Fire safety greatly contributes to feeling safe, and it is a key parameter for the selection of building materials. The combustibility of timber is one of the main reasons to have the strict ...restriction on timber for use as a building material, especially for multistory buildings. Therefore, the main prerequisite for the use of timber in buildings is to ensure adequate fire resistance, using passive and active fire protection measures. This article contains the results of mechanical and fire experimental tests of both normal and innovative hollow glued laminated timber beams. A total of 10 timber beams were tested at ambient temperature, and 3 timber beams in fire conditions, which differed in cross-section type but also in the applied fire protection. The first beam was a normal GL beam without fire protection, the second a hollow beam covered by intumescent paint, while the third was also hollow, additionally protected by mineral wool infill inside the holes. The load-carrying capacity of the hollow beam in ambient conditions was estimated at 65% of the load-carrying capacity of a normal GL beam. Fire tests indicated that hollow timber beams with both intumescent paint and mineral wool infill failed at a similar time as a normal GL beam without fire protection. One-dimensional β0 and notional charring rates βn were obtained. Time to the protective material failure was 17 min. The main cause of failure of hollow beams was the appearance of delamination due to the reduction of the lamella bonding surface.
Due to the growing need to preserve our planet and reduce carbon emissions during construction, the use of the only carbon-absorbing material, timber, is increasingly being imposed. In addition to ...the requirement of reducing emissions, there is a necessity for the shortest possible construction time and the minimum use of construction machinery, which has led to the development of prefabricated construction systems. This paper deals with the innovative, hollow, glue-laminated timber elements which are intended for modular construction. Comparing this new system with existing modular systems, the main features and behavior of the constitutive elements, i.e., the hollow, glue-laminated timber elements, are presented. Experimental and numerical analysis of the mechanical performance of the timber elements was carried out and a comparative analysis of the behavior of two different types of hollow timber elements was conducted. The finite element method was used to predict the behavior of this innovative structural system. The results are compared with the analytical procedure to provide a background for the development of standardized methods for the design of timber structures.
The TCC concept has been studied and developed over the past decades. The variety of solutions shows the meaningfulness and functionality of this system, as well as the continuous work of scientists ...over time. To benefit from these advantages, the composite needs to provide sufficient stiffness to meet the serviceability criteria and load capacity to resist loading at every stage of the building life. An example of connector types and load slip curves according to EN 1995 is given. This paper discusses possible limitations related to residential areas, and additionally, the possible solutions that EN 1995 does not discuss in the case of resonant response (f1 < 8 Hz). The theoretical studies were accompanied by numerical analyses considering certain simplifications suitable for practical use.
Timber is one of the fundamental materials of human civilization, it is very useful and ecologically acceptable in its natural environment, and it fits very well with modern trends in green ...construction. The paper presents innovative hollow glued laminated (GL) timber elements intended for log-house construction. Due to the lack of data on the behavior of the hollow timber section in compression perpendicular to the grain, the paper presented involves testing the compression strength of elliptical hollow cross-section glue-laminated timber specimens made of softwood and hardwood, as well as full cross-section glue-laminated softwood timber specimens. The experimental research was carried out on a total of 120 specimens. With the maximal reduction of 26% compared to the full cross-section, regardless of the type of wood and direction of load, the compression strength perpendicular to the grain of hollow specimens decreases by about 55% compared to the full cross-section, with the coefficient kc,90 equal to 1.0. For load actions at the edge and the middle of the element, kc,90 factors were obtained with a value closer to those obtained for full cross-section, which indicates the same phenomenology, regardless of cross-sectional weakening. At the same time, the factors in the stronger axis are lower by about 10%, and in the weaker axis by about 30% compared to those prescribed by the Eurocode. Experimental research was confirmed by FEM analysis. Comparative finite element analysis was performed in order to provide recommendations for future research and, consequently, to determine the optimal cross-section form of the hollow GL timber element. By removing the holes in the central part of the cross-section, the stress is reduced. The distance of the holes from the edges defines the local cracking. Finally, if the holes are present only in the central part of the element, the behavior of the element is more favorable.
The global objective of sustainable development has been greatly directed toward the preservation of existing structures. Therefore, condition assessment and reconstruction of existing timber ...structures have been gaining importance in recent times. This is particularly evident on timber roofs whose elements are exposed to degradation, either because of rheological effects or due to the direct influence of moisture and biological factors. In case of accidental events, such as an earthquake, the question of the structure’s condition is essential for the condition of the entire building. In order to prove the load-bearing capacity and serviceability of existing structures, as well as to check the need for reconstruction, it is necessary to define crucial parameters that are influencing the condition of materials, elements, and systems. Although there are many non destructive testing methods, the frequency and scope of their use, as well as the decision-making approach, have not been defined. In the paper, non-destructive and semi-destructive methods frequently used for timber structures are explained. A systematic review of criteria to be used in the assessment of load-bearing timber structures in a seismic active area was the main objective of this paper as well as the illustration of non-destructive and semi-destructive test methods through a case study involving roof construction of a hundred-year-old building in Zagreb, Croatia. Pre- and post-earthquake inspection was made. The overall condition of the roof structure after two significant earthquakes can be assessed as satisfactory given that the observed system is a large-span and massive roof structure. The presented results and identification of typical damages after the earthquake are presented in order to facilitate policy makers and for the future implementation of development strategies in the renovation of the city.
The basic concept of seismic building design is to ensure the ductility and sufficient energy dissipation of the entire system. The combination of wood and bearing glass represents a design in which ...each material transmits the load, and with the mutual and simultaneous interaction of the constituent elements, it is also earthquake resistant. Such a system has been developed so that the glass directly relies on the wooden frame, which allows the load to be transferred by contact and the friction force between the two of materials. Within the seismic load, friction between glass and wood is an important factor that affects both the behavior and performance of a wood–glass composite system. The set-up system consists of a single specimen of laminated or insulating glass embedded between two CLT elements. The friction force was determined at the CLT–glass contact surface for a certain lateral pressure, i.e., normal force. Friction depends on the way the elements (especially glass) are processed, as well as on the lateral load introduced into the system. Conducted experimental research was accompanied by numerical analyses. Experimental research was confirmed by numerical simulations.
Façade elements are a building component that satisfies multiple performance parameters. Among other things, “advanced façades” take advantage of hybrid solutions, such as assembling laminated ...materials. In addition to the enhanced mechanical properties that are typical of optimally composed hybrid structural components, these systems are energy-efficient, durable, and offer lighting comfort and optimal thermal performance, an example of which is the structural solution developed in collaboration with the University of Zagreb and the University of Ljubljana within the Croatian Science Foundation VETROLIGNUM project. The design concept involves the mechanical interaction of timber and glass load-bearing members without sealing or bonding the glass-to-timber surfaces. Following earlier research efforts devoted to the structural analysis and optimization of thus-assembled hybrid Cross-Laminated Timber (CLT)-glass façade elements, in this paper, special focus is given to a thermal and energy performance investigation under ordinary operational conditions. A simplified numerical model representative of a full-size building is first presented by taking advantage of continuous ambient records from a Live-Lab mock-up facility in Zagreb. Afterwards, a more detailed Finite Element (FE) numerical analysis is carried out at the component level to further explore the potential of CLT–glass façade elements. The collected numerical results show that CLT–glass composite panels can offer stable and promising thermal performance for façades similar to national and European standard requirements.
Na temelju odluka 2. plenuma Centralnoga komiteta Komunističke partije Jugoslavije iz siječnja 1949. i nakon donošenja Osnovnoga zakona o zemljoradničkim zadrugama 28. svibnja 1949. partijska tijela ...Federativne Narodne Republike Jugoslavije započela su forsirati kolektivizaciju seljaštva u zadrugama prema sovjetskom konceptu. Iako je po mišljenju političkih tijela Komunističke partije Jugoslavije taj model trebao rezultirati unapređenjem poljoprivrede, poboljšanjem životnih uvjeta seljaka i izgradnjom socijalizma, taj je sustav napušten 1953., ponajprije zbog prisilnih mjera kojima su seljaci bili izvrgnuti da bi se pridružili seljačkim radnim zadrugama, slabe učinkovitosti rada, seljačkih prosvjeda i masovnoga napuštanja Komunističke partije.Početkom 1953. u karlovačkom je kotaru djelovalo ukupno 18 seljačkih radnih zadruga. U članku je na temelju neobjavljenoga arhivskoga gradiva i novinskih članaka prikazano kako su likvidirane četiri od njih: 9 maj iz Kašta, Narodni borac iz Ladešić Drage, Ozalj i Josip Boljkovac iz Vukove Gorice.
The initiative to initiate peasant labour cooperatives in the Federal People’s Republic of Yugoslavia was introduced at the Second Plenum of the Central Committee of the Communist Party of Yugoslavia which took place from January 29 to 30, 1949. Based on the decisions, the Basic Law on Agricultural Cooperatives was adopted on May 28, 1949. This Law was the legal basis for the accelerated forming of peasant labour cooperatives and the enforced collectivisation of peasantry in accordance with the Soviet model. There are several reasons why the Communist Party of Yugoslavia lost the political will to continue establishing peasant labour cooperatives and supporting their development. Firstly, the peasants worked less on common properties than on their own, secondly, they did not receive any equipment to compensate for the decline of labour productivity; hence, the state had to compensate for the losses of cooperatives from the budget. Furthermore, the tendency of parasitism appeared among peasants. Some of the members of the cooperatives would neglect their work obligations expecting that another member would do the work. The collapse of peasant labour cooperatives started in March 1953 when the government of the Federal People’s Republic of Yugoslavia published the Decree on the reorganization of peasant cooperatives. They were gradually liquidated by the withdrawal of individual peasant farms. The rest of the property was primarily annexed to general agricultural cooperatives. The subject of this article is the liquidation of peasant labour cooperatives in the territory of Karlovac District in 1953. The article was written on the basis of unpublished archival sources and of articles published in the Karlovac Weekly, the newspaper of the Socialist League of Working People of the city of Karlovac. At the beginning of 1953 a total of 18 peasant labour cooperatives were operating in Karlovac District. By September of the same year, 15 of them had been liquidated. Due to a lack of archival records, it was possible to present only the liquidations of four peasant labour cooperatives in this paper: 9 maj from Kašt, Narodni borac from Ladešić Draga, Ozalj and Josip Boljkovac from Vukova Gorica.
Rad se bavi prikazom metode izračuna planskih cijena pridobivanja drva, koje su predmet javnih nadmetanja u Šumsko gospodarskom društvu »Hercegbosanske šume« d.o.o. Kupres te analizom odstupanja ...planskih od ugovorenih/ostvarenih cijena usluga pridobivanja drva za 97 grupa odjela, koji su bili predmet javnih natječaja u 2019. i 2020. godini.
Deskriptivnom i korelacijskom statističkom analizom obuhvaćeni su i pokazatelji grupa odjela na javnim natječajima: površina, neto obujam doznačenog drva, sječna gustoća, broj doznačenih stabala po ha, obujam srednjeg doznačenog stabla, nagib terena, srednja udaljenost privlačenja drva, stjenovitost terena i privlačenje drva uz nagib terena.
Test zavisnih parova podataka je ukazao da postoji statistički značajna razlika između planskih i ugovorenih cijena usluga pridobivanja drva (
t
= 7,78,
p
< 0,001), a rezultati korelacijske analize potvrdili povezanost utjecajnih čimbenika izvođenja šumskih radova s ugovorenom i planskom cijenom pridobivanja drva. Uslijed statistički značajne (
p
< 0,05) i vrlo jake korelacije natječajima ostvarene i prikazanom metodom izračunate planske cijene usluge pridobivanja drva, ovisnost je izjednačena linearnim regresijskim modelom uz koeficijent determinacije od 0,667. Navedenim, prikazana je metoda izračuna planske cijene usluge pridobivanja drva dobar prediktor ostvarenih cijena pridobivanja drva na javnim natječajima, što govori i o samoj dobroti prikazane metode izračuna. Slaba i negativna korelacija (
p
< 0,05,
r
= -0,22) razlike ugovorene i planske cijene usluge pridobivanja drva o obujmu srednjeg doznačenog stabla, ukazala je da bi ovu pojavu u budućnosti trebalo pratiti s ciljem utvrđivanja uzroka, koji mogu biti: 1) međusobna konkurencija između izvoditelja usluga pridobivanja drva za grupe odjela sa većim srednjim obujmom doznačenoga stabla ili 2) precjenjivanje obujma srednjeg doznačenog stabla u prikazanome modelu izračuna planske cijene pridobivanja drva.
Predložene su i smjernice povećanja točnosti određivanja ulaznih parametara (srednja udaljenost privlačenja drva, nagib i stjenovitost terena te privlačenje drva uz nagib terena) prikazane metode izračuna planskih cijena pridobivanja drva u cilju njenog usavršavanja. S obzirom da je izračun vezan za srednju plansku cijenu na razini šumskog gospodarstva, a koju utvrđuje uprava trgovačkog društva, neophodno je stalno praćenje tržišta, kako bi se na vrijeme moglo reagirati ukoliko bi došlo do većih oscilacija.
The paper presents the method of calculating planned prices of timber harvesting operations, which are the subject of public tenders in the forest management company Hercegbosanske šume Ltd. Kupres and the analysis of deviations of the planned from the contracted (realised) prices for timber harvesting operations in 97 groups of compartments, which were the subject of public tenders in 2019 and 2020. Descriptive and correlation statistical analysis also included stand and terrain indicators in groups of compartments in public tenders: area, net volume of marked trees, harvesting density, number of marked trees per hectare, volume of medium marked tree, slope, average timber extraction distance, terrain stoniness and parameter of uphill timber extraction. The test of dependent data pairs indicated that there is a statistically significant difference between planned and contracted prices of timber harvesting operations (
t
= 7,78,
p
< 0.001), and the results of correlation analysis confirmed the connection of influential factors of forest operations with the contracted and planned timber harvesting prices. Due to the statistically significant (
p
< 0.05) and very strong correlation with the contracted and the planned price of the timber harvesting operations calculated by the presented method, the dependence was equalized by a linear regression model with a coefficient of determination of 0.667. In conclusion, the method of calculating the planned price of timber harvesting operations is a good predictor of what can be contracted prices in public tenders thus showing its suitability in future calculations. Weak and negative correlation (
p
< 0.05,
r
= -0.22) of the difference between the contracted and planned price of the timber harvesting operations on the volume of the medium marked tree, indicated future monitoring to determine its causes, which could be: 1) mutual competition between timber harvesting operations providers with a larger volume of medium marked tree or 2) overestimation of the volume of medium marked tree in the presented model. Guidelines for increasing the accuracy of determining input parameters (average timber extraction distance, slope, terrain stoniness, and parameter of uphill timber extraction) are also presented. Given that the calculation is related to the average planned price at the level of forest management, which is determined by the management of the company, it is necessary to constantly monitor the market in order to react in time if major oscillations occur.
The topic of this paper are the economic processes initiated through political decisions in Karlovac and its surroundings after World War II, from 1945 to 1946. In a wider context of economic ...relations, the focus is on the confiscation of the textile industry in Karlovac and its surroundings as a leading initiator of economic development in the mentioned area. Confiscation, through judicial government, meant taking private property away by force with the aim of collectivising property for the needs of the central unitarist and totalitarian government. After studying the available documentation, it is obvious that the most successful companies in the textile industry, but not only them, became the state’s property via judicial decisions. After that, the state, through its administrative and central way of governing, made all important business decisions related to the confiscated companies as well as directly about the economic situation in the whole country. Moreover, it is important to emphasise that confiscation was one of the ways used to punish pre-war and wartime political opponents. It was also a way of making them unimportant in social relations, and finally making them dependent on the central government, which, as I have already stressed, dictated political and economic processes on all levels.
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