Procter & Gamble (United Kingdom)
GraFar - Repository of the Faculty of Civil EngineeringNot a member yet
3934 research outputs found
Sort by
Definition of Circulation Conditions and Groundwater Genesis of the Complex Krupaja Hydrogeological Karst System (Eastern Serbia)
Get PDFThe complex Krupaja karst system, located in Serbia, which consists of a strong karst spring, a thermal karst spring, and a borehole that captures sub-thermal waters, has been studied. A phenomenon which gives rise to the occurrence of karst waters of three different temperatures within a relatively short distance (about 200 m) led us to assume that these karst waters are formed within the same karst aquifer and circulate through different levels of karst channels that are zonally distributed within a vertical profile; this was confirmed by assessing the groundwater ages. Based on the development of karstification, as presented in this paper, as well as on previous investigations, explanations of four types of circulation within same karst system are provided. The results of measurements of stable isotopes (H, 18O, and 13C) and radioactive isotopes of tritium and T+He and 14C, as well as hydrochemical water analyses, speleogenetic spatial modeling, speleodiving research, etc., confirmed the assumption that these groundwaters belong to the same karst system. However, these karst waters have different residence times, i.e., from only a few days to over several decades and even up to approximately 4000 years, circulating through channels with various distributions along the depth of the karst aquifer
Numerical modelling of vegetated open-channel flows with arbitrary distribution of vegetation patches
Get PDFSa hidrauličkog stanovišta, prostorni raspored vodene vegetacije u koritima i na obalama vodotoka je slučajan i nezavisan od karakteristika toka. Vegetacija svojim prisustvom pruža otpore kretanju vode i utiče na tran-sportne procese i procese mešanja. Proračun otvorenih tokova sa promenljivim prostornim rasporedom vege-tacije zahteva da se prilikom numeričkog modeliranja vodi računa o konvektivnim članovima, jer oni pored zavisno promenljivih sadrže i prostorno promenljivu poroznost usled prisustva vegetacije u koritu. U ovom radu se za opis linijskih otvorenih tokova sa promenljivim rasporedom vegetacije koriste trostruko osrednjene Navije-Stoksove jednačine (Depth-Integrated Double-Averaged Navier-Stokes - DIDANS equations). Prikazan je postupak njihovog numeričkog rešavanja primenom metode konačnih zapremina. Za diskretizaciju jednačina u kojima se konvektivni član piše u razvijenom obliku da bi se uzela u obzir prostorna promena poroznosti, koristi se računski postupak razdvajanja fluksova (flux-difference splitting) i prilagođena Rouova računska shema za aproksimaciju zavisno promenljivih na granicama kontrolne zapremine. Modifikovan Rouov postupak testiran je na pojednostavljenom, idealizovanom primeru homogenih DIDANS jednačina (horizontalno dno i zanemareni otpori trenja i oblika). Rezultati numeričkog modela upoređeni su sa analitičkim rešenjem za ovaj pojednostavljen slučaj, pri čemu je dobijeno odlično slaganje.From the point of view of Engineering Hydraulics, the spatial distribution of the aquatic vegetation in the natural streams and their floodplanes is random and unrelated to the streams' flow characteristics. Aquatic vegetation enhances flow resistance and influences mixing and transport processes. Numerical simulation of open channel flows with variable spatial distribution of aquatic vegetation requires a special treatment of the advective terms, because, besides the main variables, they also contain the spatialy variable porosity due to the presence of vegetation in the channel. In this paper flow in open channels with variable spatial distribution of vegetation is described using triple-averaged Navier-Stokes equations (Depth-Integrated Double-Averaged Navier-Stokes, DIDANS equations). They are solved numerically using the finite volume method. The equations with the advective terms explicitly accounting for the spatial variation of porosity are solved by using the flux difference splitting and Roe's method for approximation of the dependent variables at the boundaries between the computational cells. The modified Roe's method is tested on an idealised case of homogeneous DIDANS equations (horizontal bed and all flow resistance terms neglected). Numerical results for this simplified case are in excellent agreement with the analytical solution.Istraživanje je sprovedeno uz podršku Fonda za nauku Republike Srbije, Program DIJASPORA, #Broj projekta 6466895, Akronim: DoubleVeg
This research was supported by the Science Fund of the Republic of Serbia, Program DIASPORA, #GRANT No. 6466895, Acronym: DoubleVeg
Local behaviour of the connector with mechanical coupler and rebar anchor under tension load
Get PDFIn the past few decades, demountable connectors have often been used for
connections in composite and mixed steel-concrete structures to reduce
construction time and costs. Furthermore, the application of demountable
connectors enables the reuse of structural elements in these structures, which leads
to sustainable design and a circular economy. In this paper, the demountable
connector is made out of two parts: (1) mechanical coupler and rebar anchor placed
in formwork before casting the concrete element, and (2) steel bolt used for
connecting steel to the RC element. Although this connector is increasingly being
used in contemporary building structures, its behaviour in composite connections is
still insufficiently defined. The paper presents the results of experimental tests and
numerical analysis of the connector with a mechanical coupler, focusing on the local
behaviour of the tapered threaded connection between the mechanical coupler and
rebar anchor
New Eurocode 4 design rules for composite beams with precast concrete slabs
No full textAs members of Project Team SC4.T5, the authors of this paper present the main outcomes from the work that isintended for implementation within the second generation of Eurocode 4. General design and application rules for composite design of precast concrete elements will be presented, with a particular focus on: the effective width of flanges using precast concrete elements for shear lag; design resistance to longitudinal shear; and the design resistance of headed stud connectors in the presence of precast hollow core slabs
Shear design of circular concrete sections according to the EC2 truss model
Get PDFShear design in Eurocode 2 is generally developed for rectangular sections or T-sections that have
clearly defined tension reinforcement, concentrated in the cross-sectional tension zone, and an
unambiguous width of compressed diagonals. In circular sections, which are also frequent in practice, the reinforcement is evenly distributed along the circumference of the section, while the width of the section changes continuously along the height.
Several proposals for the shear design of circular sections can be found in the literature, based on a relatively limited experimental database, which generally provide different structural resistances. This paper aims to enable the practical application of the Eurocode 2 variable-angle truss model in the shear design of elements of circular cross-section, such as columns or piles. It is intended to make a correct interpretation of the truss model with no intention to propose an improved procedure in accordance with the available experimental results
Sectorization of water distribution network into dmas with performance indices comparison
Get PDFSektorizacija odnosno podela vodovodne mreže na osnovne zone bilansiranja (eng. District Meter Areas – DMAs) predstavlja najisplativiju i opšte prihvaćenu strategiju za
kontrolu vodnog bilansa, pritisaka i smanjenje gubitaka u mreži. Izbor zona bilansiranja
nije jednoznačan zbog čega je identifikacija njihovog optimalnog rasporeda u mreži
izuzetno zahtevan zadatak, naročito u slučaju postojećih distributivnih sistema. Pored
osnovnih kriterijuma (npr. veličina zona i dužina mreže) postupak sektorizacije treba da
obuhvati i dodatne „lokalne“ kriterijume specifične za mrežu koja se razmatra kao što
su minimalni broj dovoda, zadovoljenje protivpožarnog opterećenja itd. Metodologija za
sektorizaciju primenjena u ovom radu zasnovana je na primeni indeksa uniformnosti
mreže (eng. Uniformity Index) čime se omogućava identifikacija zona u mreži
ujednačenih po potrošnji. Efikasnost, upotrebljivost i primena razvijene metodologije
obezbeđena je kroz implementaciju sledećih celina u jedinstveni hidroinformacioni alat:
1) algoritm za automatsku sektorizaciju mreže na klastere, 2) efikasni model za
hidrauličke simulacije i 3) višekriterijumska optimizacija. Osnovni kriterijumi za
vrednovanje i izbor optimalnog rešenja su minimalna ulaganja u neophodne intervencije
u mreži i očuvanje pouzdanosti sistema. Za poređenje stanja sistema pre i nakon
sektorizacije usvojeni su sledeći indikatori performasi: 1) indeks sposobnosti adaptacije
sistema (eng. Resilience Index), 2) pokazatelj zadržavanja vode u mreži (eng. Water
Age) i 3) prosečan pritisak u zonama. Rezultati testiranja metodologije na realnom
primeru distributivne mreže naseljenog mesta u Holandiji, sa primenom lokalnih
kriterijuma, potvrđuju da metodologija može biti od značajne koristi u inženjerskoj praksi
u procesu sektorizacije.Sectorization of Water Distribution Network (WDN) into District Meter Areas (DMAs) is
a proven measure for proactive leakage and pressure control. Sectorization of WDN
into an optimal system of DMAs is a hard task to achieve, especially for the existing and
continuously operating WDN. Beside general criteria (e.g. DMA size, network length),
sectorisation process should be driven by the case-specific criteria such as required
number of feeds, fire flow regulations etc. This paper presents sectorization algorithm
that utilizes newly developed uniformity index which drives the sectorization process
and identifies clusters in the network with uniform demand. The efficiency, usability and
succesufull application of the developed methodology is ensured through its’
implementation in comperhensive hydroinformatics tool encompasing: 1) algorithm for
automatic sectorization of the network into clusters, 2) efficient model for hydraulic
simulations and 3) multicriteria optimization. Least investment for field implementation
and maintaining the same level of WDN’s operational efficiency are adopted as main
criteria for solution evaluation and selection of preferable solution. To compare the state
of the system before and after sectorization, the following performance indices were
adopted: 1) Resilience Index, 2) Water Age and 3) average pressure in zones. Testing
algorithm on a real-life WDN in Netherlands, subjected to the specific local design
criteria, proved it can be a valuable decision support tool for sectorization process
Toward a Green Concrete Utopia
No full textContemporary tendency is to make everything eco-friendly, carbon-neutral or net-zero. It is with no doubt the imperative to redirect all our actions toward sustainable human development, but it is essential to understand the principles, main problems, methodologies and prevent greenwashing strategies from taking over the eco-friendly narrative. This can only be done with systematic and mindful approach implemented in all stages of formal and informal education.
It is especially challenging to implement new approaches in a conservative field like the construction industry. However, this is especially important having in mind that the construction industry uses more than 40% of natural stone, more than 25% of virgin wood, more than 16% of water and more than 40% of produced energy. Concrete itself is the most widely used material by humans after water! It has been a long way from ancient Parthenon to 100-Mile-Long Linear City, with industrialisation, capitalism and abandonment of using local materials principals that led us to this not so eco environment.
There is a great amount of pressure to lower the negative ecological effect of most harmful construction materials (e.g. cement, concrete and steel). This led to a series of new technologies and new materials intending to replace the traditional ones: recycled concrete, concrete made with waste materials as a total or partial replacement of cement, high-performance materials, self-healing materials, additive manufacturing optimization, smart concrete… Some of these materials or technologies are still far from practical application, but a lot of them are available but underutilized
Mogućnosti kombinovanja digitalnih podataka snimanja objekta graditeljskog nasleđa u kontekstu njegove obnove
Get PDFSrednjevekovna crkva manastira Savinac, datovana u 13. vek, je predmet potencijalne obnove i konzervacije, kao kulturno dobro Srbije od velikog značaja. Predmet istraživanja – jednobrodna crkva sa kulom na ulazu je u veoma ruiniranomstanju, bez delova zidova i kompletne krovne konstrukcije. Rad ukazuje na mogućnosti kombinovanja dva tipa digitalnih podataka (prikupljenih na terenu tokom 2018. god), u procesu kvalitativne ocene stanja građevine, sa stanovišta nivoa
oštećenosti, na osnovu podataka prikupljenih na terenu (tokom istraživanja u 2018. god.). To su podaci dobijeni metodama terestričkog laserskog skeniranja (TLS) i termovizijskog snimanja (delova zidova
Science behind STORMEE - STORMwater Environmental Efficiency toolkit: 1) infiltration basin
Get PDFIntroduction. When designing the road drainage system special attention is given to environmental
protection, which requires the removal of potentially hazardous elements via separators to the required
degree, usually defined by the local stakeholders and legislation. Afterwards, water is simply transferred
to a nearby convenient recipient. Modern engineering practice however dictates the design of sustainable
drainage systems (SuDS) for the collected water, which need to provide attenuation of the runoff and must
be designed to mimic the natural catchment conditions with as little disruption of natural processes as
possible [1]. SuDS are designed to maximize opportunities and benefits that can be secured from surface
water management: water quantity, water quality, amenity and biodiversity [2]. Construction of roadside
infiltration basins is one of the measures used for these purposes. Infiltration basins are relatively simple
engineering objects designed and constructed as excavations with a corresponding filter layer at the
bottom (gravel or crushed stone) [3]. Essentially, they are retention spaces for permanent water retention
that receive collected stormwater runoff and drain it slowly into the surrounding soil. Retention space of
infiltration basin provides a reduction in the maximum peak runoff value [4], while runoff quality is also
improved by filtration through the filter layer and soil. There are number of similar type objects that can
be used for this purpose, applicable to different sizes and types of surface purpose (residential, parking
lots, etc.) [2]. The main advantages of infiltration basins’ application are 1) the relatively inexpensive cost
of construction, 2) low space usage and 3) possibility of application in areas where there is no conventional
stormwater sewer network or river that could serve as a recipient of stormwater runoff. This makes them
particularly suitable for construction next to the roads of significant importance such as highways [5]. The
retention of runoff contaminants using infiltration basins have been proven through the testing of such
facilities after many years of use [6]. On the other hand, inefficiency in the operation of infiltration basins
can be caused by the construction on land of poor water permeability and high groundwater levels. The
stability of the surrounding structures can also be compromised given that infiltration increases the
moisture of the surrounding soil [7]. Over time, there may be a decrease in the efficiency of infiltration due
to clogging of the filter layer, caused by sedimentation of suspended particles. A common mistake being
made in the design procedure is wrongful selection of the design storm for sizing the infiltration basin, i.e.
the same design storm is used both for the collection system and the infiltration basin. Short duration,
high intensity design storms are used for the design of the collection system as they result in maximum
runoff peak values. Long duration, low intensity design storms should be used for the design of the
infiltration basin itself as they result in much greater runoff volume which is essential for sizing of the
infiltration basin.
To ensure the efficiency and sustainable functioning of the infiltration basin, design procedure should
carefully address the following: 1) selection of the proper design storm and 2) all aspects relevant for soil
infiltration. Basic guidelines and recommendations for the design of similar type objects can be found in
literature but are lacking in detailed description of the design procedure and infiltration calculation ([2],
[8]). This paper presents a comprehensive methodology for the design and operational analysis of
infiltration basins for road runoff that is incorporated into STORMEE – STORMwater Environmental
Efficiency toolkit. Presented methodology encompasses all relevant hydrological and hydraulic analyses in
detail, which overcomes the shortcomings present in currently available regulations and design guidelines,
and is packed into a user-friendly interface. Showcased here is the analysis of a field scale infiltration basin
346
International Conference of the International Ecological Engineering Society, Chania, Greece, October 1 – 5, 2023
intended for runoff control from the section of the railway in Serbia. STORMEE allow