Applied sciences

Archives of Civil Engineering

Content

Archives of Civil Engineering | 2017 | No 1 |

Abstract

Production rates for various activities and overall construction project duration are significantly influenced by crew formation. Crews are composed of available renewable resources. Construction companies tend to reduce the number of permanent employees, which reduces fixed costs, but at the same time limits production capacity. Therefore, construction project planning must be carried out by means of scheduling methods which allow for resource constrains. Authors create a mathematical model for optimized scheduling of linear construction projects with consideration of resources and work continuity constraints. Proposed approach enables user to select optimal crew formation under limited resource supply. This minimizes project duration and improves renewable resource utilization in construction linear projects. This paper presents mixed integer linear programming to model this problem and uses a case study to illustrate it.

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Abstract

This paper concerns an approach to model the ledger-stand joints of modular scaffolds. Based on the analysis of the working range of the ledger (represented by a linear relationship between load and displacement), two models of the ledger-stand joint are analysed: first – with flexibility joints and second – with rigid joints and with a transition part of lower stiffness. Parameters are selected based on displacement measurements and numerical analyses of joints, then they are verified. On the basis of performed research, it can be stated that both methods of joint modelling recommended in this paper, can be applied in engineering practices.

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Abstract

Considering concrete nonlinearity, the wave height limit between small and large amplitude sloshing is defined based on the Bernoulli equation. Based on Navier-Stokes equations, the mathematical model of large amplitude sloshing is established for a Concrete Rectangle Liquid-Storage Structure (CRLSS). The results show that the seismic response of a CRLSS increases with the increase of seismic intensity. Under different seismic fortification intensities, the change in trend of wave height, wallboard displacement, and stress are the same, but the amplitudes are not. The areas of stress concentration appear mainly at the connections between the wallboards, and the connections between the wallboard and the bottom.

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Abstract

The impacts of industrial wastewater contamination on the geotechnical properties of clayey soil have been studied in the research presented in this paper. The contaminant in question is industrial wastewater released from Thi-Qar oil refinery as a by-product of production, and the soil samples obtained from Thi-Qar oil refinery plant in Al-Nassyriah (a city located in the south of Iraq). The geotechnical properties of contaminated soil samples were compared with those of intact soil to measure the effects of such a contaminant. The soil samples were obtained from three locations in the study area; representing the highly contaminated area, the slightly contaminated area, and the intact area used as a reference for comparison of test results. The results of the tests showed that the contaminant causes an increase of natural moisture content, field unit weight, Atterberg’s limits, and maximum dry unit weight, as well as an increase of the compression index and the coefficient of vertical consolidation. Also, the contaminant causes a decrease in specific gravity, the optimum moisture content initial void ratio, the swelling index, the coefficient of permeability, and cohesion between soil particles.

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Abstract

Risks pertaining to construction work relate to situations in which various events may randomly change the duration and cost of the project or worsen its quality. Because of possible significant changes of random events, favorable, moderate, and difficult conditions of construction work are considered. It is the first stage of the construction risk analysis. The probabilistic parameters of construction are identified and described by using the design characteristics model of the structure and the construction technology model. The first describes the probabilistic properties of the structure execution's technology. The second describes the probabilistic properties of the works execution. Both models contain basic probabilistic data for scheduling, cost estimating, and risk assessment of the construction.

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Abstract

A description of direct simulation of crosswind loads caused by critical vortex excitation and the response of the structure to these loads are presented in this paper. Tower-like structures of circular cross-sections are considered. A proposed mathematical model of vortex excitation has been numerically implemented and a selfserving computer program was created for the purpose. This software, cooperating with the FEM system, allows for a simulation of a crosswind load and lateral response in real time, meaning that at each time step of the calculations the load is generated using information regarding displacements seen beforehand. A detailed description of the mathematical model is neglected in this paper, which is focused on numerical simulations. WAWS and AR methods are used in simulations.

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Abstract

The aim of this study is to find the cost design of RC tension with varying conditions using the Artificial Neural Network. Design constraints were used to cover all reliable design parameters, such as limiting cross sectional dimensions and; their reinforcement ratio and even the beahviour of optimally designed sections. The design of the RC tension members were made using Indian and European standard specifications which were discussed. The designed tension members according to both codes satisfy the strength and serviceability criteria. While no literature is available on the optimal design of RC tension members, the cross-sectional dimensions of the tension membersfor different grades of concrete and steel, and area of formwork are considered as the variables in the present optimum design model. A design example is explained and the results are presented. It is concluded that the proposed optimum design model yields rational, reliable, and practical designs.

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Abstract

In this paper, a semi-analytical solution for free vibration differential equations of curved girders is proposed based on their mathematical properties and vibration characteristics. The solutions of in-plane vibration differential equations are classified into two cases: one only considers variable separation of non-longitudinal vibration, while the other is a synthesis method addressing both longitudinal and non-longitudinal vibrationusing Rayleigh’s modal assumption and variable separation method. A similar approach is employed for the out-of-plane vibration, but further mathematical operations are conducted to incorporate the coupling effect of bending and twisting. In this case study, the natural frequencies of a curved girder under different boundary conditions are obtained using the two proposed methods, respectively. The results are compared with those from the finite element analysis (FEA) and results show good convergence.

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Abstract

The objective of the presented paper is to investigate the performance of concrete containing volcanic scoria as cement replacement after 7, 28, 90, and 180 days curing. Five performance indicators have been studied. Compressive strength, water permeability, porosity, chloride penetrability, and reinforcement corrosion resistance have all been evaluated. Concrete specimens were produced with replacement levels ranging from 10 to 35%. Test results revealed that curing time had a large influence on all the examined performance indicators of scoria-based concrete. Water permeability, porosity, and chloride penetrability of scoria-based concrete mixes were much lower than that of plain concrete. Concretes produced with scoria-based binders also decelerated rebar corrosion, particularly after longer curing times. Furthermore, an estimation equation has been developed by the authors to predict the studied performance indicators, focusing on the curing time and the replacement level of volcanic scoria. SEM/EDX analysis has been reported as well.

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Abstract

Shear walls are the most commonly used lateral load resisting systems in high rises. They have high plane stiffness and strength which can be used to simultaneously resist large horizontal loads while also supporting gravity loads. Hence it is necessary to determine effective and ideal locations of shear walls. Shear wall arrangement must be absolutely accurate, if not, it may cause negative effects instead. In this project, a study has been carried out to determine the effects of additions of shear walls and also the optimum structural configuration of multistory buildings by changing the shear wall locations radically. Four different cases of shear wall positions for G+10 storey buildings have been analyzed by computer application software ETABS. The framed structure was subjected to lateral and gravity loading in accordance with the Indian Standards provision and the results were analyzed to determine the optimum positioning of the shear walls.

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Abstract

Laplace Transform is often used in solving the free vibration problems of structural beams. In existing research, there are two types of simplified models of continuous beam placement. The first is to regard the continuous beam as a single-span beam, the middle bearing of which is replaced by the bearing reaction force; the second is to divide the continuous beam into several simply supported beams, with the bending moment of the continuous beam at the middle bearing considered as the external force. Research shows that the second simplified model is incorrect, and the frequency equation derived from the first simplified model contains multiple expressions which might not be equivalent to each other. This paper specifies the application method of Laplace Transform in solving the free vibration problems of continuous beams, having great significance in the proper use of the transform method.

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Abstract

The aim of the presented paper is to show the results of shape optimization of railway polynomial transition curves (TCs) of 5th, 7th, and 9th degrees through the use of the full vehicle model and new criteria of assessement concerning the jerk value. The search for the proper shape of TCs means that in this work, the evaluation of TC properties is based on select quantities and the generation of such a shape through the use of mathematically understood optimization methods. The studies presented have got a character of the numerical tests. For this work, advanced vehicle models describing dynamical track-vehicle and vehicle-passenger interactions as well as optimization methods were exploited. In the software vehicle model of a 2-axle freight car, the track discrete model, non-linear descriptions of wheel-rail contact are applied. This part of the software, the vehicle simulation software, is combined with a library optimization procedure into the final computer program.

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GUIDELINES FOR AUTHORS

1. Preparation of the paper

General: Author is responsible for the Paper contents including copyrights and text formatting. The manuscript should be written in English. It should be typed using 12 p TNR font with 1.5 line spacing, on single-sided A4 sheets with 2 cm margins. The paper should not exceed 10 pages including tables and figures plus 2 pages of an extended summary (TNR 10 pt. justify align), started from new page at the end of the manuscript. Summary in Polish for Polish natives only, others - summary in English.

The first page and the main text: The first page of the article should contain: (1) the title of the article, (2) the name, academic merits, affiliation and e-mail of each author, (3) the name and the address of the author to whom correspondence, proofs and reprints should be sent, (4) a summary of 50-150 words, (5) a list of key words (not to exceed 8). The main text should be divided into numbered (1, 2, etc.) and titled sections and, if needed, into subsections (1.1, 1.2, ... in Section 1, 2.1, 2.2, ... in Section 2, etc.). The abstract of 50-150 words is required on a separate sheet. Polish natives authors only are requested to enclose Polish translation of the abstract, others - abstract in English.

Tables and figures: Tables and figures should be inserted into the text (black-and-white figures and glossy photographs),numbered consecutively and titled. They should be referred to in the text as Fig. 1, Fig. 2, ..., Table 1, Table 2. A list of figures and tables captions (TNR 11 pt. left align, in Polish - for Polish natives only and in English) should be provided on separate sheet(s) at the end of the manuscript beforean extended summary. Colour figures will be accepted only if the colour is essential for the explanation.

Units and mathematical formulae: SI units and abbreviations are obligatory. Mathematical formulae should be typewritten and centred. The formulae referred to in the text are to be numbered consecutively in each Section, i.e. (1.1), (1.2), ... in Section 1, (2.1), (2.2), ... in Section 2, etc. The numbers should be placed in parentheses ( ) at the left margin. The formulae are to be referred to in the text as Eq. (1.1),, Eq. (1.2), ..., Eq. (2.1), Eq. (2.2), ..., etc. The formulae not referred to in the text should not be numbered.

Bibliography: References are to be listed at the end of the paper in the alphabetical order and consecutively numbered. A reference to a published paper should be referred to in the text by the last name(s) of author(s) and the reference's number in brackets [ ]. Each item should contain full bibliographical data in the format illustrated by the following examples:

[1] M. Abramowitz and I. A. Stegun, Eds. Handbook of Mathematical Functions (Applied Mathematics Series 55). Washington, DC: NBS, 1964, pp. 32-33.

[2] M. Gorkii, “Optimal design”, Dokl. Akad. Nauk SSSR, vol. 12, pp. 111-122, 1961.

(Transl.: in L. Pontryagin, Ed., The Mathematical Theory of Optimal Processes. New York: INTERSCIENCE, 1962, Ch. 2, sec. 3, pp. 127-135).

[3] B. Klaus and P. Horn, Robot Vision. Cambridge, MA: MIT Press, 1986.

[4] E. F. Moore, “Gedanken-experiments on sequential machines”, in Automata Studies

(Ann. of Mathematical Studies, no. 1), C. E. Shannon and J. McCarthy, Eds. Princeton, NJ: Princeton Univ. Press, 1965, pp. 129-153.

[5] R. L. Myer, “Parametric oscillators and nonlinear materials”, in Nonlinear Optics, vol. 4, P. G. Harper and B. S. Wherret, Eds. San Francisco, CA: Academic, 1977, pp. 47-160.

[6] L. Stein, “Random patterns”, in Computers and You, J. S. Brake, Ed. New York: Wiley, 1994, pp. 55-70.

[7] Westinghouse Electric Corporation (Staff of Technology and Science, Aerospace Div.), Integrated Electronic Systems. Englewood Cliffs, NJ: Prentice-Hall, 1970.

[8] G. O. Young, “Synthetic structure of industrial plastics”, in Plastics, vol. 3, Polymers of Hexadromicon, J. Peters, Ed., 2nd ed. New York: McGraw-Hill, 1964, pp. 15-64.

In special cases, other formats related to codes, reports, dissertations, etc. will be accepted.

Layout of the text can be downloaded from ace website: http://ace.il.pw.edu.pl

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4. Copyright: Submission of a paper to Archives of Civil Engineering implies that the material is an original and unpublished work, not under consideration for publication elsewhere. If permission for publication of any material is required, it should be obtained from appropriate sources by the author. The corresponding author is responsible for the other authors' approval of the paper publication.

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6. Other information: Apart from research papers, other articles such as review papers, brief notes, discussions and reports may be published in the journal. Monographic papers and state-of-the-art papers are accepted after prior approval of the Editor. Reports on important conferences held in Poland may also be published. Editor decides whether the paper fulfil all requirements i.e. formal and scientific. Editor nominates two reviewers, who shall forward reviews of the accepted publication.

The paper will be published in ACE provided that the reviews are positive. If reviewers have some comments authors have to correct the paper. Papers are subject to open discussion. All letters should be addressed to the Editorial Office and will be published together with the authors' response.

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