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Characteristic features of cement stabilised base courses with waste rubber
No full textU ovom radu opisane su cementne stabilizacije općenito, postupak njihove proizvodnje i ugradnje u nosive slojeve kolničkih konstrukcija cesta teškog i srednjeg prometnog opterećenja te kontrola kvalitete. Detaljno je opisana proizvodnja stabilizacijskih mješavina i materijali koji se primjenjuju u mješavinama te su navedeni uvjeti koje moraju zadovoljavati kako bi njihovom ugradnjom osigurali kvalitetnu kolničku konstrukciju. U radu je opisana mogućnost primjene reciklirane otpadne gume u stabilizacijskim mješavinama, proizvodnja i glavna svojstva takvih mješavina. Također su prikazani rezultati ispitivanja tlačne čvrstoće i otpornosti na smrzavanje stabilizacijske mješavine izrađene u betonari. Referentna mješavina se sastojala od kamenog agregata 0-32 mm, cementa razreda čvrstoće 42.5 N, u količini 0.8% od mase agregata, dok se probna mješavina sastojala od kamenog agregata frakcije 0-32 mm, cementa razreda čvrstoće 42.5 N, u količini 0.8% od mase agregata te gumenog materijala u količini 2% mase agregata. Iz rezultata ispitivanja je vidljivo da mješavina s dodatkom gume ne razvija dovoljnu čvrstoću potrebnu za ugradnju u kolničku konstrukciju cesta teškog i srednjeg prometnog opterećenja, dok obje mješavine zadovoljavaju uvjete otpornosti na smrzavanje. Na temelju rezultata možemo utvrditi da dodatak gume utječe na smanjenje čvrstoće mješavine.This paper describes cement stabilization in general, the process of their production and installation in the load-bearing layers of pavement construction of roads with heavy and medium traffic loads, and quality control. The production of stabilizing mixtures and the materials used in the mixtures are described in detail, and the conditions that must be met in order to ensure a high-quality pavement construction with their installation are listed. The paper describes the possibility of using recycled waste rubber in stabilization mixtures, the production and main properties of such mixtures. The results of testing the compressive strength and resistance to freezing of the stabilization mixture made in the concrete plant are also presented. The reference mixture consisted of stone aggregate 0-32 mm, cement of strength class 42.5 N, in the amount of 0.8% of the mass of the aggregate, while the test mixture consisted of stone aggregate of fraction 0-32 mm, cement of strength class 42.5 N, in the amount of 0.8% from the weight of the aggregate and rubber material in the amount of 2% of the weight of the aggregate. It is evident from the test results that the mixture with the addition of rubber does not develop sufficient strength required for installation in the pavement construction of roads with heavy and medium traffic loads, while both mixtures meet the conditions of resistance to freezing. Based on the results, we can determine that the addition of rubber affects the reduction of the strength of the mixture
Unforseen and subsequent works
No full textRad se sastoji od teorijskog i praktičnog dijela. U teorijskom dijelu je objašnjen pojam troškovnika i izvantroškovničkih radova, podjela izvantroškovničkih radova te njihove razlike i sličnosti. Opisane su cijene, kontrola i obračun izvantroškovničkih radova. Pojašnjen je zakonodavni okvir, navedeni su i pojašnjeni Zakon o javnoj nabavi te Zakon o obveznim odnosima. Opisano je ugovaranje izvantroškovničkih radova te što su i koji je cilj FIDIC ugovora. Objašnjena je uloga nadzornog inženjera pri izvođenju izvantroškovničkih radova.
Praktični dio na konkretnom primjeru troškovnika objašnjava koji su najčešći razlozi zbog kojih se izvode izvantroškovnički radovi te kako se financijski obračunavaju takvi radovi.The work consists of a theoretical and a practical part. In the theoretical part, the concept of a bill of quantities and extra-cost works, devision of extra-cost works and their differences and similarities are explained. The prices, control and calculation of extra-cost works are described. The legislative framework was clarified, the Law on Public Procurement and the Law on Obligatory Relations were listed and clarified. The contracting of extra-cost works is described, as well as what is the goal of the FIDIC contract. The role of the supervising engineer during the execution of extra-cost works is explained.
The practical part, using a specific example of a bill of quantities, explains the most common reasons why extra-cost works are perfomed and how such works are calculated financially
Preliminary design of road A - B
No full textNa temelju podloge i zadanih ulaznih parametara izrađen je ovaj Idejni projekt ceste između točaka A i B. Ova cesta je predviđena za mješoviti promet lokalnog značaja i pripada 4. kategoriji cestovnih prometnica. Teren na kojem se planira izgradnja ceste je brdoviti, B kategorije..
Ukupna duljina trase ceste iznosi 1304,86 metara. Za prvi zavoj usvojena je krivina s radijusom od 150 metara, dok je za drugi zavoj odabran radijus od 110 metara, u skladu s projektiranom brzinom prometa. Nagib nivelete ceste u uzdužnom smjeru konstantno iznosi 1,65%. Cesta se sastoji od dva prometna traka širine 2,75 metara, uz dodatak rubnog traka širine 0,20 metara. Pokosi ceste su oblikovani pod nagibom od 1:5 u nasipima i 5:1 u usjeku, pri čemu je pokos u nasipu zaštićen kamenom oblogom. Kolnička konstrukcija je izrađena s asflatnim zastorom
Calculation of inner forces for a three hinged frame and projections of displacements
No full textZavršni rad se sastoji od dva zadatka. U prvom zadatku potrebno je izračunati unutrašnje sile u presjeku
n-n, pomoću dvije metode proračuna. Prva metoda dobivanja unutrašnjih sila je klasičnim postupkom
iz uvjeta ravnoteže, druga metoda je metoda virtualnog rada. Rezultate iz oba postupka kontroliramo
pomoću programa Autodesk Robot Structural Analysis, te uz rezultate dobivene pomoću navedene
dvije metode potrebno je nacrtati dijagrame unutrašnjih sila.
U drugom zadatku je potrebno odrediti kuteve zaokreta tijela 2 i 3, te pomake točaka C, D, E, i F,
nosač je formiran kao trozglobni okvir. Zadatak se riješava geometrijskim putem pomoću planova
pomaka, a rezultate kontroliramo računski.This final thesis consists of two tasks. In the first task, it is necessary to calculate internal forces in the
cross section n-n using two calculation methods. The first method for determining internal forces is
the classical equilibrium approach, while the second method is the virtual work method. The obtained
results from both approaches are validated using the Autodes Robot Structural Analysis software.
Alongside the results obtained from the two mentioned methods, it is necessary to draw diagrams of
the internal forces.
In the second task, angles of rotation for bodies 2 and 3 need to be determined, as well as displacements
of points C,D,E and F, where the beam is formed as a three jointed frame. The task is solved
geometrically using displacement diagrams, and the results are validated through calculations
Keeping a construction diary
No full textOvaj završni rad sadrži opis vođenja građevinskog dnevnika, kako u papirnatom tako i u digitalnom obliku. U radu su navedeni projektni podaci koji se upisuju u građevinski dnevnik te zadaće izvođača i nadzornih inženjera koji se bave upisom tih podataka. Navedeni su uvjeti i način na koji se vodi dnevnik, a također su spomenuti i zakoni koji se trebaju poštivati tijekom vođenja dnevnika. Opisan je način na koji se građevinski dnevnik koristi kao dokaz za uporabljivost građevinske konstrukcije i dokaz provedenih mjera nadzora. U zaključnom dijelu rada objašnjeno je korištenje eGrađevinskog dnevnika kao i prednosti u odnosu na običan („papirnati“) građevinski dnevnik.This final work contains a detailed description of keeping a construction diary, both in paper and digital form. The data entered in the construction diary and the tasks of contractors and supervising engineers who deal with entering this information are described. The conditions and the way in which the diary is kept are stated, and the laws that must be observed during the keeping of the diary are also mentioned. The way in which the construction diary is used as evidence for the usability of the building structure and evidence of the implemented control measures is described. In the last part of the final work, the use of the eConstruction diary is explained, as well as the advantages compared to a regular ("paper") construction diary
Enhancing the Seismic Response of Residential RC Buildings with an Innovative Base Isolation Technique
No full textThe prediction of the magnitude and impact of forthcoming earthquakes remains an elusive challenge in the field of science. Consequently, extensive research efforts have been directed toward the development of earthquake-resistant design strategies aimed at mitigating building vibrations. This study focuses on the efficacy of fluid viscous dampers (FVDs) in augmenting the seismic response of a low-rise residential reinforced-concrete building, which is base-isolated, using high–damping rubber bearings (HDRBs). The structural analysis employs a non-linear approach, employing ETABS v16 software for building modeling and conducting non-linear dynamic analysis using artificial accelerograms specific to Algeria. Three distinct connection configurations to the building’s base are investigated: (1) a fixed-base structure; (2) a structure isolated by HDRBs; and (3) a structure isolated utilizing a novel parallel arrangement of HDRBs in conjunction with FVDs. Comparative evaluation of these configurations reveals noteworthy findings; the results demonstrate that the base isolation system, comprising HDRBs and FVDs, significantly diminishes the base shear force by over 80% and reduces acceleration by 54% while concurrently increasing displacement by 47%. These findings underscore the effectiveness of incorporating FVDs in conjunction with HDRBs as a means to enhance the seismic response of reinforced concrete buildings. This study showcases the potential of such structural analyses to contribute to the development of earthquake-resistant design approaches, providing valuable insights for architects and engineers involved in constructing resilient buildings in seismically active regions
Pregled stanja pročišćavanja komunalnih otpadnih voda u Republici Hrvatskoj
No full textU Republici Hrvatskoj od ukupne količine ispuštenih komunalnih otpadnih voda oko 90 % se prije ispuštanja u okoliš pročišćava primjenom različitih stupnjeva pročišćavanja. Otpadne vode pročišćavaju se u konvencionalnim uređajima za pročišćavanje otpadnih voda, kao i primjenom alternativnih sustava obrade, poput umjetnih močvara, bio laguna i različitih malih uređaja za pročišćavanje otpadnih voda koji pročišćavaju in situ. Ulaskom u Europsku uniju Republika Hrvatska preuzela je prava i obveze koje se u Europskoj uniji primjenjuju. Za pročišćavanja otpadnih voda, osim uređaja za pročišćavanje, potrebno je osigurati/izgraditi sustav prikupljanja i odvodnje otpadnih voda, a to podrazumijeva i priključenost stanovništva na isti. Upravljanje muljevima s uređaja za pročišćavanje otpadnih voda treba uskladiti s načelima akcijskog plana za kružno gospodarstvo. Kontinuirani pad broja stanovnika, naročito u manjim sredinama, omogućava primjenu različitih sustava odvodnje i pročišćavanja otpadnih voda koji su za okoliš prihvatljiviji. U radu će se dati usporedni pregled stanja pročišćavanja komunalnih otpadnih voda u Republici Hrvatskoj te u odabranim članicama Europske unije
The Effects of Strong Earthquakes on Built Heritage: A Preliminary Case Study of Rector’s Palace in Dubrovnik’s Old City
No full textThe Old City of Dubrovnik’s historical urban heritage architecture, consisting of poorly to well-built irregular stone masonry construction, is at high risk of earthquakes. It was enlisted as a UNESCO World Heritage after the severely damaging 1979 Mw = 7.1 Montenegro earthquake. Retrofitting strategies to a certain degree of earthquake protection have been made to the monument heritage architecture after repeating destructive earthquakes for several centuries. The originally 13th-century Rector’s Palace underwent several major modifications throughout history after disastrous events: fire in 1435, a gunpowder explosion in 1463, and earthquakes in 1520, 1667, and 1979. The design and construction information were collected from historical records and studies performed by various researchers, including field measurements and laboratory tests. Based on the data gathered, the building’s resistance to destructive earthquakes in compliance with contemporary building codes was determined using simulations on a calibrated spatial structural model. The study revealed that the building’s critical parts are most susceptible to a certain degree of damage or even collapse. The presented case study is the basis for decision-making and implementing the building’s earthquake risk reduction measures. Additionally, it will serve as a guide for earthquake risk evaluation on similar buildings, even though they may differ in degree or detail
A Brief Overview on Crack Patterns, Repair and Strengthening of Historical Masonry Structures
No full textGiven that a significant fraction of buildings and architectural heritage in Europe’s historical centers are masonry structures, the selection of proper diagnosis, technological surveys, non- destructive testing, and interpretations of crack and decay patterns is paramount for a risk assessment of possible damage. Identifying the possible crack patterns, discontinuities, and associated brittle failure mechanisms within unreinforced masonry under seismic and gravity actions allows for reliable retrofitting interventions. Traditional and modern materials and strengthening techniques create a wide range of compatible, removable, and sustainable conservation strategies. Steel/timber tie-rods are mainly used to support the horizontal thrust of arches, vaults, and roofs and are particularly suitable for better connecting structural elements, e.g., masonry walls and floors. Composite reinforcing systems using carbon, glass fibers, and thin mortar layers can improve tensile resistance, ultimate strength, and displacement capacity to avoid brittle shear failures. This study overviews masonry structural diagnostics and compares traditional and advanced strengthening techniques of masonry walls, arches, vaults, and columns. Several research results in automatic surface crack detection for unreinforced masonry (URM) walls are presented considering crack detection based on machine learning and deep learning algorithms. In addition, the kinematic and static principles of Limit Analysis within the rigid no-tension model framework are presented. The manuscript sets a practical perspective, providing an inclusive list of papers describing the essential latest research in this field ; thus, this paper is useful for researchers and practitioners in masonry structures
Contribution to the Research on the Application of Bio-Ash as a Filler in Asphalt Mixtures
No full textThe intensive construction of all categories of roads and the very demanding maintenance of the pavement structures of existing roads due to ever- increasing traffic loads confronts us with a lack of resources and also an increase in cost for the constituent materials of asphalt mixtures. On the other hand, there is another problem: large amounts of waste material in the form of bio-ash, which is obtained by burning waste wood biomass in the production of thermal energy and/or electricity. In order to solve the environmental problem of bio-ash disposal, research was conducted on the use of waste bio-ash as a constituent material in asphalt pavements. As part of this study, the effect of asphalt concrete mix, with bio-ash as a filler, on the release of harmful substances into the environment was investigated. The possibility of using wood bio- ash (BA) as a filler in asphalt mixtures was then determined through physical and mechanical property tests. The properties of the asphalt sample’s sensitivity to the action of water (indirect tensile strength ratio—ITSR) and resistance to rutting were tested for asphalt concrete type AC 11 surf with 50% bio-ash in the filler. It was established that asphalt concrete does not release harmful substances into the environment and that the 50% share of bio-ash in the filler results in asphalt that has good resistance to water sensitivity and even greater resistance to rutting