Influence Of Slenderness Ratio Research Articles

Experimental and numerical investigation on frame structure composed of steel reinforced concrete beam and angle-steel concrete column under dynamic loading

This paper describes experimental and numerical investigations on two specimens of frames composed of steel reinforced concrete beam and angle-steel concrete column under horizontal low cyclic loading. Based on the test results, the relationship curves of the horizontal load-displacement and the failure modes are acquired. Meanwhile the hysteretic behaviors, skeleton curves, stiffness degradation, energy dissipation, residential deformation of the two specimens are studied. Nonlinear structural analysis program OpenSEES is employed to predict the experimental curves. Using the verified numerical model, the influences of slenderness ratio, axial compression ratio, steel ratio of column, cross-section moment resistance of I-shaped steel in beam, ratio of longitudinal rebars of beam and prestressing level on skeleton curves are investigated. The results indicated that the two specimens exhibited the favorable ductility and energy dissipation capacity, and the beam depth could be reduced to improve service function because of the application of the prestress. The ultimate horizontal load decreases with the increase of column slenderness ratio, and firstly increases then decreases with the increase of axial compression ratio. In the meantime, the descent segment of skeleton curve is smooth with the increase of column slenderness ratio, and becomes steeper with the increase of axial compression ratio.

The Influence of Slenderness Ratio and Stress Concentration in Taps on Load Calculations to Thermal Expansion in U-shaped Compensators of Thermal Network

This article is about calculations of U - shaped regions of water heat network. The universal calculation algorithm is used for various geometric schemes and simple self-compensating pipeline sections. The influence of slenderness ratio and stress concentration factor in the smooth curved bends on voltages and maximum permissible flight compensated shoulders of U - shaped regions for different geometric configurations was taken into account in this work.

Finite Element Simulation on Behavior of the High-Strength Concrete Filled High-Strength Square Steel Tube Middle-Long Columns under Axial Compressive Load

In this paper, using ABAQUS, 16 high-strength concrete filled high-strength square steel tube middle-long columns’ axial compression process were simulated. The load-deflection relationships were obtained and the new combination in improving the bearing capacity and plastic deformation has a great advantage. Realization of length variation slenderness ratio by changing the length of column, this paper also study the influence of slenderness ratio, the main parameters of the high-strength concrete filled high-strength square steel tube middle-long column. It is found that both bearing capacity and the plastic capacity are associated with slenderness ratio.

Behaviour of concrete-encased CFST columns under combined compression and bending

The performance of concrete-encased CFST column under combined compression and bending is studied in this paper. A finite element analysis (FEA) model is developed to analyse the behaviour of the composite column, and generally good agreement is achieved between the measured and predicted results in terms of the failure mode, the load-deformation relation and the ultimate load. Typical failure modes, full-range response of load-lateral deflection relation, loading distributions of the inner CFST and the outer RC components, the contact stress between the steel tube and the concrete of the composite columns are analysed. The influence of slenderness ratio and loading paths on the composite columns are also investigated. Influence of parameters, such as the strength of concrete and steel, steel ratio of CFST, longitudinal bar ratio and diameter of CFST on the sectional capacity of the concrete-encased CSFT columns is analysed based on the FEA model. A simplified model is proposed to calculate the sectional capacity of concrete-encased CFST columns under combined compression and bending.

The Influence of Slenderness Ratios of Multi-Hole Ceramic Filters from S<sub>F</sub> - 1.67 to S<sub>F </sub>- 8.36 of Filter Surface on Efficiency of Liquid Steel Refining from Non-Metallic Phase

We propose in this publication the introduction of new, additional definition describing the multiple orifice ceramic filters used in research works on the liquid steel filtrations, calling this the filter slenderness ratio. In order to confirm the theoretical assumptions we have performed a series of the laboratory scale experiments (for the filter slenderness ratio SF - 1.67 to SF - 8.36). The influence of the filter slenderness on the filtration process efficiency has been determined through variations in quantities and surface shares of the non-metallic phase in the filtrated steel in relation to the non-filtered steel. We present also the results of researches on the separating surfaces between the liquid steel and the ceramic filter material, which in form of photos and scanning microscope microanalyses are put together in the publication.

Vibration analysis of elastically restrained double-walled carbon nanotubes on elastic foundation subjected to axial load using nonlocal shear deformable beam theories

In the context of nonlocal continuum theory, seeking an analytical solution to the equations of motion of stocky double-walled carbon nanotubes (DWCNTs) with arbitrary boundary conditions is a very problematic task. Thereby, proposing efficient numerical techniques for frequency analysis and optimal design of such nanostructures is of great advantageous. Herein, free transverse vibration of an elastically supported stocky DWCNT embedded in an elastic matrix under initial axial force is of interest. To this end, the equivalent continuum structures (ECSs) associated with the innermost and outermost tubes are taken into account. The interaction of the DWCNT with its surrounding matrix is modeled using lateral and rotary continuous springs. Through consideration of interlayer van der Waals forces via an equivalent spring system, the two tubes are appropriately interacted. Using Hamilton's principle, the dimensionless equations of motion of elastically supported DWCNTs are established using nonlocal Rayleigh, Timoshenko, and higher-order beam theories. The unknown fields of the equations of motion for each model are discretized in the spatial domain using reproducing kernel particle method. After tedious calculations, the set of eigenvalue equations pertinent to each model is extracted and numerically solved. The convergence checks of the proposed numerical models in predicting flexural frequencies of DWCNTs are carried out. The obtained results are also compared with those of other works and a reasonably good agreement is achieved. Through various numerical studies, the influences of slenderness ratio, ratio of the mean radius to the thickness of the ECSs, small-scale parameter, initial axial force, lateral and rotational stiffness of the surrounding matrix on the flexural frequencies of stocky DWCNTs are carefully examined for different boundary conditions. The capabilities of the proposed nonlocal models in capturing the flexural frequencies of stocky DWCNTs are discussed as well.

Study on Accumulated Ductility Coefficient of Concrete Filled Steel Tubular Columns Based on Experimental Results

The hysteretic behaviors of concrete filled steel tube columns under low cyclic loads were analyzed for verification the accumulated energy dissipation performance. The accumulated ductility coefficient influencing factors, such as slenderness ratio, axial compression ratio and sectional steel ratio, were analyzed. It is indicated that these columns have a better energy dissipation capacity. The energy dissipation capacity decreases with the axial compression ratio increasing, but the influence of slenderness ratio and steel ratio to accumulated ductility coefficient is not clear, this is because the influence of difference loading system.

Buckling of timber columns exposed to fire

A mathematical model for structural behavior of timber columns under fire has been proposed. The semi-analytical study has been carried out for evaluating the load-carrying capacity of timber columns exposed to fire. Particular emphasis has been given to critical buckling loads. For this purpose, a parametric study has been performed by which the influence of slenderness ratio, load level, and water content on critical buckling loads of timber columns have been investigated. The results of this preliminary study showed that the present semi-analytical method is conservative compared to the two simplified calculation methods offered by Eurocode 5 if the transfer of water is neglected, while, on the other hand, the results agree well for a water content of 12%. Moreover, for higher water contents, the present semi-analytical model is non-conservative compared to the Eurocode 5 methods.

Plastification procedure of laterally-loaded steel bars under a rising temperature

This paper investigates the structural responses of axially restrained steel beams under fire conditions by a nonlinear finite element method. The axial restraint is represented by a linear elastic spring. Different parameters which include beam slenderness ratio, external load level and axial restraint ratio are investigated. The process of forming a mid-span plastic hinge at the mid-span under a rising temperature is studied. In line with forming a fully plastic hinge at mid-span, the response of a restrained beam under rising temperature can be divided into three stages, viz. no plastic hinge, hinge forming and rotating, and catenary action stage. During catenary action stage, the axial restraint pulls the heated beam and prevents it from failing. This study introduces definitions of beam limiting temperature <TEX>$T_{lim}$</TEX>, catenary temperature <TEX>$T_{ctn}$</TEX> and warning time <TEX>$t_{wn}$</TEX>. Influences of slenderness ratio, load level and axial restraint ratio on <TEX>$T_{lim}$</TEX>, <TEX>$T_{ctn}$</TEX> and <TEX>$t_{wn}$</TEX> are examined.

Fiber-Reinforced Polymer-Confined Circular Concrete Columns: Investigation of Size and Slenderness Effects

Laboratory investigations of the compressive behavior of fiber-reinforced polymer (FRP)-confined concrete columns have generally been carried out using relatively small-scale specimens, and the majority of theoretical models that have been developed so far are based on test data from such specimens. However, the use of small specimens may conceal possible scale effects. In this study, the influence of slenderness ratio and specimen size on axially loaded FRP-confined concrete columns was investigated experimentally, and the results have been compared to theoretical models and experimental results gathered from the published literature. The investigation aims to validate past results obtained from concrete cylinders and to verify existing empirical models as well. Three different specimen diameters and two slenderness (length-to-diameter) ratios, combined with two FRP-confinement materials, were varied as parameters. According to the statistical analysis of the results, it is shown that conventional FRP-confined concrete cylinders can effectively be used to model the axial behavior of short columns. Size effects, however, are clearly evident in very small (≈50 mm diameter) specimens. The usefulness of published results involving such small-scale specimens is therefore questionable, as is the validity of theoretical models and strength predictions based on test data from small-diameter specimens.

Nonlinear vibrations of Timoshenko pipes conveying fluid

This paper presents a finite element approach for nonlinear vibration analysis of Timoshenko pipes conveying fluid. An approach using the concept of fictitious loads to account for the kinematic corrections was applied to establish the finite element model, without the need to establish the nonlinear equations of motion. Computation of system responses was carried out by iteratively updating the nodal coordinates until convergence was reached. The formulation and implementation of the approach were verified first by comparing the analysis results with those available in the literature for the case of both slender and short beams undergoing static large deformations and the case of flow induced vibration of a slender cantilever pipe with supercritical flow speeds. Limit cycle and its associated vibration amplitude for the flow induced vibration problem were discussed. Further analysis was conducted for assessment of the effects of flow speed and fluid/pipe mass ratio on the limit cycle vibration amplitude. The influence of slenderness ratio on the limit cycle amplitude was also reported.

Failure of steel columns in fire

Results of an analytical study of the performance of geometrically perfect steel colymns under fire conditions are presented. The analysis was based on the finite strip method and includes non-linear material characteristics as functions of temperature. Results obtained using different models of such functions are compared, demonstrating very significant variation in predicted behaviour. The influence of slenderness ratio was studied and shown to be a major factor controlling the failure temperature, whilst the effect of residual stress levels on column failure is little different from that at ambient temperature. Local buckling behaviour was also investigated. The results suggest that this mode of failure may be rather more critical for columns in fire than at ambient temperature. The effect of partial protection provided by blocking-in the column web was investigated. This shows that although there is relatively little improvement in failure temperature, significantly longer survival times are achieved using this form of construction. Although the study is not comprehensive, some useful indications are provided for future generation of practical design rules.

Ultimate Strength of RC Wall Panels in One‐Way In‐Plane Action

Test results of 24 reinforced concrete wall panels in one-way in-plane action are presented. The panels were loaded at a small eccentricity to reflect possible eccentric loading in practice. Influences of slenderness ratio, aspect ratio, vertical steel, and horizontal steel on the ultimate load are studied. An empirical equation modifying two existing methods is proposed for the prediction of ultimate load. The modified equation includes the effects of slenderness ratio, amount of vertical steel, and aspect ratio. The results predicted by the proposed modified method and five other available equations are compared with 48 test data. The proposed modified equation is found to be satisfactory and, additionally, includes the effect of aspect ratio which is not present in other methods.