INTERACTION DIAGRAMS AXIAL FORCE-BENDING MOMENT FOR FIRE EXPOSED STEEL-CONCRETE COMPOSITE SECTIONS

The bearing capacity of the column cross section can be determined from the interaction diagram moment-axial force (M–N). Fire induced temperatures cause reduction of the load-bearing characteristics of the constitutive materials, steel and concrete, and this effect directly reflects on the reduction of the axial force and the bending moment that could be accepted by the column cross section, respectively the interaction diagram of the column cross section is changed. The load bearing capacity of the steel-concrete composite columns exposed to fire from all four sides and loaded by axial force and uni-axial or bi-axial bending moments, was estimated on the basis of the changes in the interaction diagrams moment-axial force amd the results are presented in this paper. Different types of composite columns made of totally or partially encased steel sections, or concrete filled hollow sections were analyzed and a detailed discussion on the effects of the shape of the cross section and the cross sectional dimensions are presented

Learning from projects: Macedonian experiences with international civil engineering projects

this article Presents authors exPeriences collected during working on some international civil engineering Projects. The purpose of the article is to present possible obstacles during working on international projects, resulting from differences in levels of design, application of different standards and models for civil works, as well as different engineering practice. A special attention is given on problems connected with project management, technical documentation and construction projects determining factors. Main idea is to give possible way of overcoming the differences that can arise from different application of mentioned project elements. A main conclusion is that, before starting on working with international civil engineering projects, a detailed analyse of all law aspects, standards, technical legislative, local practice and culture is necessary. Authors believe that the gathered experiences can serve as a learning example for foreign parties and for improvement international cooperation in construction

FIRE RESISTANCE OF ENERGY EFFICIENT FLOOR STRUCTURES

This paper presents the numerically achieved results for the fire resistance of several types of floor structures which are mostly used in our residential and rural buildings and in same time fulfil the energy efficient criteria, as: semi-prefabricated reinforced concrete slabs system FERT and STIRODOM (with infill of extruded polystyrene -XPS), timber-concrete composite floor structure and traditional timber floor structure. The solid RC slab was analysed only for comparison. Using the computer programs SAFIR, the effect of the intensity of the permanent and variable actions and the effect of the thermal isolation on the fire resistance of simply supported slabs were analyzed. The fire resistance was defined with respect to the criteria of usability of the structures in fire conditions, according to Eurocodes and the standards in force

Load-bearing capacity of fire exposed composite columns

U radu se analizira nosivost poprečnih presjeka triju vrsta spregnutih stupova čelik-beton, a dobiveni rezultati se uspoređuju s nosivošću referentnog armiranobetonskog stupa. Mehanička svojstva sastavnih materijala bitno se pogoršavaju zbog visokih temperatura uzrokovanih djelovanjem požara, što dovodi do smanjenja otpornosti stupa na djelovanje uzdužne sile i dvoosnog momenta savijanja. Smanjenje otpornosti analiziranih stupova pod utjecajem visokih temperatura iskazano je kroz promjenu interakcijskih krivulja M-N.The cross-section load-bearing capacity of three types of fire exposed steel-concrete composite columns is analysed in this paper, and the results are compared with the load-bearing capacity of a reference reinforced-concrete column. Mechanical properties of constitutive materials are reduced considerably by high temperatures caused by fire action, which results in a reduced load bearing capacity of columns with regard to the longitudinal force and biaxial bending moment. The reduced load bearing capacity of analysed columns subjected to elevated temperatures is expressed through changes in the M-N interaction curves

Application of artificial neural networks in civil engineering

Primjena umjetnih neuronskih mreža za rješavanje složenih građevinskih problema je od ogromne važnosti za proces projektiranja. One se mogu uspješno koristiti za prognostičko modeliranje u različitim inženjerskim područjima, osobito u onim slučajevima u kojima već postoje neka prethodna istraživanja (numerička ili pokusna). Ovaj rad prikazuje neke od pozitivnih aspekata modela neuronske mreže kad se koriste za utvrđivanje požarne otpornosti građevinskih elemenata.The application of artificial neural networks for solving complex civil engineering problems is of huge importance for the construction design process. They can be successfully used for prognostic modelling in different engineering fields, especially in those cases where some prior (numerical or experimental) analyses were already made. This paper presents some of the positive aspects of neural network’s model that was used for determination of fire resistance of construction elements

Application of artificial neural networks in civil engineering

Primjena umjetnih neuronskih mreža za rješavanje složenih građevinskih problema je od ogromne važnosti za proces projektiranja. One se mogu uspješno koristiti za prognostičko modeliranje u različitim inženjerskim područjima, osobito u onim slučajevima u kojima već postoje neka prethodna istraživanja (numerička ili pokusna). Ovaj rad prikazuje neke od pozitivnih aspekata modela neuronske mreže kad se koriste za utvrđivanje požarne otpornosti građevinskih elemenata.The application of artificial neural networks for solving complex civil engineering problems is of huge importance for the construction design process. They can be successfully used for prognostic modelling in different engineering fields, especially in those cases where some prior (numerical or experimental) analyses were already made. This paper presents some of the positive aspects of neural network’s model that was used for determination of fire resistance of construction elements

Application of Fuzzy Logic on Selection of Contractors for Construction of High Rise Buildings

Selection process of a construction contractor is highly important and successful implementation of a project and realization of sustainability are largely dependent on it. Computer programs - expert systems - may be used to help the employer or his consultants in the process of best tenderer selection. This paper presents a new expert system based on the implementation of fuzzy logic as an aid in selecting a contractor for construction of high rise buildings

Uticaj graničnih uslova na nelinearan odgovor laminatnih kompozitnih ploča

In this paper the influence of different boundary conditions on geometrically nonlinear response of laminated composite plates is analyzed. Mathematical model, based on layer-wise displacement field of Reddy [1], is formulated using the von Karman, small strain large deflection theory. The principle if virtual displacements (PVD) is used to obtain the weak form of the problem. The weak form is discretized utilizing isoparametric finite element approximation. The originally coded MATLAB program is used to investigate the influence of different boundary conditions on geometrically nonlinear response of laminate composite plates. The accuracy of the numerical model is verified by comparison with the available results from the literature.U ovom radu analiziran je uticaj različitih graničnih uslova na geometrijski nelinearan odgovor laminatnih kompozitnih ploča. Matematički model, zasnovan na slojevitom polju pomeranja koje je predložio Reddy [1], formulisan je koristeći von Karman'ovu teoriju velikih pomeranja i malih deformacija. Princip virtulanih pomeranja je primenjen za dobijanje slabe forme problema. Slaba forma je diskretizovana koristeći izoparametarsku aproksimaciju konačnim elementom. Originalan MATLAB računski program je korišćen za analizu uticaja različitih graničnih uslova na nelinearna odgovor laminatnih kompozitnih ploča. Tačnost numeričkog modela je potvrđena poređenjem sa rešenjima iz literature.

Fire-resistance prognostic model for reinforced concrete columns

U radu je prikazan prognostički model za određivanje požarne otpornosti armiranobetonskih stupova izloženih standardnom požaru sa svih strana. Predloženi model primjenjuje koncept umjetnih neuralnih mreža čiji su ulazni parametri rezultat prethodno provedene numeričke analize. Dan je kratak opis procesa modeliranja, kao i odgovarajući primjer primijenjenog prognostičkog modela.The prediction model used for defining fire resistance of reinforced concrete columns exposed to standard fire from all four sides is presented in the paper. The proposed model relies on the concept of artificial neural networks, in which numerical analysis results are used as input parameters. A brief description of the modelling process is given, and an appropriate example of the neural network prognostic model is presented