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Abstract

Elastic lateral-torsional buckling of double-tee section structural steelworks has been widely investigated with regard to the major axis bending of single structural elements as a result of certain loading conditions. No specific attention has been paid to the general formulation in which an arbitrary span load pattern was associated with unequal end moments as a result of the moment distribution between structural members of the load bearing system.Anumber of analytical solutionswere developed on the basis of the Vlasov theory of thin-walled members. Since the accurate closed-form solutions of lateral-torsional buckling (LTB) of beams may only be obtained for simple loading and boundary conditions, more complex situations are treated nowadays by using numerical finite element methods (FEM). Analytical and numerical methods are frequently combined for the purpose of: a) verification of approximate analytical formulae or b) presentation the results in the form of multiple curve nomograms to be used in design practice. Investigations presented in this paper deal with the energy method applied to LTB of any complex loading condition of elements of simple end boundary conditions, bent about the major axis. Firstly, a brief summary of the second-order based energy equation dealt with in this paper is presented and followed by its approximate solution using the so-called refined energy method that in the case of LTB coincides with the Timoshenko’s energy refinement. As a result, the LTB energy equation shape functions of twist rotation and minor axis displacement are chosen such that they cover both the symmetric and antisymmetric lateral-torsional buckling modes. The latter modes are chosen in relation to two lowest LTB eigenmodes of beams under uniform major axis bending. Finally, the explicit form of the general solution is presented as being dependent upon the dimensionless bending moment equations for symmetric and antisymmetric components, and the in-span loads. Solutions based on the present investigations are compared for selected loading conditions with those obtained in the previous studies and verified with use of the LTBeam software. Conclusions are drawn with regard to the application of obtained closed-form solutions in engineering practice.
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Authors and Affiliations

Anna Barszcz
1
ORCID: ORCID
Marian Giżejowski
1
ORCID: ORCID
Malwina Pękacka
2

  1. Warsaw University of Technology, Faculty of Civil Engineering, Al. Armii Ludowej 16, 00-637 Warsaw, Poland
  2. Warsaw University of Technology Graduate, Faculty of Civil Engineering, Al. Armii Ludowej 16, 00-637 Warsaw, Poland
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Abstract

This paper presents the results of a cost-effectiveness analysis and a cost-benefit analysis for the production of X-type zeolites from fly ash.
Positive results of the laboratory tests on the quality of zeolites derived from fly ash initiated a cost analysis on the production of this materials on an industrial scale. The cost-effectiveness analysis was conducted using the dynamic generation cost indicator (DGC). The calculated DGC expresses the technical manufacturing cost of 1 Mg of synthetic zeolites. Whereas the cost-benefit analysis (CBA) was completed using the economic net present value (ENP V) and the economic internal rate of return (EIRR ) indicators.
The calculated unit technical cost of producing 1 Mg of zeolites using an installation consisting of five reactors with a capacity of 25 m3 each is 211 EUR and is lower than the current market price of this product, including transportation costs. This proves the financial viability of the investment. The calculations of the economic efficiency of the installation (CBA method) show that it is fully economically viable to operate and use the products from a social point of view.
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Authors and Affiliations

Barbara Białecka
1
ORCID: ORCID
Magdalena Cempa
1
ORCID: ORCID
Zdzisław Adamczyk
2
ORCID: ORCID
Henryk Świnder
1
ORCID: ORCID
Piotr Krawczyk
1
ORCID: ORCID

  1. GIG Research Institute, Katowice, Poland
  2. Silesian University of Technology, Gliwice, Poland
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Abstract

The paper attempted to define the basis of city transformations that conform to the smart concept. The objective of the paper is to relate the concept of a smart city, which is quite frequently discussed in literature related to the subject, with functioning and development of the city’s economy, in a way that would allow monitoring economic processes taking place in the city, and also to find a response to the question as to the extent to which the smart city creates a new city economy. Does it expand the city economy by new elements, generate new economic mechanisms, allow the implementation of growth paths different than those to date? This objective is particularised by a description of selected issues of urban economics. With this in mind the paper discusses an approach to managing supply and demand on the basis of theoretical assumptions defined by Mudie and Cottam (1993) transposed on realities connected with provision of municipal public services in conditions of a smart city. Furthermore, sample solutions were presented related to the smart city, which reflect theoretical conclusions contained in the paper. The paper ends with a presentation of logics related to growing economy in a smart city. The economy of a smart city, ultimately an intelligent economy of the city, is created in a laminar way. Under the pressure of technological, social and political surroundings the city is permeated by social and culture intelligence, forming gradually a new economic quality. In the paper we emphasised that the concept of a smart city still remains a question of the future to a much bigger extent than one of the present time. A smart city slowly emerges from the combination of diverse megatrends and development trends characteristic for communities and economies of the second decade of the 21st century.

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Authors and Affiliations

Marcin Baron
Florian Kuźnik

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