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Article
Publication date: 30 October 2020

Jiao-Long Zhang, Xian Liu, Yong Yuan, Herbert A. Mang and Bernhard L.A. Pichler

Transfer relations represent analytical solutions of the linear theory of circular arches, relating each one of the kinematic and static variables at an arbitrary cross-section to…

1074

Abstract

Purpose

Transfer relations represent analytical solutions of the linear theory of circular arches, relating each one of the kinematic and static variables at an arbitrary cross-section to the kinematic and static variables at the initial cross-section. The purpose of this paper is to demonstrate the significance of the transfer relations for structural analysis by means of three examples taken from civil engineering.

Design/methodology/approach

The first example refers to an arch bridge, the second one to the vault of a metro station and the third one to a real-scale test of a segmental tunnel ring.

Findings

The main conclusions drawn from these three examples are as follows: increasing the number of hangers/columns of the investigated arch bridge entails a reduction of the maximum bending moment of the arch, allowing it to approach, as much as possible, the desired thrust-line behavior; compared to the conventional in situ cast method, a combined precast and in situ cast method results in a decrease of the maximum bending moment of an element of the vault of the studied underground station by 46%; and the local behavior of the joints governs both the structural convergences and the bearing capacity of the tested segmental tunnel ring.

Originality/value

The three examples underline that the transfer relations significantly facilitate computer-aided engineering of circular arch structures, including arch bridges, vaults of metro stations and segmental tunnel rings.

Details

Engineering Computations, vol. 38 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 November 1996

C. Kropik and H.A. Mang

Contains a report on three‐dimensional finite element (FE) analyses of deformations and stresses resulting from the excavation of shallow underground railway tunnels. Multisurface…

530

Abstract

Contains a report on three‐dimensional finite element (FE) analyses of deformations and stresses resulting from the excavation of shallow underground railway tunnels. Multisurface elasto‐viscoplastic material models are employed for consideration of the mechanical behaviour of the soil and the shotcrete shell supporting the excavation. Both are formulated within the framework of closest point projection algorithms. For soil a cap model is used, consisting of a curved failure surface, a tension cut‐off and an elliptical cap. The latter allows consideration of the evolution of plastic strains even for the limiting case of a purely volumetric stress state. The movement of the cap is governed by a hardening law, describing the relation between the hydrostatic pressure and void ratio. The shotcrete model is a rotating crack model, taking ageing of the maturing concrete into account. It consists of a strain‐hardening Drucker‐Prager cone and three Rankine (crack) surfaces. Demonstrates the usefulness of the cap model to predict the mechanical behaviour of the soil by means of tests on remoulded, saturated clay. The model parameters of the clayey silt of Vienna, where the analysed tunnel is located, are fit to standard test results. The parameters of the shotcrete model are fit to test results published in the literature. Compares the analysis of a single‐track tunnel with the results of field measurements from sliding micrometers. Furthermore, the stresses in the shotcrete lining are examined. In view of the inhomogeneity of the material and of unavoidable deficiencies of the measurements it is fair to say that the mechanical effects resulting from the excavation of tunnels are modelled reasonably well.

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Engineering Computations, vol. 13 no. 7
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 March 1996

Takashi Hara, Shiro Kato and Hiroshi Nakamura

Reinforced concrete (R/C) hyperbolic cooling towers are the largest thin‐shell structures ever constructed. These towers stand more than 150m tall and have wall thicknesses of…

472

Abstract

Reinforced concrete (R/C) hyperbolic cooling towers are the largest thin‐shell structures ever constructed. These towers stand more than 150m tall and have wall thicknesses of 0.20‐0.25m. Therefore, these can be classified as thin‐shell structures. Analyses the influences of both the reinforcing ratio and the tensile strength of the concrete on the strength of the R/C cooling tower shells. In the numerical analysis Port Gibson tower is adopted for the numerical model and the finite element method is applied to examine the non‐linear behaviour of the cooling tower shells. From the load displacement curves the initial crack strength and the ultimate strength are determined. Also presents the stress redistribution processes and demonstrates the influences of these problems on the strength of the cooling tower shells.

Details

Engineering Computations, vol. 13 no. 2/3/4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 February 1994

C.H. Liu, G. Hofstetter and H.A. Mang

The paper starts with a review of constitutive equations forrubber‐like materials, formulated in the invariants of the rightCauchy—Green deformation tensor. A general framework…

564

Abstract

The paper starts with a review of constitutive equations for rubber‐like materials, formulated in the invariants of the right Cauchy—Green deformation tensor. A general framework for the derivation of the stress tensor and the tangent moduli for invariant‐based models, for both the reference and the current configuration, is presented. The free energy of incompressible rubber‐like materials is extended to a compressible formulation by adding the volumetric part of the free energy. In order to overcome numerical problems encountered with displacement‐based finite element formulations for nearly incompressible materials, three‐dimensional finite elements, based on a penalty‐type formulation, are proposed. They are characterized by applying reduced integration to the volumetric parts of the tangent stiffness matrix and the pressure‐related parts of the internal force vector only. Moreover, hybrid finite elements are proposed. They are based on a three‐field variational principle, characterized by treating the displacements, the dilatation and the hydrostatic pressure as independent variables. Subsequently, this formulation is reduced to a generalized displacement formulation. In the numerical study these formulations are evaluated. The results obtained are compared with numerical results available in the literature. In addition, the proposed formulations are applied to 3D finite element analysis of an automobile tyre. The computed results are compared with experimental data.

Details

Engineering Computations, vol. 11 no. 2
Type: Research Article
ISSN: 0264-4401

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Book part
Publication date: 4 October 2022

Tae-Youn Park, Reed Eaglesham, Jason D. Shaw and M. Diane Burton

Incentives are effective at enhancing productivity, but research also suggests that performance incentives can have “unintended negative consequences” including increases in

Abstract

Incentives are effective at enhancing productivity, but research also suggests that performance incentives can have “unintended negative consequences” including increases in hazard/injuries, increases in errors, and reduction in cooperation, prosocial behaviors, and creativity. Relatively overlooked is whether, when, and how incentives can be designed to prevent such negative consequences. The authors review literature in several disciplines (construction, healthcare delivery, economics, psychology, and [some] management) on this issue. This chapter, in toto, sheds a generally positive light and suggests that, beyond productivity, incentives can be used to improve other outcomes such as safety, quality, prosocial behaviors, and creativity, particularly when the incentives are thoughtfully designed. The review concludes with several potential fruitful areas for future research such as investigations of incentive-effect duration.

Details

Research in Personnel and Human Resources Management
Type: Book
ISBN: 978-1-80455-046-5

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Article
Publication date: 1 August 1999

D.P. Mok, W.A. Wall, M. Bischoff and E. Ramm

The present study focusses on algorithmic aspects related to deformation dependent loads in non‐linear static finite element analysis. If the deformation dependency is considered…

378

Abstract

The present study focusses on algorithmic aspects related to deformation dependent loads in non‐linear static finite element analysis. If the deformation dependency is considered only on the right hand side, a considerable increase in the number of iterations follows. It may also cause failure of convergence in the proximity of critical points. If in turn the deformation dependent loading is included within the consistent linearization, an additional left hand side term emerges, the so‐called load stiffness matrix. In this paper several numerical test cases are used to show and quantify the influence of the two different approaches on the iteration process. Consideration of the complete load stiffness matrix may result in a cumbersome coding effort, different for each load case, and in certain cases its derivation is even not practicable at all. Therefore also several formulations for approximated load stiffness matrices are presented. It is shown that these simplifications not only reduce the additional effort for linearization and implementation, but also keep the iterative costs relatively small and still allow the calculation of the entire equilibrium path.

Details

Engineering Computations, vol. 16 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 May 2001

T. Huemer, W.N. Liu, J. Eberhardsteiner and H.A. Mang

The frictional behavior of rubber materials on various contact surfaces is strongly affected by the contact pressure and the relative sliding velocity as well as the environmental…

845

Abstract

The frictional behavior of rubber materials on various contact surfaces is strongly affected by the contact pressure and the relative sliding velocity as well as the environmental temperature. Based on a great number of experiments of rubber blocks moving on concrete and ice surfaces, a friction law for 3D contact analyses is presented in this paper. It is characterized by the dependency on the contact pressure, sliding velocity and the environmental temperature. The identification and correction of the parameters of this friction law were done by means of a least‐square method followed by re‐analyses of the respective experiments. Several examples are given in a numerical investigation of the frictional behavior of rubber materials.

Details

Engineering Computations, vol. 18 no. 3/4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 February 1988

Gilles Pijaudier‐Cabot, Zdeněk P. Bažant and Mazen Tabbara

This paper presents a comparison of various models for strain‐softening due to damage such as cracking or void growth, as proposed recently in the literature. Continuum‐based…

318

Abstract

This paper presents a comparison of various models for strain‐softening due to damage such as cracking or void growth, as proposed recently in the literature. Continuum‐based models expressed in terms of softening stress—strain relations, and fracture‐type models expressed in terms of softening stress—displacement relations are distinguished. From one‐dimensional wave propagation calculations, it is shown that strain‐localization into regions of finite size cannot be achieved. The previously well‐documented spurious convergence is obtained with continuum models, while stress—displacement relations cannot model well smeared‐crack situations. Continuum models may, however, be used in general if a localization limiter is implemented. Gradient‐type localization limiters appear to be rather complicated; they require solving higher‐order differential equations of equilibrium with additional bourdary conditions. Non‐local localization limiters, especially the non‐local continuum with local strain, in which only the energy dissipating variables are non‐local, is found to be very effective, and also seems to be physically realistic. This formulation can correctly model the transition between homogeneous damage states and situations in which damage localizes into small regions that can be viewed as cracks. The size effect observed in the experimental and numerical response of specimens in tension or compression is shown to be a consequence of this progressive transition from continuum‐type to fracture‐type formulations.

Details

Engineering Computations, vol. 5 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 21 March 2022

Jason Martinez and Ann Jeffers

A methodology for producing an elevated-temperature tension stiffening model is presented.

116

Abstract

Purpose

A methodology for producing an elevated-temperature tension stiffening model is presented.

Design/methodology/approach

The energy-based stress–strain model of plain concrete developed by Bažant and Oh (1983) was extended to the elevated-temperature domain by developing an analytical formulation for the temperature-dependence of the fracture energy Gf. Then, an elevated-temperature tension stiffening model was developed based on the modification of the proposed elevated-temperature tension softening model.

Findings

The proposed tension stiffening model can be used to predict the response of composite floor slabs exposed to fire with great accuracy, provided that the global parameters TS and Kres are adequately calibrated against global structural response data.

Originality/value

In a finite element analysis of reinforced concrete, a tension stiffening model is required as input for concrete to account for actions such as bond slip and tension stiffening. However, an elevated-temperature tension stiffening model does not exist in the research literature. An approach for developing an elevated-temperature tension stiffening model is presented.

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Article
Publication date: 20 April 2015

Nikolay Asmolovskiy, Anton Tkachuk and Manfred Bischoff

Current procedures of buckling load estimation for thin-walled structures may provide very conservative estimates. Their refinement offers the potential to use structure and…

226

Abstract

Purpose

Current procedures of buckling load estimation for thin-walled structures may provide very conservative estimates. Their refinement offers the potential to use structure and material properties more efficiently. Due to the large variety of design variables, for example laminate layup in composite structures, a prohibitively large number of tests would be required for experimental assessment, and thus reliable numerical techniques are of particular interest. The purpose of this paper is to analyze different methods of numerical buckling load estimation, formulate simulation procedures suitable for commercial software and give recommendations regarding their application. All investigations have been carried out for cylindrical composite shells; however similar approaches are feasible for other structures as well.

Design/methodology/approach

The authors develop a concept to apply artificial load imperfections with the aim to estimate as good as possible lower bounds for the buckling loads of shells for which the actual physical imperfections are not known. Single and triple perturbation load approach, global and local dynamic perturbation approach and path following techniques are applied to the analysis of a cylindrical composite shell with known buckling characteristics. Results of simulations are compared with published experimental data.

Findings

A single perturbation load approach is reproduced and modified. Buckling behavior for negative values of the perturbation load is examined and a pattern similar to a positive perturbation load is observed. Simulations with three perturbation forces show a decreased (i. e. more critical) value of the buckling load compared to the single perturbation load approach. Global and local dynamic perturbation approaches exhibit a behavior suitable for lower bound estimation for structures with arbitrary geometries.

Originality/value

Various load imperfection approaches to buckling load estimation are validated and compared. All investigated methods do not require knowledge of the real geometrical imperfections of the structure. Simulations were performed using a commercial finite element code. Investigations of sensitivity with respect to a single perturbation load are extended to the negative range of the perturbation load amplitude. A specific pattern for a global perturbation approach was developed, and based on it a novel simulation procedure is proposed.

Details

Engineering Computations, vol. 32 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

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