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A new type of UHPC‐NC (normal concrete) structure in the negative moment zone was proposed to improve the bearing capacity of the connection structure in the negative moment zone of prefabricated prestressed concrete (PC) beam bridges. First, the distribution characteristics of the crack, cracking load, ultimate moment, and ductility coefficient of the new structure were obtained by the 1:4 scale model tests. The feasibility of the connection structure is verified. Then, the value ranges of critical structural parameters affecting the bearing capacity of the connection structure based on the plane section assumption analysis, including the reasonable thickness of the UHPC layer, the reinforcement ratio of the longitudinal tensile reinforcement, and the diameter of the reinforcement, are obtained. At the same time, based on the verification of the finite element model, the influence of crucial research parameters on the bending capacity of the connection structure is obtained by using the finite element method. Finally, a theoretical method for the bending moment capacity of the connection structure of the UHPC‐NC structure is proposed, considering the high ductility characteristics of UHPC materials. The average relative error between the calculation results and the finite element method is within 7.2%, which verifies the reliability of the calculation method in this paper and provides a reference for its design and engineering application. [ABSTRACT FROM AUTHOR]

In this paper, a closed form solution is proposed on bending of uniformly loaded rectangular plates with adjacent edges clamped and the two others simply supported (CCSS). Deflection surface can be expressed by a double sine series referred to as Navier solution. Numerical results of deflection, bending moments agree with existing solutions including solutions of finite element model (FEM). [ABSTRACT FROM AUTHOR]

Recently, temporary bridges have been developed to facilitate rescue operations and minimize damage to affected areas. High‐strength bolts are preferred for end‐plate connections to expedite construction, reducing the bolt count. Regarding parts reusability, we propose an I‐girder designed with an L‐shaped notch and a novel support block as a structural member. Finite Element Method (FEM) analysis was conducted to investigate the girder end's buckling behavior and failure mode and to verify the effect of the support block's geometry and bolt arrangement on load‐bearing capacity. The findings indicate that the load‐bearing capacity of the girder end with the support block is equivalent to that of a standard I‐girder end, despite reducing the area of the support block's effective compression area by 40% under shear force and bending moment. [ABSTRACT FROM AUTHOR]

This paper provides an efficient and robust numerical solution for the linear buckling analysis of tubular members, such as the supporting tower structures of wind turbines. The method uses Fourier‐series approximations for the displacement functions. Longitudinal discretization can optionally be applied, i.e., the member can be divided into segments. The strain‐displacement relationship directly considers the curved geometry. The implementation allows for arbitrary support conditions. Four pure loading situations are considered, uniform – in each segment – along the length: normal force, bending moment, torque, and shear force; however, they can arbitrarily be combined, as is commonly occurring in wind turbine towers. The applied methodology results in a computational advantage compared to the shell finite element method, while still maintaining much more generality and applicability compared with common analytical solutions. Furthermore, the method is supplemented with features, as spectral analysis and buckling length calculation. [ABSTRACT FROM AUTHOR]

In structural engineering verifications, the plastic capacity of steel members may be utilized for cross sections of class 1 and 2. In literature, algorithms for the primary torsional capacity considering different types of numerical procedures, such as finite element methods, have mainly been addressed. However, there is a lack of explicit illustration of algorithms for cross sections considering combined loading, i.e. procedures for bending and torsional analysis. This paper therefore presents an algorithm for the plastic analysis connected to a cross‐sectional finite element approach. The algorithm considers the description of bilinear material laws, accounting for ideal‐plastic behavior as well as effects of isotropic hardening. Cross sections are discretized by isoparametric two‐dimensional nine‐node elements with curvilinear boundaries, which allow describing any geometry with high accuracy. The study proves that the plastic algorithm combined with the isoparametric elements accurately represents the behavior of cross sections. In addition, precise cross‐sectional capacities of hot‐rolled U‐sections gained by the methodology, i.e. plastic torsional moments and plastic bending moments, are presented. In future research, this methodology will be combined with finite element formulations for beams. [ABSTRACT FROM AUTHOR]

Steel rolled I shape beam‐columns, especially of narrow flange sections unrestrained between the end supports are sensitive to flexural‐torsional buckling. In order to increase their resistance, in‐span lateral‐torsional restraints are applied. Experimental investigations into the behaviour of steel rolled I‐section beam‐columns under moment gradient are presented in this paper. The beam‐column tested is restrained laterally and torsionally in a mid‐length. The experimental setup and testing procedures are described. A total number of 5 specimens (used for 9 tests with different proportions between the dimensionless maximum bending moment and compressive force) were designed. Test measurements and observations are reported. Finally, the experimental resistance results are compared with those of the preliminary finite element model made available in ABAQUS. [ABSTRACT FROM AUTHOR]

As thin walled HSS columns are very flexible, they usually exhibit excessive deformation when resisting a bending moment or transverse loads. Adding exterior/interior diaphragms is one way to remedy the problem. Another option that can significantly increase strength and stiffness is to allow passing plates through the hollow column by means of Laser Cutting Technology (LCT). This solution was tested on CHS columns within the RFCS LASTEICON project. The first outcomes were promising. One of LASTTS new RFCS project's overarching concerns is to enlarge the range of application of the passing‐through solution onto SHS columns. The goal of this research paper is to present the behaviour of I‐beam‐to‐SHS column moment resisting joints using passing‐through plates under opposite bending moments. First, a solid‐based finite element model is presented. This model is used to conduct a sensitivity analysis with different SHS column and passing plates geometry. The failure mode is resulting contribution of both weld/tube‐wall tearing in tension, and chord face crushing in compression. Analytical models are developed in an attempt to ascertain the bending resistance and initial rotational stiffness of this new type of connections. [ABSTRACT FROM AUTHOR]

Conventional I‐beam‐to‐SHS‐column moment resisting connections are generally stiffened with external diaphragms in order to limit excessive deformation of the tube‐wall. Passing through plates welded to the tube is an alternative solution that can develop significant strength and stiffness. This solution has been applied to CHS column and initial findings from RFCS project LASTEICON were encouraging. RHS columns are also widely used in practice due to simplicity of connections manufacturing. The new RFCS project LASTTS aims to investigate the application of this technique of passing through plates to SHS columns using laser cutting technology. The objective of this paper is to present the behaviour of I‐beam‐to‐SHS column moment resisting joints using passing‐through plates under equal hogging bending moments. A finite element model using brick elements is firstly presented. This model is used to perform a sensitivity analysis varying passing through plates thicknesses as well as SHS column dimensions. The failure mode is caused by the flange plate buckling inside the tube. Analytical models are developed to determine the bending resistance and initial rotational stiffness of these connections. [ABSTRACT FROM AUTHOR]

This research deals with the axial‐bending interaction in bolted steel beam to column connections along the strong axis of the column. In order to define the interaction curves, firstly, a series of tests of doubly symmetric bolted connections were carried out in which two column sizes were considered, while the beam, end plate and bolts remained the same. These joints were tested under pure compression, as well as simultaneous bending and compression, and with different load levels. Afterwards, reduced finite element models including initial imperfections were made. These models are validated by means of the results obtained in the experimental program. The aim of the reduced model is to enlarge the range of studied loading combinations in terms of different percentages of axial load and bending moment. Finally, with the results obtained, a preliminary normalized interaction diagram for this type of joints was deduced. [ABSTRACT FROM AUTHOR]

End plate beam‐column bolted joints are widely used in the field of steel structures. The usual configuration consists of individual bolts that join the end plate of the beam with the column flange. Usually, the use of stiffeners is needed in this type of joints, in order to reinforce the tension and compression zones of the column web, and to avoid local buckling problems. This configuration, applied to asymmetric connections, gives rise to the appearance of shear stresses in the column web, even with symmetric loading conditions on both sides of the connection. The method proposed in this work to improve the behavior of end plate asymmetrical steel joints, without using welded stiffeners (which significantly increases the cost of the joint), consists in using threaded bars as joining elements, instead of single bolts. Threaded bars have several purposes: to create the joint itself, to reinforce the tension and compression zones, and to reduce the shear stresses in the column web panel. In the present work, two end plate steel joints made up of an HEA200 column, and IPE200 and IPE300 beams have been tested. One of them with threaded bars with double nuts (internal and external) in the traction and compression zones, and the other one with single bolts. Symmetrical forces have been applied at the ends of the beams, subjecting the joints to symmetrical bending moments on both sides of the connection. The tests have been instrumented through the use of load cells, displacement sensors and inclinometers. The results show an important increase in the stiffness and the resistance of the joint with threaded bars, compared with the single bolts joint. This work will serve as the basis for the calibration of the corresponding finite element models, and the subsequent parametric study of this type of joints. [ABSTRACT FROM AUTHOR]

The development of efficient computational models for the accurate prediction of the state variables in general composite laminated shells undergoing uniform edge loadings is a major challenge, especially when stress concentration phenomena such as the free‐edge effect have to be considered. This paper addresses this issue by introducing a higher‐order semi‐analytical approach for the assessment of the three‐dimensional stress field in circular cylindrical composite shells with arbitrary layups subjected to a uniform bending moment. The presented semi‐analytical approach combines a closed‐form analytical plane‐strain solution with a higher‐order layerwise approach, and the governing equations are derived by virtue of the principle of minimum elastic potential. The resulting system of coupled ordinary differential equations is then solved by means of the state‐space approach and the free constants are determined by evaluating the boundary conditions at the traction‐free edges. A comparison of the numerical results of the presented semi‐analytical method with finite element simulations for various composite laminates indicates that the developed method works with high accuracy, although being extremely efficient in terms of computational resources. [ABSTRACT FROM AUTHOR]

Summary: A modular prefabricated four‐side connected composite (MPFC) shear wall that consists of a composite shear wall modular (CSWM) and steel frame boundary elements is proposed. First, the finite element model (FEM) of the MPFC shear wall, which considers a plastic‐damage constitutive model of both concrete and steel materials, is established based on the finite‐element software ABAQUS. Second, the FEM accuracy of the MPFC shear wall is verified by the experimental results of a modular prefabricated two‐sided connected buckling‐restrained (MTB) steel plate shear wall. Third, the seismic performance of the MPFC shear wall is investigated based on the verified FEM. The connection between the CSWM and side column is optimized. Finally, the initial stiffness calculation formula of the MPFC shear wall that considers the impact of that the thickness ratio between the connection steel plate (CSP) and inner steel plate (ISP) is deduced. The results show that the peak bearing capacity, initial stiffness, total energy, and total strain energy of the MPFC shear wall increased by 42.47%, 44.81%, 113.24%, and 58.97%, respectively, compared with those of the MTB steel plate shear wall. The compressive corner damage of the reinforcement concrete faceplate (RCF) of the MPFC shear wall with a side column and CSWM is connected by a middle steel plate is effectively improved. Compared with those of the MPFC shear wall in which the side column and CSWM are connected by bolts, the shearing force, axial force, and bending moment of the side column of the MPFC shear wall in which the side column and CSWM are connected by the middle steel plate are notably decreased by 25.32%, 26.08%, and 39.51%, respectively. The FEM results are compared with the formula calculation results to establish its accuracy in calculating the initial stiffness of the MPFC shear wall. [ABSTRACT FROM AUTHOR]

This paper investigates a novel variable‐grade prefabricated concrete (PC) slab with surrounding composited which has high prefabrication rate, sufficient installation rigidity, high on‐site construction efficiency, and good overall working performance. To improve the crack‐resistance performance of the transverse superposed surface and the overall working performance of the proposed novel PC slab, we optimize the position of variable‐grade and arrange it at the location where the bending moment is close to zero. We perform comparatively bending tests on three two‐span full‐scale slab strips that include boundary and intermediate beam‐slab joints to systematically investigate the flexural behavior of the proposed novel slab. The load versus deflection relationship, failure mode, distribution of cracks, development law of crack width and development of steel strain are comparatively studied. The test results confirm that the flexural behavior of the proposed novel PC slabs are similar and slightly better than that of the cast‐in‐place slab in general. No crack or slippage appears at the interface between the precast panel and the post‐pouring concrete. The connection method of L‐shaped anchorage rebars lap splicing in this study is cost‐effective, efficient, and reliable. Furthermore, we establish a finite element model and perform a parametric investigation on the proposed novel PC slab. Parametric simulations conclude that the increase of the strength of post‐pouring concrete and post‐pouring layer thickness can improve the bearing capacity of the proposed novel PC slabs. [ABSTRACT FROM AUTHOR]

The design of steel structures using elements with non‐uniform geometry is common in practice, both for aesthetic reasons and material optimization. Tapered beams are one of such examples which are widely used. This work is focused on the development of artificial neural networks to predict the critical moment of tapered beams subject to bending moments applied at the extremities since no analytical methods are currently available. Almost 70k data samples were calculated using the Finite Element Method (FEM) with shell elements and were used to train and validate the neural network models. The definition of the data samples was based on a random generation procedure with constrained geometric proportions to reduce their number. The accuracy of the developed model is further illustrated on some particular cases and against the FE results of other authors. Finally, it is demonstrated that neural network models are fast and reliable assessment tools that can be employed during the search of optimal structural solutions in the early design stages. [ABSTRACT FROM AUTHOR]

Transverse stiffeners are used in slender steel plate girders along the span to give web lateral support and increase plate girder shear resistance. According to several studies, transverse stiffeners are primarily engaged in out‐of‐plane bending to laterally limit the edges of the panel as it buckles, rather than axial compression to anchor the tension field. As a result, the axial loading defined in EN 1993‐1‐5 [1] for the design of transverse stiffeners, based on tension field action, is usually deemed to be substantially larger than that observed in laboratory testing and numerical simulations. The test results of six plate girders loaded to failure, with slender webs and two transverse stiffener geometries, are presented. FE‐models that accurately replicate the tests provide a thorough view of the plate girder behaviour. The stiffeners internal forces are evaluated during plate girder loading up to failure. The transverse stiffener internal forces attained by both models are compared. It is confirmed that both the axial compression and the bending moment in the intermediate transverse stiffeners are much lower than the values prescribed by the EN 1993‐1‐5 [1]. [ABSTRACT FROM AUTHOR]

Stainless steel became a relatively common material for load‐bearing structures in corrosive environment or when maintenance is difficult. The existing design rules cover all common cases. However, for some, the experimental or numerical data are very limited. This includes studies on welded I‐section beam‐columns. This paper presents a comprehensive experimental and numerical investigation into the structural performance of welded I‐section members loaded by compression and major axis bending moment. In total, eighteen test specimens were fabricated from grade EN 1.4301 austenitic stainless steel plates using two welding methods, namely conventional and laser welding. The experimental program on pin‐ended long beam‐columns is described in the paper. The loading eccentricities for the tests varied to provide a wide range of bending moment‐to‐axial load ratios. Nonlinear finite element models were developed in ABAQUS software and validated using the test results to simulate the beam‐column behaviour accurately. [ABSTRACT FROM AUTHOR]

The rising interest in the use of high strength steel (HSS) materials is justified by several advantages that they provide. In the field of construction, their benefits range from streamlined and elegant structures to lower CO2 emissions and energy consumption. High‐rise buildings and large span bridges can be designed with smaller foundations and less structural weight, since the application of HSS makes the design with slender steel sections possible. However, special attention should be given to the stability of the compressive members since the buckling resistance generally governs their design. The existing codes to evaluate the capacity of HSS columns and beam‐columns are based on rules from experimental tests related to normal strength steel (NSS) materials, which is responsible for inconsistencies. Therefore, this current work aims to present a numerical model created and validated to evaluate the major‐ and minor‐axis flexural buckling of HSS welded I‐section columns and the combined flexural and lateral‐torsional buckling of HSS welded I‐section beam‐columns. In the following, a parametric study is also conducted, in which different cross‐sections, normalized slenderness, steel grades (from S460 up), bending moment distributions and application of restraints are considered. Finally, a comparison between the European design rules and the resistances from the Finite Element model is led, evidencing the underrating expressed by the code with a level of safety even higher when superior steel grades are evaluated. [ABSTRACT FROM AUTHOR]

In practice, the elastic lateral‐torsional buckling of doubly symmetric I‐section steel members is analyzed assuming free warping at supports. However, welded stiffeners, bolted end‐plate connections or column base plates maintain elastically the opposite flange out‐of‐plane rotations and thus induce substantial warping restraints. This paper proposes analytical formulations for the evaluation of the elastic critical bending moment for lateral‐torsional buckling of beams taking into account warping restraints at supports. Assuming series of displacement and rotation fields containing one or two terms, the energy method permits to derive expressions of the critical bending moment under constant and linear distribution of the bending moment. A single expression of the warping coefficient kw is proposed whatever the shape of the bending moment diagram. The factor C1 can be conveniently calculated by multiplying two coefficients that depend on the shape of the bending moment diagram and on the warping restraint stiffness, respectively. Finite Elements analyses of beams with warping restraints at supports have been performed considering a beam element model developed with LTBeamN and a shell element model created in ANSYS. The analytical model is in good agreement with the numerical results obtained by the two finite element models. [ABSTRACT FROM AUTHOR]

Component based finite element design of steel joints This paper describes the principles of multi‐level finite element modelling for design of structural steel joints. The internal part of the design by finite elements is the validation and verification of the model and its results. For models by shell and solid elements is mesh sensitivity study. In component bases finite element design (CBFEB) are the steel plates considered by geometrically and materially non‐linear analysis (GMNA). Its resistance in elastoplastic stage is limited by strains. The behaviour of components, e. g. of bolts, anchor bolts, welds etc., is treated by introducing nonlinear springs representing its behaviour in term of initial stiffness, ultimate resistance and deformation capacity. To show this process a contribution is prepared, which summarises the history of achievements of finite element analyses (FEA) in structural steel connections. This paper shows differences of the research‐oriented and design‐oriented models and the currents trends in modelling of connection components. Both have their roles in advanced analyses. The validation and verification is demonstrated on model of block shear during potential failure mode for gusset plate connection and for the base plates loaded by bending moments to both axes. The summary shows the potential in design of elements including its connection. [ABSTRACT FROM AUTHOR]

Repair welding for recovery from local damage of a rail head surface is known to cause high residual stress and can accelerate fatigue in the rail. This study examines repair-welded rails by applying experimental and numerical approaches. In the former approach, two newly manufactured rail specimens and four repair-welded rail specimens with two different weld depths were prepared, and their residual stresses were measured with a sectioning method. In the latter approach, a finite element repair welding simulation model was developed that adopted a prescribed temperature method with a moving block as an input heat source, and the thermal strain caused by the volume change due to solid-state phase transformation was considered. Overall, the residual stresses correlated well between the experimental and numerical approaches. The measured high compressive residual stress of −290 MPa seems to be beneficial to prevent a crack initiation in the rail surface. [ABSTRACT FROM AUTHOR]

SUMMARY The leaning Minaret of Jam, one of the tallest in the world, was declared as the Afghanistan's first World Heritage Site by UNESCO in 2002. The global stability analysis of the tower against soil collapse is first evaluated in the present configuration, in the hypothesis of increasing bending moment at the base section, assuming elastic-perfect plastic behavior for the soil. Then, a finite element model is set up, which is used for the modal analysis and then for the seismic push-over analysis, based on both single and multi-modal approaches. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The present work addresses the lower bound limit analysis (or yield design) of thick plates under shear-bending interaction. Equilibrium finite elements are used to discretize the bending moment and the shear force fields. Different strength criteria, formulated in the five-dimensional space of bending moment and shear force, are considered, one of them taking into account the interaction between bending and shear resistances. The criteria are chosen to be sufficiently simple so that the resulting optimization problem can be formulated as a second-order cone programming problem (SOCP), which is solved by the dedicated solver MOSEK. The efficiency of the proposed finite element is illustrated by means of numerical examples on different plate geometries, for which the thin plate solutions as well as the pure shear solutions are accurately obtained as two different limit cases of the plate slenderness ratio. In particular, the proposed element exhibits a good behavior in the thin plate limit. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we study the numerical approximations of a gradient flow associated with a phase field bending elasticity model of a vesicle membrane with prescribed volume and surface area. A spatially semi-discrete scheme based on a mixed finite element formulation and a fully discrete in space and time scheme are analyzed. Optimal order error estimates are rigorously derived for these numerical schemes without any a priori assumption. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Different levels of model sophistication have recently emerged to support seismic risk assessment of bridges, but mostly at the expense of neglecting the influence of vertical ground motions (VGMs). In this paper, the influence of VGMs on bridge seismic response is presented and the results are compared with the case of horizontal-only excitations. An advanced finite element model that accounts for VGMs is first developed. Then, to investigate the effect of soil-structure interaction (SSI) including liquefaction potential, the same bridge with soil-foundation and fixed boundary conditions is also analyzed. Results show that the inclusion of the VGMs has a significant influence on the seismic response, especially for the axial force in columns, normal force of bearings, and the vertical deck bending moments. However, VGMs do not have as much influence on the seismic demand of the pile cap displacements or pile maximum axial forces. Also, the significant fluctuation of the column axial force can reduce its shear and flexural capacity, and a heightened reversal of flexural effects may induce damage in the deck. In addition, relative to the fixed base case, SSI effects tend to reduce response quantities for certain ground motions while increasing demands for others. This phenomenon is explained as a function of the frequency content of the ground motions, the shift in natural vertical periods, and the VGM spectral accelerations at higher modes. Moreover, the mechanisms of liquefaction are isolated relative to SSI effects in nonliquefiable soils, revealing the influence of liquefaction on bridge response under VGMs. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Gründungspfähle können nicht nur zur Abtragung von vertikalen, sondern gleichzeitig auch von horizontalen Lasten in den Baugrund herangezogen werden. Eine derartige kombinierte Belastung führt allerdings zu Beeinflussungen im vertikalen und horizontalen Tragverhalten, welche in der derzeitigen Bemessungspraxis keine Berücksichtigung finden. Zur Identifikation und Quantifizierung dieser Interaktionseffekte wurden umfangreiche Untersuchungen mit der Finite-Elemente-Methode durchgeführt. Im vorliegenden Beitrag werden Ergebnisse dieser Untersuchungen für Pfähle in nichtbindigen Böden unter dränierten und in bindigen Böden unter undränierten Belastungsbedingungen dargestellt. Dabei wird auch der Einfluss eines Biegemoments am Pfahlkopf oder einer Pfahlkopfeinspannung behandelt. Es ergeben sich komplexe Interaktionseffekte, welche mittels Interaktionsdiagrammen dargestellt werden können. Schwerpunktmäßig werden Interaktionseffekte hinsichtlich Pfahlkopfverformungen und Pfahlgrenzlasten betrachtet. Abschließend wird aber auch die Veränderung der Biegebeanspruchung des Pfahls durch Interaktionseffekte untersucht. Investigations on the interaction relationships for piles under combined loading in cohesive and non-cohesive soils: Foundation piles are normally and favorably used for the transfer of vertical loads into the subsoil. However, in many fields of application piles are used simultaneously for the transfer of horizontal load. This so-called combined loading affects the vertical and horizontal load bearing behavior. In current engineering practice, these interaction effects are not taken into account. For the identification and quantification of the influences a comprehensive investigation based on the Finite Element Method was carried out. The paper in hand presents results of these investigations considering piles in non-cohesive soils regarding drained loading and piles in cohesive soils regarding undrained loading conditions. Thereby the influence of a moment and a rotational spring at the pile head is taken into account. It can be shown, that the combined loading leads to complex interaction effects which can be presented in terms of interaction diagrams. The main focus of the investigation is set on the interaction effects on ultimate loads and pile head displacements. Additionally the influence of combined loading on the pile bending moments is investigated. [ABSTRACT FROM AUTHOR]

The present study concerns the analysis of bending of plates and shells subjected to various boundary conditions and load. Bending stress intensity factors for plates containing through-thickness crack under edge bending load are evaluated. To accomplish this task, hierarchical degenerated plate/shell and crack-tip singular plate/shell elements were developed. The hierarchical degenerated plate shell element has four corner nodes, four mid-side nodes and one central node on the mid-surface of the shell geometry with five degrees of freedom at each node. p-Version shape functions up to order seven were used for defining the displacement field. Enriching the displacement field with the asymptotic displacement field near the crack tip, a crack-tip singular plate/shell element was developed. Some benchmark problems were analyzed and compared. Analyses were performed to obtain the stress intensity factors of plate with through-thickness crack using singular hierarchical degenerated plate/shell element around the crack tip. Numerical results obtained from the present element formulations are compared with analytical/numerical solutions available from literature. It is inferred that numerical results are in good agreement with the benchmark plate and shell problems. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

It is difficult to measure accurately the piezoelectric constant, d33, of either a thin or thick film on a substrate, because piezoelectric deformation of a film is small. The measured value of d33 for the film is often smaller than the value of d33 for the bulk material. This is partly because of bending of the sample and side clamping of the film. However, we used finite element method (FEM) to simulate common experimental conditions and show that inner local deformation was more significant than either bending or side clamping. Using our FEM results, we propose optimum conditions for making unbiased d33 measurements. [ABSTRACT FROM AUTHOR]

The combined hybrid finite element method for plate bending problems allows arbitrary combinations of deflection interpolation and bending moment approximations. A novel expression of the approach discloses the energy-adjustable mechanism of the hybrid variational principle to enhance accuracy and stability of displacement-based finite element models. For a given displacement approximation, appropriate choices of the bending moment mode and the combination parameter α ∈ (0,1) can lead to accurate energy approximation which generally yields numerically high accuracy of the displacement and bending moment approximations. By virtue of this mechanism, improvement of Zienkiewicz's triangular plate-element is discussed. The deflection is approximated by Zienkiewicz incomplete cubic interpolation. And three kinds of bending moments approximations are considered: a 3-parameter constant mode, a 5-parameter incomplete linear mode, and a 9-parameter linear mode. Since the parameters of the assumed bending moments modes can be eliminated at an element level, the computational cost of the combined hybrid counterparts of Zienkiewicz's triangle are as same as that of Zienkiewicz's triangle. Numerical experiments show that the combined hybrid versions can attain high accuracy at coarse meshes. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In Part I of this paper, using the modal superposition method, equations for dynamic SIF calculations are derived for an arbitrary linear model of an impact bend specimen. In this paper (Part II), modal parameters and other data which are necessary for the DSIF determination have been calculated for three types of specimen model: the Euler–Bernoulli beam model, and two- (2D) and three-dimensional (3D) solid models. For the latter two cases, calculations were performed using the finite element program ADINA. Results for the 2D model of the specimen were fitted by polynomials for a wide range of specimen geometry parameters and Poisson’s ratio values. Considerable differences were observed between the beam model parameters and the 2D or 3D ones. The differences in results for the 2D and 3D models are small and mainly connected with non-uniformity of the SIF distribution along the front of a through-crack in the 3D solid. Results of processing one- and three-point bend test data reported in the literature are presented. Numerical DSIF values are compared with the experimental ones. [ABSTRACT FROM AUTHOR]

A general method for the investigation of buckling of reinforced concrete beams subjected to axial loads and bending moments is presented. The beams ate subdivided into finite segments or line elements. The geometrical and mechanical properties of the cross-sections are described by means of the finite element method. The constitutive relationships of the materials employed may be of any type, as well as the location of the steel reinforcements. A computer program has been written and implemented on a microcomputer for practical use. Several examples show the capability of the presented approach. [ABSTRACT FROM AUTHOR]