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Article
Publication date: 1 April 1988

E. Oñate, S. Oller, J. Oliver and J. Lubliner

A constitutive model based on classical plasticity theory for non‐linear analysis of concrete structures using finite elements is presented. The model uses the typical parameters…

550

Abstract

A constitutive model based on classical plasticity theory for non‐linear analysis of concrete structures using finite elements is presented. The model uses the typical parameters of non‐associated plasticity theory for frictional materials and a modified Mohr‐Coulomb yield surface is suggested. Onset and amount of cracking at a point are controlled by the values of the effective plastic strain and thus it can be studied by a posteriori postprocessing of numerical results. The accuracy and objectivity of the model is checked out with some examples of application.

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Engineering Computations, vol. 5 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 5 January 2010

J. Faleiro, S. Oller and A.H. Barbat

The purpose of this paper is to develop an improved analytical model for predicting the damage response of multi‐storey reinforced concrete frames modelled as an elastic…

1371

Abstract

Purpose

The purpose of this paper is to develop an improved analytical model for predicting the damage response of multi‐storey reinforced concrete frames modelled as an elastic beam‐column with two inelastic hinges at its ends.

Design/methodology/approach

The damage is evaluated in the hinges, using the concentrated damage concepts and a new member damage evaluation method for frame members, which leads to a meaningful global damage index of the structure. A numerical procedure for predicting the damage indices of the structures using matrix structural analysis, plastic theory and continuum damage model is also developed. The method is adequate for the prediction of the failure mechanisms.

Findings

Using the proposed framework numerical examples are finally included. From the obtained results, the advantages and limitation of the proposed model are observed.

Originality/value

The numeric model presented is useful to solve multi‐storey reinforced concrete frames using an inexpensive procedure that combines structural finite elements (beams) of low execution cost, with the moment‐curvature constitutive models deriving from classic stress‐strain ones. The proposed techniques give an inexpensive and reliability procedure to model the frame structures.

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Engineering Computations, vol. 27 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 March 1992

C. SAOURIDIS and J. MAZARS

Simple but also accurate models are needed to predict the failure response of concrete structures. Simplicity involves modelling assumptions while accuracy involves objectivity of…

195

Abstract

Simple but also accurate models are needed to predict the failure response of concrete structures. Simplicity involves modelling assumptions while accuracy involves objectivity of both the experimentally identified model parameters and the numerica results. For concrete‐like heterogeneous and brittle materials, the modelling assumptions idealizing the material as a homogeneous continuum with classical linear or non‐linear behaviour, leads to some problems at the identification stage, namely the size effect phenomena. A continuum damage model, representing the non‐linear behaviour due to microcracking, is proposed here for predictive computations of structural responses. A Weibull based theory is used to determine, in a statistical sense, the value of the initial damage threshold. The essential influence of material heterogeneity on the damage evolution, is accounted for with a bi‐scale approach which is based on the idea of the non‐local continuum with local strain. It has already established that the non‐local approaches yield realistic failure predictions and the numerical results are convergent for subsequent mesh refinements. The applications presented here show the ability of the approach to predict the failure response of concrete structures without being obscured by size effect problems.

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Engineering Computations, vol. 9 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 April 1989

Eduardo N. Dvorkin, Alberto M. Cuitiño and Gustavo Gioia

A concrete material model is presented. The model is based on non‐associated plasticity for the pre‐failure and ductile post‐failure regimes and fracture (smeared crack approach…

133

Abstract

A concrete material model is presented. The model is based on non‐associated plasticity for the pre‐failure and ductile post‐failure regimes and fracture (smeared crack approach) for the brittle post‐failure regime. The implementation of the constitutive model in the 2‐D elements of a general purpose non‐linear incremental finite element code is discussed. Some important numerical features of the implementation are the implicit integration of the stress/strain relation and the use of an efficient symmetric stiffness formulation for the equilibrium iterations.

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Engineering Computations, vol. 6 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 March 1995

S. Oller, S. Botello, J. Miquel and E. Oñate

This paper shows a generalization of the classic isotropic plasticitytheory to be applied to orthotropic or anisotropic materials. This approachassumes the existence of a real…

226

Abstract

This paper shows a generalization of the classic isotropic plasticity theory to be applied to orthotropic or anisotropic materials. This approach assumes the existence of a real anisotropic space, and other fictitious isotropic space where a mapped fictitious problem is solved. Both spaces are related by means of a linear transformation using a fourth order transformation tensor that contains all the information concerning the real anisotropic material. The paper describes the basis of the spaces transformation proposed and the expressions of the resulting secant and tangent constitutive equations. Also details of the numerical integration of the constitutive equation are provided. Examples of application showing the good performance of the model for analysis of orthotropic materials and fibre‐reinforced composites are given.

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Engineering Computations, vol. 12 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 13 January 2025

Vahid Lotfi and Ali Akbar Jahanitabar

The proposed model is implemented in a special finite element program for its three-dimensional solid elements (Lotfi, 2009), with its nonlinear dynamic analysis modified…

13

Abstract

Purpose

The proposed model is implemented in a special finite element program for its three-dimensional solid elements (Lotfi, 2009), with its nonlinear dynamic analysis modified according to the HHT-α algorithm, which is fully described. Based on the prepared tools, nonlinear behavior of the Morrow Point dam is studied by applying the invoked damage plasticity concrete model in the presence of contraction joints. For this aim, four cases are considered for the present study. Case A (SF = 1.4), which is based on the linear model, is mainly used for comparative purposes. The other three cases (B, C and D) correspond to the nonlinear model (i.e. damage plasticity model for concrete and nonlinear behavior for contraction joints) with earthquake loading scaling factors of SF = 1.4, 2.0 and 2.6, respectively.

Design/methodology/approach

In the present study, the application of the damage plasticity model in nonlinear dynamic analysis of Morrow Point concrete arch dam is presented. This model is a single-surface isotropic damage plasticity concrete model based on decomposition of stresses and was proposed in a previous study. It should be emphasized that contraction joints are also considered in the model. The theoretical aspects of the model are initially reviewed, and preliminary verification examples are presented. Thereafter, the HHT-α algorithm is presented for nonlinear dynamic analysis of concrete dams.

Findings

(1) In relation with displacement response for nonlinear simulations (i.e. cases B, C and D with SF (i.e. Scaling Factor) = 1.4, 2.0 and 2.6), it is noticed that maximum value of response increases as scaling factor becomes larger. This is such that the maximum value reaches an amount −0.35 m (negative refers to upstream direction) for case D. Moreover, the period elongation becomes quite significant. (2) The nonlinear simulation reveals that Morrow Point arch dam can resist a loading scenario based on Taft earthquake excitation even with an scaling factor as high as SF = 2.6. In this case, the maximum value of upstream displacement at dam mid-crest point reaches −0.35 m which is quite high in comparison with usual linear analysis responses. The extension of tensile damages is quite widespread while for compressive damages, it is much less. Moreover, the maximum tensile and compressive stresses for this case are 3.07 MPa and −33.31 MPa, respectively.

Originality/value

(1) As for the damages plotted at the end of analysis in each case, it is noticed that tensile damage becomes widespread as scaling factor increases. This is such that for case D (SF = 2.6), tensile damage spreads throughout the top portion of the dam body above that initial D/S closed loop occurring for case B (SF = 1.4). This is in both D/S and U/S faces and actually through the whole dam thickness in most parts. In regard to compressive damages, it is observed that it is developed in quite limited portion of dam body for case B. However, it begins to become widespread as scaling factor increases. Of course, most extensive damages corresponds to case D with SF = 2.6 as expected. However, it should be emphasized that even for this case, the amount or extension of compressive damages are much less than corresponding tensile damages. (2) The nonlinear simulation reveals that Morrow Point arch dam can resist a loading scenario based on Taft earthquake excitation even with an scaling factor as high as SF = 2.6. In this case, the maximum value of upstream displacement at dam mid-crest point reaches −0.35 m which is quite high in comparison with usual linear analysis responses. The extension of tensile damages is quite widespread while for compressive damages, it is much less. Moreover, the maximum tensile and compressive stresses for this case are 3.07 MPa and −33.31 MPa, respectively.

Details

Multidiscipline Modeling in Materials and Structures, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 12 July 2024

Vahid Lotfi and Ali Akbar Jahanitabar

In the present study, the application of a recent damage plasticity model is presented for nonlinear dynamic analysis of the Koyna gravity dam. This is a single surface isotropic…

29

Abstract

Purpose

In the present study, the application of a recent damage plasticity model is presented for nonlinear dynamic analysis of the Koyna gravity dam. This is a single surface isotropic damage plasticity concrete model, which is based on the decomposition of stresses and was proposed in a previous study. The theoretical aspects of the model are initially reviewed, and a few preliminary verification examples are illustrated. Thereafter, the HHT-α (i.e. Hilber–Hughes–Taylor) algorithm is presented for nonlinear dynamic analysis of concrete gravity dams.

Design/methodology/approach

Based on the prepared tools, nonlinear behavior of the Koyna Dam is studied by applying the invoked damage plasticity model. For this purpose, three cases are considered for the present study. Case A, which is based on the linear model, is mainly used for comparative purposes. The other two cases (B and C) correspond to the nonlinear (i.e. damage plasticity) model. The basic data for these two cases are similar. However, the employed damping algorithms are different and correspond to constant and variable damping algorithms, respectively. This means that the damping matrix is either kept constant or updated for all iterations of different time increments through the course of analysis.

Findings

The time histories of horizontal displacement at the dam crest were initially compared for the three cases: the linear Case A, and two nonlinear Cases B and C. It was observed that nonlinear cases’ responses begin to deviate from the corresponding linear case after the time of about 4.3 s. However, the amount of change for Case C (i.e. variable damping) was much greater than for Case B (i.e. constant damping). This was manifested initially in the peaks of response. It was also noticed that the period of response changed slightly for Case B in comparison with the linear Case A, while this change was significant for Case C. The obtained tensile and compressive damages were subsequently compared for the two nonlinear cases. For constant damping Case B, it was noticed that tensile damage occurred in the D/S face kink and on the U/S face slightly at a lower elevation. Moreover, it had a scattered nature. However, in variable damping Case C, it was noticed that tensile damage was much more localized and acted similar to a discrete crack. Of course, both cases also show tensile damages at the dam’s heel. In regard to compressive damages, it is observed that low values are occurring for both nonlinear cases as expected.

Originality/value

The application of a recent single surface isotropic damage plasticity concrete model is presented for nonlinear dynamic analysis of the Koyna gravity dam. The nonlinear response of the dam is investigated for two different damping algorithms. Moreover, the influence of variable characteristic length is also investigated in the latter part of this study.

Details

Engineering Computations, vol. 41 no. 6
Type: Research Article
ISSN: 0264-4401

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Book part
Publication date: 27 August 2014

Thomas Mejtoft

For several hundreds of years printing has been the only effective channel for spreading mass communication. During the 1900s several new media channels have been invented and…

Abstract

For several hundreds of years printing has been the only effective channel for spreading mass communication. During the 1900s several new media channels have been invented and, with the addition of the Internet, this has both changed the way media is consumed and has increased the competition between different channels. This qualitative case study of 37 firms reports on how relationships are used in the printing industry to relieve some of the impact of the competitive forces from new, and easily accessible, media as a means for marketing and, furthermore, on the impact on the printing industry as an industry. The results from the case study show that there are both internal and external effects of forming relationships and those vertical, as well as horizontal, relationships are of great importance to create a sustainable competitive situation for the printing industry. Relationships are used to increase both the strategic flexibility of the firm and the flexibility of the print media channel. Furthermore, the study illustrates that the printing industry, and print as a medium of communication, is drifting gradually away from the actual customer due to the new paradigm of value creation.

Details

Field Guide to Case Study Research in Business-to-business Marketing and Purchasing
Type: Book
ISBN: 978-1-78441-080-3

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Article
Publication date: 17 October 2018

Xiaokai Mu, Qingchao Sun, Wei Sun, Yunlong Wang, Chuanhua Wang and Xiaobang Wang

The traditional precision design only takes the influence of geometric tolerance of the parts and does not involve the load deformation in the assembly process. This paper aims to…

329

Abstract

Purpose

The traditional precision design only takes the influence of geometric tolerance of the parts and does not involve the load deformation in the assembly process. This paper aims to analyze the influence mechanism of flexible parts deformation on the geometric precision, and then to ensure the reliability and stability of the mechanical system.

Design/methodology/approach

Firstly, this paper adopts the N-GPS to analyze the influence mechanism of flexible parts deformation on the geometric precision and constructs a coupling 3D tolerance mathematical model of the geometric tolerance and the load deformation deviation based on the SDT theory, homogeneous coordinate transformation theory and surface authentication idea. Secondly, the least square method is used to fit the deformation surface of the mating surface under load so as to complete the conversion from the non-ideal element to the ideal element.

Findings

This paper takes the horizontal machining center as a case to obtain the deformation information of the mating surface under the self-weight load. The results show that the deformation deviation of the parts has the trend of transmission and accumulation under the load. The terminal deformation cumulative amount of the system is up to –0.0249 mm, which indicated that the influence of parts deformation on the mechanical system precision cannot be ignored.

Originality/value

This paper establishes a comprehensive 3D tolerance mathematical model, which comprehensively considers the effect of the dimensional tolerance, geometric tolerance and load deformation deviation. By this way, the assembly precision of mechanical system can be accurately predicted.

Details

Engineering Computations, vol. 35 no. 7
Type: Research Article
ISSN: 0264-4401

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Book part
Publication date: 24 April 2019

Dinuka B. Herath, Davide Secchi, Fabian Homberg and Gayanga B. Herath

Abstract

Details

Business Plasticity through Disorganization
Type: Book
ISBN: 978-1-78756-211-0

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