Search results

1 – 10 of over 31000
To view the access options for this content please click here
Article

Abhishek K. Singh, Anirban Lakshman and Amares Chattopadhyay

The response of moving load over a surface is a subject of investigation because of its possible applications in determining the strength of a structure. Recently, with…

Abstract

Purpose

The response of moving load over a surface is a subject of investigation because of its possible applications in determining the strength of a structure. Recently, with the enlargement of high-speed train networks, concern has been expressed about the effects of moving loads on the track, embankment and nearby structures. Earth surface and artificial structure are not always regular in nature. Irregularities are also responsible for structural collapse of long bridge and highway of plateau area under the action of moving loads. The purpose of this paper is to investigate the influence of irregularity on dynamic response due to a moving shear load.

Design/methodology/approach

At first the authors developed the mathematical model for the problem which is comprised of equation of motion together with boundary conditions. Perturbation technique has been used to derive the stresses produced in an irregular orthotropic half-space (which is influenced by gravity) due to a moving shear load. MATLAB and MATHEMATICA softwares have been employed for numerical computation as well as graphical illustration.

Findings

In this paper the authors have discussed the stresses produced in an irregular gravitating orthotropic half-space due to a moving shear load. The expression for shear stress has been established in closed form. Substantial effects of depth, irregularity factor, maximum depth of irregularity and gravitational parameter on shear stress have been reported. These effects are also exhibited by means of graphical illustration and numerical computation for an orthotropic material T300/5208 graphite/epoxy which is broadly used in aircraft designing. Moreover, comparison made through meticulous examination for different types of irregularity, presence and absence of anisotropy and gravity are highlighted.

Practical implications

A number of classical fatigue failures occur in aircraft structures. The moving load responsible for such fatigue failure may occur during manufacturing process, servicing, etc. Apart from these the aircraft structures may also experience load because of environmental damages (such as lightning strike, overheat) and mechanical damages (like impact damage, overload/bearing failure). Therefore the present study is likely to find application in the field of construction of highways, airport runways and earthquake engineering.

Originality/value

To the best of the authors’ knowledge no problem related to moving load on irregular orthotropic half-space under influence of gravity has been attempted by any author till date. Furthermore comparative study for different types of irregularity, presence and absence of anisotropy and influence of gravity on the dynamic response of moving load are novel and major highlights of the present study.

Details

Multidiscipline Modeling in Materials and Structures, vol. 12 no. 1
Type: Research Article
ISSN: 1573-6105

Keywords

To view the access options for this content please click here
Article

Ivica Kožar

The purpose of this paper is to investigate internal forces in bridges induced by moving vehicles and compare them to earthquake loading.

Abstract

Purpose

The purpose of this paper is to investigate internal forces in bridges induced by moving vehicles and compare them to earthquake loading.

Design/methodology/approach

Dynamic analysis of bridges is performed for moving support actions, for spectral method with Eurocode 8 parameters and for moving vehicle influence. Results from all three methods have been compared on two examples and conclusions have been made. Moving vehicle analysis could be based on the moving force and on the moving mass approach where the later one requires rather accurate knowledge of structural accelerations. It has been shown that the classical Newmark formulation produces accelerations of low accuracy and a novel impulse acceleration method has been devised.

Findings

It is found that the actions induced by the moving load could be comparable or larger than those caused by the earthquake on bridges whose mass is not too large in comparison to the vehicle mass.

Research limitations/implications

The developed method will be applied to a broader choice of examples and more reliable conclusions made.

Practical implications

There are bridges where it would be appropriate to perform moving vehicle dynamic analysis, in which case the vertical earthquake actions could be neglected in the analysis.

Originality/value

In order to assess actions from moving vehicles, Newmark method has been generalized in a novel way. Paper describes vector formulation of Newmark method that permits free mixing of integration parameters that could vary from node to node. The method is advantageous for moving load analysis where loading conditions of nodes change in time.

Details

Engineering Computations, vol. 26 no. 1/2
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article

THE opening months of the last war were conducted in a very leisurely fashion because the expected disasters had not befallen us. Not until our armies were rescued from…

Abstract

THE opening months of the last war were conducted in a very leisurely fashion because the expected disasters had not befallen us. Not until our armies were rescued from the beaches of Dunkirk did the stark realities of the situation percolate into the public mind. Once the facts were understood the whole country was galvanised into activity.

Details

Work Study, vol. 8 no. 6
Type: Research Article
ISSN: 0043-8022

To view the access options for this content please click here
Article

Mario Fafard, Mallikarjuna Bennur and Marc Savard

Develops a general five‐axle vehicle model to study the dynamic interactions between the moving mass and the bridge structural components. Two‐axle, three‐axle, or…

Abstract

Develops a general five‐axle vehicle model to study the dynamic interactions between the moving mass and the bridge structural components. Two‐axle, three‐axle, or four‐axle sprung loads, and the limiting load conditions such as a moving constant force, a moving alternating force, a moving unsprung mass, and combinations thereof, can be treated as special cases of the more general case presented. Further, its integration with the versatile finite element modelling has enhanced the practical applicability of such a theoretical development. The physical characteristics of the bridge and the vehicle, such as the bridge geometry, mechanical properties, profile of the road surface, the vehicle parameters including the distance between axles, leaf springs suspension and the total weight, are considered explicitly in the present model. The dynamic equations of equilibrium in time are integrated using the Newmark integration scheme. Verifies the accuracy of the algorithm by comparing the numerical results obtained from the present formulation with the experimental results.

Details

Engineering Computations, vol. 14 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article

Arthur M. Johnston

The exceptional frictional characteristics of PTFE (polytetrafluoroethylene) make it an ideal material for use as a sliding medium when moving heavy loads. Extremely low…

Abstract

The exceptional frictional characteristics of PTFE (polytetrafluoroethylene) make it an ideal material for use as a sliding medium when moving heavy loads. Extremely low friction coefficients can be achieved with pads and slideways made from unfilled PTFE so that massive loads can be moved with relatively small forces. The use of filled grades of PTFE can provide greatly increased wear resistance with a small increase in friction coefficient.

Details

Industrial Lubrication and Tribology, vol. 28 no. 2
Type: Research Article
ISSN: 0036-8792

To view the access options for this content please click here
Article

THE improvement in the British standard of living is generally desired. Politicians have not only subscribed to that ideal but some of them have indicated the rate at…

Abstract

THE improvement in the British standard of living is generally desired. Politicians have not only subscribed to that ideal but some of them have indicated the rate at which we should advance. There are, however, certain trends in the country's economic life which must be reversed if we are to make any progress in that direction.

Details

Work Study, vol. 11 no. 2
Type: Research Article
ISSN: 0043-8022

To view the access options for this content please click here
Article

Koichi Maekawa and Chikako Fujiyama

The paper aims to propose a rate‐dependent model of structural concrete in combination with the kinematics of condensed water.

Abstract

Purpose

The paper aims to propose a rate‐dependent model of structural concrete in combination with the kinematics of condensed water.

Design/methodology/approach

First, the paper proposes the coupling model of water versus cracked concrete with a mathematical completeness of equilibrium and deformational compatibility. The proposed model deals with anisotropy of structural performance and of permeability, which is a particular issue of concrete caused by cracks. The governing equation for saturated concrete in this study is based on Biot's theory that deals with particle assembly as a two‐phase composite. Second, the paper shows the possible reduction of the fatigue life of real‐scale bridge RC decks owing to the water residing in structural cracks under moving wheel‐type loading.

Findings

The paper shows that the existence of water possibly has an influence on the rate‐dependency of structural performance. The comparison of transition of pore pressure and principal strain indicates that damage to the concrete skeleton is accelerated by internal stress caused by high pore pressure. It suggests that the existence of water can reduce the fatigue life of bridge decks, especially when the upper layer is saturated.

Originality/value

This paper clarifies the effect of pore water on structural concrete by using numerical model considering kinematics of water.

Details

Engineering Computations, vol. 30 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article

Zhi Ding and Danwei Li

This paper aims to evaluate the dynamic response of surrounding foundation and study the vibration characteristics of track system.

Abstract

Purpose

This paper aims to evaluate the dynamic response of surrounding foundation and study the vibration characteristics of track system.

Design/methodology/approach

A double-line underground coupling analysis model was established, which included two moving train, track, liner and the ground field.

Findings

Based on the 2.5D (D is diameter) finite element analysis, the influence of the important factors such as the depth of the subway tunnel, the nature of the foundation soil, the relative position relation of the double tunnel, the subway driving speed on the foundation and the orbital vibration are analyzed in this article.

Originality/value

The results in paper may have reference value for the prediction of train induced vibrations and for the research of dynamic response of ground field.

Details

Engineering Computations, vol. 36 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article

AN interesting comment from the Salisbury and South Wilts team of industrialists who put the first Local Productivity Council Circuit Scheme into operation in their area…

Abstract

AN interesting comment from the Salisbury and South Wilts team of industrialists who put the first Local Productivity Council Circuit Scheme into operation in their area suggests that this scheme may prove invaluable in awakening general interest in, and in giving practical impetus to, increased productivity at all levels.

Details

Work Study, vol. 4 no. 3
Type: Research Article
ISSN: 0043-8022

To view the access options for this content please click here
Article

Overview All organisations are, in one sense or another, involved in operations; an activity implying transformation or transfer. The major portion of the body of…

Abstract

Overview All organisations are, in one sense or another, involved in operations; an activity implying transformation or transfer. The major portion of the body of knowledge concerning operations relates to production in manufacturing industry but, increasingly, similar problems are to be found confronting managers in service industry. It is only in the last decade or so that new technology, involving, in particular, the computer, has encouraged an integrated view to be taken of the total business. This has led to greater recognition being given to the strategic potential of the operations function. In order to provide greater insight into operations a number of classifications have been proposed. One of these, which places operations into categories termed factory, job shop, mass service and professional service, is examined. The elements of operations management are introduced under the headings of product, plant, process, procedures and people.

Details

Management Decision, vol. 26 no. 2
Type: Research Article
ISSN: 0025-1747

1 – 10 of over 31000