Analysis of composite T beam composed of timber, concrete and carbon strip

This paper provides a mathematical model and numerical example of composite T-section composed of a concrete plate and a timber beam strengthened at the bottom tension side with a carbon fibre-reinforced polymer (CFRP) strip. Analysis is provided in accordance with the European standards for timber, steel and concrete structures. The tensile strength of the carbon strip as well as the compressive strength of the concrete plate are higher than the bending strength of the timber beam, therefore it is convenient to use such composition of material to gain a higher load bearing capacity. It has been shown that the inclusion of CFRP strip reinforcement on the increase of load carrying and bending stiffness capacity was not as high as expected. On the other hand, we realized the importance of variety of material grade and geometrical properties combinations between sub-components which can significantly improve load bearing capacity and stiffness of composed beam. Furthermore, the CFRP strip contribution to the bending resistance and stiffness of the element is presented as a function of the fastener spacing intervals between concrete plate and timber beam

Toplinska udobnost i unutarnja kvaliteta zraka nakon djelomične energetske obnove prefabriciranog betonskog dječjeg vrtića izgrađenog 1980-ih u Sloveniji

The majority of kindergartens situated in the territory of former Yugoslavia need renovation. Apart from their enhanced energy efficiency, renovated buildings will presumably offer better indoor environmental quality. According to the current case study, children using a classroom with new windows installed are exposed to substantially poorer indoor air quality due to airtightness and improper ventilation, which calls attention to a vital technical issue of the current renovation process.Većini dječjih vrtića smještenih na teritoriju bivše Jugoslavije potrebna je obnova. Osim naglašene energetske učinkovitosti, obnovljene će zgrade vjerojatno ponuditi i bolju kvalitetu boravka u interijeru. Prema aktualnoj studiji slučaja, djeca u učionicama s instaliranim novim prozorima izložena su osjetno lošijoj kvaliteti zraka u zatvorenom prostoru zbog zračne nepropusnosti i neispravne ventilacije. U središtu pozornosti stoga treba biti tehnička problematika aktualnih procesa obnove

Slip modeling in timber-framed walls with wood-based or fibre-plaster sheathing boards

The paper provides mathematical modelling for prefabricated timber-framed walls composed of a timber frame and two different types of sheathing boards. Since by wood-based boards (WBB) the tensile strength is similar to the compressive one, there are practically no cracks appearing in the boards. On the other hand, in case of fibre-plaster sheathing boards (FPB) the tensile strength is approximately 10-times lower than the compressive one and therefore cracks in the tensile diagonal boardćs direction usually appear. Based on analysis of experimental research results [1] special approximate mathematical models have been developed. The models enable simultaneously to consider the flexibility of mechanical fasteners in the connecting areas, as well as possible cracks appearing in the tensile area of the sheathing boards

Precision 1D Determination of Micromovements with Geodetic and Non-geodetic Instruments

Istraživanja u ovome radu temelje se na eksperimentalnom određivanju vertikalnih mikropomaka različitim geodetskim i negeodetskim instrumentima i analizi rezultata mjerenja tih pomaka. Mjerenja su provedena u laboratoriju Građevinskog fakulteta Sveučilišta u Mariboru, pri čemu je upotrebljena posebno izgrađena armiranobetonska ploča. Za postupno opterećivanje armiranobetonske ploče izračunane su teorijske vrijednosti vertikalnih pomaka, a stvarni su pomaci određivani različitim instrumentima. Na kraju se daje ocjena preciznosti određivanja pomaka.The research in this work is based on experimental determination and analysis of the results obtained from measuring the vertical micromovements with various geodetic and non-geodetic instruments. The measurements have been carried out in the laboratory of the Faculty of Civil Engineering at the University in Maribor using specially built reinforced concrete plate for that purpose. The theoretical values of vertical movements have been computed for gradual straining of the reinforced-concrete plate, and the true movements have been determined with various instruments. At the end, there is an estimation of precision in movement determination given

Precision 1D Determination of Micromovements with Geodetic and Non-geodetic Instruments

Istraživanja u ovome radu temelje se na eksperimentalnom određivanju vertikalnih mikropomaka različitim geodetskim i negeodetskim instrumentima i analizi rezultata mjerenja tih pomaka. Mjerenja su provedena u laboratoriju Građevinskog fakulteta Sveučilišta u Mariboru, pri čemu je upotrebljena posebno izgrađena armiranobetonska ploča. Za postupno opterećivanje armiranobetonske ploče izračunane su teorijske vrijednosti vertikalnih pomaka, a stvarni su pomaci određivani različitim instrumentima. Na kraju se daje ocjena preciznosti određivanja pomaka.The research in this work is based on experimental determination and analysis of the results obtained from measuring the vertical micromovements with various geodetic and non-geodetic instruments. The measurements have been carried out in the laboratory of the Faculty of Civil Engineering at the University in Maribor using specially built reinforced concrete plate for that purpose. The theoretical values of vertical movements have been computed for gradual straining of the reinforced-concrete plate, and the true movements have been determined with various instruments. At the end, there is an estimation of precision in movement determination given

Energetski učinkovita načela obnove montažnih stambenih zgrada s drvenim okvirom

The timber construction along with the use of suitable and correctly oriented glazing surfaces, whose thermal and strength properties have been considerably improved over the years, represents a great potential in residential and public building construction. However, necessary renovations of the older structures, which present quite a large share of residential fund, should not be overlooked. Moreover, those structures should be adequately energy renovated by the year 2020. Therefore, the key contribution of this paper is the presentation of the available renovation principles, and namely a combination of the improvement of buildings envelope thermal properties, usage of a proper type of installation and share of glazing surfaces in the south-oriented façade, according to affordable investment input. In order to achieve minimal heating and cooling annual energy demand, in the current parametric study, different options were carried out with double-layer and triple-pane glazing, installed in three different types of wall elements, demonstrating the value of optimal glazing surface.Drvena konstrukcija, uz uporabu odgovarajućih i pravilno orijentiranih staklenih površina čija su toplinska svojstva i čvrstoća tijekom godina znatno poboljšani, velik su potencijal u gradnji stambenih i javnih zgrada. Pritom ne smije biti zanemarena ni obnova starijih objekata, koji čine prilično velik udio u stambenom fondu. Usto ti bi objekti do 2020. godine trebali biti odgovarajuće energetski obnovljeni. Dakle, važan doprinos ovog članka jest predstavljanje raspoloživih načela obnove kao što su kombinacija poboljšanih toplinskih svojstava fasade zgrade, primjena odgovarajućeg tipa instalacija i udjela staklenih površina na južnoj fasadi, ovisno o mogućemu investicijskom ulaganju. Kako bi se postigla minimalna godišnju potreba za grijanjem i hlađenjem, u parametarskoj studiji izvedene su različite mogućnosti s dvoslojnim i troslojnim zastakljenjem, ugrađenima u tri različita tipa zidnih elemenata, čime se demonstrira vrijednost optimalnih staklenih površina

Ojačavanje podnih konstrukcija CLT pločama - numerička studija

The purpose of this article is to provide an insight into the field of timber floor strengthening with cross-laminated timber (CLT) panels. A classic timber floor strengthened with CLT panels is therefore analysed according to the current building standards in the European Union, the Eurocodes. Seven different CLT panels, with thicknesses from 60 mm to 120 mm, are taken into consideration for the numerical study. Self-tapping screws with a diameter of 6 mm and length of 200 mm are used as shear connectors. The gamma method is used for calculating the effective bending stiffness. The design procedure is briefly presented, and the results for different configurations are compared.Cilj je ovog rada pokazati kako ojačati podne konstrukcije koristeći unakrsno laminirane drvene panele (CLT paneli). Kao predmet studije uzete su klasične drvene podne konstrukcije ojačane sa CLT panelima i uspoređene s Eurocode standardima, službenim graditeljskim standardom u EU-u. Sedam različitih tipova panela debljine od 60 do 120 mm su analizirani u numeričkoj studiji. Kao sredstvo sprezanja uzeti su samourezujući vijci promjera 6 mm i duljine 200 mm. Za proračun efektivne savojne krutosti korištena je gama metoda. U radu je kratko prikazana procedura dimenzioniranja te su uspoređeni rezultati različitih konfiguracija podnih konstrukcija

Approach to refurbishment of timber preschool buildings with a view on energy and economic efficiency

The refurbishment of educational buildings usually involves a variety of measures aiming at reducing energy demands and improving building functionality to achieve higher living comfort. This paper aims to develop an approach for determination of comprehensive refurbishment strategy upon existing preschool buildings in Slovenia from the aspects of energy and economic efficiency. The main idea of the approach is to separate and individually analyse the investments into those related to energy efficiency improvements and those related to improvements of building functional quality through the step-by-step evaluation of individual measures. The proposed approach was applied on the case study of the existing timber preschool building in the city of Maribor. Generally, the highest energy savings are detected only in the case of combination of multiple renovation measures. Moreover, the economic indicators show low efficiency for almost all measures if they are treated separately. Additionally, the analysis reveals that certain measures are totally inefficient in terms of energy, yet they are highly beneficial from the viewpoint of building functional quality, which indicates the importance of the multi-perspective assessment of renovation process. The conclusions of this study can be implemented to similar building types and construction ages in similar climatic and economic environments

Usporedba segmenata vanjskog zida zgrade na osnovu potencijala globalnog zagrijavanja

Lowering environmental impacts in the operational phase of the building’s life cycle has been achieved by introducing highly-insulated thermal envelopes in temperate and cold climates. However, the emissions and energy used in other life cycle phases should also be considered. The paper presents the comparison of the building’s external wall components based on global warming potential in the production phase. Four types of construction (reinforced concrete, brick, cross-laminated timber and timber-frame) and three types of insulation materials (rock wool, expanded polystyrene and wood fibre) used within external wall components are analysed. Three heat transfer coefficients of the wall components were selected and compared. The results of the study demonstrate the potential of lowering environmental impacts of building external wall components by selecting suitable materials and present the solutions for the optimization of thermal envelopes in the design phase.Korištenje sofisticiranih termalnih izolacija u operativnoj fazi vijeka trajanja zgrade je značajno smanjilo utjecaj na okoliš u područjima blage i hladne klime, no potrebno je uzeti u obzir emisije i potrošnju energije u drugim fazama vijeka zgrade. U ovom će se radu prikazati usporedba segmenata vanjskog zida zgrade na osnovi potencijala globalnog zagrijavanja, ali u fazi proizvodnje građevinskih materijala. Posebno će se analizirati četiri tipa gradnje (armirani beton, cigla, unakrsno lamelirane drvene panele i drveni okvir) i tri tipa izolacijskog materijala (kamena vuna, ekspandirani polistiren i drvna vlakna) koji su korišteni u segmentima vanjskog zida. Odabrana su i uspoređena tri koeficijenta provođenja topline za predmetne segmente zida. Rezultati analize su pokazali potencijal smanjenja utjecaja na okoliš segmenata vanjskog zida uslijed odabira odgovarajućih materijala što predstavlja rješenje optimizacije termalne izolacije u fazi projektiranja