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Preliminary design of road A - B
No full textPrema zadatkom definiranim podatcima izrađen je idejni projekt cestu od točke A do točke B. Projekt je načinjen u programu Autodesk AutoCAD 2020. Cesta je lokalnog značaja, 5. kategorije i namijenjena je mješovitom prometu. Teren u kojem se gradi predviđena cesta je brdovit, a tlo je A kategorije. Na temelju navedenih podataka i važećih tehničkih propisa za projektiranje cesta određena je projektna i računska brzina, a na prema njima su proračunati potrebni elementi iskolčenja. Duljina ukupne
trase ceste je 786,88 m, a sastoji se od dva pravca i dva zavoja. Niveleta je izvedena s dva uzdužna nagiba s1 = 2,54 % i s2 = 1,33 %. Poprečni presjek se sastoji od dvaju prometnih trakova širine 2,50 m i bankina širine 1 m. Kolničku konstrukciju čine površinski sloj asfalt betona, nosivi sloj asfalt betona i nevezani sloj drobljenog kamena. Kako bi bila ostvarena efikasna odvodnju ceste poprečni nagib kolnika u pravcu iznosi q = 2,5 % dok nagibi u zavojima iznose q = 6,5% i q = 5,7 %. Pomoću bankina, bermi i rigola oborinska voda se dalje odvodi kako ne bi ugrozila stabilnost podloge. Za odvodnju vode koja se slijeva s višeg terena
predviđena su dva cijevna betonska propusta promjera 100 cm
Calculation of the fire resistance of the riding hall
No full textOvim diplomskim radom obuhvaćen je proračun požarne otpornosti drvenih i čeličnih elemenata glavnih i sekundarnih nosača hale za jahanje. Hala je smještena u Dugom Selu na nadmorskoj visini od 115 m.n.m., a njene tlocrtne i visinske dimenzije određene su zadatkom. Proračunu požarne otpornosti prethodi analiza opterećenja te dimenzioniranje nosača, provedeno sukladno važećim HRN EN normama i propisima. Sve podrožnice izvode se od cjelovitog drveta razreda čvrstoće C24. Statički sustav rubnih i sljemenih podrožnica je prosta greda, dok je statički sustav veznih podrožnica gerberov nosač. Statički sustav glavnog nosača je dvozglobni okvir sa zategom. Za njegovu izradu korištene su grede od lijepljenog lameliranog drveta razreda čvrstoće GL28h, čelični stupovi kvalitete S275, te čelične zatege kvalitete BST500/550. Grafički prilozi, uključujući dispoziciju glavnih i sekundarnih nosača, izrađeni su računalnim programom Autodesk AutoCAD, dok su za analizu modela konstrukcije i njenih dijelova korišteni računalni programski paketi Autodesk Robot Structural Analysis Professional i Tower 8.This thesis covers the calculation of fire resistance for both wooden and steel elements constituting the primary and secondary supports within the riding hall. The hall is situated in Dugo Selo at an elevation of 115 m.a.s.l., and its dimensions of the floor plan and height are predefined by the project requirements. The evaluation of fire resistance follows a load analysis and dimensioning of the supports conducted in accordance with currently valid HRN EN norms and regulations. Purlins are constructed using solid timber of strength class C24. The static system of the edge and ridge purlins is a simply supported beam, while the static system of the midfield purlins is a Gerber girder. The static system of the main girder is a two-hinged frame with a tension member. Glued laminated timber beams of strength class GL28h, steel columns of quality S275, and steel tension members of quality BST500/550 were used for its construction. Graphical attachments, including the layout of both main and secondary girders, were made using the Autodesk AutoCAD software, while the computer software packages Autodesk Robot Structural Analysis Professional and Tower 8 were used to analyze the structural model and its components
Calculation of inner forces for a three-hinged frame and projections of velocity
No full textOvaj završni rad obuhvaća proračun unutarnjih sila i kinematskih pomaka u konstrukcijskim sustavima. Prvi dio sadrži analizu trozglobnog okvira pod djelovanjem zadanog opterećenja, pri čemu su unutarnje sile izračunate korištenjem dviju metoda: klasičnog postupka čiji su temelj uvjeti ravnoteže i metode virtualnog rada. Obje metode dale su identične rezultate, a proračuni su
dodatno provjereni pomoću softverskog alata Autodesk Robot Structural Analysis. Također su prikazani dijagrami momenata savijanja, poprečnih i uzdužnih sila. Drugi dio rada posvećen je kinematskim pomacima u zadanom mehanizmu. Prikazano je kako se stvarni pomaci i kutovi zaokreta tijela unutar mehanizma mogu odrediti pomoću planova pomaka, s dodatnom vektorskom kontrolom rezultata.This final thesis covers the calculation of internal forces and kinematic displacements in structural systems. The first part includes an analysis of a three-hinged frame during the acting of a set load. Internal forces are calculated using two methods: the classical approach based on equilibrium conditions and the principle of virtual work. Both methods gave identical results, and the calculations were validated using the Autodesk Robot Structural Analysis software. The thesis also presents diagrams of bending moments, shear forces, and axial forces. The second part of the thesis is dedicated to kinematic displacements in a given mechanism. It demonstrates how real displacements and rotation angles of bodies within the mechanism can be
determined using displacement diagrams, with additional verification of the results
Architecture and urban design of Retfala south business zone
No full textSam koncept proizašao je iz teme zadatka "prostor za radnike", koja me odmah asocirala na marljive mrave. Iz te usporedbe nastala je i moja zgrada, koja, izvlačenjem sadržaja iz zemlje, preuzima mravlje tunele i pretvara ih u tunele za radnike hodnike i komunikacijske prolaze kako bi ih usmjerila prema njihovim radnim stanicama i uredima.The concept emerged from the task theme "space for workers," which immediately evoked the image of hardworking ants. This association inspired my building design, where the extraction of elements from the ground mirrors the tunnels of ants. These tunnels have been reimagined as pathways for workers corridors that facilitate communication and guide them to their workstations and offices. Key Themes
Identification and analysis of working time losses of workers and machines at construction contractors in Croatia
No full textDoktorski rad obuhvaća opsežan pregled prethodnih istraživanja utjecaja na produktivnost i iskorištavanja radnog vremena u građevinarstvu. Na temelju toga određena je metodologija istraživanja u Hrvatskoj na sličnim principima, ali prilagođena tako da se izbjegnu ili umanje neki uočeni nedostaci prethodnih studija. Prema rangu važnosti čimbenika utvrđenog sintezom rezultata 70 istraživanja od 2011. do 2021. godine u inozemstvu i kroz polustrukturirane intervjue sa stručnjacima s dugogodišnjim iskustvom na realizaciji građevinskih projekata u Hrvatskoj, definirana su 24 čimbenika koja negativno utječu na produktivnost radnika i posebno 31 čimbenik produktivnosti strojeva na gradilištu. Njihov utjecaj ocijenjen je putem upitnika, davanog „na ruke“ različitim vrstama radnika i menadžmenta u hrvatskoj građevinskoj praksi. S indeksima relativne važnosti i indeksima učestalosti, izračunatim na temelju prosječnih ocjena, određen je rang ukupnog značaja (ozbiljnosti) za sve čimbenike i utvrđeno je da ih 53 % ima umjereni značaj. Spearmanov koeficijent i Kendallov koeficijent pokazali su korelaciju ranga značaja dobivenog od različitih grupa ispitanika, a utvrđena je i vrlo dobra korelacija između rangiranja od pretežitog dijela ispitanika iz pet slavonskih županija i rangiranja ispitanika iz drugih dijelova Hrvatske. Kako bi se osigurala generalizacija rezultata, udjeli produktivnog i izgubljenog vremena utvrđeni su kod izvođenja građevinskih radova od strane 51 izvođača na 68 različitih projekata, s pomoću 5-minutnog ocjenjivanja i dvije tehnike terenskog ispitivanja. Pri tome su evidentirani uočeni načini gubljenja radnog vremena i njihova učestalost. Rezultati dobiveni različitim tehnikama otkrivaju „mrtve kuteve“ perspektive pojedinih tehnika i potrebnu korekciju utvrđenog udjela izgubljenog radnog vremena. Procijenjeno prosječno gubljenje radnog vremena od oko 34 % u granicama je rezultata prethodnih istraživanja u inozemstvu. Od toga, blizu 74 % gubljenja vremena imalo je uzroke pod kontrolom izvođača, a to predstavlja veliko područje za moguća djelovanja s odgovarajućim mjerama za povećanje produktivnosti. Mjere poboljšanja izvođača razmotrene su uzimajući u obzir rang značaja utjecajnih čimbenika, odnosno načine na koje se najviše gubi radno vrijeme. Za odlučivanje o primjeni tih mjera definirani su kriteriji, koji mogu biti polazište analitičkog hijerarhijskog procesa za svaki konkretni slučaj.The doctoral dissertation includes an extensive review of previous research on the impact on construction productivity and utilization of working time. Based on this, the research methodology in Croatia was determined based on similar principles but adjusted to avoid or minimize some perceived shortcomings of previous studies. According to the ranking of the importance of the factors determined by the synthesis of the results of 70 research from 2011 to 2021 abroad and through semi-structured interviews with experts with many years of experience in the implementation of construction projects in Croatia, 24 factors that negatively affect the productivity of workers and especially 31 factors of the productivity of machines on construction site. Their impact was evaluated through a questionnaire, given "hands-on" to different types of workers and management in Croatian construction practice. With relative importance indices and frequency indices calculated based on average scores, the rank of overall importance (severity) was determined for all factors, and it was determined that 53% of them have moderate importance. Spearman's and Kendall's coefficients showed the correlation of the rank of significance obtained from different groups of respondents, and an excellent correlation was established between the ranking of the majority of respondents from the five Slavonic counties and the ranking of respondents from other parts of Croatia. To ensure the generalizability of the results, the proportions of productive and lost time were determined in the performance of construction work by 51 contractors on 68 different projects, using a 5-minute rating and two field survey techniques. In doing so, the observed ways of losing working time and their frequency were recorded. The results obtained with different techniques reveal the "blind spots" of the perspective of individual techniques and the necessary correction of the determined share of lost working time. The estimated average loss of working time of around 34 % is within the limits of the results of previous research abroad. Of these, close to 74 % of time wastage had causes under the control of the contractor, and this represents a large area for possible actions with appropriate measures to increase productivity. The contractor's improvement measures were considered, taking into account the ranking of the importance of the influencing factors, i.e., how working time is wasted the most. Criteria are defined for deciding on applying these measures, which can be the starting point of the analytical hierarchical process for each case
The influence of nanosunflower ash and nanowalnut shell ash on sustainable lightweight self-compacting concrete characteristics
No full textThe absence of biodegradability exhibited by plastics is a matter of significant concern among environmentalists and scientists on a global scale. Therefore, it is essential to figure out potential pathways for the use of recycled plastics. The prospective applications of its utilisation in concrete are noteworthy. The use of recycled plastic into concrete, either as a partial or complete substitution for natural aggregates, addresses the issue of its proper disposal besides contributing to the preservation of natural aggregate resources. Furthermore, the use of agricultural wastes has been regarded as a very promising waste-based substance in the industry of concrete manufacturing, with the aim of fostering the creation of an environmentally sustainable construction material. This paper illustrates the impact of nano sunflower ash (NSFA) and nano walnut shells ash (NWSA) on durability (compressive strength and density after exposure to 800 °C and sulphate attack), mechanical properties (flexural, splitting tensile and compressive strength) and fresh characteristics (slump flow diameter, T50, V-funnel flow time, L-box height ratio, segregation resistance and density) of lightweight self-compacting concrete (LWSCC). The waste walnut shells and local Iraqi sunflower were calcinated at 700 ± 50 °C for 2 h and milled for 3 h using ball milling for producing NSFA and NWSA. The ball milling succeeded in reducing the particle size lower than 75 nm for NSFA and NWSA. The preparation of seven LWSCC concrete mixes was carried out to obtain a control mix, three mixtures were created using 10%, 20% and 30% NWSA, and the other three mixtures included 10%, 20% and 30% NSFA. The normal weight coarse aggregates were substituted by the plastic waste lightweight coarse aggregate with a ratio of 75%. The fresh LWSCC passing capacity, segregation resistance, and filling capability were evaluated. The hardened characteristics of LWSCC were evaluated by determining the flexural and splitting tensile strength at 7, 14 and 28 days and the compressive strength was measured at 7, 14, 28 and 60 days. Dry density and compressive strength were measured after exposing mixes to a temperature of 800 °C for 3 h and immersed in 10% magnesium sulphate attack. The results demonstrated that the LWSCC mechanical characteristics were reduced when the percentages of NWSA and NSFA increased, except for 10% NWSA substitution ratio which had an increase in splitting tensile strength test and similar flexural strength test to the control mixture. A minor change in mechanical characteristics was observed within the results of LWSCC dry density and compressive strength incorporating various NSFA and NWSA` contents after exposing to temperature 800 °C and immersed in 10% magnesium sulphate attack. Furthermore, according to the findings, it is possible to use a combination of materials consisting of 10–20% NSFA and 10–20% NWSA to produce LWSCC.</jats:p
Behaviour of ultra-high strength concrete-filled dual-stiffened steel tubular slender columns
No full textThis paper is concerned with the behaviour of square concrete-filled dual-stiffened steel tubular (CFDSST) slender columns with a concentrically-placed inner circular steel tube. Previous studies have illustrated that these columns have greater structural performance in terms of load-carrying capacity compared with conventional concrete-filled stiffened steel tubular (CFSST) columns. However, the behaviour of CFDSST slender columns filled with ultra-high strength concrete (UHSC) has not been investigated and current design codes do not include provisions for UHSC, although it is increasingly popular owing to demands for structures to be lighter and more sustainable. Accordingly, the current paper fills that gap in existing knowledge and explores the behaviour of CFDSST slender columns using finite element (FE) analysis. The available test results from previous studies were collated and are employed to validate the numerical model. The validated FE model is then employed to investigate the axial load versus deflection responses for a wide variety of UHS-CFDSST slender columns. The behaviour of both intermediate-length and long columns is assessed through parametric analyses. The results of these studies show that the strength of the concrete sandwiched between the two steel sections, the yield strength of outer steel tube, and the outer tube slenderness ratio have a significant effect on the axial resistance of UHS-CFDSST intermediate-length columns, while the capacity of long columns is most affected by the sandwiched concrete strength. The ultimate resistances are compared with different available design methods, and AISC 360–16 code is recommended for predicting the ultimate resistance of UHS-CFDSST slender columns with modifications proposed to account for the different components forming this innovative cross-section
Calculation and charging of performed works in construction
No full textU radu je analiziran proces obračuna i načini naplate izvedbenih radova. S naglaskom na dokazivanje količina dogovorenih radova, oblicima naplate pojedinih ili cjelokupnih radova. Pojašnjeni su pojmovi građevinske knjige, računa, troškovnika, obrasci situacije, rokovi situacije i isplate situacija. Navedeni su načini ugovaranja radova, te obračun i naplata ugovorenih radova. Objašnjena je poveznica investitora, nadzornog inženjera, projektanta i izvođača radova prije, tijekom i prilikom završetka izvedbenih radova, te njihove dužnosti prilikom prikupljanja dokumentacije, ovjere i naplate izvedenih radova.The paper analyzes the process of calculation and methods of payment for construction works. Emphasis is placed on verifying the quantities of agreed-upon works and the forms of payment for individual or entire works. The terms construction log, invoice, cost estimate, progress reports, timelines for progress reports, and payment schedules are explained. The methods of contracting works, as well as the calculation and payment of contracted works, are outlined. The connection between the investor, supervising engineer, designer, and contractor before, during, and upon completion of construction works is explained, along with their responsibilities in collecting documentation, certification, and payment for the completed
works
Comparison of Maximum Peak Pressures of Free Underwater Explosion by Numerical Modeling and Empirical Expressions
No full textThe article compares the results of empirical expressions for the maximum peak pressures of an underwater explosion and numerical models made in hydrocode software LS-DYNA. Spherical charge of 136.08 kg TNT explosive was chosen and observed distance was up to 15 m. An overview of empirical expressions is given and the results according to several authors are compared. The Cole expression was chosen as a reference for comparison. For the purpose of the numerical modelling, the influence of the size of the finite elements of the explosive, the size and shape of the volume of water and the size of the finite elements of water was examined. The size of the finite elements of the medium (water) was shown to be the most significant parameter that affects the magnitude of the pressure results, and recommendations for modelling were given
Trends, Problems, and Solutions from Point Cloud via Non-Uniform Rational Basis Spline to Building Information Modelling: Bibliometric and Systematic Study
No full textBuilding Information Modelling (BIM) has found applications not only in the planning and designing of new buildings but also in project monitoring, record-keeping, and analyses of existing structures. In addition to its primary application, information modelling spreads to other areas, developing solutions for their specific uses. This study engaged a mixed-method literature review according to the extent of the pool of knowledge for two research steps between three concepts—from point cloud to NURBS and then from NURBS to BIM. In the first step, the keywords point cloud and NURBS were analysed using scientometric methods. In the second step, a systematic analysis of the content of works obtained with the keywords NURBS and BIM is presented, extracting problems and proposed solutions for information transfer technology. The results of a quantitative analysis identified major trends, (1) research is distributed in interdisciplinary and multidisciplinary areas and historical (heritage) modelling is the highlighted one, (2) development of technologies for object surveying, and (3) the application of data in different engineering fields, while a qualitative analysis points at problems in (1) model building, (2) interoperability, and (3) automatization. Solutions such as mixed models, multi-layered models, a mix of formats, or bridging elements (semantics, proto-model) are proposed