimate loads predicted using the finite element analysis.

Design and analysis of automotive carbon fiber composite bumper beam based on finite element analysis

In this article, the most important part of the automotive front bumper system, namely, the bumper beam, is studied by changing the material and thickness to improve the crashworthiness performance in low-velocity impact. According to the low-speed standard of automotives stated in E.C.E. United Nations Agreement, Regulation no. 42, the low-velocity impact simulation based on finite element analysis is carried out. Lightweight is the main purpose of this article. First, the bumper beam analysis is accomplished for carbon fiber composite and steel material to analyze their deformation, weight, impact force, energy absorption, and the acceleration of the impactor. As a consequence, the bumper beam made by carbon fiber composite achieves better impact behavior. Second, on the purpose of lightweight, the bumper beams of different thickness including 5.4, 6, 6.6, and 7.2 mm are investigated. The results show that the 5.4 mm bumper beam is the best selection without sacrificing the impact performance. Third, according to the stress distribution, the thickness distribution of the bumper beam is changed to get better lightweight results. It is indicated that the weight of the improved bumper beam is further reduced and the impact performance is not weakened.

Flexural-torsional coupled vibration of anisotropic thin-walled beams with biconvex cross-section

This study investigates the flexural–torsional coupled vibration of thin-walled composite beams. We first derived the thin-walled beam theory for an arbitrary cross-section and applied it to a biconvex cross-section. The flexural–torsional coupled motion is generated featuring a symmetric lay-up composite configuration. The natural frequencies are determined by solving the eigenvalue problem, which are obtained both for the warping restraint and the free-warping models. The variations of the natural frequencies with respect to the ply angle orientation are computed for selected values of thickness, slenderness and aspect ratios. We find that the natural frequencies have a tendency to increase with increasing slenderness and thickness ratios, while they tend to decrease with increasing aspect ratio. We also observed that omission of the transverse shear effect, particularly at the ply angles between 60° and 120°, led to an overestimation of the natural frequencies of the first and the second modes for higher slenderness ratios, while overlapping results are obtained for any thickness or aspect ratios regardless of including/omission of transverse shear deformation. Overall, we point out that the geometrical aspects have a substantial influence on dynamic characteristics in the design of thin-walled composite beams.