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Reinforcement soil slope with pile penetration is a new load bearing structure, which has a complex working mechanism, but few studies have been carried out. This paper aims to investigate the stability characteristics of this structure using model tests. The study investigates the lateral displacement and-pile bending moment caused by vertical loads and evaluates the influence of different factors, including the structure type (such as pile, cap of pile, and reinforcement material), number of reinforcing layers, spacing of reinforcement material, pile length, and slope rate on the load-carrying capacity of the pile penetration fill-reinforced load-bearing structure. The findings suggest that within a certain range, increasing the pile length and number of reinforcing layers, the limiting effect of the pile on the lateral displacement in the middle and at the bottom of the slope of the pile-penetrating reinforced structure is enhanced, which can reduce the extreme value of the bending moment and make the distribution of the bending moment of the pile more reasonable. The lateral limiting effect on the soil body can be maximized by appropriate reinforcement spacing. Within a certain range, the slope rate is reduced, which can reduce the extreme value of the bending moment, make the bending moment distribution of the pile more reasonable, and avoid the phenomenon of the localized force concentration of the pile. [ABSTRACT FROM AUTHOR]

Preclinical and clinical research on two-piece zirconia implants are warranted. Therefore, we evaluated the in vitro fracture resistance of such a zirconia oral implant system. The present study comprised 32 two-piece zirconia implants and abutments attached to the implants using a titanium (n = 16) or a zirconia abutment screw (n = 16). Both groups were subdivided (n = 8): group T-0 comprised implants with a titanium abutment screw and no artificial loading; group T-HL was the titanium screw group exposed to hydro-thermomechanical loading in a chewing simulator; group Z-0 was the zirconia abutment screw group with no artificial loading; and group Z-HL comprised the zirconia screw group with hydro-thermomechanical loading. Groups T-HL and Z-HL were loaded with 98 N and aged in 85 °C hot water for 107 chewing cycles. All samples were loaded to fracture. Kruskal–Wallis tests were executed to assess the loading/bending moment group differences. The significance level was established at a probability of 0.05. During the artificial loading, there was a single occurrence of an implant fracture. The mean fracture resistances measured in a universal testing machine were 749 N for group T-0, 828 N for group Z-0, 652 N for group T-HL, and 826 N for group Z-HL. The corresponding bending moments were as follows: group T-0, 411 Ncm; group Z-0, 452 Ncm; group T-HL, 356 Ncm; and group Z-HL, 456 Ncm. There were no statistically significant differences found between the experimental groups. Therefore, the conclusion was that loading and aging did not diminish the fracture resistance of the evaluated implant system. [ABSTRACT FROM AUTHOR]

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Copyright of Railway Investigation & Surveying is the property of Railway Investigation & Surveying Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A problem of stability of cylindrical shells made of a composite material is solved, taking into account the momentum and nonlinearity of their subcritical stress–strain state. In geometric terms, the nonlinear stability problem is solved by finite element methods and the Newton–Kantorovich linearization. Critical loads are determined in the process of solving a nonlinear problem using the Sylvester criterion. The study is carried out using the finite elements of composite cylindrical shells of natural curvature developed on the basis of the Timoshenko hypothesis, with rigid displacements being explicitly distinguished within their displacement approximation, which significantly affects the convergence of the solution. The stability of a circular cylindrical shell made of a polymer composite material under combined loading by torque, bending moment, and internal pressure is investigated. This study also touches upon the influence of the stacking method of monolayers, deformation nonlinearity, and internal pressure on critical loads at which shell buckling is observed. [ABSTRACT FROM AUTHOR]

In United States practice, the strength of composite columns is assessed with available strengths that are computed considering member length effects. This approach has advantages; however, developing axial compression‐bending moment interaction diagrams that account for member length effects is not a straightforward task. Current methods result in unconservative error for highly slender members with large bending moments. While it is theoretically possible to develop more accurate interaction diagrams, a simpler approach, and one which more directly addresses the cause of the unconservative error, is to improve the accuracy of the stiffness used in the elastic analyses to determine required strengths. In this work, new recommendations are developed for this stiffness for steel‐concrete composite columns. The recommended stiffness is a function of required axial compression and bending moment, which increases accuracy and enables improved available strength calculations, resulting in more efficient designs. [ABSTRACT FROM AUTHOR]

A finite element formulation of solving the stability problems for composite cylindrical shells is presented, taking into account the momentness and nonlinearity of their subcritical stress-strain state. The stability of a circular cylindrical shell made of a polymer composite material under combined loading by torsion and bending moments is investigated. The influence of the methods of laying monolayers, the nonlinearity of deformation on the critical loads of the shell stability loss and the weight efficiency of composite shells in comparison with metallic ones is clarified. [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]

Purpose: Surgical treatment of thoracolumbar A3-fractures usually comprises posterior fixation—in neutral position or distraction—potentially followed by subsequent anterior support. We hypothesized that additional posterior compression in circumferential stabilization may increase stability by locking the facets, and better restore the sagittal profile. Methods: Burst fractures Type A3 were created in six fresh frozen cadaver spine segments (T12–L2). Testing was performed in a custom-made spinal loading simulator. Loads were applied as pure bending moments of ± 3.75 Nm in all six movement axes. We checked range of motion, neutral zone and Cobb's angle over the injured/treated segment within the following conditions: Intact, fractured, instrumented in neutral alignment, instrumented in distraction, with cage left in posterior distraction, with cage with posterior compression. Results: We found that both types of instrumentation with cage stabilized the segment compared to the fractured state in all motion planes. For flexion/extension and lateral bending, flexibility was decreased even compared to the intact state, however, not in axial rotation, being the most critical movement axis. Additional posterior compression in the presence of a cage significantly decreased flexibility in axial rotation, thus achieving stability comparable to the intact state even in this movement axis. In addition, posterior compression with cage significantly increased lordosis compared to the distracted state. Conclusion: Among different surgical modifications tested, circumferential fixation with final posterior compression as the last step resulted in superior stability and improved sagittal alignment. Thus, posterior compression as the last step is recommended in these pathologies. [ABSTRACT FROM AUTHOR]

This paper focuses on predicting regenerative chatter onset conditions in machining stainless steel. To establish a credible regenerative chatter model, the mass and flexibility of the workpiece are considered and modeled for lateral deformations using the Timoshenko beam theory; the motion of the cutting tool is modeled as a mass-spring-damper system. The varying natural frequencies and dynamic stiffness of the tool-workpiece system during the cutting process are simulated to study the influence of tool position and material loss. The Johnson-Cook (JC) material model is firstly used as the cutting force model for AISI 316L in chatter analysis to understand the influence of tool geometry and cutting parameters. The effect of dynamic bending moment caused by the axial component of the cutting force is also considered for the first time. Simulations were conducted to understand the influence of tool geometry and cutting parameters on chatter onset conditions. Experiments were carried out to verify the proposed approach on three types of cutting tools. [ABSTRACT FROM AUTHOR]

Prior investigations have revealed that the stress characteristics of columns at different locations beneath an embankment vary. A failed column releases stress and causes significant increases in the stresses within neighbouring columns, possibly leading to progressive failure of adjacent columns and global failure of the embankment. Prior studies have presented insights into the progressive failure of column-supported embankments. However, limited insight has been provided into the progressive failure mechanism of geosynthetic-reinforced and rigid column-supported embankments. In this technical note, the effects of geosynthetic reinforcement on progressive failure are numerically analysed. A comparison of the progressive failure of rigid columns with and without geosynthetic reinforcement is first conducted. The restraining effects of geosynthetics on progressive failure of the columns and the influence of geosynthetic tensile stiffness on embankment stability are analysed. The results reveal that progressive failure is primarily governed by the distribution of the bending moment and the axial force within the columns. To further investigate the contribution of geosynthetics to resisting progressive failure of rigid columns, the internal forces in the columns and tensile strains in the geosynthetics are discussed. [ABSTRACT FROM AUTHOR]

In practical applications, asymmetric sandwich panels with tapered and junction regions are frequently used. Under uniaxial compressions, asymmetric sandwich panels are collapsed with complex failure mechanism, and its mechanical behaviour is affected by tapered regions. For structure safety consideration, it is necessary to systematically investigate the stability and damage behavior of full-scaled asymmetric sandwich panels under uniaxial compression experimentally and numerically. For comparison, symmetric sandwich panels were also studied. Quasi-static compression tests and numerical modeling were conducted. Experimental data were sufficiently recorded and carefully analyzed. Meanwhile a nonlinear finite element model was advanced for evaluating stability and predicting failure behaviours and load-bearing capacity of test specimen. Comparisons between numerical predictions and experimental measurements showed that a good agreement was achieved. The tapered region had significant influence on stability behavior and load-bearing capacity. It intensified the asymmetry and introduced additional bending moments into asymmetric sandwich panels and thus caused early local buckling. Thicker core thickness enhanced the structural stiffness and load-bearing capacity. Large amounts of matrix cracking, fibre push-out and core-skin delamination were captured in asymmetric sandwich panels. Overall, buckling occurred in symmetric sandwich panels instead of local buckling in asymmetric sandwich panels, and brittle fibre breakage dominated the failure. [ABSTRACT FROM AUTHOR]

According to Eurocode, the computation of bending strength for steel cantilever beams is a straightforward process. The approach is based on an Ayrton‐Perry formula adaptation of buckling curves for steel members in compression, which involves the computation of an elastic critical buckling load for considering the instability. NCCI documents offer a simplified formula to determine the critical bending moment for cantilevers beams with symmetric cross‐section. Besides the NCCI recommendations, other approaches, e.g. research literature or Finite‐Element‐Analysis, may be employed to determine critical buckling loads. However, in certain cases they render different results. Present paper summarizes and compares the abovementioned analytical and numerical approaches for determining critical loads and it exemplarily analyses corresponding cantilever beam capacities using numerical approaches based on plastic zones theory (GMNIA). [ABSTRACT FROM AUTHOR]

This paper studies the critical issue of thin-walled beams with laterally fixed ends. The method for defining the formulae of twist moment for the beams subjected to combined loads was elucidated. Based on this, the governing differential equations of the beam were developed. The procedure for determining the critical state of the beam by the energy method was presented. With this procedure, the critical state of the beam concerned under three types of loadings such as axial force F , bending moment M and distributed load q (or concentrated load P) was examined deliberately. The outcomes were presented in explicit closed-form, which can be illustrated in 2D and 3D graphs. Also, the analytical solution obtained was in agreement with the numerical one obtained by the commercial software NX Nastran. Furthermore, the analytical solutions were applied straightforwardly to explore the stability and design optimization of the tooth-blade for the new frame-type saw machine under an eccentric load. The result can also be promisingly used to study problems of thin-walled beams with laterally fixed ends subjected to other types of loads. [ABSTRACT FROM AUTHOR]

Post-earthquake fires occur after earthquakes and have commonly been encountered throughout history. The fires are particularly deadly and threaten the stability of buildings as possible structural damages caused by seismic loading can be exacerbated by temperature loading. Moreover, damage to insulation during seismic events causes accelerated heating in portions of members experiencing large bending moments. A method is proposed for evaluating the stability and deflection of a semi-braced structural steel frame subjected to post-earthquake fire conditions. The proposed method adopts the interstorey drift concept and assumes that each member in the frame has three segments of differing temperatures, modelling the damage to insulation near moment connections and/or midspans of flexural members. The method is presented in the form of a deflection equation, which indicates the instability of the frame when the lateral stiffness in the denominator reaches zero. The proposed method is demonstrated via a numerical example, and the duration of fire until the given frame becomes unstable is computed, with the results validated via finite element analysis. The degrees of structural and insulation damage are also varied in parametric analyses, showing that the lateral stiffness and critical temperatures of a frame subjected to post-earthquake conditions can be severely reduced. [ABSTRACT FROM AUTHOR]

In this work, the problem of the propagation of a deflection wave in a Bernoulli–Euler beam during motion of the thermal source is solved, and the influence of the thermal bending moment and longitudinal force is analyzed. It has been established that the concentrated bending moment moving together with the heated region boundary determines the mode of the deflection wave, but cannot lead to a significant increase in its amplitude. It is shown that the average longitudinal compressive force increases linearly with time during uniform motion of the heating source. For the initial parameters, such as the source motion velocity and the temperature, the values enabling a loss of stability and a significant increase in deflection have been found. [ABSTRACT FROM AUTHOR]

This paper focuses on grasping and manipulation of an object by two one-link flexible arms. By taking rolling constraints between the arm tip and the grasped object, the arms have the potential to grasp and manipulate an object at the same time. To realize grasping and manipulation by two flexible arms, a boundary controller is derived from a Lyapunov functional related to the total energy of a dynamic model described by a hybrid partial differential equation-ordinary differential equation (PDE-ODE) model. The derived controller consists of the bending moment at the root of the arm, the rotational angle, and the angular velocity of the motor. In particular, the controller does not need the feedback of the information of the grasped object, and thus, it is easy to implement the controller. Further, it is shown that the derived controller realizes stable grasping and orientation control of the object as well as vibration control of the arms. Finally, experiments and numerical simulations are conducted to investigate the validity of the derived boundary controller. [ABSTRACT FROM AUTHOR]

The non-linear in-plane stability of pin-ended circular shallow arches is analytically investigated. The arches are made of functionally graded material with the material properties varying along the thickness. The external load is a radial concentrated force in the direct vicinity of the crown. The effect of the bending moment on the membrane strain is included in the one-dimensional model. The equations of the pre-buckling and buckled equilibrium are derived using the principle of minimum potential energy. Analytical solutions are found for both bifurcation and limit point buckling. Extensive parametric studies are performed to find and demonstrate the effect of various parameters on the buckling load and in-plane behaviour. It is found that most arches have multiple stable and unstable equilibria and the number of equilibria increases with the modified slenderness. When the load is applied exactly at the crown, the lowest buckling load is related to bifurcation buckling for most geometries and material compositions but when there is a small imperfection in the load position, only limit point buckling is possible. The position of the load can have quite a huge influence on the buckling load, therefore pin-ended functionally graded shallow arches are sensitive to small imperfections in the load position. • The sensitivity of shallow arches to small loading imperfections is studied. • The arches are made of transversely FGM. • The effect of various geometrical-material parameters is investigated analytically. • Results show that the load position has huge influence on the buckling behaviour. [ABSTRACT FROM AUTHOR]

Rigid columns penetrating a firm underlying stratum have often been used to enhance the stability and improve the settlement of embankments over soft ground. Furthermore, an inclined underlying stratum is commonly encountered in engineering practice. This investigation experimentally and numerically studies the performance of embankments over soft ground reinforced by rigid columns with various embedment depths. In centrifuge tests, a tilting failure occurs for columns with an embedment depth Le of 2D (D is the diameter of columns), whereas the embankments remain stable for Le of 7D. This result indicates that the inclined underlying stratum weakens the restraint effect at the column base and that a greater embedment depth is required to ensure the stability of embankments. Parametric studies numerically reveal that there exists a critical embedment depth, which represents a shift in the failure mechanism. The optimum column layout is determined based on the contributions of columns in different locations beneath an embankment. Finally, the influence of the embedment depth on the distribution of the bending moment of the columns and the soil reaction are discussed. [ABSTRACT FROM AUTHOR]

Safety aspects in the proof of stability of angle profiles using the second order theory Angle profiles compared to other cross‐sectional shapes have small second moments of inertia. These are used therefore predominantly in lattice constructions for example in towers. The installation is constructively unproblematic. Beams of the diagonal bracing can be joined with the corner beam by bolts. Often there are no joining plates necessary. The stress in the profiles is often caused by axial forces. The tension proof uses an effective net area. In case of axial force stress without additional bending moments the pressure proof can use the first order theory or the second order theory. In case of compressive axial force with additional bending moments the pressure proof has to use the second order theory. DIN EN 1993‐1‐1 accepts an interaction proof using the first order theory only for double symmetric cross‐sectional shapes. The repealed DIN 18800‐2 accepted an interaction proof using the first order theory without constraints. This article compares utilisation rates and safety indices for a pressure stressed example beam using the first order theory and the second order theory. Finally it examines the effect of an additional bending moment caused by a force vertical to the axis on the safety index. [ABSTRACT FROM AUTHOR]

We consider the Timoshenko beam equation with locally distributed Kelvin{Voigt damping; i.e., the damping; is effective only in a part of the spatial domain for both shear stress and bending moment. We prove eventual differentiability, exponential and polynomial stability of the associated semigroup under some smoothness condition on the damping coefficient functions, particularly, at the interface of the damped and undamped region. [ABSTRACT FROM AUTHOR]

This paper discusses a thermoelastic Timoshenko system with viscoelastic damping acting on the shear force, and heat conduction given via Maxwell-Cattaneo’s law (usually called second sound) on the bending moment. We establish a general decay estimate for the solution energy. The exponential and polynomial decay results are only special cases of the present work. The obtained result shows that the viscoelastic damping on the shear force and the thermal damping on the bending moment are strong enough to stabilize the system without any additional restrictions like “the equal-wave of speed propagation” or “the stability number” conditions which are usually associated with similar problems [ABSTRACT FROM AUTHOR]

For compression members with primarily axial forces, steel angles with bolted connections are often used. Due to the eccentric connection on only one leg additional bending moments are acting on the member, leading to a complex load carrying behaviour with flexural and/or lateral torsional buckling phenomena. The paper mainly focuses on the presentation of the influence of realistic end support conditions at the gusset plates on the member capacity in compression. In the first part of the paper, about 300 existing test results for steel angles in compression with bolted connections are prepared in such a way that they can be compared with different design rules. This was achieved through the common representation of all test results as a function of the normalized slenderness λ ¯ v about the weak axis. In the second part, systematic numerical calculations are conducted for limit cases of the stiffness of the boundary condition of the load-introducing gusset plates (rigid/hinged). The results are also presented in dependency of the relative slenderness λ ¯ v . The consolidation of all tests and numerical results shows (besides the well-known difference between one-bolt and two-bolt connections) a very high influence of the end support of the gusset plate. [ABSTRACT FROM AUTHOR]

This paper presents a design proposal for the out-of-plane buckling resistance of prismatic beam-columns subject to axial compression and uniaxial major-axis bending that was developed based on the well-known Ayrton-Perry format. Firstly, the relevant theoretical background is summarized, closely following the theoretical derivation performed by Szalai and Papp (2010). Secondly, the required transformations for the engineering application of the design procedure are detailed and extended to arbitrary bending moment distributions. Appropriate generalized initial imperfection factors for the out-of-plane buckling of beam-columns are defined so as to achieving complete consistency across the stability verifications for columns, beams and beam-columns. The proposed procedure is subsequently validated against a large set of advanced numerical simulations. A good agreement was found between the numerical results and the estimates provided by the proposed design procedure, both in terms of the overall trend and the specific quantitative results. Based on a statistical assessment, the comparison with the interaction expression of Eurocode 3 (2005) (method 2) showed that this proposal slightly outperforms the Eurocode procedure, both in terms of average values and dispersion of results. [ABSTRACT FROM AUTHOR]

In the field of structural engineering the design of cost efficient structures is highly important. This led to the development of cold-formed steel structures (CFS). An advanced CFS structure is introduced in this paper, which uses a special type of polystyrene aggregate concrete (PAC) as bracing material. This material has beneficial insulating and fire protection properties, which makes it a reasonable choice for residential buildings. An experimental program was performed, to gain information on the flexural and axial behaviour of PAC-braced CFS elements and panels. Both unbraced and braced members were tested to gain information on increment of load-bearing capacity. Several different element sizes were used to be able to investigate the different stability failure modes (i.e. local, distortional and global). Results showed that PAC was able to restrain the global and distortional buckling modes of steel elements, thus providing “full bracing” in most practical cases. These results are introduced in two papers (Part I and II), detailing the failure modes, load increments and the effect of composite action. In this paper – Part I – the background and the results of bending tests are presented, and the experiments on the compression elements are detailed in Part II [1] . [ABSTRACT FROM AUTHOR]

This paper focuses on calculating the load level and the ultimate state of steel plane frames consisting of straight slender nonprismatic rods. The plastic behavior is modeled in the theory of second order with a step-by-step method that only considers the bending moment effect and leads to the formulation of sudden concentrated plastic hinge. The plastic process results in the loss of stiffness, leading to lower strength of the section of the structure as a whole. Therefore, it also affects the stability of the whole, which is checked during the loading process each time a new plastic hinge is formed by the equations of stability. Thus, it is well known that it is necessary to suggest the static equilibrium in the deformed or actual configuration. The plastic design allows saving materials as well as ensuring the safety, functionality, and durability of the structure. In addition to the static analysis, the ability to evaluate the frequencies and the associated vibration modes is included. All this enables a tracking process of the structure response for each load state until the collapse. [ABSTRACT FROM AUTHOR]

Open cross sections are used in structural applications to resist bending moments. The buckling length specified in the current standards and specifications was firstly defined by Nethercot [13] and covered only doubly symmetric I-sections. In this research, a theoretical program was performed to study the elastic and inelastic behavior of overhanging C-section beams bent about the major axis. A finite element model, correlated well with experimental results, was used in this study to perform a parametric study. Nonlinear geometrical and material analyses were incorporated in the model. Four types of lateral supports at the tip of the overhanging beams were studied. The effect of different boundary conditions at the root (intermediate support) of the overhanging beams was studied. Only concentrated load at the tip was considered. Three different loading positions, with respect to cross-section height, were studied. Based on the parametric study, proposed design model, taking into consideration the effect of different parameters on the ultimate moment capacity of such beams, was presented. Modified effective buckling lengths of such beams were compared to those suggested by SSRC Guide [8], which were incorporated in most current standards and specifications. This comparison showed that the ultimate moment capacities of such beams computed according to AISC Specification [1], BS5950 [3], Eurocode3 [7] and ECP [5] varied from overconservative up to 85% to unconservative up to 15%, depending on the overhanging length, back span length, boundary conditions and the load location along the beam depth. [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]

Substantiated the influence of longitudinal forces on the stress state stretched-bent wooden elements of the building frame and update their bearing capacity. [ABSTRACT FROM AUTHOR]

Abstract: EC3 provides several methodologies for the stability verification of members and frames. Regarding tapered beam-columns, in EC3-1-1, the safety verification may be performed by the General Method. However, application of this method has been shown not to be reliable. On the other hand, the interaction formulae in EC3-1-1 were specifically calibrated for stability verification of prismatic members. Recently, Ayrton–Perry based proposals for the stability verification of web-tapered columns and beams, in line with the Eurocode principles for the stability verification of prismatic members, have shown to lead to a substantial increase of accuracy and to provide mechanical consistency relatively to application of the General Method. Such methodologies may be further applied to the existing interaction formulae. It is the purpose of this paper to propose a verification procedure for the stability verification of web-tapered beam-columns under in-plane loading by adaptation of the interaction formulae in EC3-1-1, validated through extensive FEM numerical simulations covering several combinations of bending moment about strong axis, My , and axial force, N, and levels of taper. [Copyright &y& Elsevier]

Abstract: In this paper, the elastic stability of slender columns weakened by multiple edge cracks subjected to concentrated loads applied at the ends is presented. The analysis is carried out by using the minimum potential energy technique. The cracked section is modeled by a massless rotational spring which causes discontinuity in the rotations due to bending moments. In the present work, columns with various end conditions such as pinned ends, fixed ends, fixed-pinned ends and fixed-free ends are studied. The analysis depends on the assumed deflection function, which satisfies exactly the end conditions. The buckling loads for each case of end conditions for a column with arbitrary number of cracks along the column length are given in simple and practical equations which also gave accurate results. A comparison between the results of the present analysis and that of some previous studies shows the accuracy and the simplicity of the developed method to find the critical load in such cases. [Copyright &y& Elsevier]

To study the stability of aluminum alloy columns (AACs) under an axial compressive load and a bending moment at high temperatures, 30 AACs under eccentric compression were tested in a high-temperature environment. All the specimens were H-shaped, and the material was 6082-T6 aluminum alloy. After the test, it was found that all the AACs suffered bending and torsional instability. ABAQUS software was used to establish a finite element (FE) model. The accuracy of the FE model was validated by comparing the experimental results with those of the FE model. A design formula for the stability capacity of AACs under eccentric compression at high temperatures was proposed. To study the reliability of the formula, 2520 FE models were established at five different temperatures with two different cross sections. The results showed that the formula for the stability bearing capacity of AACs under eccentric compression at high temperatures was safe and reliable. Finally, the test results were compared with the results obtained using a fitting formula and European standard EC9. The results of EC9 were found to be more conservative, while the results of the fitting formula were closer to the experimental data. • 30 6082-T6 aluminum columns under eccentric compression were tested at high temperatures. • Capacity formula for aluminum columns under eccentric compression at high temperatures was proposed. • 2520 FE models were established at five different temperatures to verify the proposed formula. • The results of the fitting formula were closer to the experimental data compared with EC9. [ABSTRACT FROM AUTHOR]

Abstract: Eurocode 3 provides several methods for the stability verification of members and frames. However, several inconsistencies and difficulties have been noticed in the case of non-uniform members regarding in what concerns stability verification. In this paper, the case of web-tapered beams is studied. In a first step, available methods for stability verification of web-tapered beams are discussed. A second order analytical model based on an Ayrton–Perry approach is then derived for the case of tapered beams with uniform bending moment and further extended to other bending moment distributions. Several consistent simplifications are carried out in order to build a simple but coherent design model for the stability verification of tapered beams subject to linear bending moment distributions and to parabolic bending moment. More than 3000 numerical simulations are carried out for calibration and analysis of the results. Throughout the paper, specific issues such as the presence of shear or the codified imperfections for welded cross-sections are brought in and taken into account. Finally, it is noted that the proposed model is consistent with recently proposed design models for the stability verification of prismatic beams. [Copyright &y& Elsevier]

Abstract: An analytical method that evaluates the stability and induced bending moments and second-order deflections in slender prismatic columns with initial geometric imperfections (i.e., initial curvature, out-of-plumb, and axial load eccentricities) and non-linear semirigid connections subjected to axial load at both ends and lateral load at the top end is presented. The proposed method is based on the classical Euler–Bernoulli theory for slender columns with sidesway uninhibited, partially inhibited, and totally inhibited. The effects of shear and axial deformations along the member are not included. The proposed model is limited to prismatic columns subjected to eccentric axial loads at both ends and a lateral load at the top end, causing bending about one of the principal axes with inelastic behavior taking place at the end rotational connections only. The three-parameter power model developed by Richard and Abbot is adopted to represent the non-linear moment-rotation behavior of the end connections. The effects of initial imperfections and non-linear semirigid connections are condensed into the proposed equations. These effects must be taken into account in the analysis and design of slender columns subjected to high axial loads, particularly when sidesway between their ends is uninhibited or partially inhibited because of possible excessive lateral sway and failure by lateral collapse. The proposed method can be used by researchers and structural engineers to investigate the effects of initial imperfections and non-linear semirigid connections on the inelastic stability and non-linear behavior of columns under heavy eccentric axial loads, including cases with relatively large lateral deflections. Five classical column cases and sensitivity studies are presented and discussed to show the effects of initial imperfections, lateral bracing and semirigid inelastic connections and the effectiveness and accuracy of the proposed iterative method on the non-linear second-order behavior and inelastic stability of prismatic columns. [Copyright &y& Elsevier]

Abstract: The verification of the stability of frames or their parts carried out considering imperfections and second order effects accounted for by global analysis. The shape of the elastic critical buckling mode r/ CT (x) of the structure is applied as a unique global and local initial (“ugli”) imperfection t] U gli(x) =t]i n it(x) with amplitude t]Q U gU m proposed by Professor Chladny. Detailed description of the procedure of iterative calculation based on Chladny''s method but different from it may be found in . The graphical interpretation of the results proposed by the authors and numerical example for two-hinged portal frame with uniform cross-sections and uniform axial compression forces based on are presented. [Copyright &y& Elsevier]

A method is introduced to quickly measure the total bending moment and shear force for any ship due to soft groundings. Therefore, the ship design program e4 and the FE program ANSYS are used and coupled. The grounding points or areas are combined with different load cases. These combinations are being considered for different water levels due to tide. The critical combinations that lead to an exceedance of the maximal allowable bending moment and shear force according to classification societies can be determined. The ship is modelled as a rigid body and the sliding phase is not considered. The presented method is verified through existing formulas. Also, the acting forces and moments as well as the sections at risk can be identified. The method is exemplary applied for a container vessel. [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, linear buckling analyses of plates with longitudinal stiffeners having various shapes and positions and subjected to axial force, in-plane bending and shear are developed. The aim is to give some new practical insights about the shape and optimum position of longitudinal stiffener in webs when axial force, bending moment and shear act. By means of a comprehensive numerical investigation, some practical issues for buckling phenomena in stiffened plates, taking into account (a) dimensions and shape (square and rectangular) of the plate, (b) dimensions and shape of the stiffener (with open and closed cross-sections), (c) location of the stiffener, and (d) load configuration (uniform compression, pure bending, combinations of axial compression and bending, and shear) are developed. [ABSTRACT FROM AUTHOR]

The assessment of the design buckling resistance of single members is usually based either directly on the elastic buckling resistance of the member or indirectly on its non-dimensional slenderness computed from the elastic buckling resistance. Specifically, Eurocode 3 buckling curves define the buckling reduction factors as a function of non-dimensional slenderness and, according to EC3 "General Method", these curves may also be used for non-uniform members. In this context, a new procedure will be presented for the computation of the elastic critical moment of tapered members. As is well known, the elastic critical moment strongly depends on both the bending moment diagram and end support restrictions. For uniform members, elastic critical moments may be computed using a relatively simple formula in which the bending moment distribution is taken into account by an equivalent uniform moment factor, and the end support restrictions are introduced through the buckling length. Unfortunately, this formula has not been extended to tapered members and, as a consequence, the elastic critical moment for tapered beams must be obtained using numerical methods such as the finite element methods. Based on a comprehensive parametric study for the elastic critical moment of tapered beams with different moment diagrams, this paper offers a new procedure, called the Equivalent Moment Approach, for the substitution of a tapered beam with any moment diagram by an equivalent uniform beam. One advantage of the present procedure is that closed form expressions valid for uniform beam can be generalized and used for tapered beams. [ABSTRACT FROM AUTHOR]

In this paper we study the stabilization problem and Riesz basis property of two serially connected Timoshenko beams whose left end is simply supported and the right end is free. Suppose that the displacement and bending moments of the beams at the interior node are continuous, but the shearing force and rotational angle are discontinuous. We design the compensator and feedback controllers at the left end and the interior node of the beams so as to derive the beams back to their equilibrium position. We prove that this closed loop system is well-posed and asymptotically stable. By the spectral analysis, we also show that its root vectors form a Riesz basis with parentheses for the state space. Hence the spectrum determined growth condition holds. Further, we show that this system is not exponentially stable. Finally, we give a numerical simulation of this kind of closed loop system to support our results. [ABSTRACT FROM AUTHOR]

Abstract: In this paper linear buckling analyses of square and rectangular plates with circular and rectangular holes in various positions subjected to axial compression and bending moment are developed. The aim is to give some practical indications on the best position of the circular hole and the best position and orientation of rectangular holes in steel plates, when axial compression and bending moment act together. Two different orientations are considered for rectangular holes: holes with major dimension parallel to the vertical plate axis (RS holes) and major dimension parallel to horizontal plate axis (RL holes). The effect of bending moment on the stability of the plate is studied and some differences with respect to the uniform compression load case are shown. Some design suggestions on the best orientation of rectangular for stability purposes are given. The influence of dimension and position of perforations on linear buckling behaviour and, in particular, on buckling coefficient of the plate is observed. Some practical design formulations for the calculation of the buckling coefficient, taking into account (a) dimensions and shape (square and rectangular) of the plate, (b) dimensions and shape (circular and rectangular) of the hole, (c) position of the hole (centre in the “maximum” and in the “nodal” point), (d) orientation (RS and RL) of the rectangular hole, and (e) load configuration (uniform compression, combinations of axial compression and bending and pure bending) are finally proposed. [Copyright &y& Elsevier]

Abstract: In this study, linear buckling analysis of unstiffened plates under interacting patch loading and bending moment is developed. The study focuses on estimation of the elastic critical load due to patch load, and concomitant linearly variable compressive stress in the normal direction, with analysis of mechanisms of plate instability. The present work proposes simple design equations for the elastic critical load of rectangular plates subjected to both patch load, and uniform compressive stress, and also patch load with linearly varying compressive stresses for the serviceability limit state. The proposed analytical relationship, obtained on the basis of parametric numerical analyses, is validated by comparing analytical predictions with experimental tests from the literature, and full numerical models; good agreement was obtained for practical situations in steel bridge design, such as the erection of steel bridges with the launching construction technique. In the launch phase, web panels of the open-section girders are subjected to concentrated loads applied to the lower flange, and considerable bending moment. [Copyright &y& Elsevier]

A study is made of the stability of cylindrical shells of oval cross section loaded by a shear force combined with torsional and bending moments. The variational method of finite elements in displacements is used. The subcritical stress-strain state of the shells is considered momental and nonlinear. The effects of the nonlinearity of shell deformation and shell ovalization on the critical load and buckling mode are determined. [ABSTRACT FROM AUTHOR]

A simplified model of bending dynamics of a hydrostatically compressed thin shell near the threshold of stability of its form is constructed within the framework of the nonlinear theory of elasticity. Conditions of existence and explicit expressions for spatially localized perturbations and patterns composed of dents on the shell surface, which are “precursors” of subsequent changes in the shell form, are found. [ABSTRACT FROM AUTHOR]

Abstract: An interior three-storey frame structure with a column and 4 beams in each floor is investigated. The vertical and horizontal (seismic) forces, normal forces and bending moments as well as elastic interstorey drifts are calculated. The welded box columns and rolled I-section beams are designed for minimum weight and cost. The beam-to-column connections are selected from a number of structural versions improved for seismic resistance. The fabrication costs are calculated in detail. Design constraints relate to interstorey drifts and to the stability of column parts and beams loaded by compression and bending. Calculations show that, after a connection type is selected, the fabrication cost has little effect on the optimum design, since it varies proportionally with the mass according to the present calculating method. Thus, the minimum weight design gives suitable results. [Copyright &y& Elsevier]

The governing differential equation for buckling of a non-uniform column is expressed in the form of bending moment. The special solutions for 14 types of non-uniform columns are derived from the governing equation. Using a rotational spring and a hinge connection to describe the local flexibility induced by a crack in the column yields the eigenvalue equation for buckling. The main advantage of the proposed method is that the eigenvalue equation for buckling of a non-uniform column with an arbitrary number of cracks, any kind of two end supports, and an arbitrary number of rotational and translational spring supports at intermediate points can be conveniently determined from a second-order determinant based on the fundamental solutions and recurrence formula developed in this paper. As a consequence, the decrease in the determinant order as compared with previously developed procedures simplifies the analysis. A numerical example is given to illustrate the application of the proposed method and to study the effect of cracks on the critical buckling force of a non-uniform column. [ABSTRACT FROM AUTHOR]

The stability problem of a cylindrical shell of oval cross section loaded by a bending moment and internal pressure is studied. The variational displacement finite-element method is used. For the prebuckling stress-strain state, the bending and nonlinearity are taken into account. The effects of the nonlinear nature of the deformation and the cross-sectional ovality of the shells on the critical loads and buckling modes are determined. [ABSTRACT FROM AUTHOR]

A refined model for free vibrations of a Griffith crack in layered composites is investigated. The delamination of the composites along an interface is studied in the context of growth of instability of the stressed layer. This is analogous to the bending of a beam on an elastic foundation. The second-order gradient terms are taken into account in the power-series expansion of deflections. These terms are responsible for nonlinear phenomena in the interaction zone. The zero-order frequency of free vibrations of the crack along the interface and the time of instability growth are determined. [ABSTRACT FROM AUTHOR]