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This research presents measurements and simulations of the full-scale behavior of a test embankment built on a soft marine clay deposit improved using soil–cement mixing (SCM) columns in Bangkok, Thailand, using both two-dimensional (2D) and 3D finite element analyses (FEAs). Fixed SCM columns with two different installation patterns, that is, column groups and column rows, were constructed in the soft clay foundation prior to the construction of the embankment. Three column wall methods, namely, equivalent width, equivalent axial rigidity, and equivalent flexural rigidity approaches, were used to convert the 3D individual columns into 2D plane strain column walls. A comparison of the results obtained through the 3D and 2D FEAs revealed that the 2D analyses provide inaccurate results in terms of the column lateral movements, bending moments, and axial loads induced in the SCM columns in addition to the factors of safety against slope failure. This outcome occurred because the actual columns in the 2D FEA were modeled using extended walls, which essentially prevent the movements of soil between two columns or column rows. Correction factors used to convert the 2D analysis results into 3D analysis results were also proposed in this study. [ABSTRACT FROM AUTHOR]

Plate-reinforced composite (PRC) coupling beams are manufactured by embedding a vertical steel plate into conventionally reinforced concrete coupling beams to enhance their strength and ductility. This study presents a series of quasi-static tests conducted to examine the seismic behavior of PRC coupling beams and provide a scientific basis for the analysis of the shear bearing capacity of PRC coupling beams. The experimental results of seven PRC coupling beam specimens with low span-to-depth ratio tested under reversed cyclic loading are discussed. Particle image velocimetry technology is used to accurately measure the deformation performance of PRC coupling beams. The influence of span-to-depth ratio, sectional steel plate ratio, and the slab on the seismic behaviors of specimens were investigated. The experimental results indicate that, compared with PRC coupling beams without slab, PRC coupling beams with slab can increase horizontal cracking displacement and significantly improve the shear capacity and energy dissipation capacity of PRC coupling beams without slab. Embedded steel plates can improve the limited values of the shear compression ratio of coupling beams. Nonlinear finite element analysis was also carried out to model the PRC coupling beams. The numerical results indicate that the tension-softening property of concrete was more accurately simulated by the stress-crack width relationship of concrete. The internal force distribution of concrete stress, steel plate shear force, bending moment, and axial force of PRC coupling beams with low span-to-depth ratios were further analyzed. This study will benefit engineers designing PRC coupling beams. • The limited values of the shear compression ratio of coupling beams were significantly improved. • Particle image velocimetry technology is used to accurately measure the deformation performance of PRC coupling beams. • The PRC coupling beam with slab has a greater energy dissipation capacity. • The steel plate along the beam span was under tension, and the distribution of the tension is in M-mode. [ABSTRACT FROM AUTHOR]

• Several novel prefabricated shear walls with different filling forms and materials was developed. • Seismic behaviour of the walls were studied through quasi-static tests and finite element analysis. • Effects of parameters on seismic behaviour were evaluated. • The optimization program of opening filling was proposed. Six double-short-limb reinforced concrete (RC) prefabricated shear walls with different infill wall were constructed and tested under cyclic horizontal load and constant vertical load to study the seismic performance, including unfilled shear wall, ceramsite concrete hollow block masonry infilling, concrete integration infilling with hollow tube (HTCI), concrete integration infilling with polystyrene plate sandwich (PPSCI), lightweight partition board infilling and ceramsite concrete infilling. The hysteretic curve, failure mode, stress feature, shear bearing capacity, deformation ability, stiffness, ductility and energy dissipating capacity were obtained. The testing results showed that, the prefabricated integration shear wall (HTCI infilling, PPSCI infilling) failed due to the combined action of bending moment and shear force. Compared to the specimen without infill wall, infilled by masonry and lightweight partition board, the integration shear wall and the shear wall with ceramsite concrete infilling owns better shear bearing capacity, stiffness, energy-dissipating capacity and reliable seismic performance. Finite element (FE) model of all tested specimens were developed by using software OpenSEES, and the precision and utility of these FE models verified by testing data. Using the proposed FE models, an extensive parametric study was performed to investigate the influence factors on the seismic performance of precast fabricated RC shear wall including length of the infill wall, concrete strength, ratio of longitudinal reinforcement in wall limbs and axial compression ratio. Finally, the optimization program of infill wall for the opening of the precast fabricated shear wall are studied based on thickness of polystyrene plate sandwich and setting of steel fabric. [ABSTRACT FROM AUTHOR]

The shear stability of steel webs near the support section for long-span composite girders with corrugated steel webs is one of the main control factors for structural safety, which should be paid special attention to. Generally, concrete is poured on the inner side of corrugated steel webs to improve its shear stability, but encased concrete increases the weight of the girder, raises the difficulty of the construction process, and reduces the efficiency of the prestressing application. This paper proposes a new type of stiffened corrugated steel webs at the support area by adopting vertical or/and horizontal stiffeners instead of encased concrete. In order to explore the shear performance of proposed stiffened corrugated steel webs, experimental and numerical investigations were carried out in the present paper and the companion paper [1] , respectively. Four steel I-girders with corrugated webs considering different stiffener arrangements were designed and tested under shear loading. The failure modes, shear strength and stiffness, strain distributions were obtained and analyzed in detail. The test results show that all specimens failed due to interactive shear buckling of corrugated steel web; shear buckling occurred between horizontal stiffeners and bottom flange for horizontal stiffened corrugated steel webs, but extended to the entire height for vertical stiffened corrugated steel webs, the stiffeners distorted associated with the deformation of corrugated steel web. Shear strength of corrugated steel webs can be improved by vertical and horizontal stiffeners. The vertical stiffeners do not affect the "accordion effect" of corrugated steel webs, but the horizontal stiffeners increase the axial stiffness of corrugated steel web in local area and resist bending moment together with top and bottom flanges. The shear strain of stiffened corrugated steel web still distributes uniformly along the height of the web. All the experimental results are then employed in the companion paper for the validation of finite element method and the evaluation of existing analytical models for predicting shear strength of un-stiffened and stiffened corrugated steel webs. • We proposed a new type of stiffened corrugated steel web. • Shear behavior of steel I-girder with stiffened corrugated webs has been experimentally investigated. • Shear strength of corrugated steel web can be improved by vertical and lateral stiffeners. • Lateral stiffeners increase the axial stiffness of corrugated steel webs in local area. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to analyse the deflection of the flexible airship structure in a new way which can decrease the calculation amount and improve the calculation speed. Design/methodology/approach: Infinitesimal method and tapered inflatable beam theory are combined to study the mechanics characteristics of the airship. Firstly, infinitesimal method is introduced into the airship structure analysis. The airship structure can be divided into several tapered inflatable beam elements. Then, tapered inflatable beam theory is improved and a developed model of the tapered inflatable beam under bending moment is presented. Besides, it is proved that deflection caused by pure load and pure moment can be linearly superimposed. Finally, the deflection of the airship structure is studied by means of tapered inflatable beam theory. Findings: This paper improved the tapered inflatable beam theory. Besides, the proposed method for deflection analysis of the flexible airship in this paper can reach the same accuracy with traditional finite element method (FEM). However, the number of beam elements is much less than the one of FEM shell elements, which will decrease the calculation amount much and improve the calculation speed. Practical implications: The flexible airship is a new and developing research area in engineering practice. The proposed method in this paper provides one precise and high-speed way to analyse the deformation of the airship. Originality/value: The paper draws its value from the contributions to development of inflatable structure and the flexible airship mechanics research. [ABSTRACT FROM AUTHOR]

This paper presents some closed form solutions for the buckling problem of periodic Vierendeel girders subjected to compressive axial loads. These are obtained by studying a geometrically non-linear ideal discrete beam, composed of cells or panels that deform only according to the inner forces transferring modes of the girder unit cell. In particular, the recursive equations governing the equilibrium of this discrete system are derived by the virtual works principle. Then, they are exactly solved and formulae for the critical loads are achieved. Although the ideal girder deforms with geometrically not compatible longitudinal shear strains, it gives very accurate predictions in a wide range of conditions of technical interest. These theoretical results are used as starting point for the analysis of the stiffening effect yielding a Euler critical load significantly higher than the buckling load evaluated on the basis of the classical Engesser's assumptions. Specifically, by an ideal girder auxiliary solution, the discrete systems of self-equilibrated inner bending moments (self-moments) restoring the longitudinal shear strains compatibility are studied and it is shown that the axial loads under which these moments exist are accurate critical loads estimates of the real girder. Closed form solutions are obtained also for this problem and a simplified formula is derived for evaluating real girders buckling loads. The applicability of the reported solutions is verified by a validation study based on a series of finite element girder models. • Closed form solutions for the axial load critical responses of a periodic Vierendeel girder. • A discrete girder model by the unit cell inner forces transferring modes. • Analysis and solution of girder recursive equilibrium equations. • Stiffening 'discrete effect' of web rods and joints explained in terms of self-moments. • Improved solutions for critical axial loads response by cells shear strains compatibility. [ABSTRACT FROM AUTHOR]

The fault zone plays a vital role in the internal force responses of the tunnel. An analytical solution of the tunnel under the fault zone creeping is developed by taking account of normal and tangential interaction between the ground and tunnel. First, the elastic foundation beam model is used. Wherein, the normal interaction is considered by applying the displacements of the free field on the distal end of normal foundation springs. And the tangential interaction is transformed into bending moment applied on the beam. The analytical solution of the tunnel's response is gotten based on the model. Secondly, the numerical solutions from finite element model of 3D are provided to verify the validity of the proposed analytical solutions. Finally, the effect of the fault zone width, the elastic modulus of the fault and the concrete's grade of the lining are investigated. The results show that with the width of the fault zone increasing, the internal force decrease. The concrete's grade of the lining has opposite effects on the internal force of the tunnel. And with the growth of the elasticity modulus of the fault zone, the shear force and bending moment increase and decrease, respectively. • An analytical solution considering the tangential interaction at the ground-tunnel interface is developed. • The proposed analytical solution is verified by the numerical result obtained from the finite element model of 3D. • Effects of fault zone width, elasticity modulus of fault zone and concrete's grade of the lining are discussed. [ABSTRACT FROM AUTHOR]

• Influence of 3D spatial effects of underground structure on its seismic response. • 2D model cannot correctly reflect deformation characteristics at 1/2 length of 3D model. • Results of 2D model roughly equivalent to that at 1/4 length of 3D model. • In-plane bending deflection of slabs well reflect structural 3D cooperative work degree. • Conversion coefficients from 2D model to 3D model with 95% probability guarantee. This paper takes an actual station of Nanjing Metro Line 2 as the research object and establishes the corresponding 2D and 3D overall time-domain nonlinear finite element models, respectively. By analyzing the results of the two models, the influence of the 3D spatial effects of the underground structure on the seismic response of the structure is studied. The results show that the 2D model cannot correctly reflect the deformation characteristics of the 3D station structure at the middle of the longitudinal length. The results obtained from the 2D model are roughly equivalent to the results at 1/4 of the longitudinal length of the 3D station structure. The overall longitudinal bending deflection of the station's top and middle slabs in their own plane can well reflect the 3D cooperative work degree of the station. Based on this, the conversion coefficient of the maximum inter-story displacement angle proposed in this paper can better convert the 2D model results. The minimum error between the converted 2D model results and the 3D model results is only 0.78%, and the maximum error is only about 10%. The maximum inter-story displacement angle conversion coefficient with 95% probability guarantee finally given is 1.447. Through the statistical analysis of the internal force ratio of the 3D model and the 2D model at the key cross-sections, this paper also gives the conversion coefficients with 95% probability guarantee for the bending moment, the axial force and the shear force of the key cross-sections, which are 0.696, 0.773, and 0.785, respectively. [ABSTRACT FROM AUTHOR]

In this study, the structural response of piles during shield machine cutting is analyzed using p-y curves based on the finite element method (FEM). In the FEM program, the tangent stiffness matrix of the nonlinear soil-pile spring is derived from the tangent modulus of the p-y curve. The nonlinear finite element equation is solved using the Newton-Raphson iterative method. The program can consider the influence of the shield thrust force, the soil reinforcement, and the cross-sectional area decrease during shield cutting. The program output comprises the lateral displacement, internal force, and bending moment of the laterally loaded monopile. The correctness and accuracy of this method are validated with both field test data and commercial finite difference method (FDM) program. The results show that shield thrust force is the main factor affecting the lateral displacement and bending moment of the pile; as the cutting section area of the pile is decreasing, the maximum negative moment increases while the maximum positive moment decreases; soil reinforcement has a negligible effect on the internal force but can effectively reduce the lateral displacement of the pile head. [ABSTRACT FROM AUTHOR]

• Three-center-combined spherical shells are modelled as egg-shaped containment structures. • Surface fundamental forms of shell surface with two different radii of curvature are derived. • Large displacement analysis of three-center-combined spherical shells is performed. • Lagrange multipliers technique is used to enforce the discontinuity effect. • Nonlinear finite element analysis with a fifth-order polynomial shape function is performed. In this paper, a large displacement analysis of three-center-combined spherical shells, used as egg-shaped containment structures, is performed using the first and second fundamental forms of the shell surface with two different radii of curvature. The energy functional of the three-center-combined spherical shells system is derived using a variational formulation, and is written in the appropriate form to reduce the computation time in an iterative procedure. The numerical results in terms of displacement, membrane stress, and bending moment resultants are obtained by nonlinear finite element analysis with a fifth-order polynomial shape function. At the spherical shell edge, the Lagrange multipliers technique is used to enforce the discontinuity effect. The main conclusions are that the displacement responses, membrane stress, and bending moment resultants depend on the geometric parameters of the three-center-combined spherical shells. The Lagrange multipliers correspond to the internal forces due to the displacement and the slope at the shell edge in order to sustain the smooth curve for deformed configuration of the three-center-combined spherical shells under uniform pressure. The volume capacity of the three-center-combined spherical shells are more than the spherical shells with a constant radius. Finally, the results indicate that the linear assumption is good enough for all practical purposes. However, the large displacement analysis becomes significant on the tangential displacement, meridional, and circumferential moments under the large value of uniform pressure. [ABSTRACT FROM AUTHOR]

• Established experimental method for composite pre-tightened tooth connections under bending and tension coupling load. • Based on the USDFLD subroutine, a finite element model of progressive failure of composite pre-tightened tooth connections is developed. • The analysis of the failure process of composite pre-tightened tooth connections under bending and tension coupling load. With the application of composite pre-tightened tooth joint in engineering practice, relevant studies have found that in actual structures, the joints are subjected not only to axial tension but also to bending and tension coupling force. Therefore, to analyse the load mechanism and progressive failure process of the joint under bending-tension coupling, a experiment loading method for joint structure was first designed in this paper, and axial-tension and bending-tension coupling experiments of single and double teeth were carried out by this method. Then, a three-dimensional model of progressive failure based on the USDFLD subroutine and Tsai-Wu failure criterion is established based on the experiment condition, and finally, the progressive failure process of the joint in the case of bending-tension coupling is analysed by verifying the correctness of the finite element simulation. The study revealed that the top surface of the composite tooth is subjected to the combined effects of tension stress from the bending moment and tension stress from the axial force at the same time, so the joint damage starts at the top surface and the stress state at the top surface of the composite tooth needs to be considered. [ABSTRACT FROM AUTHOR]

The bending moment response of straight pile foundations, as the dominant factor of spudcan-pile interaction, has received focused attention in the close joint operation between jacket platforms and jack-up drilling rigs. As the foundation for the same widely used in jacket platforms, the research on the batter pile is still a knowledge gap in this field. This paper presents a numerical study of the bending moment response of batter piles at different inclination angles and azimuthal angles during spudcan installation. Using a coupled Eulerian-Lagrangian finite element method, the effects of flexural rigidity, stiffness ratio, spudcan-pile clearance distance, and pile length on the pile head bending moment were sequentially evaluated. It was found that the pile bending moment response is related to the change in soil flow mechanism caused by spudcan penetration and becomes more significant with the increase of inclination angle; under the same inclination angle, the bending moment response is the most dangerous when the azimuthal angle is 0°. Based on the parameter study, a simple method is proposed to estimate the pile head bending moment during spudcan installation. The outcome may facilitate incorporating pile spatial inclination into spudcan-pile interaction research and contribute to related safety design. [ABSTRACT FROM AUTHOR]

Welded T-joints are commonly used in manufacturing of stiffened panels or crossbeams. However, welding of web-to-flange joint induces residual stresses and distortions resulting in significant challenges during both manufacturing and service. These issues can ultimately impact the structural performance, including fatigue and stability, and lifetime of the weldment. The purpose of current paper is determining the distribution and magnitude of manufacturing-induced longitudinal residual stresses in welded T-joints. Influence of hot rolling, thermal cutting, prestressing, welding, etc. are all included using the so-called contour method. Deformed surfaces are measured using coordinate measuring machine after wire electrical discharge machining of specimens. An inverse linear elastic finite element analysis is carried out for assessing residual stresses after data smoothing. Two-dimensional longitudinal residual stress patterns are evaluated in representative cross-sections clearly indicating high stress peaks near the welds, even exceeding yield strength of the base material. In addition, longitudinal membrane residual stresses are determined based on through-thickness stresses. In addition, a simplified residual stress model, satisfying the requirement for equilibrium of internal forces and bending moments, is developed for welded T-joints with double-sided fillet welds based on contour method results. [Display omitted] • A novel application of contour method is used for determining residual stresses. • Longitudinal residual stresses are assessed in welded T-joints. • Tensile residual stress peaks near the welds exceed yield strength of the material. • A simplified residual stress model is developed for welded structural steel T-joints. • Residual stress model satisfies equilibrium of internal forces and bending moments. [ABSTRACT FROM AUTHOR]

A non-negligible percentage of steel products for civil and industrial constructions is realised with members characterised by a mono-symmetric cross-section. The non-coincidence between the centroid and the shear centre reflects in a quite complex behaviour that is remarkably influenced by the warping effects. Usually, frame design is based on the output data of commercial Finite Element Analysis Packages (FEAPs) but only few of them offer a refined beam element formulation able to reproduce the response of non-bisymmetric cross-section members (like the 7 degrees of freedom, DOFs, beam element). As a consequence, warping effects are usually neglected in routine design, leading in several cases to assess non-correct internal stresses, global displacements and critical buckling multipliers. This paper is focussed on mono-symmetric cross-section members and deals with the influence of the interaction between axial force, bending moments and bimoment in linear elastic range. In particular, the two strategies that FE developers usually adopt, in the 7 DOFs beam formulation, to pass from the local to the global reference system are herein shortly introduced and discussed. The effects of the associated transformation matrices have been investigated in few examples, also reproduced via closed expressions derived from the mixed torsion theory and FE shell models. Paper outcomes show that the results in terms of generalised displacements, internal forces and, consequently, stress distribution along the member cross-section are significantly different, strictly depending on the adopted transformation matrix. The importance of a correct evaluation of the bimoment distribution is stressed also by the fact that the new edition of the EN1993-1-1, expected in the next months, includes also the bimoment contribution for member checks. • Interaction between bending moments and bimoment in linear elastic range for mono-symmetric cross-section members. • The two strategies adopted in 7DOFs beam formulation, to pass from the local to the global reference system are discussed. • Vlasov's theorems are discussed and applied to example of practical interest for structural design. • Displacements and internal forces are significantly different, strictly depending on the adopted transformation matrix. [ABSTRACT FROM AUTHOR]

This paper aims to experimentally and numerically investigate the structural performance of speed-lock joints with split bolts in steel storage racks. There are no bolts in the typical speed-lock joint for its ease of installation, and the joint transmits and bears force through interactions of the tabs and upright beam holes. However, the joint under seismic loading shows large looseness and slippage with low stiffness. Also, the energy dissipation capacity is insufficient and the failure of tabs in the joints might lead to brittle behavior. In this study, new detail of the speed-lock joint with bolts is proposed by adding a pair of split bolts in the beam end plate while still preserving its merit of ease of installation. A double-cantilever beam test was designed to test this speed-lock joint with split bolts along with the typical speed-lock joint. Low cyclic loading tests were performed on both types of joints: with split bolts and without split bolts. The results revealed the benefits that the split bolts could bring to significantly enhance the performance of the joint in terms of the maximum bending moment, the initial stiffness, the displacement ductility coefficient, the equivalent viscous damping coefficient, and the energy consumption. In addition, a two-step analysis method was proposed for the high-fidelity finite element model of the joints to overcome the complex contact nonlinearity. The numerical model was then validated with the tests for further numerical studies on the performance of speed lock joints with/without bolts. • Experimental tests were designed and conducted on the typical speed-lock joint and proposed joint with added split bolts. • With split bolts, the joint has less slippage and looseness and effectively eliminates the brittle tab failure. • Speed-lock joints with split bolts possess an additional load bearing mechanism that improves the seismic performance. • Atwo-step analysis method was proposed for the finite element model of the joints to overcome the complex contact nonlinearity. • Stress distributions from experimental and numerical results reveal the joint's improved bearing mechanism. [ABSTRACT FROM AUTHOR]

Marine engineering structures may be subjected to various levels of vessel collisions, causing different degrees of damage to the RC piles. However, the influence of different combinations of impact mass and velocity under the same initial kinetic energy or momentum on the impact behavior of RC piles has not been explored. A numerical investigation of the impact responses of RC pile structures (including plumb piles and inclined pile groups) considering the material strain rate effect is carried out using the software ABAQUS/Explicit in this paper. Parametric studies are conducted based on the validated finite element models of RC piles subjected to horizontal impact. The internal force distributions, as well as the effect of the impact kinetic energy and the momentum (including different combinations of impact mass and initial velocity) on the impact response of RC piles, are discussed. The results indicate that the development path of the bending moment‒overall structural displacement curves in the plastic hinge regions of RC piles are almost identical under both impact and static loading conditions. Compared to momentum, the impact response of RC piles is insensitive to the variation of impact kinetic energy with different combinations of impact mass and velocity. Therefore, the impact kinetic energy is more suitable for evaluating the structural deformation of RC piles after impact. Finally, a performance-based impact-resistance design framework for RC piles is proposed. • A numerical investigation of the impact responses of RC pile structures is carried out. • The internal force distributions on the impact response of RC piles are discussed. • The effect of different combinations of impact mass and initial velocity on the response of RC piles is studied. • A performance-based impact-resistance design framework for RC piles is proposed. [ABSTRACT FROM AUTHOR]

• A new type of cross-laminated bamboo and timber, consisting of flattened bamboo boards and fast-growing timber was prepared. • The effect of the number of layers of the flattened bamboo board on the engineering performance of CLBT was investigated. • A finite element model based on the Tsai-Wu failure criterion was used to predicting the bending performance of CLBT. Bamboo-wood composites are effective for utilizing the mechanical properties of bamboo and fast-growing wood resources. Investigation the application of flattened bamboo in engineering structures provides added value to bamboo resources. This paper analyzes the flatwise bending and shear properties of cross-laminated bamboo and timber (CLBT) panels consisting of flattened bamboo boards and Chinese fir lumber. A three-layer cross-laminated timber (CLT) panel made from Chinese fir lumber was used for comparison. The mechanical properties of the CLBT and CLT panels in the major strength direction were obtained through experimental tests, and theoretical and finite element models were developed to predict the panels' bending stiffness and strength. The calculated values were compared with the experimental data. The results showed that the failure modes of the three groups of CLBT panels were similar to those of the CLT panel and were predominantly rolling shear and bonding delamination. The bending strength and modulus of the CLBT were higher than that of the CLT. Increasing the number of layers of the flattened bamboo board improved the maximum bending moment and bending stiffness of the CLBT. The bending stiffness and strength of the CLBT/CLT obtained from the finite element model were in better agreement with the static test values than the theoretical model values. The results of this study provie new information for future engineering applications and the structural design of CLBT. [ABSTRACT FROM AUTHOR]

• A simplified customizable mesh model speeds up computer-based diagnosis and prediction. • The current FE model predicts geometric, material, and contact nonlinearity. • The mesh model can be morphed into a particular anthropometry for prediction. • Flexion, extension, bending, axial rotation, disc pressure, disk displacement, and facet contact forces were validated through the model. Instrumentation alters the biomechanics of the spine, and therefore prediction of all output quantities that have critical influence post-surgically is significant for engineering models to aid in clinical predictions. Geometrical morphological finite element models can bring down the development time and cost of custom intact and instrumented models and thus aids in the better inference of biomechanics of surgical instrumentation on patient-specific diseased spine segments. A comprehensive hexahedral morphological lumbosacral finite element model is developed in this work to predict the range of motions, disc pressures, and facet contact forces of the intact and instrumented spine. Facet contact forces are needed to predict the impact of fusion surgeries on adjacent facet contacts in bending, axial rotation, and extension motions. Extensive validation in major physiological loading regimes of the pure moment, pure compression, and combined loading is undertaken. In vitro , experimental corridor results from six different studies reported in the literature are compared and the generated model had statistically significant comparable values with these studies. Flexion, extension and bending moment rotation curves of all segments of the developed model were favourable and within two separately established experimental corridor windows as well as recent simulation results. Axial torque moment rotation curves were comparable to in vitro results for four out of five lumbar functional units. The facet contact force results also agreed with in vitro experimental results. The current model is also computationally efficient with respect to contemporary models since it uses significantly smaller number of elements without losing the accuracy in terms of response prediction. This model can further be used for predicting the impact of different instrumentation techniques on the lumbar vertebral column. [ABSTRACT FROM AUTHOR]

Effective and convenient prediction of the peak displacement of piles under collision conditions facilitates the design framework preparation and pile damage evaluation. Hence, an energy-based method was proposed to predict the peak displacement of the widely used steel casing composite (SCC) piles under impact loading. The pile deformation energy was first calculated based on its deformation characteristics and the relationship between the sectional bending moment and curvature. The pile deformation energy and pile–soil energy distribution ratio were then employed to determine the relationship between the total absorbed impact energy and pile head displacement, which was represented by curves. The peak pile displacement under lateral impact loading was finally obtained by interpolating the absorbed impact energy curves. By conducting sectional analysis of the pile considering the strain rate effects and using a structural pushover procedure, the peak pile head displacements for various collision cases were predicted with reasonable accuracy. The effectiveness and reliability of the proposed method were verified by comparing its results with those of previous reduced-scale impact tests and validated full-scale finite element models. • An energy-based method was proposed to predict the peak displacement of the SCC pile under lateral collision. • The proposed method required only impact energy input, sectional analysis, and pushover procedure. • The deformation and energy distribution characteristics of piles under static and impact loading were similar. • The SCC piles had two deformation forms: a single plastic hinge and a double plastic hinge. • Pile deformation energy was derived from its deformed shapes and the sectional bending moment–curvature relationship. [ABSTRACT FROM AUTHOR]

Fatigue damages of an offshore wind turbine (OWT) would be caused by long-term wind and wave loads, necessitating the importance of fatigue life analysis to ensure the in-service behaviors of OWT. This study evaluates the fatigue damage and predicts the fatigue life of OWT considering full-directional wind inflow under the coupling effects of non-Gaussian wind field and wave. The forces and bending moments are assessed in three types of the wind field, i.e., Gaussian, softening non-Gaussian, and hardening non-Gaussian, according to the Kaimal spectrum by using OpenFAST. The dynamic responses of OWT are implemented by a three-dimensional finite element model (FEM) established by ABAQUS. The fatigue life is assessed in the tower base section and the pile of OWT under different loading combinations. Results show that the crack initiation life is greatly affected by the non-Gaussian wind field, while the crack propagation life is not that sensitive. The fatigue life of OWT under a full-directional wind inflow is approximately three times longer than that under a single-directional wind inflow. It is recommended to consider full-directional wind inflow in the non-Gaussian wind field for OWT design. • It is found that the crack initiation life is greatly affected by the non-Gaussian wind field. • The fatigue life of OWT under a full-directional wind inflow is longer than that under a single-directional wind inflow. • It is recommended to consider full-directional wind inflow in the non-Gaussian wind field for OWT design. [ABSTRACT FROM AUTHOR]

The ship shaft alignment is crucial to achieve a high-performance propulsion system. This alignment is carried out, still in drydock, by adjusting the bearings' offsets. However, there are numerous available combinations sets of vertical offsets which results in good alignment final condition. Defining an optimum set of vertical displacements is costing shipyards a valuable time. Therefore, this work proposes the use of machine learning algorithms to predict if a given set of offsets, following the mandatory rules in force, should be implemented or not. In this manner, this paper presents a case study where a finite element model of an Anchor Handling Tug Supply (AHTS) vessel' shaft line was assembled in order to obtain the bearings reactions, shaft line deflections, shear forces, bending moments and, finally, the influence coefficients matrix (ICM). Those data were used to feed machine learning (ML) models based on four different algorithms, namely, K-Nearest-Neighbors, Extremely Randomized Trees, Random Forest and Gradient Boosting in order to solve multiclass classification problems concerning the offset's set to be applied in the alignment of the shaft line. Results showed that the Gradient Boosting and Random Forest algorithms presented the best results, achieving up to 98.1% of precision in one of the 36 scenarios tested, and an average precision above 96.0%. Such results corroborated with the authors' proposal to implement ML techniques as a way to speed up the currently very time-consuming shaft alignment process. • Machine learning algorithms applied in ships shafting system alignment. • Techniques to predict if the bearings' offsets return an aligned shaft system. • Machine learning classification models applied in shaft alignment. • Influence coefficients matrix verifying the shaft system alignment. • Stiffness method calculating bearings reactions. [ABSTRACT FROM AUTHOR]

Beam-to-beam connections are widely used in steel structures, especially in large floor applications and in cases where they are dictated by architectural restrictions. This type of connection is often designed without rotational restrictions (pinned connections), leading to relatively high bending capacity demands for the connected secondary beam, particularly when larger spans are employed. A commonly used practice to limit the above mentioned effect is to design beam-to-beam fixed connections at both ends of the secondary beam. Although joints transferring bending moments are covered in EN-1993 Part 1–8, there is no standardization for beam-to-beam fixed connections, often resulting in questions about their rotational capacity. Moreover, there is very little guidance on the design of beam-to-beam connections in the open literature. Therefore, this paper presents a comprehensive investigation of the beam-to-beam eccentric end plate connections using finite element analysis following the experimental tests. The parametric study is conducted using experimental data to propose a reliable analytical model of structural behavior under monotonic gravitational loading. The eccentric end plate connection exhibited satisfactory rotational stiffness and bending capacity. The failure mechanism on the connection parts is also presented for a better evaluation of the key parameters affecting the connection's structural performance. • Beam-to-beam eccentric end plate connections using finite element analysis. • Stiffeners and end plates are the critical components for failure. • The span of the secondary beam length directly affects the initial stiffness boundary. • Larger section sizes lead to the semi-rigid classification. • Level difference has an effect on the initial stiffness and the joint strength. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations into the cross-section behaviour and resistance of press-braked ferritic stainless steel channel sections under combined compression and major-axis bending moment. An experimental programme, including initial local geometric imperfection measurements and ten major-axis eccentric compression tests, was firstly conducted, with the test setup, procedures and results reported in detail. This was followed by a numerical modelling programme, where finite element models were developed and validated against the major-axis eccentric compression test results and then adopted to conduct parametric studies to expand the test data pool over a wider range of cross-section dimensions and loading combinations. Based on the obtained test and numerical data, the design interaction curves for press-braked ferritic stainless steel channel sections under combined compression and major-axis bending moment, as given in the American specification and European code, were evaluated. The evaluation results revealed that the American specification resulted in a good level of design accuracy, while the European code led to conservative resistance predictions, due to the conservative bending end point and inefficient linear shape of the design interaction curve. New design interaction curves were also developed and shown to offer more accurate and consistent resistance predictions for press-braked ferritic stainless steel channel sections under combined compression and major-axis bending moment than the codified design interaction curves. • The local buckling of ferritic stainless steel channel sections under major-axis combined loading was studied. • Ten major-axis eccentric compression tests were carried out. • FE models were developed to simulate the test results and then adopted to conduct parametric studies. • The codified design interaction curves were evaluated, with shortcomings highlighted. • New improved design interaction curves were proposed. [ABSTRACT FROM AUTHOR]

Internal solitary waves with a huge amount of energy easily trigger the large dynamic responses of riser-wellhead system and threaten its structural safety. However, previous studies have only focused on the dynamic response of the riser under internal solitary waves. The riser may experience excessive traction from the platform, especially from the mooring platform, in response to the arrival of internal solitary waves. The bottom of the riser connects to the wellhead system, which in turn exerts a reaction force on the riser. To address this problem, a coupled dynamic model of deep-water drilling mooring platform-riser-wellhead system under internal solitary waves is developed in this paper. A dynamic response analysis method based on the fourth-order Runge-Kutta method and finite element method is also proposed for the mooring platform-riser-wellhead system. A dynamical solver for the coupled system is then developed using MATLAB. The dynamic response characteristics of the riser-wellhead system under internal solitary waves are calculated. Results show that the displacement and bending moment of the system initially increases and then decreases along with the propagation of internal solitary waves, and finally reach equilibrium position. The displacement and bending moment reach their peak before the trough of internal solitary waves passes through the riser-wellhead system. The dynamic responses of the riser-wellhead system under the influence of internal solitary wave loads are much larger than those without the effect of internal solitary wave loads. The riser system experiences shearing loads at the interface of internal solitary waves, which trigger a step-like bending moment variation. The bending moment of the conductor under the mudline is greatly increased by the internal solitary waves. • A coupled dynamic model of deep-water mooring platform-riser-wellhead system under internal solitary waves is developed. • A dynamic response analysis method for the coupled dynamic model is proposed. • The dynamic responses reach their peak with the influence of the trough of internal solitary waves. • The riser-wellhead system has much larger dynamic response under the internal solitary wave loads. • The bending moment of the riser at the interface of internal solitary waves has a "step"-like form. [ABSTRACT FROM AUTHOR]

Abstract This paper applies the topology optimization (TO) technique to the design of custom compression casts/braces on two-manifold mesh surfaces. Conventional braces or casts, usually made of plaster or fiberglass, have the drawbacks of being heavy and unventilated to wear. To reduce the weight and improve the performance of a custom brace, TO methods are adopted to optimize the geometry of the brace in the three-dimensional (3D) space, but they are computationally expensive. Based on our observation that the brace has a much smaller thickness compared to other dimensions and the applied loads are normal forces, this paper presents a novel TO method based on thin plate elements on the two-dimensional manifold (2-manifold) surfaces instead of 3D solid elements. Our working pipeline starts from a 3D scan of a human body represented by a 2-manifold mesh surface, which is the base design domain for the custom brace. Similar to the concept of isoparametric representation, the 3D design domain is mapped onto a two-dimensional (2D) parametric domain. An Finite Element Analysis (FEA) with bending moments is performed on the parameterized 2D design domain, and the Solid Isotropic Material with Penalization (SIMP) method is applied to optimize the pattern in the parametric domain. After the optimized cast/brace is obtained on the 2-manifold mesh surface, a solid model is generated by our design interface and then sent to a 3D printer for fabrication. Compared with the optimization method with solid elements, our method is more efficient and controllable due to the high efficiency of solving FEA in the 2D domain. [ABSTRACT FROM AUTHOR]

In recent years, the need to rehabilitate / consolidate the existing built-up fund has become of particular importance for many reasons (extension of the construction exploitation period, economic considerations, etc.). This paper presents the results of a numerical investigation of flexural and shear strengthening of reinforced concrete (RC) roof elements (T - section beams) with externally bonded Carbon Fibre Reinforced Polymer (CFRP) strips and sheets of a water tank. The assessment has been conducted using two software design programs. Firstly, the input data values have been collected on the basis of an experimental program. The numerical evaluation of the reinforced concrete structural element has been calculated as a simply supported beam using SCIA Engineer software program, by FEM (Finite Element Method), in order to determine the maximum values of the internal efforts (bending moment, shear force) in different load combinations. Subsequently, based on the results obtained, the design of the consolidation solutions using CFRP has been realised with the Sika® Carbodur® FRP Design program. This program allows the design of flexural strengthening (using the maximum value of the bending moment) to determine the dimensions of CFRP strip and the design of shear strengthening (using the maximum value of the shear force) to determine the dimensions and the number of layers of CFRP sheet. In the case of shear strengthening, it has been calculated two types of application of CFRP on the structural elements: continuous jacketing and discrete strips. The obtained results for both variants present some advantages and disadvantages. In both situations, the results are valid and the design is made according to the norms, conclude the fact that the use of CFRP (Carbon Fibre Reinforced Polymer) represents an effective consolidation method which can be used to repair and strengthen damaged/deteriorated beams. [ABSTRACT FROM AUTHOR]

In the recent past, in order to cater lateral loads, provision of fins to monopiles is evolving as an option for enhancing their lateral load capacity. Numerical and experimental studies pertaining to fin piles subjected to lateral loading are very limited. It is very difficult to understand the behaviour of fin piles through conventional soil pile theories, due to their different fin configurations. In the present study, three-dimensional finite element analyses were performed on regular piles (pile without fins) as well as fin piles. For fin piles, different fin lengths, orientation and position were considered during the analyses. The results have shown that fins placed at the top portion of the piles are more effective than fins placed at bottom of the pile. In all cases, fin piles exhibited more lateral load-carrying capacity compared to regular piles. When fin's length is less than half of the pile length, lateral load-carrying capacity of fin piles is same irrespective of their orientation. However, fin's orientation is significant, when fin length is more than 0.5 times length of piles, star fin piles exhibit more lateral load-carrying capacity compared to diagonal and straight fin piles. Fin piles experienced less bending moment compared to regular piles for a given lateral load. Further, it was also noticed that lateral load-carrying capacity of the fin piles depend upon fins' length and their orientation. [ABSTRACT FROM AUTHOR]

This paper presents a PM pole with varied width in the axial direction for vibration mitigation in permanent magnet brush dc motors, which is proposed to decrease the deformation caused by radial pulsating force and bending moment together. First, the air gap flux density distribution and radial force density distribution are derived in detail. After two types of vibration modes and their reasons as pulsating force and bending moment are analyzed, the difficulty in vibration mitigation is pointed out. By investigating the change rule of the pulsating force and bending moment with PM pole width, a type of PM pole with varied width in the axial direction is proposed. Its principle of deformation reduction is presented, and the optimized pole shape is derived. A three-dimensional finite-element method is used to calculate the magnetic field, Maxwell force, modal analysis, and deformation of motors. In order to verify the effectiveness of the proposed method, the vibration of the proposed motor is compared with the other three types of traditional motors, including skewing slot or skewing pole. Finally, experimental results of two types of motors are compared to validate the proposed technique. [ABSTRACT FROM AUTHOR]

This study aims to investigate the strength reduction effect of chord axial stresses on the static strength of cracked tubular T/Y-joints under out-of-plane or in-plane bending moment using finite element analyses. The cracked tubular T/Y-joints contain a semi-elliptical surface crack at the weld toe of the chord. The benchmark analysis compares the numerically computed load–deformation response of a cracked X-joint fabricated from high-strength steel reported in a recent experimental study. This investigation quantifies the strength reduction caused by the chord axial stresses using the chord stress function Qcf. The parametric study covers the effect caused by the variation in both the local crack geometries, that is, the crack area and the global joint dimensions on the computed chord stress function. Finally, we give recommendations to calculate the strength reduction of the investigated cracked joints due to the chord axial stresses. [ABSTRACT FROM AUTHOR]

Highlights • Effects of axial force and bending moment on the burst pressure of corroded pipelines are studied. • Burst pressure is significantly reduced under compressive axial force and closing bending moment. • Developed failure loci considering axial forces, bending moments and internal pressures. • The failure loci are found to depends on corrosion depths and load combinations. • The failure loci can be used for burst pressures assessment with known axial force and bending moment. Abstract The remaining strength of corroded pipeline is generally assessed considering the internal pressure only. However, pipelines are often subjected to axial forces and bending moments due to external loadings, which may significantly reduce the burst pressure of the pipeline. This paper presents a study using finite element analysis on the effects of axial forces and bending moments to the burst pressures of corroded pipelines. It is revealed that the compressive axial force and the closing bending moment, causing compression in the corroded area, affect the burst pressure most significantly. Considering the axial compression and closing bending moment, failure loci of combined bending moments and internal pressures are developed for different axial forces. The developed failure loci can be used for assessing the burst pressure of corroded pipelines subjected to axial forces and bending moments. [ABSTRACT FROM AUTHOR]

A new finite element with an additional degree of freedom at the crack location is derived for static bending analysis of a transversely cracked uniform slender beam. In the simplified computational model, which is based on Euler-Bernoulli's theory of small displacements, the crack is represented by a linear rotational spring connecting two elastic parts. The derivation of the transverse displacements, the coefficients of the stiffness matrix as well as the load vector for uniformly distributed load along the whole beam element was based on the utilization of polynomial interpolation functions of the fourth degree and all derived expressions were obtained in the closed form. The novelty of the new model, by comparison to the previously presented simplified finite element models, is that the transverse displacements functions obtained by utilization of the newly presented interpolation functions for the case of uniform continuous transverse load along whole beam element, as well as the functions of the bending moments and transverse forces, are accurate. The values obtained by the simplified model also exhibited good agreement in additional comparison with the results from more demanding and more detailed 2D models. [ABSTRACT FROM AUTHOR]

The rod-fastened rotor is the core component of the gas turbine. It comprises several discs and tie rods. The flexural stiffness of the contact interface is the key factor for rotordynamic analysis. The contact interfaces of the discs are usually manufactured by grinding. The measured contour curve of the contact interfaces of an experimental rod-fastened rotor is analyzed by the structural function method, which shows that the contact interfaces can be well described by the double fractal model with fractal dimensions D1 and D2 and the fractal roughness parameters G1 and G2. The Hertz model is used to analyze the contact of the single asperity on the contact interface. On this basis, the flexural stiffness of the contact interface considering the pretightening force and the bending moment is derived. Modal frequencies of the experimental rod-fastened rotor under different pretightening forces and the bending moment (caused by gravity) are obtained by three-dimensional finite element analysis and experimental modal tests. It is observed that the modal frequencies increase with the nominal pressure of the contact interface, and the experimental results are consistent with the calculated results. [ABSTRACT FROM AUTHOR]

An analytical method is proposed to predict springback and residual stress distribution of the multi-point formed cylindrical workpiece. Considering the loading model of the multi-point forming process, the bending moment can be obtained by superimposing the bending moment generated by each punch, which is calculated through the stress in the thickness direction. The springback value and the residual stress in the tangential direction are obtained theoretically. The strain and stress variation in the thickness direction during the loading and unloading process are also analyzed. The finite element (FE) simulation and the bending experiment (EXP) are conducted to make a comparison with the analytical (ANA) results. The results show that the proposed method can effectively predict the springback value and the residual stress distribution in multi-point forming of a cylindrical workpiece. [ABSTRACT FROM AUTHOR]

Abstract A high-fill slope located in Zhenxiong County, Yunnan Province, China, was designed for building placement on its top platform. A reinforcement system consisting of a geogrid, front stability piles (FSPs), retaining sheets, prestressed anchors, and rear deeply buried piles (DBPs) has been used to stabilize the slope. Two typical slope sections were selected to study the high-fill slope stability and retaining mechanism of the reinforcement system. Field measurements of the horizontal displacement and strain in the piles, as well as the anchor working load, were collected and analyzed. In addition, a series of two-dimensional finite element method (FEM) analyses combined with a strength reduction technique was conducted to analyze two selected cross sections. The results show that the retaining structure behavior is closely related to the fill construction process of a high-fill slope. The deflection of the stabilizing pile increases almost linearly with the filling height in the initial stage of fill construction. The variation in the working load of the prestressed anchor shows an offset between prestress loss and increasing fill pressure. The FEM results can provide insight into the pile-soil interaction mechanism and its contribution to fill slope stabilization. The FSPs shift the sliding surface from through the slope toe to through the top of the FSPs. The anchors can reduce the bending moment by supplying additional bearing points. The DBPs can share a portion of the sliding thrust and effectively enhance the safety factor. This paper provides a reference for reinforcement system design for similar engineering projects considering high-fill slopes. Highlights • A case of reinforcement and monitoring for a high-fill slope is presented. • The reinforcement system includes two rows of piles, retaining sheets and anchors. • The behavior of the reinforcement system is investigated through field measurements. • The reinforcement mechanism is analyzed by FEM combined with monitoring. • This study provides a reference for the design of similar high-fill slopes. [ABSTRACT FROM AUTHOR]

Passenger transport is an inseparable ingredient of public transport system for developing and developed nations. In present work design and analysis of state transport utility vehicle ~ bus is carried out. Present paper focuses on the design enhancements in structural features of sub and superstructure without any alterations on the chassis provided by OEMs. Limiting dimensions of bus as prescribed by automotive industry standard and central motor vehicle rules are the design constraints accounted in the present work. This work was commenced with the thorough study of sub and superstructure configurations, seat locations, passenger load patterns, locations of doors, windows & emergency exits and other relevant bus attributes. Hand calculations for evaluation gross section modulus of chassis and cross member combination are presented. Usage of shear force and bending moment diagrams to evaluate the stress and deflection for the proposed load patterns is made before proceeding for finite element analysis. Finite element modelling and analysis of the sub and super structure combination is carried using shell elements with the presumption that chassis of the bus is rigid. Roll-over analysis of bus for the present configuration is presented. [ABSTRACT FROM AUTHOR]

Reinforced concrete flat slab systems are supported to columns directly without beams. In this analytical study, a structure which has reinforced concrete flat slab with four storey is investigated under earthquake effect. The structure was analyzed by three different methods to compare bending moments in columns and flat slabs. In this study, explanatory information about flat slab systems is presented and different types of solution methods which are adopted our countries specification was compared through a structural example under the horizontal loads. Under the influence of horizontal earthquake forces; selected bearing system have been analyzed by the equivalent frame method, called the moment transfer coefficients method developed by Ünlüoğlu and finite elements method based SAP2000 software. The result of comparing the findings obtained from different solution methods to each other is presented with the help of column top and bottom moments in all floors, flat slab bending moments in inner and edge column strands, tables and graphs. According to this, the method developed by Ünlüoğlu using moment transfer coefficients and the results obtained from finite elements based SAP2000 software are very close to each other. The results obtained from the equivalent frame method are different from those result of the other methods of analysis. Because the equivalent frame method is an approximate method, it does not give as accurate results as the results obtained by the finite element method. However, the method developed by Ünlüoğlu may be an alternative to the finite element method. [ABSTRACT FROM AUTHOR]

The study deals with mathematical modeling of a typical three storeyed building frame supported by a pile group of four piles (2×2) embedded in soft marine clay, a cohesive type of soil mass, using three dimensional finite element analysis. For the purpose of modeling, the elements such as beams, slabs and columns, of the superstructure frame; and that of the pile foundation such as pile and pile cap are descretized using twenty noded isoparametric continuum elements. The interface between the pile and the soil is idealized using sixteen node isoparametric surface element. The soil elements are modeled using eight nodes, nine nodes and twelve node continuum elements. The present study considers the linear elastic behaviour of the elements of superstructure and substructure (i.e., foundation); and the soil is assumed to behave non-linear. The parametric study is carried out for studying the effect of soil- structure interaction on response of the frame by resorting to the sub-structure approach. The frame is analyzed initially without considering the effect of the foundation (non-interaction analysis) and then, the pile foundation is evaluated independently to obtain the equivalent stiffness; and these values are used in the interaction analysis. The embedment depth ratio is varied to evaluate its effect on the interactive behaviour of frame in the context pile spacing of 2D. The response of the frame included the horizontal displacement at the level of each storey, shear force in beams, axial force in columns along with the bending moments in beams and columns. The effect of the soil- structure interaction is observed to be significant for the configuration of the pile groups. [ABSTRACT FROM AUTHOR]

Abstract Due to being increasingly used in infrastructure, studying stress concentration in concrete-filled steel tubular joints is necessary. In this study, the variation of the maximum Stress Concentration Factor (SCF max) with non-dimensional geometric parameters in steel circular hollow section brace welded to concrete-filled circular hollow section chord (CHS-to-CFCHS) T-joints under in-plane and out-of-plane bending moment has been investigated. A database of the maximum SCFs in CHS-to-CFCHS T-joints under in-plane and out-of-plane bending moment is developed based on three-dimensional (3D) finite element (FE) models. The 3D FE models developed using ABAQUS software, have been verified using experimental results. Graphs showing variation of the maximum SCF, in CHS-to-CFCHS T-joints, with non-dimensional geometric parameters have been produced and compared with those for non-filled empty T-joints. Parametric equations for predicting the maximum SCFs in CHS-to-CFCHS T-joints under in-plane and out-of-plane bending moment have been developed in a multiple nonlinear regression analysis. There is a good agreement between the maximum SCFs predicted by the parametric equations and those determined from the experiments. Highlights • The effect of the concrete infill in reducing the SCF max is moderate under in-plane bending and its effect is significant under out-of-plane bending. • Parameter β has very little effect on the SCF max under in-plane bending and has significant effect under out-of-plane bending. • The trend in variation of the SCF max under in-plane and out-of-plane bending with parameter τ in CHS-to-CFCHS T-joints is similar to that in empty T-joints yet its effect is less under out-of-plane bending in the CHS-to-CFCHS T-joints due to significant effect of the concrete infill. • The trend in variation of the SCF max under in-plane and out-of-plane bending with parameter γ in CHS-to-CFCHS T-joints is similar to that in empty T-joints yet its effect is less under out-of-plane bending in the CHS-to-CFCHS T-joints due to significant effect of the concrete infill. • Parameter α has no effect on the SCF max under out-of-plane bending. [ABSTRACT FROM AUTHOR]

Bolted flanges in aero-engine casings exhibit a nonlinear response when subjected to forced vibration. The current models for the structural dynamic analysis of bolted flanges are accurate, but they are cumbersome for the design of new structures. These models either require model updating from modal testing, or they require a large number of nonlinear elements. This study presents a new lump model that accounts for the nonlinear phenomena of partial clearance and friction, and has analytical parameters related to the flange geometry. The model was implemented in finite element analysis and compared with an experiment where a test structure is excited by an electromechanical shaker. The lump model predicts the structural response better than a traditional linear method; yet it does not require model updating, and it uses a very limited number of nonlinear elements. The model is therefore well suited for the early design phase of new aero-engine casings. This study supports the use of geometric lump models in the field of nonlinear structural dynamics. [ABSTRACT FROM AUTHOR]

Peridynamic (PD) theory is a new continuum mechanics formulation introduced to overcome the limitations of classical continuum mechanics such as predicting crack initiation and propagation, and capturing nonlocal effects. PD theory is based on integro-differential equations and these equations are generally difficult to be solved by using analytical techniques. Therefore, numerical approximations, especially with meshless method, have been widely used. Numerical solution of three-dimensional models is usually computationally expensive and structural idealization can be utilized to reduce the computational time significantly. In this study, two of such structural idealization types are considered, namely Timoshenko beam and Mindlin plate, and their peridynamic formulations are briefly explained. Moreover, the implementation of these formulations in finite element framework is presented. To demonstrate the capability of the present approach, several case studies are considered including beam and plate bending due to transverse loading, buckling analysis and propagation of an initial crack in a plate under bending loading. [ABSTRACT FROM AUTHOR]

Abstract Structural design formulae for beam-columns require accurate end points (i.e. accurate resistance predictions for pure compression and pure bending), should be of suitable form to capture the interaction between the different components of loading and should take due account of the influence of a moment gradient along the member length. However, existing design rules for stainless steel beam-columns do not fully capture the interaction responses observed in experiments and numerical simulations, and are often tied to inaccurate end points; the adopted equivalent uniform moment factors can also be unconservative in the case of high moment gradients. As a consequence, previous comparisons of stainless steel beam-column experimental and finite element results with codified strength predictions have often revealed a rather high degree of scatter. This prompted the present research, to develop improved design proposals for stainless steel square hollow section (SHS) and rectangular hollow section (RHS) beam-columns under moment gradients. To this end, revised design approaches are proposed firstly through the derivation of more accurate design interaction curves for stainless steel SHS and RHS beam-columns under uniform bending moment and then through the employment of more suitable equivalent uniform moment factors, underpinned by and validated against over 1500 test and numerical data points. The new design approaches are shown to lead to improved (safe-sided, accurate and consistent) resistance predictions for stainless steel SHS and RHS beam-columns under moment gradients over the current codified design rules. Finally, statistical analyses are performed to demonstrate the reliability of the proposed approaches, according to the requirements specified in EN 1990. Highlights • Current codified design rules for stainless steel beam-columns under moment gradients were briefly reviewed. • Shortcomings in the existing design codes were identified, and methodologies for overcoming them were described. • Improved design approach for stainless steel beam-columns under moment gradients was proposed. • Assessment of the new proposal indicates a higher level of design accuracy and consistency. • The reliability of the new proposal has been confirmed by means of statistical analyses. [ABSTRACT FROM AUTHOR]

Abstract The local cross-section behaviour of stainless steel channel sections under the combined actions of axial compression and minor axis bending moment is investigated in the present paper and its companion paper, based on a comprehensive experimental and numerical study. Two channel section sizes were considered in the experimental programme, with the test specimens laser-welded at the two flange-to-web junctions from hot-rolled EN 1.4307 and EN 1.4404 austenitic stainless steel plates. The experiments involved initial local geometric imperfection measurements and 15 eccentrically loaded stub column (combined loading) tests. The loading eccentricity was varied to achieve a range of ratios of axial compression to minor axis bending moment; both orientations of bending (web in compression and web in tension) were considered. The test setup and procedures, together with the key experimental observations, including the load-carrying and deformation capacities, load-end rotation histories and failure modes, are fully reported. A finite element simulation study is then presented, in which the models were first validated against the obtained test results and then employed, in the companion paper, for parametric investigations and the assessment of design provisions. Highlights • Laser-welded stainless steel channel sections under combined compression and minor axis bending moment has been studied. • An experimental programme including 15 combined loading tests has been carried out. • Finite element models have been developed and validated against experimental results. [ABSTRACT FROM AUTHOR]

Abstract Following the experimental study and finite element (FE) model validation described in the companion paper, numerical parametric studies and the evaluation of design provisions for stainless steel channel sections under combined axial compressive load and minor axis bending moment are presented herein. The parametric studies were carried out to generate additional structural performance data over a wider range of cross-section aspect ratios and slendernesses, loading combinations and bending orientations. The test data and numerical results have been carefully analysed to develop a comprehensive understanding of the structural performance of stainless steel channel sections under combined compression and minor axis bending moment, and to assess the accuracy of the existing design provisions in Europe and North America. Comparisons of ultimate loads from the tests and FE simulations with the codified resistance predictions revealed that the current design standards typically under-estimate the capacity of stainless steel channel sections under combined compression and minor axis bending moment; this is attributed primarily to the neglect of material strain hardening and the employment of conservative interaction formulae. Improved design rules featuring more efficient interaction curves, anchored to more precise end points (i.e. cross-section resistances under pure compression and bending moment), are then proposed and presented. The new design proposals are shown to yield both more accurate and more consistent resistance predictions over the existing design provisions. Finally, statistical analyses are presented to confirm the reliability of the new design proposals according to EN 1990. Highlights • Parametric studies were carried out to generate further structural performance data. • Design provisions in EC3 and AISC were assessed against test and FE data. • New proposals were made, leading to substantial improvement in resistance prediction. • The reliability of the new proposals was confirmed according to EN 1990. [ABSTRACT FROM AUTHOR]

Highlights • A modified DCB-UBM test rig based on independent torsional actuators is presented. • The proposed rig is stand-alone, compact and high load rated. • Mixed-mode fracture characterization of E-glass/H45 sandwich system is performed. • The interface fracture toughness data is fitted using a phenomenological expression. Abstract A novel double cantilever beam test method for interface fracture toughness characterization of debonded sandwich composites is introduced. The method is called DCB-UBM (Double Cantilever Beam loaded with Uneven Bending Moments), where pure moments are applied to the beams at the crack end using torsional actuators, to generate crack propagation along the face sheet/core interface. A data reduction method is proposed to determine the fracture toughness. Fracture testing is performed on a typical marine grade sandwich configuration consisting of PVC H45 foam core and glass fiber face sheets to demonstrate the applicability of the test method. The obtained fracture toughness agrees with interface toughness values in the literature measured using other test methods with the same material system. The effective kinematics of the test rig is measured using Digital Image Correlation (DIC) by studying the rotations and moments of a specially designed calibration specimen and comparing the results against finite element results. The DCB-UBM specimen and test method is a promising candidate for obtaining face sheet/core interface fracture toughnesses in sandwich composites. [ABSTRACT FROM AUTHOR]

Highlights • Pounding and soil support significantly affects the response of skewed bridges. • Pounding shifts predominant responses to high frequency region. • Having soil support shifts responses to the lower frequency region. • Combining individual effects may differ from considering factors simultaneously. • Omitting effects of any factor can cause underestimation of skewed bridge response. Abstract Some of the factors that are known to significantly affect the seismic response of bridges include bridge pounding and the influence of the supporting soil. For skewed bridges, the skew angle is another crucial factor. Although some studies on this topic have been done, most have been numerical. Experimental work has been scarce. Furthermore, none has considered the factors simultaneously. This study aims to bridge this gap in knowledge by conducting shake table experiments on a straight, 30°, and 45° bridge considering bridge-abutment pounding and soil support, separately and simultaneously. In most cases, the effects of pounding and soil support simultaneously can be seen as a combination of the effects of each factor separately. However, with a 45° skew angle, when pounding and supporting soil were considered separately, the bending moments near the base of the piers were increased compared to the idealised fixed base case without considering pounding. When both factors were considered simultaneously, the opposite was observed. In addition, in the transverse direction, the relative displacement of the girder would always be significantly underestimated if the assumption of fixed base and no pounding was adopted. [ABSTRACT FROM AUTHOR]

Abstract Within the offshore oil and gas industry, the subsea pipelines in riser configuration are the main choice for petroleum transportation till the processing platform. The subsea pipeline is subject to considerable loads ranging from hydrodynamics forces from the sea current to seabed contact forces. Those contact forces are very important in risers design life, since high and concentrated bending moment stresses are observed in the region where the pipeline starts to be supported by the seafloor. The proper representation of the soil behavior in contact with the structure comprises a very important topic of study in subsea pipelines. In this context, a consistent pipeline–seabed interaction model based on Kerr-type foundation is presented. A finite element formulation for the soil, where the stiffness matrix is derived from a variational formulation of a three parameter elastic foundation model, is proposed. The pipeline is modeled as a planar beam undergoing large displacements using a co-rotational approach. The unilateral contact between soil and pipeline is dealt with a step-loading procedure. The proposed model is able to solve problems where the pipeline is initially placed above the foundation surface and subsequent contact with the seafloor is induced by large displacement of the structure. Numerical examples are presented in order to validate the foundation formulation and explore the proposed contact solution between a pipeline and the seabed. A static analysis of a steel catenary riser (SCR) is presented using the proposed soil–structure interaction model. [ABSTRACT FROM AUTHOR]

Overhanging rock instability is a serious geological problem in mountainous regions. The initiation and propagation of a controlling crack are the fundamental causes of overhanging rock failure. In the view of fracture mechanics, the instability of toppling overhanging rock can be equivalent to the effect of pure shear and pure bending moment. This paper analyzes the evolution of displacement-load curves and failure modes of overhanging rock models at different crack lengths, crack angles, and load distances based on fracture tests of the toppling overhanging rock model. Maximum circumferential stress theory is used as the fracture criterion of mixed mode I-II fractures to calculate the stress intensity factor (SIF) of the crack tip and the theoretical failure load of the overhanging rock model. The fracture mode mechanism is analyzed by the calculated SIF. We use the extended finite element method to simulate the crack propagation path and analyze the change process from equivalent stresses of the numerical model using propagation steps. Comparisons between the physical tests, theoretical calculations, and numerical simulations verify the rationality of the experimental results. [ABSTRACT FROM AUTHOR]

The use of rigid inclusions for soil bearing capacity and/or settlement control offers an efficient and economical alternative to the traditional pile foundations. The general approach towards analyzing a slab or a raft foundation on a rigid inclusion system is through the use of unit cell models constructed in programs which incorporate either the finite element or finite difference method. This type of model offers information regarding the interaction of the rigid inclusion with the surrounding soil and with the transfer layer. However, the effect of the inclusions on the global behavior of the slab or raft foundation cannot be anticipated in this manner. As such, three dimensional finite element models are necessary in order to study aspects such as the influence of foundation rigidity and the type and distribution of foundation loading on the bending moments and shear forces that develop in the raft or slab. In this article the results of an analysis of a raft foundation on a rigid inclusion reinforced soil, modelled in the finite element software, Plaxis 3D, are presented and discussed. [ABSTRACT FROM AUTHOR]

Numerical investigation is conducted in this paper on both intact and dented seamless metallic pipelines (diameter-to-thickness ratio D / t around 21), deploying nonlinear finite element method (FEM). A full numerical model is developed, capable of predicting the residual ultimate strength of pipes in terms of bending capacity ( M c r ) and critical curvature ( κ c r ). The simulation results are validated through test results by using the measured material properties and specimen geometry. An extensive parametric investigation is conducted on the influences of material anisotropy, initial imperfection, friction of the test set-up and dent parameters. It is found that the structural response is quite sensitive to the frictions that have been introduced by the test configuration. For a pipe with a considerable dent size, the effect of manufacturing induced initial imperfection is insignificant and can be neglected in the FEM simulation. The material yield stress in the pipe longitudinal direction dominates the bending capacity of structures. In the end, formulas are proposed to predict the residual ultimate strength of dented metallic pipes under pure bending moment, which can be used for practical purposes. A satisfying fit is obtained through the comparison between the formulas and FEM methods. [ABSTRACT FROM AUTHOR]