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Article
Publication date: 2 September 2019

Faezeh Nejati and S.A. Edalatpanah

The purpose of this paper is to investigate the effect of steel and carbon fibers on the mechanical properties of light concrete in terms of tension strength, compressive…

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Abstract

Purpose

The purpose of this paper is to investigate the effect of steel and carbon fibers on the mechanical properties of light concrete in terms of tension strength, compressive strength and elastic modulus under completely dry and wet conditions.

Design/methodology/approach

In this study, the lightweight concrete made of Light Expanded Clay Aggregate (LECA) as coarse aggregate and sand as fine aggregate was used. To achieve a compressive strength of at least 20 MPa, microsilica was used 10 percent by weight of cement. In order to compensate for the reduction of tension strength of concrete, steel and carbon fibers were used with three volume ratio of 0.5, 1 and 1.5 percent in concrete. The results of concrete specimens were studied at the age of 7, 28, 42 and 90 days under controlled dry and wet conditions.

Findings

The results showed that the addition of steel and carbon fibers to the concrete mixture would reduce the drop in slump. Also, the use of steel and carbon fibers plays a significant role in increasing the tension strength of the specimens. Furthermore, the highest increase in tension strength of steel and carbon fiber samples was 83.3 and 50 percent, respectively, than the non-fibrous specimen when evaluated at 90 days of age. Moreover, the steel and carbon fiber increased the water absorption of the samples. Adding steel and carbon fibers to a lightweight concretes mixture containing LECA aggregates plays a significant role in increasing the modulus of elasticity of the samples. The highest increase in the elastic modulus of steel and carbon fibers was 18.9 and 35.4 percent, respectively, than the non-fibrous specimen at 28 days of age.

Originality/value

In this paper, the authors investigated the mechanical properties of steel fiber and carbon reinforced concrete. Also, according to the conditions of storage of samples and the age of concrete (day), the experiments were carried out on samples.

Details

International Journal of Structural Integrity, vol. 11 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 21 March 2022

Jason Martinez and Ann Jeffers

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

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.

Details

Journal of Structural Fire Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 8 January 2020

Ante Džolan, Mladen Kožul, Alen Harapin and Dragan Ćubela

This paper aims to present an approach for the numerical simulation of concrete shrinkage. First, some physical mechanisms of shrinkage are described and then the…

Abstract

Purpose

This paper aims to present an approach for the numerical simulation of concrete shrinkage. First, some physical mechanisms of shrinkage are described and then the developed numerical model for the analysis of shrinkage of spatial three-dimensional structures using thermal analogy is presented. Results of the real behavior of structures because of concrete shrinkage using the developed numerical model are compared with the experimental and it is clearly shown that the developed numerical model is an efficient tool in predicting the time-dependent behavior of all concrete structures.

Design/methodology/approach

In this paper, Fib Model Code 2010 to predict shrinkage deformation of concrete is used, and it was incorporated in the three-dimensional numerical model using the thermal analogy. Mentioned three-dimensional numerical model uses the modified Rankine material law to describe concrete behavior in tension and modified Mohr-Coulomb material law to describe concrete behavior in compression. The developed three-dimensional numerical model successfully analyzes the behavior of reinforced and/or prestressed concrete structures including time-dependent deformations of concrete as well.

Findings

Results are shown in this paper clearly demonstrate the reliability of the developed numerical model in predicting the shrinkage strain, as well as its impact on concrete and reinforced concrete structures. The results obtained using the developed numerical model are in better agreement with the experimental results, than the results obtained using the numerical models from literature that also use the Fib Model Code 2010 to predict the shrinkage strain. So, it can be concluded that for a real simulation of concrete structures, alongside the model for predicting the shrinkage strain, the models for concrete behavior in tension and compression have a very important role.

Originality/value

Results of the developed three-dimensional numerical model were compared with experimental results from literature and with theoretical foundations, and it can be talked that this numerical model presents a good tool for analysis of reinforced and prestressed concrete structures including shrinkage deformation of concrete. Results obtained using the developed three-dimensional numerical model are better agreed with experimental than results of other numerical model from literature.

Details

Engineering Computations, vol. 37 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 30 May 2019

J. Esfandiari and Y. Khezeli

An analytical investigation is performed on zipper-braced frames. Zipper-braced frames are an innovative bracing system for steel structures. Conventional…

Abstract

Purpose

An analytical investigation is performed on zipper-braced frames. Zipper-braced frames are an innovative bracing system for steel structures. Conventional inverted-V-braced frames exhibit a design problem arising from the unbalanced vertical force generated by the lower story braces when one of them buckles. This adverse effect can be mitigated by adding zipper columns or vertical members connecting the intersection points of the braces above the first floor.

Design/methodology/approach

This paper critically evaluates over strength, ductility and response modification factors of these structures. To achieve the purpose of this research, several buildings of different stories are considered. Static pushover analysis, linear dynamic analysis and nonlinear incremental dynamic analysis are performed by OpenSees software concerning ten records of past earthquakes.

Findings

Also, ductility factor, over strength factor and response modification factor, has been calculated for zipper-braced frames system. The values of 3.5 and 5 are suggested for response modification factor in ultimate limit state and allowable stress methods, respectively.

Originality/value

The fragility curves were plotted for the first time for such kind of braces. It should be mentioned that these curves play significant roles in evaluating seismic damage of buildings.

Details

World Journal of Engineering, vol. 16 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 1 September 1955

W.H. Burdon

The standard diagram is described, giving the relationship between R and S for constant value of N. The line of infinite endurance is obtained, and the relationship of N

Abstract

The standard diagram is described, giving the relationship between R and S for constant value of N. The line of infinite endurance is obtained, and the relationship of N and S is shown. The effects of stress concentration and of shape are studied and tabulated. The variation of KF with S1 is plotted, and the relationship between KF, KT and S1 is examined. Comments are made on the variation of KF with material, on high compressive stress, on surface finish effect and on the relationship between the grades of light alloy. The effects of bending, riveting and bolting are shown. General discussion summarizes the results and makes suggestions for future research and testing for fatigue. An appendix contains notes on practical use of the results in design, and some examples of fatigue stress analysis and its application to pressurized cabins.

Details

Aircraft Engineering and Aerospace Technology, vol. 27 no. 9
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 November 2002

Herbert Martins Gomes and Armando Miguel Awruch

In this paper, special emphasis is given to uncertainties in the evaluation of the structural behavior, looking for a better representation of the system characteristics…

Abstract

In this paper, special emphasis is given to uncertainties in the evaluation of the structural behavior, looking for a better representation of the system characteristics and quantification of the significance of these uncertainties in structural design. The reliability analysis of reinforced concrete structures is performed taking into account the spatial variability of material properties. The finite element method is used to analyze reinforced concrete structures. A multidimensional non‐Gaussian stochastic field generation model (independent of the finite element mesh) is developed and used. The reliability analysis is carried out employing the first order reliability method. Numerical examples are presented to study how to generate correlated non‐Gaussian stochastic fields and determine the reliability of a reinforced concrete structure with respect to a limit state function.

Details

Engineering Computations, vol. 19 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 September 1942

George W. DeBell

MANY engineers look upon plastics and allied materials as entirely new to the aircraft industry, but such is not the case. Phenol fibre sheet and resin bonded waterproof…

Abstract

MANY engineers look upon plastics and allied materials as entirely new to the aircraft industry, but such is not the case. Phenol fibre sheet and resin bonded waterproof plywood have been used for years, and acrylic resin sheet has been in use for transparent enclosures for some time past; yet all come under the above category. The primary difference between the past and present uses of these materials is that they are now used in applications where structural loads are involved, while they were previously used only in non‐stressed parts where special characteristics, such as transparency or insulating qualities, were of paramount importance. If these materials are classified according to their major characteristics they fall into three categories; those made with thermosetting resins, those made with thermoplastic resins, and those made with wood veneer. This classification also in a general way divides them according to their principal uses; thermosetting materials being used mostly in the production of relatively small structural parts, the thermoplastics being used mostly for their transparent properties, and the wood veneer materials being used mostly in relatively large structural parts and assemblies.

Details

Aircraft Engineering and Aerospace Technology, vol. 14 no. 9
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 2 March 2015

Ching-Ho Yen, Heng Ma, Chi-Huang Yeh and Chia-Hao Chang

– The purpose of this paper is to develop an economic model, which could determine the acceptance sampling plan that minimizes the quality cost for batch manufacturing.

Abstract

Purpose

The purpose of this paper is to develop an economic model, which could determine the acceptance sampling plan that minimizes the quality cost for batch manufacturing.

Design/methodology/approach

The authors propose a variable sampling plan based on one-sided capability indices for dealing with the quality cost requirement.

Findings

The total quality cost is much more sensitive to process capability indices and inspected cost than internal and external failure costs.

Research limitations/implications

The experimental data were randomly generated instead of real world ones.

Practical implications

The proposed model is specifically designed for manufacturing industries with high sampling cost.

Originality/value

The one-sided capability indices were utilized for the first time to be suitable for the purpose.

Details

Kybernetes, vol. 44 no. 3
Type: Research Article
ISSN: 0368-492X

Keywords

Article
Publication date: 3 August 2021

Jinhua Chen, Graeme Harrison and Lu Jiao

This paper examines how lateral accountability mechanisms may be used to address the unity–diversity tension in a large not-for-profit (NFP) inter-organizational…

Abstract

Purpose

This paper examines how lateral accountability mechanisms may be used to address the unity–diversity tension in a large not-for-profit (NFP) inter-organizational partnership governed under a lead organization model.

Design/methodology/approach

A case study was conducted in the New South Wales Settlement Partnership comprising 23 NFP organizations providing settlement services for migrants and humanitarian entrants. Multiple data sources included semi-structured interviews, proprietary and publicly available documents and observation.

Findings

The paper demonstrates (1) the usefulness of a strength-based approach that the lead organization adopts in enacting lateral accountability mechanisms, which enables a balance between unity and diversity in the partnership; and (2) the capability of the lead organization governance model to address the unity–diversity tension.

Research limitations/implications

The paper (1) identifies the importance of a strength-based approach in implementing lateral accountability mechanisms to address the unity–diversity tension; and (2) challenges prior research that advocates the network administrative organization governance model in addressing the tension.

Practical implications

For practice, the paper identifies a suite of lateral accountability practices designed to address the unity–diversity tension. For policy, it provides confidence for government in promulgating the lead organization governance model in “purchasing” public services.

Originality/value

The paper demonstrates how lateral accountability mechanisms may be used to provide a balance between the objectives of preserving and leveraging the benefits of partner diversity and achieving unity. The strength-based approach (used in enacting the accountability mechanisms), while having a history in psychology and social work research, has not been recognized in prior partnership accountability and governance studies.

Details

Accounting, Auditing & Accountability Journal, vol. 35 no. 2
Type: Research Article
ISSN: 0951-3574

Keywords

Open Access
Article
Publication date: 10 March 2022

Henrik Virtanen and Soren Kock

The purpose of this study is to elaborate on the management, sources, levels of strength and dynamics of inherent tension in coopetition between small- and medium-sized…

Abstract

Purpose

The purpose of this study is to elaborate on the management, sources, levels of strength and dynamics of inherent tension in coopetition between small- and medium-sized firms (SMEs).

Design/methodology/approach

An embedded single-case design is applied in the study. Two manufacturing SMEs in coopetition are studied. The units of analysis are their past dyadic coopetition with other competitors, their present coopetition with each other and their view of possible dyadic coopetition with other partners in the future.

Findings

This study addresses the call for more research on coopetition and tension dynamics. It gives longitudinal insight into the changes of a coopetitive relationship through the evolution of tension inherently present in the relationship. Furthermore, the results show that a partial separation of the cooperative and competitive dimensions enables entrepreneurs’ integration of a contradictory logic. The successful management of tension also relies on mechanisms for mutual value appropriation, which eventually enhances the ability to embrace contradictions.

Originality/value

This study contributes to the limited knowledge on tension management by showing how partners in coopetition apply different tension management principles or combinations of principles due to how the tension in the relationship evolves. Furthermore, on a practical level, it introduces a mapping or configuration scheme to identify the sources and levels of strength of inherent tension, enhancing coopetition partners’ ability to monitor their relationship over time.

Details

Journal of Business & Industrial Marketing, vol. 37 no. 13
Type: Research Article
ISSN: 0885-8624

Keywords

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