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Two approaches for modeling CFST columns under fire conditions
No full textThe paper presents a study on the advanced nonlinear analysis of concrete-filled steel tube (CFST) columns at
elevated temperatures. Two computationally efficient approaches are analyzed: modeling CFST columns using
the concentrated plasticity element based on the generalized plasticity material model (GP model) and using
the fiber-based distributed plasticity beam–column element based on the displacement formulation. The GP element is for the first time used for fire analysis of columns with rectangular and circular cross-sections and the formulation is extended to consider additional reinforcement bars. The applied modeling with both elements follows, where possible, the recommendations of the second generation of the Eurocode 4 standard. The applicability of the optimized cross-section discretization schemes in nonlinear fire analysis with fiber element is also investigated. Through extensive validation studies, the results of the two approaches are compared with the available experimental and numerical results. This comparison includes not only the determination of the critical fire exposure time but also the quality of the whole force–displacement response, deformed shape and aspects of computational efficiency. Finally, the benefits and limitations of one approach and the other are discussed and summarized
Impact of inter-panel connections on vibrations of CLT floors
No full textCross-laminated timber (CLT) floors are typically composed of multiple CLT panels. At design stage, such floors are usually modelled numerically either as a single solid slab or more frequently as a set of independent panels with no inter-panel connections. This paper aims to demonstrate numerically a significant effect of two common interpanel connections, i.e. single surface spline and half-lapped joint, on vibration modes of CLT floors composed of two and three panels. The onnections are modelled as an equivalent 2D elastic strip nested inbetween the CLT panels. This
relatively simple yet robust numerical model can be used conveniently in design offices, regardless finite element (FE) software. The matching monolithic slabs and floors without the inter-panel connections are studied for comparison. The results showed that the difference is far too big to ignore
Weighted quasisymmetric functions and stabilization of graph-associated generalized permutohedra
No full textWeighted quasisymmetric functions and stabilization of graph-associated generalized
permutohedr
Uporedna analiza čvrstoće pri pritisku i vodonepropustljivosti betona − slučaj jedne mostovske konstrukcije
No full textU radu je prikazana uporedna analiza stvarnih i empirijski dobijenih čvrstoća betona pri
pritisku. Analiza je obuhvatila rezultate ispitivanja na 1.251 uzorku betona. Dobijeni rezultati su
pokazali da empirijski obrazac po Bolomeju daje najmanja odstupanja u odnosu na stvarne
vrednosti. Takođe na dve betonske mešavine izvršeno je poređenje klasa vodonepropustljivosti prema
povučenim i trenutno važećim standardima
Brodske prevodnice - hidraulički proračuni i ocena efikasnosti
No full textU deset poglavlja, na preko 300 strana, ova knjiga se bavi brodskim prevodnicama, fokusirajući se na hidrauličke i logističke aspekte projektovanja i korišćenja ovih, veoma specifičnih hidrograđevinskih objekata. Pretežno kroz fotografije i skice, u uvodnom delu se prikazuju osnovni elementi brodskih prevodnica (komore, prilazni kanali, bazeni za uštedu vode) i daju preporuke za njihovo dimenzionisanje. Efikasnost prevodnica razmatrana je na osnovu glavnih eksploatacionih pokazatelja, kao što su: ciklus prevođenja, tranzitno vreme i propusna moć (kapacitet) prevodnica. Prikazana su dva pristupa u proračunu kapaciteta: tradicionalni, deterministički (koji je prikladan niskom intenzitetu vodnog transporta) i savremeni – stohastički (koji je namenjen intenzivnom vodnom saobraćaju). Prikazan je i način proračuna godišnjih troškova prevodnice. Hidraulika brodskih prevodnica obuhvata: (i) prevodnice sa čeonim sistemima punjenja (bez prisustva brodova u komori i sa prisustvom brodova); (ii) prevodnice sa podeonim (prostim i složenim) sistemima punjenja; (iii) bazene za uštedu vode; (iv) specifične hidrauličke pojave, kao što su linijski gubici energije, vodni udar i kavitacija u zoni zatvarača. U okviru hidraulike prevodnica sa čeonim sistemima punjenja (sa otvorima u kapijama, kratkim galerijama i ustavama) razmatra se korišćenje numeričkih modela različitog nivoa složenosti: od uprošćenog (“neinercijalnog”) linijskog modela, preko složenih modela zasnovanih na rešavanju kompletnih jednačina linijskog (1D) neustaljenog tečenja, do višedimenzionih (2D i 3D) modela, neophodnih za numeričku simulaciju strujanja u komorama prevodnica. U okviru hidraulike podeonih sistema prikazana su dva modela. Prvi - uprošćeni model, namenjen preliminarnim proračunima, pogodan je za ispitivanje inercijalnih efekata koji su kod ovakvih prevodnica veoma izraženi, pa stoga bitni već za početnu fazu projektovanja. Drugi model je složeni inercijalni model, koji omogućava detaljnu analizu strujanja u glavnim (podužnim) galerijama i sekundarnim (poprečnim) galerijama podeonog sistema. Posebno poglavlje je posvećeno bazenima za uštedu vode. Ova tema je do sada bila od značaja samo u područjima koja su deficitarna vodom, a sa klimatskim promenama i ekološkim zahtevima, postaje svuda sve više aktuelna. Knjiga se bavi i fizičkim modelima prevodnica, kao komplementarnom sredstvu za rešavanje praktičnih problema, a takođe i sredstvu za kalibraciju numeričkih modela. Nakon definisanja zakona sličnosti, opisana su standardna merenja, koja obuhvataju: strujno polje u komori i prilaznim kanalima, pomeranja broda i sile koje na njega deluju tokom prevođenja. Prikaz je ilustrovan sa nekoliko primera iz svetske i naše prakse. Kvalitetu ove knjige doprinosi 32 rešena računska primera, koji prate prikaz svih razmatranih numeričkih metoda. Knjiga sadrži preko 120 bibliografskih jedinica (19 sa interneta) i registar (indeks) od oko 150 pojmova.In ten chapters, on more than 300 pages, this book deals with ship locks, focusing on the hydraulic and logistics aspects of the design and operation of these very specific hydraulic structures. Predominantly through photos and sketches, the introductory part shows the basic elements of ship locks (chambers, approach channels, water saving basins) and gives recommendations for their dimensioning. The lock efficiency is considered based on the main exploitation indicators, such as the locking cycle, transit time and the capacity. Two approaches to capacity calculation are presented: traditional, deterministic (which is suitable for low-intensity water transport) and modern - stochastic (which is intended for intensive water transport). The method of calculating the annual costs of locks is also presented. The hydraulics of ship locks includes: (i) locks with the head filling systems (without the presence of ships in the chamber and with the presence of ships); (ii) locks with the split distributed filling systems (long culvert systems); (iii) water saving basins; (iv) specific hydraulic phenomena, such as friction energy losses, water hammer and cavitation. Within the hydraulics of locks with the head filling systems (with openings in gates, short galleries and sluice gates), the use of numerical models of different levels of complexity is considered: from a simplified ("non-inertial") linear model, through complex models based on solving the complete equations of linear (1D) unsteady flow, to multidimensional (2D and 3D) models, necessary for the numerical simulation of flows in the lock chambers. Within the hydraulics of the split, long culvert systems, two models are presented. The first, simplified model, intended for preliminary calculations, is suitable for testing inertial effects, which are very pronounced in such locks, and therefore important for the initial phase of their design. The second model is a complex inertial model, which enables a detailed analysis of the flow in the main (longitudinal) culverts and secondary (transverse) culverts of the split system. A special chapter is dedicated to water saving pools. Until now, this topic has only been relevant in water-deficient areas, but with climate change and environmental demands, it is becoming more and more relevant everywhere. The book also deals with physical models of locks, as a complementary tool for solving practical problems, and also as a tool for calibrating numerical models. After defining the law of similarity, standard measurements are described, which include: the current field in the chamber and approach channels, the displacements of the ship and the forces acting on it during the locking process. The presentation is illustrated with several examples from domestic and foreign practice. The quality of this book is contributed by 32 solved computational examples, which accompany the presentation of all considered numerical methods. The book contains over 120 bibliographic items (19 internet sources) and an index of about 150 terms
Investigating Flood-Driven Nexus Interlinkages: Insights into Strengthening Urban Resilience in Changing Climate Conditions
No full textFloods, as one of the most frequent and disruptive natural hazards, are becoming increasingly
severe under the pressures of climate change, rapid urbanization, and altered land-use
patterns. Beyond their immediate physical damage, floods initiate complex and often
underexplored chains of interdependencies across key urban systems, intensifying systemic
vulnerabilities. This study employes a multidimensional assessment framework – Water
Energy-Food-Health-Transport-Ecosystem-Land Use-Soil-ICT (WEF+ Nexus) framework to
analyze how floods trigger systemic vulnerabilities through short-, mid-, and long-term
interlinkages, thereby reducing urban resilience.
Drawing on five major European flood events selected based on severity criteria from the
EM-DAT disaster database (Serbia, Bosnia and Hercegovina, Croatia in 2014, Slovenia in
2023, Germany in 2021, Poland in 2001, and the UK in 2007), the analysis highlights how
different types of flooding (riverine, flash, coastal, and pluvial) generate immediate and
delayed disruptions. Nexus trees and interlinkage matrices were constructed to visualize and
quantify cascading effects across critical sectors. Common interlinkages include disruptions
in electricity and water supply, impacts on food production and transport, ecosystem
degradation, public health threats, and land-use dislocations.
The findings emphasize that these impacts are rarely isolated, but rather, they interact in
feedback loops that can exacerbate long-term recovery challenges. To address this, the study
proposes a three-tiered set of recommendations – strategic, tactical, and operational.
Operational, short-term actions involve practical, on-the-ground responses, such as rapid
drainage system clearance or deploying mobile ICT units for emergency communication.
Tactical, mid-term solutions suggest adaptive planning approaches, including mobile supply
logistics and modular transport networks. Strategic, long-term interventions include green
infrastructure deployment, flood-adapted land-use planning, and Nature-based Solutions
(NbS).
This work contributes to urban disaster risk reduction and Nexus governance by offering a
structured methodology to identify and mitigate cascading impacts of floods. The findings
support the integration of WEF+ Nexus thinking into resilience strategies, planning policies,
and early-warning frameworks across European cities
Digitalization of Medieval Romanesque Church Portals in Serbia: From Underlying Geometry to the Reasemblable 3D Printed Models
No full textContemporary technological advancements have
brought new approaches in the area of cultural heritage protection
and education. The aim of this research is to deepen the
understanding of architectural designs, construction technique
and underlying geometry for medieval portals in the Studenica and
Decani monasteries through the digitalization: 3D computer
modeling and printing. Based on reliable data collection from both
classical architectural documentation and digital sources,
geometric analyses were conducted, and 3D digital models were
created and printed in adequate scales for the two selected portals.
3D-printed models are decomposed on structural elements
allowing for observation of mutual correlations and their
incorporation in the wall thickness. This approach delivers new
educational tool for cultural heritage knowledge gaining
Srpski srednjevekovni manastir Sopoćani: geometrijske proporcijske analize u digitalnom okruženju
No full textKatolikon manastira Sopoćani je jedan od
najznačajnih objekata graditeljske kulturne baštine Srbije iz doba
vladavine Nemanjićke dinastije. U arhitektonskom smislu crkva
Hrama Svete Trojice nosi nosi obležja Raške arhitektonske škole,
koju je karakterisala postupnost izmena prostorne koncepcije
sakralnih građevina kroz tok vremena, čiji je vrhunac složenosti
ovde dosegnut. Ovo istraživanje se odnosi na “skrivenu”
geometriju koja prati prostornu koncepciju i oblik građevine, kako
u horizontalnom planu-osnovi, tako i u poprečnim presecima. U
istraživanju su korišćeni principi proporcionisanja – pronalaženja
harmoničnih odnosa dimenzija objekta kako spoljašnjosti, tako i
unutrašnjosti, metodom upisivanja i opisivanja geometrijskih
figura jednakostraničnog trougla i kvadrata uz dodatak
geometrijskih konsturukcija izvedenih iz ove dve figure. Postupak
je sproveden na digitalnom zapisu – oblaku tačaka, dobijenom
terestričkim laserskim skeniranjem crkve. Prostorne
karakteristike unutrašnjosti crkve su prikazane kroz 3D modele
svakog pojedinačnog strukturnog oblika koji definiše arhitekturu
ove crkve
WEFE Nexus Interlinkages of Tsunami-Type Natural Hazards: Case Studies in the Aegean and Marmara Sea, and Baffin Bay
No full textThe aim of this study is to understand and evaluate the WEFE Nexus interlinkages related to tsunami-type natural hazards incorporating the Nexus dimensions of Water, Energy, Food, Ecosystems, Climate, Soil, Land Use, Health, Transport, and Information and Communication Technology (ICT). The Nexus tree approach is employed in analyzing the case studies of three tsunami events. The case studies are selected based on the location and the triggering mechanism. İzmit tsunami occurred in 1999 in Marmara Sea due to the Izmit Earthquake; Samos tsunami occurred in 2020 in Aegean Sea due to the Samos earthquake; and Karrat Fjord tsunami occurred in 2017 due to the landslide to Karrat Isfjord. To develop the nexus interlinkage matrix for tsunamis, the implications of interlinkages are determined according to the short-term, mid-term and long-term time scales for each case study. Then, the synthesis of the interlinkages of all case studies are performed to determine the common nexus interlinkages among the case studies. Finally, an inventory of recommendations for decoupling the interlinkages is developed under the categories of operational, tactical, and strategic levels. Analyses of the three tsunami events show that tsunamis impact Water-Transport, Water-Soil, Water-Health, Water-Food, Water-Energy and Water-Ecosystem Interlinkages significantly. Both the ports and coastal roads are severely damaged and inundated with flood waters resulting in major disruptions in sea and ground transportation. Moreoever, enormous amounts of debris flow and sediment transport are observed during tsunamis, disturbing the soil cover and causing erosion and deposition in the seabed, which negatively affect biodiversity and the ecosystem. Implementation of coastal forest as Nature-based Solutions (Nbs) to control tsunami sediment movement and construction of barrier structures such as breakwaters and seawalls, coastal dike, water gates to block the tsunami are among the featured recommendations as effective long-term measures.Апстракт чланова радне групе за Екстремне догађаје и природне непогоде који су истраживали узроке и последице цунамија кроз везе ове елементарне непогоде са водом, храном, енергијом и екосистемима
A note on maximal Schatten p-norms of a graph
No full textIn this note we solve the conjecture of V. Nikiforov posed in the paper ”Beyond
graph energy: Norms of graphs and matrices” (Linear Algebra and its
Applications, 506 (2016), 82–138). This conjecture states: if p > 2 and G is
an undirected graph of order n with Schatten p-norm ∥G∥p, and Kn is the
complete graph of order n, then ∥G∥pp
≤ ∥Kn∥pp
. We also provide a sharp
upper bound for the sum of the p-th powers of the k largest singular values
of a graph for p ≥ 2