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Physical and mechanical properties of self-compacting rubberized concrete reinforced with macrosynthetic fibers
No full textRad se bavi istraživanjem mogućnosti upotrebe različitih vrsta makrosintetičkih vlakana kao ojačanja u samozbijajućem betonu s recikliranom gumom. Za izradu betona korištena su reciklirana ugljična vlakna, konvecionalna makrosintetička vlakna i polipropilenska vlakna. Ispitivanja u svježem i čvrstom stanju provedena su na četiri različite mješavine samozbijajućeg betona s recikliranim gumom, od čega je jedna mješavina služila kao referentna bez vlakana. Rezultati eksperimentalnih mjerenja analizirani su i prikazani za mješavine sa i bez vlakana te su doneseni zaključci o utjecaju vlakana na svojstva samozbijajućeg betona srecikliranom gumom.The paper investigates the possibility of using different types of macrosynthetic fibers as reinforcement in self-compacting concrete with recycled rubber. Recycled carbon fibers, conventional macrosynthetic fibers and polypropylene fibers were used to make the concrete. Testing of self-compacting concrete in the fresh and hardened state was performed on four different mixtures of self-compacting concrete with recycled rubber, of which one mixture served as a referent mixture. The experimental measurements were analyzed and presented for mixtures with and without fibers. Conclusions were drawn on the influence of fibers on the properties of self-compacting concrete with recycled rubber
External walls energy renovation technology based on an improved temperature based method
No full textIn situ nerazorne metode vrlo su korisne za određivanje stvarnih toplinskih svojstava građevnih dijelova postojećih zgrada, posebice jer vrijednosti utvrđene mjerenjem na terenu u stvarnim uvjetima mogu značajno varirati od teorijskih vrijednosti. Zbog uočenih ograničenja standardiziranih metoda, razvijaju se nove metode s ciljem poboljšanja točnosti i pouzdane procjene in situ mjerenja. Osnovna ideja je pronaći brzu, jednostavnu i jeftinu metodu mjerenja te definirati točnost i uvjete primjene iste. Detaljnim i iscrpnim pregledom stanja područja in situ ispitivanja koeficijenta prolaska topline (U vrijednosti) vanjskih zidova nerazornim metodama, uočene su značajne prednosti temperaturne metode u odnosu na standardizirane metode poput brzine provođenja mjerenja, jednostavnosti obrade podataka i smanjenih troškova ispitivanja. Međutim pokazalo se kako nedostaju smjernice za provođenje ispitivanja te ispitivanja na različitim vrstama građevnih elemenata i u različitim uvjetima kako bi se definirala ograničenja, uklonili mogući negativni utjecaji i donijeli detaljni zaključci o mogućnosti pouzdane procjene U vrijednosti ovom metodom.U doktorskoj disertaciji istražena je mogućnost primjene temperaturne metode za ispitivanje koeficijenta prolaska topline (U vrijednosti) vanjskih zidova in situ. S ciljem proširenja spoznaja o pouzdanosti mjerenja i poboljšanja pouzdanosti mjerenja temperaturnom metodom provedeno je eksperimentalno i numeričko istraživanje. Eksperimentalna ispitivanja provedena su na 18 modela zidova od različitih zidnih elemenata. Na temelju rezultata provedenih eksperimentalnih ispitivanja u različitim temperaturnim uvjetima i numeričkih simulacija prijenosa topline provedena je analiza utjecaja različitih parametara na rezultate ispitivanja i analiza ušteda koje je moguće ostvariti primjenom temperaturne metode za određivanje U vrijednosti na troškovima obnove i tijekom razdoblja uporabe zgrada izborom ekonomski opravdanih tehnologija obnove vanjskih zidova. Također, na temelju prikazanih eksperimentalnih rezultata predloženi su pojednostavljeni matematički modeli za predviđanje U vrijednosti vanjskih zidova temperaturnom metodom. Kako bi se osigurala šira praktična primjena temperaturne metode, na temelju prikazanih rezultata i analize predložene su detaljne smjernice kojih bi se trebalo pridržavati prilikom provođenja ispitivanja temperaturnom metodom.In-situ non-destructive methods are very useful for determining the actual thermal performance of building elements of existing buildings, especially since the values determined in situ in real conditions can significantly vary from theoretical values. Due to the observed limitations of standardized methods, new methods are being developed with the aim of improving the accuracy and reliability of in situ measurements. The basic idea is to find a quick, simple, and inexpensive method and to define the accuracy and conditions of its application. A detailed and comprehensive literature review of current experimental in-situ non-destructive approaches used to determine the thermal transmittance (U-value) of walls, revealed significant advantages of recently proposed Temperature Based Method (TBM) over standardized methods such as measurement duration, simple data processing and reduced measurement costs. However, detailed guidelines for conducting in situ measurement using TBM are still missing as well as further testing on different types of building elements in different conditions to minimise all possible negative impacts and to determine all parameters affecting the accuracy of measurement.In the doctoral dissertation, the possibility of applying the TBM for in situ measurement of U-value of external walls was investigated. To improve the reliability of the TBM for in situ measurement of U-value, experimental and numerical research was conducted. For this purpose, 18 different types of external walls were experimentally investigated. Based on the experimental results performed in different thermal conditions and numeric simulations of the heat transfer, the analysis of the impact of various parameters on the results of the experiment was done. Savings analysis on the reconstruction expenses and for the period of the use of buildings that can be achieved by choosing appropriate and cost-effective building technology for renovation of external walls was done by using U-values determined by temperature based method. To provide a wider practical application of the TBM, detailed guidelines for conducting in situ measurements with TBM have been proposed based on the presented results and analysis
Architecture and urban design of Gacka business zone
No full textKako bi se stvorila simbioza između urbanističkog
rješenja, petlje i tornja cijela zgrada oblikovana je sa
ciljem da se stvori prostor koji će zaintrigirati korisnka i
potaknuti ga na istraživanje. Oko jezgre tornja stvoreni
su promjenjivi popratni sadržaji koji se tlocrtno
izmjenjuju u parovima. Poslovna zgrada projektirana je
tako da se prizemlje i prvi kat prožimaju sa tornjem.
Kako bi se dodatno sljubio toranj s petljom postavljena
su vertikalna aluminijska rebra. Jezgra unutar tornja je
promjenjive geometrije kako bi korisnik imao osjećaj na
kojem se katu nalazi, a u isto vrijeme se postiže
dinamična vizura koja dodatno oplemenjuje prostor.In order to create a symbiosis between the urban
solution, the loop and the tower, the whole building was
designed with the aim of creating a space that will
intrigue the user and encourage him to explore. Around
the core of the tower, variable accompanying contents
have been created, which alternate in pairs in terms of
layout. The office building is designed so that the
ground floor and the first are permeated with the tower.
In order to additionally match the tower with a loop,
vertical aluminum ribs were placed. The core inside the
tower is of variable geometry to give the user a sense
of which floor he is on, while at the same time
achieving a dynamic view that further enriches the
space
Architecture and urban design of Gacka business zone
No full textLokaciju zgrade karakterizira izražen fokus sadržaja na istoku, koji se očituju u vidu linearnog trga i
pješačkog nathodnika koji dominira istočnim pročeljem zgrade. Sama pozicija sugerira jasnu podjelu
na javni i privatni dio, što se očituje u njenoj funkciji i oblikovanju. Prizemlje je javno, usmjerno na
trg. Na prvom katu pojavljuje se traka javnih sadržaja direktno povezanih sa nathodnikom. Viši
katovi prvenstveno su namjenjeni uredskim prostorima i sadržajima. Ovakva funkcionalna podjela
naglašena je oblikovanjem fasade. Privatni, odnosno uredski prostori zgrade na pročeljima su
omeđeni horizontalnim lamelama koji vanjskom korisniku sugeriraju unutrašnju podjelu zgrade, te ga
usmjeravaju prema javnim sadržajima.The location of the building is characterized by a pronounced focus of content in the east, which is
manifested in the form of a linear square and a pedestrian overpass that dominates the eastern
facade of the building. The position itself suggests a clear division of public and private spaces,
which is reflected in its function and design. The ground floor is public, facing the square. On the
first floor, a strip of public content directly connects to the overpass. Higher floors are primarily
intended for office space and facilities. This functional division is emphasized by the design of the
facade. The private or office spaces of the building on the facades are bounded by horizontal
lamellas which suggest to the external user the internal division of the building, and direct them
towards the public content
Fresh and mechanical properties overview of alkali-activated materials made with glass powder as precursor
No full textAlkali‐activated materials (AAMs) are promising materials that can be used as alternatives for conventional Portland cement (PC) materials. In this paper, the fresh properties, and mechanical properties of AAMs made with glass powder (GP) as the precursor were explored and discussed. The discussions presented in this paper showed that the incorporation of GP as the precursor in AAMs resulted in an improvement in the workability and extension of the set times. However, the use of GP especially at early ages could result in a detrimental impact on the mechanical performance of AAMs due to the lower reactivity of GP compared to other precursors. Nonetheless, AAMs with acceptable mechanical performance for non‐ structural and structural applications can still be produced with the use of GP as the precursor
Investigation of leadership competences of project managers in construction industry
No full textLeadership has been widely studied both in business schools and by scholars. However, little attention has been given to leadership specifics in project- based organizations, especially in the construction industry. Aiming to decrease the gap in aforementioned body of knowledge, this article intended to contribute by identifying competences that are crucial to the success of project management as well as by revealing their manifestation in future construction project engineers. Therefore, theoretical framework of this article offers a literature review on variety of leadership theories. Building onto that, empirical part investigated importance of different leader competences, as perceived by future project managers, being graduate civil engineering students. The use of the mixed method research has been chosen as the most appropriate for this study. It combined the use of qualitative methods with survey obtained data based on a Likert scale. In respect of that, theoretical framework was constructed relying on the research of secondary data sources, whilst empirical part data were processed using descriptive statistics and nonparametric tests. Findings show that there are no significant differences in opinion among students in respect of their gender and almost none in respect of study course. The lowest rated competence concerns indecisiveness, suggesting high level of students’ self-confidence and self- awareness. The highest rated competence indicates students’ tendency to have things under control. Such reluctance toward risk taking has been found as potentially harmful for their personal and professional growth. Although their propensity to risk is expected to increase with experience, fostering emotional intelligence related competences has been advised as a tool of smarter risk perception
Residual Compressive Behavior of Self-Compacting Concrete after High Temperature Exposure—Influence of Binder Materials
No full textThis paper presents an experimental investigation of the compressive behavior of highstrength self- compacting concrete exposed to temperatures up to 600 C. Ten different concrete compositions were tested, in which part of the cement (by weight) was replaced by three different mineral additives (5– 15% metakaolin, 20–40% fly ash and 5–15% limestone). The stress–strain curves, compressive strength, modulus of elasticity and strain at peak stress were evaluated from uniaxial compression tests. Scanning electron microscope micrographs were also taken to evaluate the damage caused by the high temperatures. A sharp decrease in mechanical properties and an increase in peak strain were observed already after 200 C for all mixes tested. The different mineral additives used in this study affected the variations of residual compressive strength by 24% and peak strain by 38%, while the variations of residual modulus elasticity were 14%. Comparing the obtained results with the recommendations for compressive strength given in regulatory code EN 1992-1-2 for high strength concrete, it can be concluded that the strength loss observed in EN 1992-1-2 at temperatures up to 400 C is too conservative. The Popovics model for the relationship between stress and strain provided a good approximation for the experimentally determined stress–strain curves at different temperatures
Disappearance and Sustainability of Historical Industrial Areas in Osijek (Croatia): Three Case Studies
No full textHistorical industrial areas are considered as areas of particular importance in terms of their heritage value and cultural significance. They are usually located in city centers and have great potential for economic, cultural and urban development. At the beginning of the 20th century, Osijek was well known as an industrial city, but the globalization had a ripple effect on the industry, leaving industrial sites of Osijek in ruins. Although comprehensive studies have not yet been made, field research into historical industrial areas of Osijek showed that they are mostly abandoned. A literature review showed that there is not even one document that contains locations and basic information on the historical industrial areas that existed in Osijek from 1824– 1945. The aim of this paper is to define exact locations of historical industrial areas that existed in Osijek from 1824– 1945 and to analyze their current state, their architectural, urban and identity features. The research resulted in a database containing basic information about 59 historical industrial areas in Osijek. An analysis and comparison of the current state of 13 remaining existing historical industrial areas in Osijek is given. The three case studies present detailed analysis, comparison and evaluation of observed historical industrial areas
Architectural-urban design of Gacka business zone
No full textCilj urbanističkog rješenja stvaranje je javnog prostora koji uvlači korisnike i poziva ih na otkrivanje središta. Glavna karakteristika urbanizma je središnji "lijevak" koji privlači prolaznike unutar obuhvata.. Osnovna ideja pri arhitektonskom oblikovanju poslovne zgrade je staklenik unutar kojeg su smještene tri kuće. S obzirom da je kompleks poslovnih zgrada međusobno povezan terasama, projektiranjem internih terasa stvorena je direktna veza vanjskog i unutrašnjeg prostora
Extra-costs in cost estimate - subsequent and unforeseen works
No full textU teorijskom dijelu rada potrebno je opisan je pojam i podjela izvantroškovničkih radova, razlika više/manje radova, u kojim situacijama dolazi do nepredviđenih radova, a u kojima do naknadnih radova. Opisan je način obračuna i kontrole ovih radova. Opisane su odredbe Zakona o javnoj nabavi (NN 120/16), dio vezan za dogovaranje, odnosno izmjenu osnovnog ugovora bez provedbe novog postupka javne nabave, i Zakon o obveznim odnosima. Detaljno su objašnjeni FIDIC ugovori, ciljevi te osnovne vrste ugovora. Objašnjeno je naknadno ugovaranje izvantroškovničkih radova te uloga nadzornog inženjera kod provjere i odobravanja izvantroškovničkih radova.
U praktičnom dijelu rada analizirani su odabrani primjeri ugovora, prikazani su najčešći razlozi koji dovode do potrebe za izvođenjem izvantroškovničkih radova te primijenjeni postupci kontrole i obračuna ovih radova