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Offshore wind turbines, crucial for electricity generation worldwide, face challenges from strong winds, waves, and uneven ocean floors. To address these issues while remaining cost-effective, an innovative foundation is essential. The study introduces a helical monopile with a circular helix made of the same material as the shaft, representing a significant advancement. The study employs both 1 g model experimental tests and numerical simulations (PLAXIS 3D) to explore how changing slope conditions, pile positions, and the inclusion of the helix affects the response under monotonic lateral loading. Factors studied include ground slope angles (flat, 1 V:5H, 1 V:3H, 1 V:2H, and 1 V:1H), pile positions along the slope (c = 0Dp, 2.5Dp, 5Dp, and 7.5Dp), and variations in the number and positions of the helix (Hp) (0.25Lp, 0.5Lp, and 0.75Lp). The investigation involved analyzing the spacing between helices about both the length of the pile (Lp) and the diameter of the helix (dh). The eccentricity to the diameter of pile ratio (e/Dp) is maintained as 12. The main objective is to compare the effectiveness of large-diameter helical piles to conventional monopiles in resisting upward and lateral forces. Results show helical piles offer a 100% improvement in uplift resistance and a 53% increase in lateral resistance compared to monopiles. This significant enhancement in capacity, particularly on sloping surfaces where monopiles typically exhibit reduced performance, underscores the effectiveness of helical piles in enhancing lateral capacity compared to monopiles. [ABSTRACT FROM AUTHOR]

Fibre-reinforced foamed urethane (FFU) composite sleepers and bearers are safety-critical components installed in complex railway switches and crossings. Not only does they need to provide vertical track support, the composite sleepers and bearers must also endure longitudinal and lateral actions stemming from complex wheel and rail interactions. In reality, the railway bearers at crossing noses are susceptible to coupling torsional-flexural loading. The complex non-linear behaviours have never been investigated numerically nor experimentally. It is thus necessary to comprehend torsional-flexural behaviours of FFU composite sleepers and bearers through finite element and experimental approaches. 3D finite element modelling of FFU composite beams have been established to predict the non-linear coupling behaviours. Three specimens of FFU beams have been prepared for robust experiments under each load case. Our studies exhibit excellent agreement between numerical and experimental results. The ductile failure behaviours (post yield point) have been observed from the experiments. Considerable effects of load eccentricity on the flexure–torsion behaviours of the composite members can also be noted. In addition, the load-eccentricity curves have been identified to portray the non-linear behaviour of the railway components under coupling flexural and torsional loadings. The new insights considering their load–displacement relationships, modes of failure and damage, flexural and torsional interactions are the precursors for railway engineers to design and adopt FFU composite sleepers and bearers in practice where complex wheel/rail interface generally causes coupling torsional and vertical loading conditions.

In this paper, a novel methodology is developed for the characterization of the capacity of rectangular-shaped concrete-filled steel tubes (CFSTs). In the scientific research field, of particular interest is the behavior of long CFST columns under eccentric compressive load. These conditions promote failure mechanisms involving global member buckling. The developed methodologies are based on machine learning techniques found on artificial neural networks (ANNs). Furthermore, optimization methodologies, employing the grey wolf optimization algorithm and the firefly algorithm, have been attempted. For the training and validation of the models, a database consisting of 1,641 experimental tests collected from literature sources has been prepared, containing long and short specimens as well as specimens with or without load eccentricity. As the vast majority of the available experimental tests involve short specimens, the database has been augmented with 216 3D finite element models (FEMs), featuring increased member slenderness values. The calibration of the FEMs has been performed against experimental tests. The performance of the developed models has been measured through a number of performance indices, and compared with available code procedures. They have been found to provide significant improvements, both for short and long CFST columns, with the ANN model optimized with the firefly algorithm outperforming the others. Furthermore, a graphical user interface (GUI) has been developed which can be readily used to estimate the axial load capacity of CFST columns through the optimal ANN model. The developed GUI is made available as a supplementary material. [ABSTRACT FROM AUTHOR]

This paper evaluates the behavior and ultimate load that previously identified parameters have on stub and long slender rectangular concrete‐filled double skin tubular (CFDST) columns subjected to eccentric loading. The investigation was performed using FE models that were calibrated and validated to eccentrically loaded experimental responses. A parametric investigation was thereafter conducted on seven parameters to establish the parameter priority on stub and long slender rectangular CFDST columns subjected to eccentric loading. The strong and weak axis minimally affects the parameter priority for a particular slenderness ratio. The investigation revealed that the parameter priority is different for stub and long slender columns. For load eccentricity, lateral curvature, steel strength, outer tube thickness, concrete strength, fixity, and inner tube thickness affect the ultimate load by 60.2%, 14.0%, 8.1%, 8.0%, 4.3%, 3.4%, and 2.1%, respectively, when compared to all parameters. For long slender columns, the load eccentricity, fixity, outer tube thickness steel strength, lateral curvature, concrete strength, and inner tube thickness affect the ultimate load by 70.7%, 10.6%, 6.2% 5.9%, 2.4%, 2.3%, and 2.0%, respectively, when compared to all parameters. [ABSTRACT FROM AUTHOR]

AbstractThe connection of steel elements to concrete is typically achieved through embedded shear connectors (anchors) placed at the interface of concrete and steel. These shear connectors come in various types, such as headed studs, welded or coupled rebars, shear lugs, or a combination of these, designed to handle large shear forces. Shear connectors primarily resist shear forces and bending loads. However, when the load is not applied along the centroid of the shear connector, it generates a torsional moment in addition to shear- and flexure-induced moments, impacting the performance of shear connectors. To address this phenomenon, this experimental study assesses the behavior of shear connectors, including studs, shear lugs, and rebars, both individually and in combination, under three different load eccentricities relative to anchors spacing connectors (0, 0.25, 0.50, and 0.75). The results are then compared with the control specimen (without eccentricity). The findings revealed that vertical shear lugs can significantly enhance the shear capacity, and ACI 318-19 is conservative in this regard by 41.5% for a relative load eccentricity of 0.75. Nonetheless, it gives good estimations of the shear capacity of connectors without vertical shear lugs. HIGHLIGHTSContributing to the very limited data on the performance of anchors under the combined action of shear and torsion.ACI 318-19 [1] provides reliable estimations of shear strength for studs/rebars, both with and without eccentricity. However, it tends to be conservative by 41.5% (for a relative eccentricity of 0.75) when horizontal and vertical shear lugs are utilized.Contributing to the very limited data on the performance of anchors under the combined action of shear and torsion.ACI 318-19 [1] provides reliable estimations of shear strength for studs/rebars, both with and without eccentricity. However, it tends to be conservative by 41.5% (for a relative eccentricity of 0.75) when horizontal and vertical shear lugs are utilized. [ABSTRACT FROM AUTHOR]

Water table elevation leads to saturation of the soil surrounding the foundation. Saturated soil loses its load-bearing capacity due to suction reduction, becoming less stable and more prone to settling. This phenomenon can result in differential settlement, leading to uneven stress distribution on the structure. Over the last few years, substantial research efforts have been dedicated to analyzing the bearing capacity of saturated reinforced sand when subjected to loading at the foundation center, with limited attention given to unsaturated reinforced sand under eccentric loading. Eccentric loading can also result in additional stresses and moments that need to be considered in the design of the foundation to ensure its long-term integrity and functionality, especially when subjected to wetting conditions. Hence, this study investigated this aspect experimentally and numerically using the discrete element method (DEM) to uncover the intricate interactions between soil-reinforcement conditions, applied stress, and wetting-induced settlement. The results reveal that the geosynthetic reinforcement influences the extent of collapse settlement. While the reinforcement reduces collapse settlement, the enhancement is particularly notable when subjected to eccentric loadings. For both semisaturated and fully saturated conditions, the bearing capacity ratio (BCR) not only increases with the number of geosynthetic layers but also exhibits a higher rate for fully saturated sand than for the dry and semisaturated states. Unlike unreinforced sand where load eccentricity increases collapse settlement and differential settlement, reinforced sand experiences reduced settlement as load eccentricity increases. Finally, an empirical relationship by assessing the effect of the interface between the soil and the reinforcement layer was derived from regression analyses to predict the eccentric bearing capacity of strip footing under conditions of upward seepage. Practical Applications: Alterations in pore-water pressure can influence the bearing capacity of shallow foundations. When the ground beneath a foundation reaches complete saturation, the in situ stresses that usually act as confining pressure experience an abrupt decrease. This phenomenon can induce additional settlements, which is very critical in foundation design applications, especially for foundations with eccentric loading, e.g., foundations subjected to wind load. Many shallow foundations are rested on deposits in coastal regions and along riverbanks. The failure due to the accumulation of pore-water pressure occurs when the shear stress applied by the superstructure surpasses the shear strength of the compromised soil. However, in cases where failure does not emerge, there remain issues related to serviceability and the potential for excessive settlement. This research demonstrates that the geosynthetic layers not only enhance the bearing capacity of strip footing but also show a greater improvement for eccentrically loadings in fully saturated sand compared to dry and semisaturated states. [ABSTRACT FROM AUTHOR]

Piled raft foundations (PRFs) below stepped high rise towers are often subjected to non-uniform loads with eccentricities. In this study, twenty five cases of rectangular rafts with different pile configurations and orientations embedded in sand are analyzed using nonlinear three-dimensional finite element analysis. These PRFs are subjected to different triangularly distributed loads and uniformly distributed loads with and without eccentricities. The piled raft responses investigated are the maximum and differential settlements, angular distortion, tilt, load sharing between the raft and the piles, the load carried by the individual piles, and the subgrade modulus (spring constant) at the raft-soil and pile-soil interfaces. The PRF responses are greatly influenced by the distribution of the applied loads and the magnitudes of the load eccentricities. The study provides insights into the PRF behavior under nonuniform and eccentric loads and may help practitioners in making informed design decisions. [ABSTRACT FROM AUTHOR]

This study investigates the ultimate bearing capacity (UBC) of an eccentrically loaded strip footing of width, B, resting above circular dual cavities in the rock mass using the Generalized Hoek–Brown (GHB) yield criteria for the rock mass. The stability number (Ns) is determined using upper and lower-bound finite element limit analysis (FELA), incorporating an adaptive meshing technique. The study considers two configurations: symmetrical and parallel outlines based on the relative positions of the dual cavities and the footing. The effects of the numerous governing parameters, including the load eccentricity (e/B), the vertical distance of dual cavities from the ground surface (δ/B), the spacing between dual cavities (β/B), the uniaxial compressive strength of intact rock, ( σ ci /γB), geological strength index (GSI), and material constant for intact rock (mi) on the Ns are studied. The study finds that the magnitude of e/B significantly affects Ns. For symmetrical outline, Ns improves with increasing δ/B, and the effect of δ/B is insignificant when δ/B ≥ 3, corresponding to β/B = 4 irrespective of e/B. Moreover, Ns increases with β/B for δ/B ≤ 3 and e/B ≤ 0.2. However, the effect of β/B on Ns is insignificant beyond δ/B > 3, irrespective of e/B. For the parallel outline case, the strip footing achieves maximum Ns under centrally placed load (i.e., e/B = 0), regardless of β/B and δ/B values. The study presents potential failure envelopes that might include all representative cases to provide insights into the possible failure mechanism of such foundation systems. [ABSTRACT FROM AUTHOR]

This paper presents an efficient approach for the failure probability assessment of reinforced concrete (RC) columns under the combination of the gravity and seismic loads considering uncertainty in the load eccentricity. In the proposed approach, Limit State Function (LSF) are conditionally formulated for the load eccentricity in column and the conditional reliability index is assessed using Refined First-Order Reliability Method (R-FORM) based on cross-entropy optimization method. The conditional reliability index along with the probability density function of the load eccentricity have been used to estimate the failure probability of the column. The important feature of the proposed approach is precise find of the most probable failure point, which provide a precise estimation of the failure probability of the RC columns under different load eccentricities. The results indicate that the failure probability of the RC columns is sensitive to uncertainty in the load eccentricity as well as of structural system, particularly when the load eccentricity is in the tension failure region. The effect of longitudinal reinforcement varies depending on the probability density function of the load eccentricity and the region of the interaction diagram where the column is loaded.

This study investigates the monotonic and cyclic performance of composite bucket foundation breakwater in clay through centrifuge modeling. The application of monotonic loads simulates extreme wave conditions, and cyclic load corresponds to long-term serviceability conditions. In centrifuge tests, three typical soil strengths were tested, and two load eccentricities were simulated to check the influence of wave force height. Multiple measurements were conducted, including rotation angle, horizontal displacement, vertical settlement, and pore pressure variation. When soil strength increases in monotonic centrifuge tests, the ultimate bearing capacity of the bucket foundation experiences significant growth, and the foundation failure pattern varies. In responding to the monotonic test, the foundation's rotation center constantly moved downward during the loading process, indicating that the deeper soil would be activated to resist the horizontal loading. In contrast, the rotation center movement in the symmetric centrifuge test was opposed to the non-symmetric test because the deeper soil was required to provide resistance to balance the more severe load under the non-symmetric loading condition. It should be noted that non-symmetric loading does not impact the bucket foundation as seriously as symmetric loading. The utilization of deep-soil resistance in non-symmetric tests is beneficial in controlling deformation. [ABSTRACT FROM AUTHOR]

The present study focuses on estimating the transient response of shallow strip footing on granular soil using soft computing techniques. A shallow foundation is numerically modelled using Beam on Nonlinear Winkler Foundation model. Then the footing is subjected to a combination of allowable static and cyclic load depending on the ultimate bearing capacity of the footing. The eccentricity and angle of load inclination of static load are varied to simulate more practical conditions. The cyclic load is rectangular pulse load. One cycle of rectangular pulse load is applied to observe the immediate response of the foundation, referred as the transient response. Apart from the loading parameters, three granular soils of three different relative densities (Dr = 35%, 51% and 69%) are considered. Based on numerical simulation of 1728 conditions, soft computing models are developed using five techniques, viz. Neural Networks, Support Vector Machines, Multivariate Adaptive Regression Splines, Adaptive Neuro Fuzzy Interface System and Multi Gene Genetic Programming. It is found that the static load on the foundation is the most important parameter controlling the transient response of the footing. [ABSTRACT FROM AUTHOR]

The use of nonmetallic reinforcement in concrete aims at the decrease in material consumption by reducing the component sizes when compared to conventional reinforced concrete structures, which inherently results in very filigree structures. Although intensive basic research has been carried out on textile-reinforced concrete for about 30 years, the subject of stability behavior has hardly been investigated so far. This study focuses the fundamental understanding of the structural behavior of slender carbon-reinforced concrete (CRC) structures subjected to axial compression. Therefore, buckling experiments have been carried out in order to quantify the influence of two parameters: the slenderness ratio of the specimens (varying between 60 and 130) and the load eccentricity (0, 2, and 4 mm). The results of the specimens that were tested with the initial load eccentricities revealed a good overall agreement with those obtained by a second-order theory approach throughout all of the investigated slenderness ratios. For the centrally pressed samples that featured high slenderness ratios, the failure stresses could successfully be predicted with Euler's buckling formula, whereas this theory overestimated the results of the specimens with intermediate to low slenderness ratios due to the plastic buckling phenomenon. The presented study emphasizes that the consideration of the stability problem is inevitable when designing material-efficient structures made of textile-reinforced concrete. [ABSTRACT FROM AUTHOR]

Springs are widely used in the automobile industry. They can produce large elastic deformation under the action of load. The fracture failure of springs will cause significant loss or maintenance costs. The fatigue life of springs is greatly affected by load eccentricity and residual stress. Some existing methods are not accurate enough to predict the life of springs. The cracked spring stresses are computed considering load eccentricity. Based on the Walker model, a method for predicting the spring fatigue life is proposed. The model combines the superposition principle and the closure effect, and it can consider residual stress, crack closure effect, and load eccentricity at the same time. The results demonstrate that the improved model has a better performance than the Walker model. Highlights: Load eccentricity is used to correct the critical crack size.Superposition principle is applied to spring life prediction.A spring life model considering crack closure effect and residual stress is proposed.This model is suitable for the fatigue life of coil springs. [ABSTRACT FROM AUTHOR]

This study investigates the monotonic and cyclic performance of composite bucket foundation breakwater in clay through centrifuge modeling. The application of monotonic loads simulates extreme wave conditions, and cyclic load corresponds to long-term serviceability conditions. In centrifuge tests, three typical soil strengths were tested, and two load eccentricities were simulated to check the influence of wave force height. Multiple measurements were conducted, including rotation angle, horizontal displacement, vertical settlement, and pore pressure variation. When soil strength increases in monotonic centrifuge tests, the ultimate bearing capacity of the bucket foundation experiences significant growth, and the foundation failure pattern varies. In responding to the monotonic test, the foundation’s rotation center constantly moved downward during the loading process, indicating that the deeper soil would be activated to resist the horizontal loading. In contrast, the rotation center movement in the symmetric centrifuge test was opposed to the non-symmetric test because the deeper soil was required to provide resistance to balance the more severe load under the non-symmetric loading condition. It should be noted that non-symmetric loading does not impact the bucket foundation as seriously as symmetric loading. The utilization of deep-soil resistance in non-symmetric tests is beneficial in controlling deformation.

An analytical method for determination of a stress condition of butt welded thin-gauge plates with asymmetrical reinforcement is developed. The proposed method allows take into account the effect of the load application eccentricity on the tensile stress concentration factor (SCF) in the weld root zone. It is presented that the bending stresses, caused by this eccentricity, result in increasing the total stresses up to 75%. The results of analytical SCF calculations are in good agreement with the results obtained using the finite element method.

The use of nonmetallic reinforcement in concrete aims at the decrease in material consumption by reducing the component sizes when compared to conventional reinforced concrete structures, which inherently results in very filigree structures. Although intensive basic research has been carried out on textile-reinforced concrete for about 30 years, the subject of stability behavior has hardly been investigated so far. This study focuses the fundamental understanding of the structural behavior of slender carbon-reinforced concrete (CRC) structures subjected to axial compression. Therefore, buckling experiments have been carried out in order to quantify the influence of two parameters: the slenderness ratio of the specimens (varying between 60 and 130) and the load eccentricity (0, 2, and 4 mm). The results of the specimens that were tested with the initial load eccentricities revealed a good overall agreement with those obtained by a second-order theory approach throughout all of the investigated slenderness ratios. For the centrally pressed samples that featured high slenderness ratios, the failure stresses could successfully be predicted with Euler’s buckling formula, whereas this theory overestimated the results of the specimens with intermediate to low slenderness ratios due to the plastic buckling phenomenon. The presented study emphasizes that the consideration of the stability problem is inevitable when designing material-efficient structures made of textile-reinforced concrete.

Distributed fiber optic sensors (DFOS) were used, for the first time, to monitor lateral buckling of a rail under axial loading with different boundary conditions. In the experiments, two types of DFOS systems were used to collect the distributed strain data, and the performance of the two systems was compared. The distributed strain data were used to develop a fitted strain plane at each cross-section along the rail, and axial strain and bending curvature were derived from the fitted strain plane. A data extrapolation method using the distributed curvature data was developed to evaluate the actual boundary conditions at the ends of the rail since they did not match assumed ideal behaviour. The distributed rail deflection along the length of rail was calculated by integrating distributed curvature data and the results were compared with the deflection measured by linear potentiometers (LPs). [ABSTRACT FROM AUTHOR]

In recent years, Concrete Filled Tube (CFT) columns have been very much taken into consideration due to the many advantages of the instrument. In experimental studies, the focus has been on compressive loading. Although in many cases the eccentric loading (the presence of a bending moment) has also been investigated, further research is needed in this regard. Therefore, in this study, the steel columns filled with concrete with a regular octagonal cross section were studied under the influence of pressure axial load with eccentricity. The parameters studied in this study include bearing capacity, coefficient of ductility and energy absorption. To test and compare the stated parameters, specimens of 150 cm height, which were filled with plain concrete and fiber reinforced concrete were tested. The compressive axial load has been applied to the specimens by the eccentricity of 50, 100 and 150 mm. The results show that at pure compressive loading, the increase in concrete core capacity increases the load bearing capacity of the specimens so that by increasing the concrete compressive strength by 50%, the bearing capacity of the cross section increases by about 15%. Also, based on the results, the average ductility coefficient for specimens was 7.4, and it seems that this value is independent of the type of loading. The use of concrete with intermediate grade resistance can increase the energy absorbed. However, according to the results, it seems that by increasing the bending moment the positive effects of the concrete core are greatly reduced.

Piled raft foundations (PRFs) below stepped high-rise towers are often subjected to nonuniform triangular-shaped loads with eccentricities. In this study, 20 rectangular piled rafts with different pile configurations and orientations, embedded in medium-dense sandy soil, are analyzed using three-dimensional nonlinear finite-element (FE) analysis in which the critical state–based Clay and Sand Model (CASM) is used as the soil constitutive model. Different triangularly distributed loads with and without eccentricities are considered in addition to uniformly distributed loads. A systematic parametric study is performed by varying the different design parameters based on which the PRF behavior is systematically investigated in terms of multiple performance parameters such as maximum settlement, differential settlement, angular distortion, tilt, and load distribution between the raft and the piles and between the individual piles. It is observed that the pile diameter, number of piles, and raft plan area control the differential settlement, angular distortion, and tilt the most. Based on the insights gained from the parametric study, a design optimization exercise is performed, in which the most optimal pile configuration is selected based on the criteria of allowable settlement and angular distortion with additional considerations for tilt, load distribution, and the volume of concrete required. [ABSTRACT FROM AUTHOR]

This paper presents an experimental program to study the behavior of short high strength concrete composite columns subjected to either uniaxial or biaxial eccentric loading. The paper also includes a study on a suitable repairing technique for those columns by using carbon fiber reinforced polymers. The experimental program divided into two phases, the first consists of studying the behavior of six high strength reinforced concrete composite columns, three of them subjected to uniaxial eccentric loading as well as the other three subjected to biaxial eccentric loading, while the second phase deals with the behavior of five columns from the first phase after repairing them by carbon fiber reinforced polymers and subjecting them to the same eccentric loading. The main variables were the load direction, the number of sheets of carbon fiber reinforced polymers used and their arrangements. A comparison between the behavior of each column before and after repairing, using different numbers and arrangements of sheets of carbon fiber reinforced polymer layers was made. The comparison showed that wrapping composite steel columns with carbon fiber reinforced polymers is considered a very effective technique for repairing. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of cross-section aspect ratio and the effect of load eccentricity on the behavior of RC short columns with large-scale specimens wrapped with external carbon fiber polymers (CFRP) using finite element. Firstly, to study the effect of cross-section, six models have been conducted with various aspect ratios defined as the depth per the width of the cross-section with a constant number of carbon fiber layers. While the behavior of each aspect ratio in both axial and transverse directions was investigated, the results demonstrate that while the CFRP jackets increase the efficiency of square sections significantly, however, CFRP jacket's effect reduces when cross-section aspect ratio becomes more than 2.0. Secondly, twelve finite element models have been built to study the effect of load eccentricity on the behavior of RC short columns wrapped with external CFRP. The results showed that external confinement can significantly increase the strength of columns under concentric loading, while the enhancement in columns under eccentric loading is not the same. [ABSTRACT FROM AUTHOR]

In this paper the stability of a cantilever two-member column made of an aluminum host rod and a discretely mounted piezoceramic rod is discussed. Both rods are connected to each other at the column's free end by an ideally rigid mounting head. Knowing that in practical engineering it is impossible to achieve an ideal axiality of the load application and that the assembling of structure components may lead to an unintended mounting inaccuracy, the presence of the unintentional eccentricity of the axial load is taken into considerations. To prevent prebuckling of the column, the piezo rod is proposed to be mounted discretely with an offset distance in regard of the host column. Next, the static deflection and the internal axial force distribution are determined to estimate how the electric field application modifies the static behavior of the system resulting originally from the external force loading. During numerical calculation, the offset distance and the eccentricity of the external load are taken as control parameters to prove that piezo actuation is efficient for suppressing column's deformation when the external eccentric load is relatively small. It is also shown that column deflection may be reduced, reverted and even its rectilinear shape may be recovered. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the use of compact tension specimen calibration curves for evaluation data of fracture properties measurement performed on modified compact tension specimen made from cement based composites. From literature, the well-known calibration curve for compact tension specimen is compared with calibration curves for Modified compact tension specimen that are obtained from numerical calculation. The obtained results are quantified and accuracy of solution is discussed. The suggested curves could be preferably used for determining of the fracture parameters.

Abstract The study investigates the effect of eccentric load on the stability and postcritical states of thin-walled CFRP channel section columns under compression. Test specimens are subjected to compression on a testing machine provided with a fixture for applying eccentric compressive loads. Loading forces, deflection and strains of the column walls and web are measured. The experiments also involve examination of the operating performance of a structure undergoing buckling and determination of its postcritical equilibrium paths describing the relationship between load and deflection. Based on experimental results, numerical models of composite structures are designed and verified by the FEM. The scope of the numerical analysis involves performing a linear analysis of stability, which allows for determining the buckling mode depending on the amplitude of compressive load eccentricity and corresponding critical loads. The next stage of the analysis involves performing a nonlinear analysis of the structures with implemented geometric imperfections reflecting the lowest buckling modes. Based on obtained results, postcritical equilibrium paths of the developed FEM models are determined. Obtained equilibrium paths are then compared with experimental characteristics of real structures. The numerical results and experimental findings show a satisfactory agreement. [ABSTRACT FROM AUTHOR]

The sewing needle of the industrial sewing machines is an essential element. Its’ target is to penetrate the sewn fabric layers by a penetrating axial compressive force, which, coincides with the sewing needle geometrical axis. Author wise, it will cause stress on the needle’s cross section. Practically, there is always a shift – eccentricity- between the effective action line of the force and the sewing needle geometrical axis. In the present work a mathematical approach has been carried out to study the mathematical relationship between the eccentricity ecr2 and the penetration force (Pa), taking into consideration the critical load (Pcr) (Euler load) of the sewing needle. This relationship is named the “Secant formula”, where it was computerized and graphed. It was found that; the limiting values for the ecr2 was 0.7 and for the ratio Pa/Pcr was 0.8 to make the needle to run in its design stress 538 MPa (steel). When the ratio Pa/Pcr was equal to unity, the sewing needle max stress σmax changed from 101 MPa to 58 GPa i.e. the working penetration force Pa must be far enough from the critical load by about 20%. The required value of Pa must be equal or less than 0.8 Pcr. This work focused on the static case.

Loading tests on model horizontal grounds and slopes are performed using a 100-mm-wide strip footing with restrained and free-rotation conditions. Test results reveal that complete restraint against rotations on the footing generates larger values of ultimate bearing capacity and deeper failure surfaces than those for footings with a free-rotation condition. This is true for horizontal and slanted grounds with various slope angles. Test results also reveal that for a vertically loaded footing, a major factor that influences the ultimate bearing capacity of the footing (qu) is the load eccentricity (ec) at the footing base. The influence of load inclination on the values of qu for free-rotating and fixed footings is minor because the load inclination angles measured during the loading tests were negligibly small. In the case of a footing placed on a slanted ground, a load eccentric toward the heel of the footing is associated with a larger value of qu than that for a load eccentric toward the toe of the footing when subjected to similar extents of load eccentricity. This observation suggests that the currently used formula for correcting load eccentricity (ec) has to be updated in order to address the issue of increased qu induced by a load eccentricity toward the heel of the footing. [ABSTRACT FROM AUTHOR]

Abstract In evaluating the ultimate bearing capacity (q u) of a strip footing adjacent to a slope, conventional correction formulas for the effect of load eccentricity may not be applicable because these formulas were developed exclusively for footings situated on horizontal grounds, where loads eccentric to opposite sides of the footing yield identical results for q u. In this study, loading tests and analyses are conducted on a strip footing placed adjacent to a model slope with various slope angles. The experimental evidence shows that a load eccentric toward the heel of a footing leads to an increase in bearing capacity, whereas the analytical results based on conventional formulas show the opposite trend. To address this discrepancy, an approach is proposed that uses a bearing capacity correction formula for a footing with a setback from the crest of the slope. Results of a comparative study show that the experimental values for bearing capacity factor N γ(test) , with full corrections for load inclination, load eccentricity, and footing setback are comparable to the theoretical solutions. Furthermore, fully corrected values for N γ(test) for the fixed footing approximately follow the line of the upper boundary; those for the free-rotating footing follow the lower boundary of the theoretical solutions reported in the literature. This discrepancy is due to the different failure mechanisms induced by the restraining conditions of the footing which have yet to be considered in engineering practice. [ABSTRACT FROM AUTHOR]

The ultimate buckling strength of axially loaded cold-formed lipped channel columns is studied. Variations of boundary conditions and eccentricities of the applied load are considered. The strength is calculated by a geometrically and materially nonlinear FEM analysis. Numerical study is carried out for two columns previously analysed under fixed boundary conditions and centroidal load. Geometrical imperfections in the shapes of eigenmodes of the corresponding linearized buckling problem are assumed. For comparing the imperfections their sizes are set to a uniform level of an energy measure. Particularly the worst eigenmode imperfection is determined for each studied design case. By the corresponding lowest collapse loads the effects of varying boundary conditions and load eccentricities on the ultimate buckling strength of the columns are shown. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the use of compact tension specimen calibration curves for evaluation data of fracture properties measurement performed on modified compact tension specimen made from cement based composites. From literature, the well-known calibration curve for compact tension specimen is compared with calibration curves for Modified compact tension specimen that are obtained from numerical calculation. The obtained results are quantified and accuracy of solution is discussed. The suggested curves could be preferably used for determining of the fracture parameters. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the effect of the recently developed corner strip-batten (CSB) technique on rectangular columns strengthened with carbon fiber-reinforced polymer (CFRP) sheets. In this technique, fiber-reinforced polymer (FRP) battens do not experience any curvature in confining the section, but are stretched as completely flat strips similar to flat coupons. For this purpose, 12 rectangular reinforced concrete (RC) columns, each with a cross section of 110 x 160 mm (4.33 x 6.30 in.) and a height of 500 mm (19.69 in.), were subjected to load eccentricities of 0, 30, 90, and 120 mm (0, 1.18, 3.54, and 4.72 in.). Results showed that the CSB technique improved the performance of rectangular specimens in terms of both axial strength and ductility. However, comparison of the results obtained in the authors' previous experimental study on square RC columns revealed that the improvement (that is, load-carrying capacity and ductility enhancement) gained with rectangular specimens was not as prominent as that obtained with square ones. Finally, comparison of the experimental axial load-bending moment (P-M) interaction diagrams for the strengthened columns and those obtained from the expressions suggested in such different codes as ACI 440.2R, fib Bulletin 14, and CNR-DT 200 R1, showed that the estimates of the codes were conservative when compared to experimental results. [ABSTRACT FROM AUTHOR]

• Experimental study into the load carrying capacity of straw bale wall assemblies. • Characterised and compared the vertical load carrying performance without and with plaster coatings. • Studied the effect of wall height, plaster use, and load eccentricity on compressive resistance. • Results from 29 wall tests presented. To reduce the significant carbon emissions associated with construction materials, there is growing recognition of the potential for bio-based resources, including materials derived from agricultural crops such as straw, hemp and flax. The biogenic carbon stored with plant based materials can significantly reduce carbon emissions compared to other products. Uses of bio-based materials are however generally limited to non-structural, in particular as insulation, but in contrast to many other solutions straw bales can also be used structurally in low-rise construction. Despite the use of straw bales for over 100 years there is still relatively little known about their compression performance, and there are no recognised guides or standards to support structural engineers. This paper describes an experimental study into the load carrying capacity of straw bale wall assemblies. In keeping with practice in the UK, and different to previous North American studies, the wall plates do not directly bear onto the plaster coats. The aim of the paper is to characterise and compare the vertical load carrying performance of straw bale walls without and with plaster coatings, and study the effect of wall height, plaster use, and load eccentricity on compressive resistance. A series of wall assemblies were built from stacking 1 m long wheat straw bales. Wall assembly heights varied with the number of bale courses: one, two, three and four bales high. In total results from 29 tests are presented. Key findings of the study concern the influence of load eccentricity, use of plaster and wall geometry on compression performance. In the absence of national guidance, the results of this experimental study will support structural engineers designing loadbearing straw bale walls. [ABSTRACT FROM AUTHOR]

The new method of the reliability calculation of buildings and structures’ earth foundations based on limited statistical information on controlled parameters in the operation stage is considered. The reliability is calculated by criterion of foundation deformations (settlement) in the presence of load eccentricity of the foundation and using possibility distribution functions for the description of fuzzy variables. New approach to the reliability calculation of a foundation bed is offered with describing eccentricity characteristic as random variable by the probability distribution law and properties of soil – by the possibility characteristic. The way for determination of eccentricity value of load on the foundation bed by measurement of deformations in the foundation material at the expense of unloading the part of the foundation on the area with resistance strain gages is considered. Reliability as the probability of failure-free operation of the foundation is characterized by the interval with minimum and maximum values.

Application of carbon fiber-reinforced polymer (CFRP) composites has been promoted successfully for strengthening or repairing concrete structural members. However, if a column member is strengthened with longitudinal FRP sheets in which fibers are laid parallel to the column axis, the FRP composite will soon buckle under compression to ultimately debond off the concrete surface. It is the objective of the current research to investigate the effect of the recently developed grooving method (GM) on cylindrical specimens strengthened with FRP sheets under compressive loading, and to determine whether GM postpones the buckling of FRP sheets and their debonding off the concrete substrate. For the purposes of this study, 35 cylindrical reinforced concrete specimens, 150 mm in diameter and 500 mm in height, were tested under compressive loading with eccentricities of zero, 30, 60, and 90 mm. The specimens were additionally subjected to the fourpoint flexural bending test to represent infinity eccentricity. Fiber-reinforced polymer (FRP) sheets with longitudinal fibers parallel to the column axis were installed using the conventional externally bonded reinforcement (EBR) and grooving method, taking advantage of the special technique of externally bonded reinforcement on grooves (EBROG). Experimental results revealed that the grooving method was much more effective than the EBR in increasing the load-carrying capacity of the specimens. Moreover, it was found that longitudinal fibers exhibited an enhanced effect with increasing load eccentricity. The results showed that in the columns strengthened with longitudinal FRP strips using the EBROG method, the load-carrying capacity enhancements of 8.3, 12.2, 25.8, 36.0, and 53.3% relative to those of the controls were achieved for 0, 30, 60, 90 mm, and infinity eccentricities, respectively. [ABSTRACT FROM AUTHOR]

The ultimate bearing capacity of an eccentrically loaded strip footing above twin square tunnels buried in rock masses was examined using the generalized Hoek-Brown (GHB) yield criteria. To get reliable findings, the stability assessments were carried out using finite element limit analysis (FELA) code in combination with a sophisticated adaptive remeshing approach. Case studies with two different tunnel layouts, parallel and symmetrical, were examined. Comprehensive parametric analyses were given to demonstrate the effect of load eccentricity, rock mass strength parameters, and tunnel position on the stability of the strip footing. The visualized results of the FELA programme were presented to show how the failure mechanism would change with different influential factors. Moreover, the results were validated by comparing them to earlier investigations. [ABSTRACT FROM AUTHOR]

Nonlinear finite-element (NLFE) calculations were used to compare and optimize the load transfer and failure mode of precast and cast-in-place bridge barriers subjected to transverse loads on bridge deck overhangs. The NLFE calculations were validated by successfully simulating the behavior of concrete barriers anchored to bridge deck overhangs and submitted to static transverse loading. The behaviors of three different barrier configurations—a normal concrete cast-in-place barrier, high-performance fiber-reinforced concrete (HPFRC) precast barriers, and HPFRC precast barriers with barrier-to-barrier connections—anchored to slab overhangs were accurately simulated with NLFE models. The validated models were then used to investigate the impact of the fiber orientation in the HPFRC precast barriers, the effect of the precast barrier length, the eccentric load application, and the utilization of a HPFRC slab overhang. The fiber orientation of the HPFRC precast barriers was shown to be well oriented to resist the applied overturning moment. The adequate performance of 4-m-long precast barrier modules commonly used in actual industrial projects was confirmed, although the reduced loadcarrying capacity of a smaller 2-m-long precast barrier with shear keys also surpasses the design requirements. The precast barrier length was as critical to the structural performance as an eccentrically applied load. The HPFRC slab allowed the reduction of crack spacing and crack-opening widths and increased the rigidity and load-carrying capacity of the bridge deck overhang. [ABSTRACT FROM AUTHOR]

The sewing needle of the industrial sewing machines is an essential element. Its’ target is to penetrate the sewn fabric layers by a penetrating axial compressive force, which, coincides with the sewing needle geometrical axis. Author wise, it will cause stress on the needle’s cross section. Practically, there is always a shift – eccentricity- between the effective action line of the force and the sewing needle geometrical axis. In the present work a mathematical approach has been carried out to study the mathematical relationship between the eccentricity ec r 2 and the penetration force ( P a ) , taking into consideration the critical load ( P cr ) (Euler load) of the sewing needle. This relationship is named the “Secant formula”, where it was computerized and graphed. It was found that; the limiting values for the ec r 2 was 0.7 and for the ratio P a / P cr was 0.8 to make the needle to run in its design stress 538 MPa (steel). When the ratio P a / P cr was equal to unity, the sewing needle max stress σ max changed from 101 MPa to 58 GPa i.e. the working penetration force P a must be far enough from the critical load by about 20%. The required value of P a must be equal or less than 0.8 P cr . This work focused on the static case. [ABSTRACT FROM AUTHOR]

Blockhaus structural systems are obtained by assembling multiple timber logs able to interact with each other by means of simple mechanisms (e.g. contacts, tongues and grooves, and carpentry joints, also referred to as ‘corner’ joints). Although these systems have ancient origins, the structural behaviour of Blockhaus systems under well-defined loading and boundary conditions is still complex to predict. The paper focuses on the assessment of the typical buckling behaviour and resistance of in-plane compressed timber log-walls. The effects of various mechanical and geometrical aspects such as in-plane rigid inter-storey floors, load eccentricities, different types of lateral restraints, openings (e.g. doors or windows) or additional metal stiffeners, are investigated by means of full-scale buckling experiments. Results are then critically discussed and preliminarily assessed via analytical formulations taken from classical theory of plate buckling and column buckling. Although further advanced studies are required for the development of a generalized buckling design method, it is shown that several mechanical and geometrical aspects should be properly taken into account to correctly predict the structural capacity of Blockhaus systems under in-plane compression. [ABSTRACT FROM AUTHOR]

Highlights: [•] Buckling experiments are performed on laminated glass columns. [•] Effects of load eccentricity are experimentally, analytically and numerically investigated. [•] Influence of imperfections, temperature, time-loading on their buckling response is analyzed. [•] Viscoelastic numerical models provide good correlation with test results. [•] Equivalent thickness approaches can be used to correctly predict the critical buckling load. [Copyright &y& Elsevier]

Purpose – The paper aims to present an experimental testing program regarding reinforced concrete slabs, with and without shear reinforcement, submitted to punching under both symmetric and eccentric loading. Comparisons between numerical simulations and experimental behaviour results are carried on. The capabilities and limitations of the numerical model to reproduce the brittle punching-shear failure are discussed. Design/methodology/approach – The paper opted for a performance assessment of a numerical model, comparing FEM results with known experimental tests properly instrumented. Capability of DIANA software to simulate the punching behaviour of slabs is discussed. Findings – The paper demonstrates that the mechanical properties assigned to the element layer containing the bending reinforcement impose the load deflection stiffness behaviour. Good agreement was found between the predicted and the observed deformation behaviour. Nevertheless, the reproduction of the punching ultimate capacity is strongly dependent on the adopted value for the shear retention factor, which appears to be the major decisive parameter. Originality/value – This paper demonstrates that the smeared crack model based on both the concept of strain decomposition (SD) and total strain with fixed orthogonal cracks approach (TSF) can correctly be used for the analysis of the behaviour of slabs submitted to punching shear. [ABSTRACT FROM AUTHOR]

Abstract: In order to correctly model the behavior of slender columns made of lightly reinforced concrete (RC) subjected to buckling load, both tensile fracture and compressive damage should be taken into account. In this work, we propose to consider both failure types as cohesive cracks, governed by a bilinear cohesive law for traction or a linear-decreasing softening equation for compression. Since the columns are lightly reinforced, we assume only one single crack is to propagate at the column central section. The resulted two-dimensional FEM model is implemented in a commercial software for large deformations to take into account geometry changes in each iteration. The model is validated against experimentally obtained results. In addition, parametric studies are carried out to study the sensitivity on slenderness ratio, reinforcement ratio and concrete compressive strength. Good agreement for the comparison with both experimental data and ACI code is achieved. Due to its simplicity, the developed model provides a useful tool for the design of structural elements. [Copyright &y& Elsevier]