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In drilling and completion operations, a packer is a downhole tool to seal the annular space between various sizes of string and borehole. As a key component of packer, slip plays a role of fixed support in the process of setting, thus ensuring a long-term stable sealing of the packer. Aiming at the problem of damage caused by casing pressure on the slip after setting, based on the stress analysis of slip during setting, the slip material with hardness lower than casing was selected, and its finite element analysis model was established. Then, the pressure-bearing law of the slip teeth under three tooth parameters was analyzed. The results of analysis were as follows. With the increase of the number of slips or the distance between teeth or tooth top angle, the strain of slips decreased, but the bending moment of slips increased. At the same time, orthogonal test method was used to optimize the parameters of the slips. The conclusion is that the tooth top angle is 90 degrees, the distance between teeth is 6 mm and the number of teeth is 16, which is the best combination of compressive effect. It will provide a reference for improving the long-term effectiveness of the packer seal in drilling and completion engineering. [ABSTRACT FROM AUTHOR]

The application of carbon nanotubes (CNTs) to improve postbuckling characteristics of T-section nanocomposite strut is the subject of this research. A solution procedure according to the layerwise theory along with the first-order shear deformation theory (FSDT) by taking into account the von Karman geometrical nonlinearity is proposed. Nonlinear governing equations are developed in regard to the minimum total potential energy principle, and solved by the aid of the Rayleigh–Ritz method in conjunction with Newton–Raphson method. A comprehensive parametric study is conducted to provide an insight into effects of CNT volume fraction and dispersion, geometrical parameters and boundary conditions on the bifurcation points and paths, in-plane displacement, normal stress and strain, and bending moment of T-section nanocomposite struts. A three dimensional finite element analysis using the ABAQUS commercial software is carried out to verify the obtained results, which shows close agreement. Results indicate that dispersion of CNTs plays a dominant role in bifurcation behavior of nanocomposite struts. The results also show that volume fraction of CNTs has a significant effect on the load-carrying capacity of open section nanocomposite struts. The results of this research shed light into using ultra-high-strength and light-weight open section nanocomposite struts for civil and aerospace applications. • Buckling strength of nanocomposite strut can be increased by proper CNT distribution. • Bending moment at junction of web and flange shows very complex behavior. • Distribution of the stress and strain strongly depends on the CNT dispersion. • Proposed methodology is effective in reducing computational costs and storage requirements. [ABSTRACT FROM AUTHOR]

This paper presents an evaluation of the design rules for the bending moment–shear force (M − V) interaction of cold- and hot-formed square, and rectangular hollow steel sections (SHS & RHS). More specifically, the design rules, as provided by EN1993-1-1 regarding RHS and SHS of section class 1 and 2 are covered for the steel grades S235 up to and including S460. A 4-point bending test was simulated by means of a finite element model, which was validated on the basis of experimental tests from existing literature. A parametric study was performed and numerical M − V interaction results were compared to the provisions in EN1993-1-1. This comparison indicates that the current design rules in EN1993-1-1 regarding M − V interaction are conservative and overestimate the reduction of the bending resistance due to the presence of shear. Alternative design rules for the shear area and M − V interaction of RHS and SHS are proposed and evaluated by means of a statistical assessment procedure based on existing literature and EN1990-1-1. Both newly developed design rules are shown to ensure an adequate reliability level when a partial safety factor equal to 1 is used. • Evaluation of the design rules for the M − V interaction of RHS and SHS. • An alternative design rule is proposed. • The proposed shear area matches the numerical results for all tested sections. [ABSTRACT FROM AUTHOR]

The assembling rivet-fastened rectangular hollow flange beam (ARHFB) is a new type of cold-formed steel beam. The ARHFB section has two rectangular hollow flanges formed by U-shaped and C-shaped components that connected by self-locking rivets. A finite element model is developed to simulate 16 four-point bending experiments. Details of the modeling including finite element meshing, loading and boundary conditions, contact and analysis methods are presented. The accuracy of the developed finite element model is verified by comparing the ultimate moment capacity, applied load versus deflection curves, bending moment versus deflection curves, strain versus deflection curves and failure modes obtained from the tests and the finite element analysis. Based on the validated finite element model, a parametric analysis is carried out to discuss the effects of rivet spacing, section depth, flange thickness, and web thickness on the bending performance of ARHFB. The moment capacities of these sections obtained from the parametric study are compared with predictions from Australia and New Zealand, Chinese design standards for cold-rolled sections and the DSM (Direct Strength Method). It is found that GB50018 can conservatively predict the bearing capacity of ARHFB with a large error, while AS / NZS 4600 and DSM (Direct Strength Method) cannot provide reliable prediction results. • A novel assembling rivet-fastened rectangular hollow flange beam (ARHFB) is analyzed in finite element model. • An extensive parametric investigation using a verified finite element model is conducted. • The feasibility of current design codes for ARHFBs is evaluated and judged. [ABSTRACT FROM AUTHOR]

This study presents experimental and numerical research on the dynamic behaviors and resistances of square concrete-filled steel tubular members internally strengthened by I-shaped CFRP profile (SCFST-CFRP) with fixed boundary conditions subjected to lateral impact loads. Dynamic impact tests were conducted on five SCFST-CFRP specimens and a traditional concrete-filled steel tubular (SCFST) specimen, examining their dynamic responses with respect to deformation modes, impact force, displacement, and strain distribution at different levels of impact energies and impact momentums. The test results indicated that the deformation of the specimens was concentrated in the impact region, approximately 0.38 L above the base, due to the transient localized characteristics of the lateral impact load. In terms of displacement and impact force, the SCFST-CFRP member exhibited better impact resistance compared to the SCFST member. Finite element models of the SCFST-CFRP members were created using LS-DYNA and validated against the impact tests. These validated models were then utilized to explore the damage patterns, dynamic bending moment, and load transfer mechanism of the SCFST-CFRP member under lateral impact loading. Additionally, a parametric study was conducted to evaluate the effects of load and structural parameters, including CFRP profile, impact energy, and impact momentum, on the impact resistance and dynamic flexural capacity of the SCFST-CFRP member. The results demonstrate that the enhancement in impact resistance caused by the inner CFRP profile was more significant under higher impact energy. Based on the parametric analysis results, empirical equations were proposed to predict the dynamic flexural capacity of lateral impact-loaded SCFST-CFRP members. • Impact tests of CFST member strengthened with CFRP profile under fixed boundaries. • Evolutions and distributions of deformation and internal force were summarized. • Impact load transfer mechanisms of the composite member were revealed. • Effects of load and structural parameters on the impact resistance were evaluated. • An equation for the dynamic flexural capacity of the composite member was proposed. [ABSTRACT FROM AUTHOR]

This paper presents a novel mechanical model for seismic response analysis of vertical shafts. The model is based on elastic foundation beam theory and simplifies the shaft linings as parallel Euler Bernoulli beams. Their interaction is simulated using uniformly distributed springs. The governing differential equation for shaft vibration is derived for SH wave excitation. The seismic input motion is applied to the primary lining by converting the free field displacement into harmonic form. The closed-form solutions for seismic response of both primary and secondary linings are obtained via the transfer function method. The accuracy of analytical solution is validated by comparing with finite element analysis results. Additionally, the impact of foundation stiffness, secondary lining thickness, shaft outer diameter, and relative stiffness between linings on seismic response are investigated in the parametric analysis. The analytical solutions of the seismic response analysis of vertical shafts indicates that the relative stiffness between linings significantly affects the secondary lining's peak bending moment. Furthermore, higher stiffness of the elastic connection layer between the two linings can effectively reduce the peak displacement response of the secondary lining. [ABSTRACT FROM AUTHOR]

Over the past decade, the previous hysteretic recognition of the fire threat to bridges has provoked significant progress in understanding the fire performance of bridges. However, despite the growing maritime shipment of combustibles, scarce studies have contributed to evaluating the safety of steel cable-stayed bridges subjected to under-girder ship fires. Limited existing knowledge is still based upon the less precise temperature curve method and flame geometry modeling. This study developed an advanced numerical method to more accurately evaluate the response of steel cable-stayed bridges subjected to ship fires. First, the computational fluid dynamics (CFD) approach was used to reproduce realistic fire conditions. An efficient thermal boundary, adiabatic surface temperature, was then transferred to the thermal finite element model of affected girder segments for calculating the temperature propagation. Lastly, this paper used the multiscale structural finite element method to incorporate the local performance variation of exposed girders into the response of the entire bridge. The proposed method was validated by predicting a thermomechanical response of the steel beam exposed to realistic underneath fires, agreeing well with the data from two large-scale structural fire experiments by NIST. Based on the method, the response of a typical steel cable-stayed bridge subjected to ship fires was simulated. Results show that fires can introduce local damage to the girder segments above the fire and alter the internal force distribution of the entire bridge. The bending moment of the girder sections over the fire significantly increases, and the flexural characteristic of pylons is also altered. Both thermal convection and radiation contribute to the temperature increment, and the latter dominates at the locations above fires. Adopting temperature curves can overestimate or underestimate the fire impact, introducing uncertainties to the safety of steel cable-stayed bridges in ship fires and can cause unrealistic stress concentration on the border of heated and unheated domains of exposed floors. The developed advanced method is more competent in capturing the inhomogeneous temperature and stress distribution. • CFD fire models were coupled with FEM for steel cable-stayed bridges in ship fires. • Thermal radiation governs the heat absorbed by the girder floor exposed to ship fires. • Temperatures of the girder floor propagate from the central region to the periphery. • Ship fires bring local damage to the girder and alter the entire structural behavior. • CFD-FEM method is more competent than traditional temperature-curve methods. [ABSTRACT FROM AUTHOR]

Thanks to the axial resisting contribution, inclined screw connections offer a mechanical advantage over connections with purely transversely loaded fasteners. However, the strong coupling between the axial and the transversal behaviour of the screw makes it challenging to predict the actual connection behaviour. Moreover, the presence of polyurethane interlayers for soundproofing or OSB interlayers of light-frame buildings between main members may increase the bending moment component interacting with the axial force in the screw, thus reducing the connection failure load. This paper experimentally assesses the behaviour of steel-to-timber connections, and a parametric finite element model of Winkler non-linear beam is presented and validated. Finally, a simplified analytical model for capacity prediction is presented. The results of the approach currently provided by the Eurocode 5, of an additive model and the proposed analytical model, are then compared with the results of 500 finite element analysis. • Timber-to-steel connections with soundproofing and OSB interlayers are tested. • Interlayers reduce slip modulus more than strength. • Non-linear beam on foundation model is suitable for screws connections. • Bending moment interacts with axial force reducing the connection capacity. • An elementary capacity model is validated on 500 finite elements analysis results. [ABSTRACT FROM AUTHOR]

Non-uniform elements, such as non-prismatic and those made from composite materials, are commonly used in structures. This is because the variation in their internal forces makes uniform elements less effective to withstand the external loads. This paper presents the formulation of the Green's Functions Stiffness Method (GFSM) for the static analysis of non-uniform Euler–Bernoulli frames subjected to arbitrary external loads and bending moments. The GFSM is a mesh reduction method that combines the strengths of the Stiffness Method (SM) and the Finite Element Method (FEM) with those of Green's functions, resulting in an analytic method for obtaining closed-form solutions of reticular structures. As a particular case, the GFSM is closely related to the Transcendental Finite Element Method (TFEM), which allows to obtain closed-form solutions from an implementation of the latter by only making changes at the post-processing stage. Two examples are provided with the analysis of a beam and a plane frame. Additionally, two appendices are included with the particularization of the GFSM for some specific non-uniform elements, and general stepped elements. • Closed-form solution of non-uniform Euler–Bernoulli frames. • New numerical method closely related to the Finite Element Method. • Decomposition of the structural response as a homogeneous and a fixed one. • The fixed response is obtained using Green's functions of fixed elements. • Closed-form solutions for arbitrary external forces and bending moments. [ABSTRACT FROM AUTHOR]

This work aims to solve the problem that plastic instability occurs in large-scale flat ring rolling and the geometry accuracy is hard to control due to the bending moment in the radial deformation zone exceeds its ultimate bending moment, i.e. the plastic bending moment. An analytical calculation model is put forward to design the feed strategy in large-scale ring rolling process to avoid ring plastic instability. In this analytical model, the effects of ring diameter revolution, cross-section shape variation including thickness and end surface on ring plastic instability are considered, and finally are combined in an optimized stiffness condition. The radial-axial feed coordinated strategy for a large-scale flat ring with 5 m diameter deduced from the analytical model was submitted to finite element method (FEM) simulation. The shape of the ring cross-section in the deformation zone, the variation of the ring diameter and the rolling force obtained by the analytical model and the numerical simulation are compared to verify the accuracy of the analytical model. Numerical simulations and trial production have shown that this coordinated feed strategy can avoid plastic instability in ring rolling, which effectively improves the geometry accuracy of rolled ring in large-scale ring rolling. This study is valuable for achieving low cost and high accuracy in rolling of large-scale ring. [ABSTRACT FROM AUTHOR]

This paper focuses on the electromagnetic vibration and its reduction in PM brush dc motors. First, the air gap flux density distribution and the radial force density distribution are derived in detail, and compared with the results of the finite element method. Next, two types of vibration sources, called pulsating force and bending moment, are analyzed. Then, two passive improvement methods, called varied PM pole width in axial direction and copper ring, are proposed to reduce the magnetic forces and their vibration, and their principles of the vibration reduction are described in detail. For further explanation, a rotor-skewed motor is used for comparison, and the radial force on the motor is discussed and the influence of four different thicknesses of copper ring on the motor vibration is analyzed. Finally, three 2p/24s sample motors are manufactured and the experimental vibration results confirm the analysis and the proposed improvement technique. [ABSTRACT FROM AUTHOR]

• The ultimate strength of a tubular structure subjected to a bending moment is analysed. • Three specimens are designed for the experimental test. • The moment-curvature and the stress-strain relationship of the tested specimens are studied. • The tested specimens are also evaluated based on the finite element method. • The results of the finite element analysis and the experiments are compared and discussed. The objective of the present work is to analyse the ultimate strength of a tubular structure subjected to a bending moment. The tubular monopile structures are experimentally tested as well as the nonlinear finite element analysis is performed. Three specimens are designed for the experimental test by taking into consideration the typical ranges of the monopile support structures used in offshore wind turbines. The moment-curvature and the stress-strain relationship of the tested specimens are studied. The tested specimens are also evaluated numerically based on the finite element method employing a nonlinear FE analysis. The finite element analysis accounts for the nonlinearities associated with the geometry and material. The geometrical imperfections are introduced to the structure together with the initial stress arisen in the process of fabrication. The results obtained from the finite element analysis and the experimental tests are compared to each other and discussed. [ABSTRACT FROM AUTHOR]

With the continuous construction of 500 m concrete-filled steel-tube (CFST) arch bridges such as the Bosideng Yangtze River Bridge and the Hejiang Changjiang Highway Bridge, the deviation between the dead pressure line and the arch axis produced by extant arch axis optimization methods increases. Therefore, an arch axis optimization method for long-span CFST arch bridges with a truss section must be designed. Following the optimization of the truss arch axis, this study develops the minimum section eccentricity method that aims to optimize the arch axis of long-span CFST arch bridges. To minimize the main tube eccentricity of the truss arch, the bending moment of the main tubes is reduced by applying the main tube eccentricity method iteratively in a finite element model. Afterward, a smooth and reasonable arch axis is fitted by applying a cubic spline interpolation function in MATLAB. The entire optimization procedure is performed using the Bosideng Yangtze River Bridge as an example. Compared with that of optimal arch axis line types (e.g., parabola and catenary) and other traditional arch axes, the bending moment of main tubes optimized by the proposed method is substantially lower and more uniformly distributed along the arch axis span. The mechanical properties of the finished bridge, including its strength, stiffness, and stability, are all improved, thereby verifying the feasibility of using the proposed method to optimize the arch axis of CFST arch bridges with a truss section. [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]

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]

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]

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]

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]

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]

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]

The most commonly and popular type of bridge used in Nepal is T beam bridge due to it's simple in design, construction and maintenance than other types. T-beam Bridge comprises of a concrete slab integral with girders. This type of bridges is more preferred when it comes to connectivity to short distances. So, it is necessary to update the analysis and design methods. Here, in this paper, there is an attempt to study the comparison of maximum bending moment due to live load in a girder and slab bridge for varying span length as 15m, 20m and 25m respectively of T Beam bridge using conventional method. The same bridge is analyzed as a three-dimensional model in finite element software as SAP2000, apply the same loading done for conventional methods and compared the results. The maximum bending moment results obtained from finite element model are lesser than Courbon's method which looks more conservative. [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]

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]

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]

• 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]

present work it is pretended to estimate elastic parameters of beams through the combined use of precision geomatic techniques (laser scanning) and structural behaviour simulation tools. The study has two aims, on the one hand, to develop an algorithm able to interpret automatically point clouds acquired by laser scanning systems of beams subjected to different load situations on experimental tests; and on the other hand, to minimize differences between deformation values given by simulation tools and those measured by laser scanning. In this way we will proceed to identify elastic parameters and boundary conditions of structural element so that surface stresses can be estimated more easily. [ABSTRACT FROM AUTHOR]

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Bending is one of the most common forms of deformation that may cause failure of a structural member, such as a column, especially when the member is exposed to fire. Fire resistance design is therefore an important factor that must be considered in the design process of modern building structures. Based on the authors' previous work on the unified formulation of axially loaded CFST hollow and solid columns with circular and polygonal sections, a unified formula for calculating the ultimate bending moment of solid and hollow CFST columns at room temperature is proposed first in this paper. The formula is then extended to include elevated temperature using the average temperature method. Finally, a unified formula for both room and elevated temperature are presented. Validations are carried out through comparisons with the results from experimental tests and finite element simulations. [ABSTRACT FROM AUTHOR]

This paper provides an engineering assessment of an oval-shaped clad pipes with a circumferential part-through surface crack subjected to bending moment based upon equivalent stress-strain relationship method (ESSRM) in conjunction with EPRI J -estimation procedure. Plastic limit load equations are developed specially to determine the equivalent stress-strain relationship of the welded clad pipe. Then, the conventional EPRI J -estimation procedure is extended to calculate J values of the equivalent configuration with oval cross-section converted from the welded clad pipe using the ESSRM. The validation of the ESSRM/EPRI estimation framework mentioned in the above is carried out by comparing with the results obtained from 3-D elastic-plastic finite element (FE) analysis. [ABSTRACT FROM AUTHOR]

The formulation of an Euler-Bernoulli beam finite element with spatially varying uncertain properties is presented. Uncertainty is handled within a non-probabilistic framework resorting to a recently proposed interval field model able to quantify the dependency between adjacent values of an interval quantity that cannot differ as much as values that are further apart. Once the interval element stiffness matrix is defined, the set of linear interval equations governing the interval global displacements of the finite element model is derived by performing a standard assembly procedure. Then, the bounds of the interval displacements and bending moments are determined in approximate explicit form by applying a response surface approach in conjunction with the so-called improved interval analysis via extra unitary interval. For validation purposes, numerical results concerning both statically determinate and indeterminate beams with interval Young's modulus are presented. [ABSTRACT FROM AUTHOR]

The cracked chevron notched semi-circular bending (CCNSCB) method for measuring mode I fracture toughness of rocks has many favorable properties similar to those of the notched semi-circular bending (NSCB) method, which has been suggested by the International Society for Rock Mechanics (ISRM). In this study, the lengths of fracture process zones (FPZs) in the NSCB and CCNSCB tests with representative specimen geometries were theoretically estimated using the maximum normal stress criterion, and their effects on these fracture toughness tests were evaluated according to the effective crack model. The CCNSCB method was found to be less affected by the existence of FPZ and the measured fracture toughness was not that conservative as that using the NSCB method. Furthermore, even relatively small-size CCNSCB specimen could obtain the fracture toughness value that might require the use of a much larger sample size in the NSCB method. Subsequently, to further verify these theoretical results, laboratory tests using a total of 36 CCNSCB and NSCB specimens of three different sizes were conducted. For the same specimen size, the NSCB test always produced conservative fracture toughness value compared with the CCNSCB test. Additionally, even the toughness value measured using the NSCB specimen with a 75 mm radius was still lower than that using the 25-mm-radius CCNSCB specimen. Given the experimental and theoretical results, the CCNSCB method is demonstrated to be less influenced by the presence of FPZ than the NSCB method for mode I fracture toughness measurements. [ABSTRACT FROM AUTHOR]

In the paper, the results of an experimental and numerical study on the out-of-plane bending effectiveness of a modern strengthening technique applied to existing masonry walls are presented. The technique consists in the application, on both wall faces, of a mortar coating reinforced with glass fiber-reinforced polymer (GFRP) meshes. Four point bending tests of full scale masonry samples (1000 width, 3000 mm height) were carried out considering three types of masonry (solid brick, 250 mm thick, rubble stone and cobblestones, 400 mm thick). The performances of plain and reinforced specimens were analysed and compared. It emerged that strengthened specimens are able to resist out-of-plane bending moments almost 4–5 times greater than those of plain specimens; moreover they can overcome deflections more than 25 times higher, due to the presence of the GFRP mesh, which contrasts the opening of cracks. The cracking and the ultimate bending moments of reinforced samples can be analytically predicted using relationships quite close to those used in the design of reinforced concrete beams subjected to combined axial and bending actions. The results of nonlinear static analyses performed on a 2D numerical model were also presented, so to comprehend the mechanical behaviour of reinforced masonry walls. Their agreement with the experimental results proved the reliability of the simulations; moreover, the extension of the 2D model to a 3D one, necessary to analyze the behavior of perforated walls, was also made. [ABSTRACT FROM AUTHOR]

With the purpose to characterize the behavior of a transfer slab system, a slab-wall full-scale specimen was designed, build and tested to cyclic loads in the Laboratory of Structures at UAM. The prototype slab-wall was subjected to three load patterns: 1) gravitational load; 2) horizontal load only; and 3) a combination of gravitational and lateral loads. The specimen consists of a masonry wall placed on top of a squared two-way slab of 4.25 m by side, thickness of 12 cm, on four reinforced concrete beams. The most important results presented herein are the resistance capacity of the slab supporting a load-bearing wall subjected to vertical and horizontal load. Analytical finite element slab-wall models were used. [ABSTRACT FROM AUTHOR]

This paper offers an actuating equation for MFC arc-plate structures to obtain MFC's accurate actuating force and actuating bending moment to are-plate structures and increase MFC control effect on vibration. This paper proposes the P1 type MFC arc-plate actuating equation which considers the recombination action of MFC and controlled structure, and arc-plate curvature influence on MFC, obtaining the MFC actuating force and actuating bending moment for arc-plate structures. The vibration control experiment of MFC arc-plate structures is performed, and the deviation between finite element simulation results adopting this equation and the experimental data is less than 8.5 %. The research shows that the P1 type MFC actuating equation deduced in this paper is correct and fully applicative to the MFC vibration control simulation to arc-plate structures. [ABSTRACT FROM AUTHOR]

The first objective of this research is to indicate the steps that are necessary to generate an exact non-circular (Lancert type) helix geometry as an alternative to the widely used approximate geometrical functions obtained by exploiting exact circular helix geometry. A parametric analysis is performed in order to determine the range of the geometric parameters in which the approximate geometry is insufficient to provide the precision required by exact geometry. This investigation is considered important since the validity of approximate helix geometry is satisfied in a limited range of geometric parameters. The exact conical helix geometry is based on associated plane curves, namely either the Archimedean spiral or logarithmic spiral. The second objective of this research is to determine the necessary conditions to use the Archimedean spiral and logarithmic spiral to supply nearly the same geometry of the conical helix. The final aim is to compare the numerical performance of curved mixed type finite elements with straight displacement type elements over exact conical helix geometry. This is based on the Archimedean spiral. For this purpose, static and free vibration analyses are performed. Curved mixed finite element formulation is based on Timoshenko beam theory which considers shear angle and rotary inertias. The degrees of freedom at a node is twelve: three translational displacements, three cross-sectional rotations, three force components, two bending moments and torque. Approaching the exact geometry of the conical helix with approximate geometry assumptions is only possible under some limitations of the taper ratio and the number of active turns of the conical helix. In free vibration analysis, the mixed-curved elements are considerably faster than straight displacement type elements. In the case of static analysis, convergence performance the two different FE formulations differ in terms of boundary conditions. [ABSTRACT FROM AUTHOR]