Influence Of Slenderness Ratio Research Articles

Influence of Slenderness Ratio and Sectional Geometry on the Behavior of Steel braced Frames

Influence of Slenderness Ratio and Sectional Geometry on the Behavior of Steel braced Frames

Limit elastic speed analysis for functionally graded rotating beam

This study aims to determine the limit elastic angular speed of the rotating beam made up of functionally graded material. The speed at which the material yielding is instigated is termed as limit elastic speed. Assuming material distribution as function of power law, modified rule of mixture was used to determine the distribution of material properties and later was used to calculate the effective yield stress for different volume fraction index. A metal matrix of aluminium has been considered with a reinforcement of silicon carbide. The B-spline collocation method has been used to solve the governing equation obtained using the principle of virtual work. This paper outlines the effect of volume fraction on the deformation and stress at limit elastic speed; influence of slenderness ratio on the limit speed was also reported.

A parametric study on influence of slenderness ratio on the nonlinear dynamic behaviour of rotating tapered beams

In the present work, the effect of slenderness ratio on the nonlinear vibration attributes of the rotating tapered cantilever beam in the flap-wise direction is studied. Different variations and combinations of tapered beams like single tapered in depth and breadth direction, unequal and equal double tapered beams are considered for this work. The equations of motion are derived using energy method and subsequently nonlinear governing equations are solved using the framework of minimum potential energy with the help of trail functions. Geometric non linearity caused by large amplitude vibration is considered an iterative algorithm is adopted to solve for the nonlinear governing equations. The results obtained are quite accurate and matching with some available results. Furthermore, the effect of nonlinearity on the vibration attributes of the tapered beams with different combinations for different slenderness ratios being presented. The algorithm which is adopted to solve the problem, takes less computational time and relatively easy to formulate.

Influence of slenderness ratio on the lateral force of a slender body at high angle of attack

The slenderness ratio is an important feature of the slender body, but the effect of slenderness ratio on the lateral force of the slender body at high Angle of attack have not clearly. In this paper, the Detached eddy simulation (DES) method is verified and adopted to simulate the flow of five models with slenderness ratio SR=10, 12.5, 15, 17.5 and 20. The simulation is carried out under the conditions of 15.3m/s incoming flow and 55° Angle of attack. Based on the simulation results, the vorticity magnitude and surface pressure coefficient of the five models are compared. It is concluded that the increase of slenderness ratio will increase the fluctuation cycle of pressure along the axial direction. To further analysed the relationship between pressure distribution and lateral force in different models, the pressure values of multiple sections were extracted and integrated to draw the change curve of unit lateral force coefficient along the X direction. From the analysis of unit lateral force coefficient, the difference of pressure between the two sides induced by asymmetric vortex at the head is the main source of lateral force. The unit lateral force coefficient (Cfzpm ) of the model with small slenderness ratio oscillated more dramatically and attenuated more slowly than that of the model with large slenderness ratio, due to the interaction between the head vortex and the high-pressure region at the bottom of body with a small slenderness ratio at a large Angle of attack. The interaction between the head vortex and the bottom high-pressure region makes the lateral force coefficient of the model with small slenderness ratio not necessarily significantly smaller than that of the model with large slenderness ratio. With the increase of slenderness ratio, the influence of head vortex on the pressure distribution of rear surface decreases, and the asymmetry of rear surface pressure distribution decreases. The conclusion of this paper can help to solve the problem of lateral force coefficient variation that may occur in multistage rocket engineering.

Design of multi-cell T-shaped concrete-filled steel tubular columns under compression and bending

To date, a number of studies have been done on the calculation methods for predicting bearing capacities of multi-cell special-shaped concrete-filled steel tubular (MS-CFST) columns under axial, pure bending, and eccentric load. However, most of the existing methods only apply to a specific combination form of cross-section and have not been established in a unified formulation. In this study, finite element (FE) models were established to predict the performances of the four common combination forms of multi-cell T-shaped concrete-filled steel tubular (MT-CFST) sections subjected to axial, eccentric, and pure bending loads, and verified with the available test data. The parametric analyses were conducted to investigate the effects of steel thickness t, concrete strength fck, steel yield strength fy, aspect ratio of the web c/b, and slenderness ratio λ on the flexural and eccentric compressive performance based on the FE models. The study results demonstrated that the four common combination forms of MT-CFST sections showed the same changing trends of flexural capacity with different parameters, and the flexural capacity rose almost linearly with the increase of the parameters. The parameters (t, fy, fck, c/b, and λ) had a definite effect on the N/Nu-M/Mu correlation curve, especially c/b and λ. Furthermore, by analyzing the stress distribution of mid-span cross-section at ultimate state, the simplified calculation model for asymmetric flexural capacity applicable to different combination forms of MT-CFST section was put forward. The reduction factor of 0.9 for positive flexural capacity (WC) and the restricted width-to-thickness ratio 60235/fy are recommended. Based on the study of the constraint stress of steel tube to core concrete and the concrete constraint region distribution for the columns subjected to compression, the calculation method for predicting the axial bearing capacity applicable to different combination forms of MT-CFST section was proposed. According to the parametric analysis and shape of N/Nu-M/Mu correlation curve, the simplified method for N/Nu-M/Mu correlation curves applicable to different combination forms of MT-CFST sections was developed, which simultaneously took the influence of slenderness ratio into consideration. Besides, the calculation methods for MT-CFST members proposed in this paper have been verified with available test results and FE ones.

An experimental investigation and machine learning-based prediction for seismic performance of steel tubular column filled with recycled aggregate concrete

Abstract This work presents the design and application of a low-cycle reciprocating loading test on 23 recycled aggregate concrete-filled steel tube columns and 3 ordinary concrete-filled steel tube columns. Additionally, a systematic study on the influence of various parameters (e.g., slenderness ratio, axial compression ratio, etc.) was conducted on the seismic performance of the specimens. The results show that all the specimens have good hysteresis performance and a similar development trend of skeleton curve. The influence of slenderness ratio on the seismic index of the specimens is more significant than that of the axial compression ratio and the steel pipe wall thickness. Furthermore, artificial intelligence was applied to estimate the influence of parameter variation on the seismic performance of concrete columns. Specifically, Random Forest with hyperparameters tuned by Firefly Algorithm was chosen. The high correlation coefficients (R) and low root mean square error values from the prediction results showed acceptable accuracy. In addition, sensitivity analysis was applied to rank the influence of the aforementioned input variables on the seismic performance of the specimens. The research results can provide experimental reference for the application of steel tube recycled concrete in earthquake areas.

Role of timber pegs in reinforcing stop-splayed scarf joints

The effectiveness of an all-timber solution, based on the uses of timber pegs, to reinforce stop-splayed scarf joints with transverse key has been investigated in this paper. An experimental program on unreinforced and timber pegged reinforced scarf joints subjected to tensile loadings has been carried out. Two timber pegs made with ash, and having a diameter equal to 20 mm, have been used as fasteners to reinforce the scarf joints.The experimental outcomes have been analysed and critically discussed, focusing on the role of timber pegs in reinforcing scarf joints. Three fundamental aspects have been investigated: load-bearing capacity, ductility and influence of slenderness ratio (between thickness of members and diameter of the peg) due to the introduction of timber pegs. Test results showed that timber pegs provide adequate robustness to the connections because they modified both force-displacement constitutive behavior (increasing load-bearing capacity, stiffness and ductility) and failure mechanisms from brittle to ductile. It has been also proved that greatest slenderness ratios are effective in enhancing the ductility of the connections; thus, at the same thickness of members, pegs with reduced diameters could be preferred in reinforcing scarf joints.From testing, important findings on the qualitative behavior of scarf joints reinforced by timber pegs are emerged, but the reduced number of specimens did not allow conclusive considerations and future investigations will be necessary to support the obtained results.

Experimental and numerical study on eccentric compression properties of laminated bamboo columns with a chamfered section

The eccentric compression behavior of laminated bamboo lumber (LBL) columns with a chamfered section was investigated using eccentricity of 30 mm, 60 mm, 90 mm and 120 mm. The effect of eccentricity ratio on the ultimate bearing capacity, ultimate strain and failure mode was analyzed through eccentric compression tests. The failure modes of LBL columns with different eccentricities were basically same, which belonged to brittle tension failure. With the increase in eccentricity ratio, the ultimate bearing capacity and ultimate strain gradually decreased. The cross-section strain of the specimen was linearly distributed along the height direction, which conformed to the plane section assumption. The lateral deflection curves had similar characteristics under different load levels and could be expressed by sine half-wave curves. Based on the Hill failure criterion, a 3D finite element model was developed to calculate the ultimate bearing capacity of LBL columns with different dimensions under eccentric compression. According to the simulation results and test results, a general empirical formula was proposed considering both the influence of slenderness ratio and eccentricity ratio. The reliability of the proposed formula was verified by comparing the calculated results with the results in the existing literature.

Influence of slenderness ratio and sectional geometry on the axial compression behavior of original bamboo columns

Bamboo has been widely used as a load-bearing material in construction; however, there are limited studies on the stability of slender original bamboo columns. Based on the experimental investigation of thirty-nine original bamboo columns, parametric analyses were conducted to investigate the influence of the diameter–thickness ratio, cross-sectional area and slenderness ratio on the axial compression behavior of original bamboo columns. The test results indicate that the failure modes of the columns are substantially affected by the slenderness ratio and diameter–thickness ratio. For columns with the same diameter–thickness ratio, the ultimate bearing capacity was negatively correlated with the slenderness ratio, and the highest reduction rate for the load-bearing capacity caused by the slenderness ratio was 44.39%. Under the same slenderness ratio, when the diameter–thickness ratio increased by 18.75%, the ultimate bearing capacity increased by 82.65%. An excessive slenderness ratio may result in local buckling, leading to underutilization of the material strength when failure occurs and substantially reducing the load capacity of bamboo columns. Local buckling can be mitigated by decreasing the slenderness ratio and increasing the diameter–thickness ratio. According to the test results, the model predicting the compressive bearing capacity of the original bamboo column was proposed considering the slenderness ratio and diameter–thickness ratio, and it was indicated that the proposed model can provide satisfactory predictive results.

Simulation of Turbulent Flow with High Reynolds Number over an Elliptical Cylinder

A complex turbulent flow with high Reynolds number (Re= 5 × 105, 1 × 106, 2 × 106 and 3.6 × 106) over an elliptical cylinder, is investigated using 2D URANS equations with a standard k-ε turbulence model. The present study compares the effect of various upstream velocity profiles on the variations in flow characteristics along the surface of an elliptical cylinder having variable axis ratios. The comparison of results with the published data for a circular cylinder in cross flow shows the importance of axis ratio and other velocity profiles to reduce the drag force and variation in pressure distribution. Drag force over an elliptical cylinder is found to be lower than that of a circular cylinder. The drag force is seen to increase with increasing slenderness ratio. The drag coefficient of an elliptical cylinder with an axis ratio 0.6 is found to reduce by half as compared to that of a circular cylinder. The influence of slenderness ratio and velocity profile over back pressure recovery, flow separation and shear stress distribution is observed for an elliptical cylinder.

Comparative Study on Axial Compressive Behaviour of CFST and Externally Wrapped CFRP Columns

Concrete column fails by crushing or bucking due to axial load in order to resist failure of confinement, concrete filled steel tubular column (CFST) and carbon fibre reinforced polymer (CFRP) wrapping are used. CFST member has its consecutive progression in the construction industries due to its high load carrying capacity upgraded ductile performance, need for form work is minimized and has greater confinement effect. CFRP wrapping provides resistance towards corrosion, light weight exceptional durability, increases strength over confinement. In this work, an experimental investigation between stunt and slender concrete filled steel tubular column is compared with conventional pcc strut and slender column externally wrapped by single and double layer of CFRP. Total of 8 specimen were tested under axial compression. The parameter varied is height (750mm, 1050mm). The diameter of the column is 75mm. M30 grade concrete is cast. End support condition is hinged. For short column slenderness ratio is 40, L/D is assumed to be 10 and for slender column slenderness ratio is 60 and L/D is assumed to be 14. From this study, the influence of slenderness ratio over an effect of confinement is observed. Maximum axial compressive strength of the column is recorded and it is compared with eurocode4, AS/ACI code, IS516:1959 code. The behaviour of column both experimental and analytical results is observed.

Behavior of three-chord concrete-filled steel tube built-up columns subjected to eccentric compression

An experimental investigation of a series of three-chord concrete-filled steel tube (CFST) built-up columns was conducted under eccentric compression. The influences of slenderness ratio, eccentricity ratio, eccentricity direction, and brace pattern (battened or laced) on the load bearing process, failure modes, and ultimate load-carrying capacities of the specimens were analyzed. The test results indicate that a CFST built-up column exhibits better performance than a corresponding plain steel built-up column. The ultimate strengths and stiffnesses of the three-chord CFST built-up specimens decreased with increasing slenderness ratio or eccentricity ratio. Battened specimens exhibited lower load-carrying capacities than laced specimens, and different load-bearing capacities were obtained for specimens under different directions of compression eccentricity. Using the proposed equivalent slenderness ratio, three existing design codes were evaluated to predict the stability coefficient, and a new correlation equation considering two failure modes is suggested for calculating the ultimate strength of three-chord CFST built-up columns subject to combined compression and flexure.

Comparison of theoretical and analytical investigation on axial compressive behaviour of concrete filled steel tubular columns

Concrete filled steel tubular (CFST) members has its successive footprints in the construction industry, owing to its high load carrying capacity, improved ductile performance, large energy absorption capacity etc. CFST column has its own advantages like maximizing the useable floor area and minimizing the need of formwork. In this research work, experiments are carried out on 8 circular CFST columns with 60 mm diameter and 2.5 mm thickness. The parameters varied are height (960 mm, 900 mm, 840 mm and 750 mm) and the in-filled materials like normal strength concrete and high strength concrete. The study mainly focused on analysing the codal provisions like Eurocode4, ACI and AS codes with the experimental results. From the study, the influence of slenderness ratio over effect of confinement is observed and evaluated. As the codal provision seems to be too conservative in predicting the compressive behaviour of CFST columns, a modified approach is derived. The analytical expression predicted by this simplified method is applicable for CFST columns with L/D ratio varies from 13 to 16.

Discrete lattice fracture modelling of hydrated cement paste under uniaxial compression at micro-scale

A combination of laboratory experiments and numerical simulations at multiple length scales can provide in-depth understanding of fracture behaviour of hydrated cement paste (HCP). To that end, the current work presents a numerical study on compressive failure of hydrated cement paste (HCP) at the micro-scale. Virtual specimens consisting of various phases were obtained using a combination of X-ray computed tomography and image segmentation techniques. The discrete lattice fracture model was used for the deformation and fracture analysis of the specimens subjected to uniaxial compression. The input local mechanical properties of each individual phase were taken from the literature in which a micro-scale compression test was conducted for the calibration of the same type model. The influence of slenderness ratios (1 and 2), water-to-cement ratios (0.3, 0.4 and 0.5 respectively) and lateral confinement of the specimen ends (free and restricted) on the failure behaviour were investigated. It has been shown by the current study that the stress–strain response cannot be completely separated from the used boundary conditions. The proposed model provides an effective tool to understand the compressive fracture behaviour of cement paste at the micro-scale.

Influence of Slenderness Ratio on the Buckling Behaviour of Curved Panels in Pure Shear

ABSTRACTCurved steel plates are commonly used in aerospace and naval engineering, using very thin plates in order to create lightweight structures. In recent years, the use of this kind of plates is extended towards bridge design, with several examples in Belgium. Since bridges have to carry larger loads, the thicknesses of these plates increase up to several centimetres. The decreased plate slenderness influences the buckling behaviour of the plates, leading to elastoplastic buckling. Multiple finite element models are created to investigate the buckling response of these plates. A single plate with simply supported and clamped supported edges are subjected to pure shear. The parameters used are the plate thickness and the curvature ratio in order to have a large spectrum of stability influence. Results show that for the perfect plates the buckling behaviour changes with increasing curvature. With the use of the American Specifications AISI and their specifications for flat plate thicknesses, new rules are determined to predict the buckling behaviour for all kinds of curved panels.

Influence of slenderness ratio on the structural performance of lightweight foam concrete composite panel

In this research paper is reported the analytical and experimental investigations on the influence of slenderness ratio on the structural performance of lightweight foam concrete composite panel (LFCCP). Six full-scale tests of LFCCP panels differing in thickness were implemented under compression load. Compression load strength, load-strain profiles, load-deflection curves, influence of slenderness ratio, deformation, cracking patterns and classic modes of failure under incremental compression loads were analysed and deliberated. Nonlinear finite element modeling (FEM) using commercial software named LUSAS was used to simulate the structural behavior of LFCCP. The calculated ultimate compression strength capacity using empirical formulas established by many researchers, to expect the ultimate strength capacity of composite LFCCP panels were in comparison with the laboratory test results and FEM data attained; thus, a substantial agreement with the FEM data that were obtainable with a reasonable degree of accuracy, presented the increase in slenderness function.

Small size and rotary inertia effects on the natural frequencies of carbon nanotubes

Abstract In the present paper, rotary inertia and small size effects on the free vibration response of single-walled carbon nanotubes are examined. The equations in motion and associated boundary conditions are obtained by using Hamilton’s principle on the basis of modified couple stress and Rayleigh beam theories. The size effect is taken into account by modified couple stress theory while the rotary inertia effect is considered by Rayleigh beam theory. The resulting equations are analytically solved by implementing Navier’s solution technique for pinned-pinned carbon nanotubes. Influences of slenderness ratio, length scale parameter and rotary inertia on the natural frequencies of single-walled carbon nanotubes are studied in detail.

Numerical Analysis of the Ultimate Bearing Capacity of Thin-walled Rectangular-section Columns Using 18Mn2CrMoBA High Strength Steel in Bending and Axial Compression

The ultimate bearing capacity of thin-walled rectangular-section columns (which is welded by channel section steel plate) using 18Mn2CrMoBA high strength steel in bending and axial compression was studied by finite element method. The influence of slenderness ratio, flange width-thickness ratio and section side ratio on the ultimate bearing capacity of member was studied. The calculation method for ultimate bearing capacity of member was proposed on the basis of previous study (which can be found reference document) and many numerical calculation results. Results show that the moment-compression interactive curve changes downward concave from upward bulge with the increasing of slenderness ratio, the ultimate bearing capacity was reduced with the flange width-to-thickness ratio and section side ratio increased, the effects of these parameters were interactive. The proposed calculation formula is in good agreement with the finite element numerical results.

Effects of thermal and shear deformation on vibration response of functionally graded thick composite microbeams

Abstract In this paper, thermal and shear deformation effects on the vibrational response of non-homogeneous microbeams made of functionally graded (FG) materials are carried out. It is assumed that the temperature-dependent material properties of FG microbeams change smoothly and gradually throughout the height according to the classical rule of mixture. The governing differential equations and related boundary conditions are derived by implementing Hamilton's principle on the basis of hyperbolic shear deformation beam and modified couple stress theories and they are analytically solved. The results are given together with other beam theories. A detailed parametric study is performed to indicate the influences of slenderness ratio, material length scale parameter, gradient index, shear correction factors and temperature rise on natural frequencies of FG microbeams. It is revealed that the use of modified shear correction factor can provide more accurate and valid results for first-order shear deformable microbeam model.

Large deformation of uniaxially loaded slender microbeams on the basis of modified couple stress theory: Analytical solution and Galerkin-based method

Large deformation regime of micro-scale slender beam-like structures subjected to axially pointed loads is of high interest to nanotechnologists and applied mechanics community. Herein, size-dependent nonlinear governing equations are derived by employing modified couple stress theory. Under various boundary conditions, analytical relations between axially applied loads and deformations are presented. Additionally, a novel Galerkin-based assumed mode method (AMM) is established to solve the highly nonlinear equations. In some particular cases, the predicted results by the analytical approach are also checked with those of AMM and a reasonably good agreement is reported. Subsequently, the key role of the material length scale on the load-deformation of microbeams is discussed and the deficiencies of the classical elasticity theory in predicting such a crucial mechanical behavior are explained in some detail. The influences of slenderness ratio and thickness of the microbeam on the obtained results are also examined. The present work could be considered as a pivotal step in better realizing the postbuckling behavior of nano-/micro- electro-mechanical systems consist of microbeams.