Procter & Gamble (United Kingdom)
GraFar - Repository of the Faculty of Civil EngineeringNot a member yet
3934 research outputs found
Sort by
Application of Two Seismic Risk Assessment Methodologies on the Data Set of School Buildings in Serbia
Get PDFThis paper presents a comprehensive investigation into seismic risk assessment methodologies applied to a dataset comprising school buildings in Serbia. Earthquakes pose a significant threat to the structural integrity of buildings, especially those housing critical infrastructure such as schools. The study employs two distinct seismic risk assessment methodologies, providing a comparative analysis to enhance the understanding of seismic vulnerability in the context of Serbian school buildings. The first methodology employed is the Adriseismic methodology, a recognized approach developed within the Adriseismic project. The second methodology is the MM Risk method, developed during the field work and collection of the data for 213 schools. MM Risk takes into account the building's vulnerability, exposure, and social aspect, providing a holistic understanding of the seismic risk. Through this approach, the paper aims to assess the potential performance to school buildings during seismic events and evaluate the associated risks to occupants and infrastructure.
The comparative analysis of these methodologies allows for a more robust seismic risk assessment tailored to the specific characteristics of school buildings in Serbia. The study contributes to the development of targeted seismic mitigation strategies and the enhancement of overall resilience in the educational infrastructure. The findings are crucial for policymakers, engineers, and stakeholders involved in seismic risk management and can inform decision-making processes related to retrofitting, construction practices, and emergency preparedness in the context of seismic-prone regions like Serbia
A Unified Approach and Related Fixed-Point Theorems for Suzuki Contractions
Get PDFThis paper aims to give an extended class of contractive mappings combining types of
Suzuki contractions α-admissible mapping and Wardowski F-contractions in b-metric-like spaces. Our
results cover and generalize many of the recent advanced results on the existence and uniqueness of
fixed points and fulfill the Suzuki-type nonlinear hybrid contractions on various generalized metrics
Towards camera-based sewer discharge monitoring: experiences using a low-cost DIY setup
No full text• Camera-based velocimetry can be viable alternative for discharge measurements in sewers.
• Computer vision algorithms were employed for the automatic generation of rating curves.
• Environmental conditions can have a considerable impact of the data accuracy and reliability
Main findings of the SUZI-SAEE reconnaissance missions after the november 26, 2019 Albania earthquake (MW 6.4) and december 29, 2020 Petrinja earthquake (MW 6.4)
No full textDuring a one-year period, several moderate intensity earthquakes occurred in the Balkan Peninsula, including four significant earthquakes, two of which had the same magnitude of Mw 6.4. The first earthquake took place on November 26, 2019, in Albania, and the second occurred on December 29, 2020, in Petrinja, Croatia. Following both events, the Serbian Association for Earthquake Engineering (SUZI-SAEE) dispatched expert teams to assess the earthquake impact on the built environment and assist in damage evaluation. Both events had devastating effects on for the building stock in the epicentral area. However, notable differences were observed between these two events and they are presented in this paper. This paper provides an overview of the most common types of failure, highlighting structural deficiencies, as well as examples of good behaviour in each earthquake. Additionally, recovery aspects of the earthquakes are compared, and the aim is to summarize key findings that could serve as a basis for lessons to help communities in the Balkan region prepare for and respond effectively to future earthquakes
Analytic and experimental determination impulse response of single degree of freedom system
Get PDFThe paper presents an experimental and analytical way of determining the impulse response of
a linear time-invariant damped system with one degree of freedom.
An experiment was conducted where the mass was excited by an impact load. Both the mass
acceleration and impact force values were recorded. The magnitude of the system's frequency
response was determined based on the recorded values, ensuring the relatively simple
identification of the system's basic parameters. Those parameters were used to define a suitable
mathematical model of the system, transfer function, and frequency response function in an
analytical form.
The impulse response of the system based on the recorded values of mass acceleration and impact
load is expressed as a discrete function. This function is determined by applying the inverse
discrete Fourier transform of the corresponding frequency response function.
The impulse response of the system, based on the mathematical model, is expressed as a
continuous function. This function is determined by applying the inverse Fourier transform of
the corresponding frequency response.
Finally, it was shown that the response of a system to arbitrary load could be determined by
convolving the impulse response of the system with the load function. Convolution of continuous
functions is difficult to perform, and it can be used only for the simplest problem and for
understanding the physical phenomenon. Discrete convolution has a practical utility because it
is easy to perform in some program languages like Matlab. However, discrete impulse response
has limitations depending on the test conditions
Structural fire resistance design of the football stadium roof steel structure
Get PDFWhen analysing the fire resistance of the steel structure of the stadium roof in the event of a fire,
the specific features of the stadium building must be taken into consideration. The stadium stands
are open units of the building that are directly connected to the surrounding area. The clear height
between the stadium roof and the stands is commonly large. However, the clear height between
relatively small parts of the roof, directly above the top of the stands, could be smaller, potentially
making this part of the roof the most vulnerable. On the stands of the stadium, it is prohibited to
bring items that contain combustible material. In addition, the structure of the stadium, benches
or chairs must be made of non-combustible material. Therefore, a fire that could compromise the
steel structure of the stadium roof can only come from the stadium premises on the stands or
under the stands. The fire scenarios on the stadium roof are not described in detail in the literature
compared to indoor (covered) sports arenas. To assess the fire resistance of the roof structure, it
is necessary to check all possible and potentially dangerous scenarios. The subject of the analysis
presented in this paper is the roof steel structure of the stadium in Loznica, Serbia, which was
built in the period 2021–2023. The study considers the following fire scenarios and their effects
on the roof steel structure: (i) a local fire on the stands, and (ii) a fire in the stadium premises
affecting the external members. The fire in stadium premises was analysed using the analytical
expressions provided in Annex B of EN 1991-1-2 and EN 1993-1-2, as well as through CFD
(Computational Fluid Dynamics) analysis of fire propagation. The calculation was performed
for the domains of temperature, time and resistance, depending on the applied fire load analysis.
Results showed that the steel structure of the stadium roof in Loznica meets the load-bearing
codified criteria for the fire effects, with the exception of only one main roof truss. To address
this issue, it was decided to install fire-resistant glass in the TV studio on the building's third
floor to separate this area from the stands and prevent fire effects on the critical main roof truss
Circular Economy Innovation in Urban Infrastructure: Harnessing the Power of Solidified WWTP Sludge in Porous Concrete Pavements for Flood-Resilient Cities
No full text- Incorporating waste materials into useful building materials and environmental benefits;
- Understanding benefits of the addition of solidified wastewater treatment sludge (SWWTS) to porous concrete pavements;
- Wise application of waste in urban infrastructure adopting and applying the principles of circular economy
Demountable connections between steel and reinforced concrete elements with mechanical couplers under combined shear and tension loads
No full textPrimena spregnutih i mešovitih konstrukcija od čelika i betona u savremenoj građevinskoj praksi proistekla je iz težnje ka racionalnijoj upotrebi čelika i betona, kao i skraćenju vremena i smanjenju troškova izgradnje građevinskih objekata kao što su poslovne zgrade, garaže, mostovi i sl. Savremeni trendovi u građevinarstvu, koji su usmereni ka održivom razvoju i primeni principa cirkularne ekonomije, nameću mogućnost demontaže konstruktivnih elemenata kao dodatni projektni zahtev za spregnute i mešovite konstrukcije. Upotreba prefabrikovanih armiranobetonskih (AB) elemenata i demontažnih konektora sa mehaničkom spojnicom i armaturnim ankerom za vezu sa čeličnim elementom predstavljaju jedno od mogućih rešenja kojim se unapređuje održivost građevinskih konstrukcija. Spoj između čeličnog i armiranobetonskog elementa na gradilištu ostvaruje se pomoću kratkog demontažnog zavrtnja koji se vezuje za mehaničku spojnicu, prethodno ubetoniranu sa armaturnim ankerom u prefabrikovani AB element. Tom prilikom, površina AB elementa na mestu spoja je ravna pa primena ovakvog tipa konektora omogućava jednostavniju demontažu u poređenju sa primenom ostalih tipova demontažnih konektora. Takođe, pravilnim oblikovanjem spoja sa mehaničkim spojnicama omogućava se potencijalna ponovna upotreba svih komponenata spoja na kraju „prvog upotrebnog veka“.
Iako je njihova primena u savremenoj građevinskoj praksi rasprostranjena, ponašanje konektora sa zavrtnjem, mehaničkom spojnicom i armaturnim ankerom pri dejstvu sile smicanja, sile zatezanja i njihove interakcije još uvek nije dovoljno istraženo. Adekvatna analiza ovakvog konektora treba da obuhvati sve moguće vidove loma pri proizvoljnom opterećenju, uključujući sve moguće vidove loma betona i vidove loma konektora. Pri tome, ponašanje konektora sa mehaničkom spojnicom je složenije od ponašanja ostalih tipova konektora jer se konektor sastoji od tri elementa koji imaju različite geometrijske karakteristike i mehaničke karakteristike materijala. U savremenim tehničkim normama i smernicama, nosivost konektora sa mehaničkom spojnicom određuje se na osnovu analogije sa tradicionalnim tipovima spojnih sredstava za beton, sa konstantnim poprečnim presekom duž konektora. Skorašnja istraživanja pokazala su da ovakva aproksimacija može rezultovati značajnim odstupanjima od realnog ponašanja ovakvog konektora.
Istraživanje u ovoj doktorskoj disertaciji obuhvata eksperimentalnu i numeričku analizu spoja sa mehaničkim spojnicama pri dejstvu sile smicanja, pri dejstvu sile zatezanja i pri kombinovanom dejstvu sila smicanja i zatezanja. Analizirano je ponašanje samostalnih konektora u spoju, bez uticaja međusobnog rastojanja pojedinačnih konektora na nosivost i deformabilnost spoja. Posebna pažnja posvećena je ponašanju i nosivosti konektora sa mehaničkom spojnicom sa malim rastojanjem konektora od ivice AB elementa odnosno u uslovima koji odgovaraju spojevima čeličnih elemenata sa AB elementima ograničenih dimenzija na mestu spoja.
Prvi deo eksperimentalnog istraživanja obuhvatio je ispitivanje ponašanja i nosivosti samostalnih konektora pri dejstvu sile smicanja. Ispitivanje je izvršeno primenom „push-out“ testa, u skladu sa preporukama standarda EN 1994-1-1 (CEN, 2004). U sopstvenom eksperimentalnom istraživanju varirana je srednja vrednost čvrstoće betona pri pritisku (fcm = 28-38 MPa), rastojanje konektora od ivice AB elementa (c = 75 mm i c = 150 mm) i tip oslonaca na koje su uzorci oslonjeni (pokretni oslonci i oslonci na sloju gipsa). Razmatrani su samo konektori sa M20 zavrtnjem. Rezultati ispitivanja dopunili su postojeću bazu podataka o nosivosti i ponašanju ovakvog spoja koja obuhvata, pored pomenutih parametara, i različite prečnike konektora sa zavrtnjem M16 i M20 (Milosavljević, 2014). Pri tome, uzorci sa rastojanjem konektora od ivice AB elementa c = 75 mm imalu su konektore sa M16 zavrtnjem (nije razmatran uticaj različitog prečnika konektora).
Drugi deo eksperimentalnog istraživanja usmeren je na ispitivanje ponašanja i nosivosti samostalnih konektora pri dejstvu sile zatezanja primenom „pull-out“ testa. U svim slučajevima, konektor se nalazio blizu ivice AB elementa (c = 75 mm) a variran je prečnik konektora (sa M16 i M20 zavrtnjem) i srednja vrednost čvrstoće betona (fcm = 28-38 MPa). Pored ispitivanja ponašanja spoja, ispitano je i ponašanje neubetoniranih konektora sa M16 i M20 zavrtnjem pri zatezanju kako bi se analiziralo lokalno ponašanje svih elemenata konektora i njihovih međusobnih veza.
Treći, glavni, deo eksperimentalnog istraživanja obuhvatio je ispitivanje ponašanja i nosivosti samostalnih konektora pri interakciji sila smicanja i zatezanja. Ispitivanje je izvršeno primenom modifikovanog „push-out“ testa. U ovom delu istraživanja variran je prečnik konektora (sa zavrtnjem M16 i M20), rastojanje konektora od ivice AB elementa (c = 75 mm i c = 150 mm), čvrstoća betona (fcm = 28-38 MPa) i intenzitet aplicirane sile zatezanja (T = 0-100 kN).
Na osnovu rezultata eksperimentalnog istraživanja formirani su numerički nelinearni modeli spoja sa konektorom koji ima M20 zavrtanj, odgovarajuću mehaničku spojnicu i armaturni anker u programskom paketu Abaqus/Explicit. Numerički modeli obuhvatili su plastifikaciju i oštećenje komponentalnih materijala. Validacijom numeričkih modela pokazano je dobro poklapanje sa rezultatima eksperimentalnog istraživanja. Ovi modeli iskorišćeni su za numeričku parametarsku analizu u kojoj su varirani: rastojanje konektora od ivice AB elementa (c = 75-200 mm), čvrstoća betona (fcm = 28-58 MPa), nosivost armaturnog ankera na zatezanje (Tu,a = 133-200 kN) i intenzitet aplicirane sile zatezanja (T = 0-134 kN).
Rezultati eksperimentalne i numeričke analize pokazali su da ponašanje i nosivost konektora značajno zavisi od prečnika konektora, rastojanja konektora od ivice AB elementa i intenziteta aplicirane sile zatezanja. Lom spoja nastao je usled sledećih vidova loma: (i) loma demontažnog zavrtnja pri čistom smicanju i pri interakciji smicanja i zatezanja, (ii) loma i mehaničke spojnice pri smicanju i pri interakciji smicanja i zatezanja (iii) loma armaturnog ankera (veze ankera i spojnice) pri čistom zatezanju, i (iv) loma betona u blizini ivice AB elementa pri čistom smicanju i pri interakciji smicanja i zatezanja. Uporednom analizom pokazano je da trenutno važeće tehničke norme i smernice za projektovanje spojeva sa mehaničkim spojnicama u pojedinim slučajevima imaju značajna odstupanja od rezultata istraživanja sprovedenog u ovoj doktorskoj disertaciji. Ovo se pre svega odnosi na nosivost konektora pri lomu betona u blizini ivice AB elementa, nosivost mehaničke spojnice i nosivost demontažnog zavrtnja pri interakciji smicanja i zatezanja. Stoga, predloženi su novi predikcioni modeli za određivanje nosivosti ovih komponenata spoja. Rezultati analize ovih modela imaju dobra poklapanja sa rezultatima eksperimentalne i numeričke analize. Predloženi predikcioni modeli za određivanje nosivosti demontažnih konektora sa mehaničkom spojnicom i armaturnim ankerom, kao i preporuke za projektovanje formulisani su tako da su u saglasnosti sa, trenutno važećim, evropskim standardom za projektovanje spojnih sredstava za beton EN 1992-4 (CEN, 2018).The use of composite and mixed steel-concrete structures in contemporary structural building practice arose from the desire for optimal usage of steel and concrete, as well as to reduce the construction time and costs of building structures such as office buildings, garages, bridges, etc. Modern trends in construction industry, which are focused on sustainable design and circular economy, impose the possibility of disassembly of structural elements as an additional design objective for composite and mixed structures. The use of prefabricated reinforced concrete (RC) elements and demountable bolted connectors with mechanical coupler and rebar anchor represent one of the possible solutions towards more sustainable design of building structures. The connection between steel and reinforced concrete on site is achieved by connecting short demountable bolt to previously embedded mechanical coupler and rebar anchor in precast RC element. In this type of connection, the concrete surface is flat and, therefore, the use of demountable connectors enables easer disassembly compared to the use of other types demountable connectors. Furthermore, potential reuse of all connection components can be achieved after the “End-of-First-Use” by adequate design of the connection with mechanical couplers.
Over the last 15 years, bolted connectors with mechanical coupler and rebar anchor are more widely used in contemporary structural practice. However, their behaviour under shear load, under tension load and under combined shear and tension loads is still insufficiently known. The adequate design of this type of connector needs to include all possible failure modes under arbitrary loads, including all possibly concrete failure modes and failure modes of connector components. In this regard, the behaviour of bolted connector with mechanical coupler is more complex than the behaviour of other types of connectors. The reason lies in the fact that this type of connector is comprised of three components with different geometrical characteristics and mechanical characteristics of steel. In contemporary design codes and recommendations, the resistance of bolted connectors with mechanical coupler is determined by using the analogy with the traditional type of connectors, with constant diameter over the connector length. Recent studies have shown that this approximation can result in large deviations from the real behaviour of bolted connectors with mechanical coupler.
The research presented in this doctoral dissertation covers experimental and numerical analysis of the connection with mechanical couplers under shear load, under tension load and under combined shear and tension loads. The behaviour of single connector is analysed, without the influence of spacing of the connectors within the connection on the resistance, stiffness and ductility. The research is mainly focused on the behaviour and resistance of bolted connectors with mechanical couplers located close to the concrete edge i.e., in situations where RC elements have limited dimensions at the location of the connection.
The first part of experimental research focuses on the analysis of the behaviour and resistance of single connectors under shear load. Experimental tests were conducted using “push-out” tests according to recommendations given in EN 1994-1-1 (CEN, 2004). Mean concrete strength (fcm = 28-38 MPa), concrete edge distance (c = 75 mm and c = 150 mm) and support type (roller and gypsum supports) were varied. Only the connectors with M20 bolts were analysed. Research results have extended the existing database of resistance and behaviour this type of the connector (Milosavljević, 2014). Apart from the above-mentioned parameters, the existing database covers the results for different connector diameters with M16 and M20 bolts. In this regard, only specimens with concrete edge distance c = 75 mm and M16 bolts were analysed.
The second part of experimental research focuses on the testing of the behaviour and resistance of single connectors under tension load in “pull-out” tests. In all tests, the connector was located close to the concrete edge (c = 75 mm), while the connector diameter (with M16 and M20 bolts) and mean concrete strength (fcm = 28-38 MPa) were varied. In addition, tensile behaviour of “in-air” specimens with M16 and M20 bolts was analysed, in order to closely establish the local behaviour of connector components as well as component connections.
The third and the main part of experimental research focuses on the analysis of the behaviour and resistance of single connectors under combined shear and tension loads. Tests were conducted using the modified “push-out” test. In this part of research, the connector diameter (with M16 and M20 bolts), concrete edge distance (c = 75 mm and c = 150 mm), mean concrete strength (fcm = 28-38 MPa) and the level of the applied tension force were varied.
Based on the experimental test results, the nonlinear finite element models with M20 bolts and corresponding coupler and rebar anchor were constructed and calibrated using software Abaqus/Explicit, which included plasticity and damage of component materials. The validation of numerical models showed good agreement with experimental test results. These models were used for numerical parametric study which included the variation of concrete edge distance (c = 75-200 mm), mean concrete strength (fcm = 28-58 MPa), tensile resistance of rebar anchor (Tu,a = 133-200 kN) and the level of applied tension force (T = 0-134 kN).
The results of experimental and numerical research have shown that the behaviour and resistance of the connector highly depends on the connector diameter, concrete edge distance and the level of the applied tension force. Different failure modes of the connection were detected: (i) bolt failure under shear load and under combined loads, (ii) mechanical coupler failure under shear load and under combined loads, (iii) rebar anchor failure (anchor-coupler connection) under tension load, and (iv) concrete edge failure under shear load and under combined loads. The comparative analysis has shown that, in most cases, the prediction equations for resistance of the connector from technical codes and guidelines give significant deviations from the resistance determined in tests and numerical analysis. This conclusion mostly applies for the concrete edge resistance, mechanical coupler resistance and bolt resistance under combined shear and tension loads. Therefore, a new prediction models for calculating the resistance of these components were developed. These models have good agreements with experimental and numerical results. The calculation models for resistance of bolted connector with mechanical coupler and rebar anchor as well as the design recommendations are formulated in form which is suitable for inclusion in current European design codes for design of fastenings for use in concrete EN 1992-4 (CEN, 2018)
Analyzing Chebyshev polynomial-based geometric circulant matrices
No full textThis paper explores geometric circulant matrices whose entries are Chebyshev polynomials of the first or second kind. Motivated by our previous research on circulant matrices and Chebyshev polynomials, we focus on calculating the Frobenius norm and deriving estimates for the spectral norm bounds of these matrices. Our analysis reveals that this approach yields notably improved results compared to previous methods. To validate the practical significance of our research, we apply it to existing studies on geometric circulant matrices involving the generalized Horadam numbers. The obtained results confirm the effectiveness and utility of our proposed approach
Enhancing Earthquake Recovery: The RELAR Project's Rapid Loss Assessment Framework
No full textThis paper outlines the RELAR project, funded by the Science Fund of the Republic of Serbia,
seeks to enhance earthquake loss assessment and recovery. It utilizes Machine Learning and
Image Recognition to speed up response and improve accuracy in estimating damages and repair
costs. Traditional methods are slow and error-prone due to data limitations and rigidity. RELAR
provides innovative solutions for timely and accurate information regardless of ground motion
data. The project aims to deliver practical ML algorithms, validated assessment models, and
proactive risk mitigation guidelines