scholarly journals A Nonlocal Model for Carbon Nanotubes under Axial Loads

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Raffaele Barretta ◽  
Francesco Marotti de Sciarra
Keyword(s):  
Axial Load ◽  
Constitutive Law ◽  
Nonlocal Model ◽  
Axial Loads ◽  
Load Distributions ◽  
Variational Framework ◽  
Nonlocality Effect ◽  
Gradient Type ◽  
Constant Axial Load ◽  
Beam Theories

Various beam theories are formulated in literature using the nonlocal differential constitutive relation proposed by Eringen. A new variational framework is derived in the present paper by following a consistent thermodynamic approach based on a nonlocal constitutive law of gradient-type. Contrary to the results obtained by Eringen, the new model exhibits the nonlocality effect also for constant axial load distributions. The treatment can be adopted to get new benchmarks for numerical analyses.

scholarly journals A Numerical Investigation on Behavior of Column Base Plates with Different Configurations

2018 ◽  
Vol 4 (6) ◽  
pp. 1223 ◽  
Author(s):  
Mohamadreza Shafieifar ◽  
Vahid Khonsari
Keyword(s):  
Stress Distribution ◽  
Axial Load ◽  
Design Procedure ◽  
Load Level ◽  
Stress Distributions ◽  
Axial Loads ◽  
Different Types ◽  
Base Plates ◽  
Constant Axial Load ◽  
Column Base

Base plates are one of the most important types of connections in structures. Due to complicated steel-concrete interaction, simple assumptions of the stress distributions are usually employed for designing the connection. Simple assumptions of compressive stress distribution in concrete may accelerate the design procedure, but they may lead to overdesign results. In this study, six different types of base plates with different configuration were studied numerically using a commercial Finite Element (FE) software and the numerical model was calibrated with an experimental test. The models were subjected to a constant axial load and then a monotonic moment loading was applied. To investigate the effects of the axial load, several axial load level were considered for each configuration. As a result, moment-rotation curves of these base plates, including their rotational stiffness, in the absence and presence of the axial loads, were compared. Moreover, the stress distribution in the concrete was studied in the FE models. For all cases, the stress distribution in the concrete was semi-triangular with the maximum stress between the column flange and the edge of the plate. Based on numerical results, some concepts of simplified assumptions were proposed to find the stress distribution of the base plates. These assumptions are more realistic than current assumptions in structural specifications.

Experimental Behaviour of Self-Consolidating Concrete (SCC) Filled Hollow Structural Steel (HSS) Columns Subjected to Cyclic Loadings

2005 ◽  
Vol 8 (5) ◽  
pp. 497-512 ◽  
Author(s):  
Lin-Hai Han ◽  
Jing-Tuan You ◽  
Xiao-Kang Lin
Keyword(s):  
Structural Steel ◽  
Axial Load ◽  
Load Level ◽  
Axial Loads ◽  
Normal Concrete ◽  
Self Consolidating Concrete ◽  
Flexural Loading ◽  
Test Parameters ◽  
Constant Axial Load ◽  
Very High

The present paper is an attempt to study the cyclic behaviours of self-consolidating concrete (SCC) filled hollow structural steel (HSS) columns. The test parameters include the sectional types, the strength of concrete and steel and the axial load level ( n). Eighteen self-consolidating concrete filled hollow structural steel (SCCHSS) column specimens, including 10 specimens with circular sections and 8 specimens with square sections were tested under constant axial load and cyclically increasing flexural loading. It was found that, in general, SCCHSS columns exhibit very high levels of energy dissipation and ductility, particularly when subjected to high axial loads. The features of SCCHSS columns under constant axial load and cyclically increasing flexural loading are similar to those of normal concrete-filled HSS columns. Comparisons are made with predicted column strengths and flexural stiffness using the existing codes such as AIJ-1997, AISC-LRFD-1994, BS5400–1979 and EC4–1994.

scholarly journals Improved design criterion for frictionally engaged contacts in overrunning clutches

2021 ◽  
Author(s):  
Nadine Nagler ◽  
Armin Lohrengel
Keyword(s):  
Design Process ◽  
Contact Area ◽  
Axial Load ◽  
State Of The Art ◽  
Tangential Force ◽  
Design Criterion ◽  
Hertzian Contact ◽  
Loss Of Function ◽  
Axial Loads ◽  
Improved Design

AbstractOverrunning clutches, also known as freewheel clutches, are frictionally engaged, directional clutches; they transmit torque depending on the Freewheel clutch rings’ rotation directions. The torque causes a tangential force in the Hertzian contact area. The hitherto “state-of-the-art design criterion” bases on this load situation. In practice, axial loads additionally act on the frictionally engaged Hertzian contact area. This additional axial load can cause the loss of the friction connection and so the freewheel clutch slips. This publication presents an improved design criterion for frictionally engaged contacts in freewheel clutches. It allows to consider tangential as well as axial loads during the design process. Additionally, it offers the possibility to estimate the probability of frictional engagement loss and gross slip based on the freewheel clutch’s application scenario. This publication points out how to use the improved design criterion to design freewheel clutches that are more robust against a loss of function.

scholarly journals Results of theoretical and experimental studies on determining the coefficient of subgrade reaction of sleepers for the conditions of main railways with axial loads of 30-35 tons per axle

2018 ◽  
Vol 230 ◽  
pp. 01003
Author(s):  
Oleksandr Darenskiy ◽  
Eduard Bielikov ◽  
Olexii Dudin ◽  
Alina Zvierieva ◽  
Anatolii Oleshchenko
Keyword(s):  
Sustainable Development ◽  
Reinforced Concrete ◽  
Axial Load ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Railway Track ◽  
Rolling Stock ◽  
Subgrade Reaction ◽  
Axial Loads ◽  
Interaction Dynamics

The article considers obtaining numerical values of the coefficient of subgrade reaction of wooden and reinforced concrete sleepers with axial loads up to 30-35 tons per axle. It has been concluded that using the rolling stock with axial loads of up to 35 tons per axle is necessary in order to ensure sustainable development of the railway complex. The performance of the railway track thus should be investigated in order to predict its operation in such conditions. Generally, such studies are performed using numerical methods. One of the parameters that are required for such calculations is the parameter which is commonly called the coefficient of subgrade reaction. Empirical dependencies of the coefficient of subgrade reaction of wooden and reinforced concrete sleepers on the axial load and on the operating conditions of the track have been obtained. The obtained results can be used in studies of the interaction dynamics of the track of main railways with rolling stock with axial loads of 30-35 tons per axle, which will give an opportunity to provide well-grounded recommendations on the rules for the arrangement and maintenance of the track in such conditions.

scholarly journals On Bending of Bernoulli-Euler Nanobeams for Nonlocal Composite Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Luciano Feo ◽  
Rosa Penna
Keyword(s):  
Differential Equation ◽  
Order Differential Equation ◽  
Scale Parameter ◽  
Elastic Equilibrium ◽  
Functionally Graded ◽  
Constitutive Law ◽  
Bending Moments ◽  
Innovative Methodology ◽  
Governing Differential Equation ◽  
Nonlocality Effect

Evaluation of size effects in functionally graded elastic nanobeams is carried out by making recourse to the nonlocal continuum mechanics. The Bernoulli-Euler kinematic assumption and the Eringen nonlocal constitutive law are assumed in the formulation of the elastic equilibrium problem. An innovative methodology, characterized by a lowering in the order of governing differential equation, is adopted in the present manuscript in order to solve the boundary value problem of a nanobeam under flexure. Unlike standard treatments, a second-order differential equation of nonlocal equilibrium elastic is integrated in terms of transverse displacements and equilibrated bending moments. Benchmark examples are developed, thus providing the nonlocality effect in nanocantilever and clampled-simply supported nanobeams for selected values of the Eringen scale parameter.

Experimental Behavior of Nonconforming RC Columns with Plain Bars under Constant Axial Load and Biaxial Bending

2013 ◽  
Vol 139 (6) ◽  
pp. 897-914 ◽  
Author(s):  
M. Di Ludovico ◽  
G. M. Verderame ◽  
A. Prota ◽  
G. Manfredi ◽  
E. Cosenza
Keyword(s):  
Axial Load ◽  
Biaxial Bending ◽  
Rc Columns ◽  
Experimental Behavior ◽  
Plain Bars ◽  
Constant Axial Load

Seismic Evaluation of Existing Reinforced Concrete Building Columns

1996 ◽  
Vol 12 (4) ◽  
pp. 715-739 ◽  
Author(s):  
Abraham C. Lynn ◽  
Jack P. Moehle ◽  
Stephen A. Mahin ◽  
William T. Holmes
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Lateral Displacement ◽  
Concrete Columns ◽  
Vertical Load ◽  
Seismic Evaluation ◽  
Severe Damage ◽  
Reinforced Concrete Columns ◽  
Concrete Building ◽  
Constant Axial Load

Past earthquakes have emphasized the vulnerability of reinforced concrete columns having details typical of those built before the mid-1970's. These columns are susceptible to axial-flexural, shear, and bond failures, which subsequently may lead to severe damage or collapse of the building. Research was undertaken to investigate the lateral and vertical load-resisting behavior of reinforced concrete columns typical of pre-1970's construction. Eight full-scale specimens were constructed and were loaded with constant axial load and increasing cyclic lateral displacement increments until failure. Test data are presented and compared with behavior estimated by using various evaluation methods.

Towards an understanding of the loosening characteristics of prevailing torque nuts

2010 ◽  
Vol 224 (2) ◽  
pp. 483-495 ◽  
Author(s):  
W Eccles ◽  
I Sherrington ◽  
R D Arnell
Keyword(s):  
Axial Load ◽  
Axial Loading ◽  
Transverse Displacement ◽  
Test Machine ◽  
Transverse Joint ◽  
Metal Type ◽  
Prevailing Torque ◽  
Transverse Movement ◽  
Complete Detachment ◽  
Constant Axial Load

Prevailing torque nuts are an extremely popular method of providing resistance to vibration-induced self-loosening of fasteners. Such nuts have a self-contained prevailing torque feature that provides a degree of resistance to rotation. Although such nuts are frequently used, it is not widely realized that they can occasionally come completely detached from bolts. The mechanism by which this can occur has hitherto been unidentified since it has not been possible to replicate detachment under laboratory testing. This article identifies a general condition that can result in the complete loosening and detachment of prevailing torque type nuts. This mechanism involves the application of an axial load when transverse joint slip is occurring. This article describes a modified Junker test machine that allows the application of axial loading to a joint while experiencing transverse displacement. Tests have been completed using an intermittent as well as a constant axial load. Loading in both modes has been demonstrated to result in the complete detachment of this nut type. Based on this investigation, if the magnitude of the axial loading exceeds the residual preload in the bolt retained from sustaining transverse movement alone, the all-metal type of prevailing torque nut can completely detach. Applications that involve shear and axial loading being simultaneously applied to a joint are numerous in engineering.

STRUCTURAL PERFORMANCE OF DAMAGED OPEN-WEB TYPE SRC BEAM-COLUMNS WITH BOLT-CONNECTED BATTEN STEEL PLATES AFTER RETROFITTING

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Takahiro Kume ◽  
Takashi Fujinaga ◽  
Yuping Sun
Keyword(s):  
Axial Load ◽  
Steel Plates ◽  
Analytical Models ◽  
Structural Performance ◽  
Test Results ◽  
Beam Columns ◽  
Cyclic Lateral Load ◽  
Load Carrying ◽  
Lower Load ◽  
Constant Axial Load

In this paper, structural performance of damaged SRC beam-columns with open-web type of batten steel plate after retrofitting was investigated. Three open-web type SRC beam-columns with bolt-connected batten steel plates were fabricated and tested under combined constant axial load and cyclic lateral load. At first, each beam-column was　cyclically loaded to the targeted displacement. After the first loading, the test columns were retrofitted and reloaded till large deformation or failure. The damaged portion of each column was retrofitted with the polymer cement mortar and epoxy resin was injected into the cracks. The measured stiffness of retrofitted columns varied between 71.4% and 85.5% of the initial one. And, test results also indicated that the column which experienced the larger displacement and higher axial load showed lower load carrying capacity, but the others showed approximately the same capacities as the initial columns. Numerical analysis was also conducted to explain the retrofitted columns. Analytical results predicted the experimental behavior fairly well, which verifies the validity of the analytical models in low axial load.

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