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Seismic performance of RC buildings with wide-beams during 2019 Albania and 2023 Türkiye earthquakes
No full textThe performance of concrete buildings with concealed wide beam floors is in focus in this paper. These types of buildings were highly affected and damaged during the Albania, November 26th, 2019 and the Türkiye, February 6th, 2023 earthquakes. This typology has been widely used in Albania after ’90 and in Türkiye since the ’60s, and it can be found in buildings with different heights, from low to high rise. In cases of low to mid-rise buildings, wide beam–column frames are predominant, whereas, in high-rise buildings, wide concealed beams are present in both moment frame and dual RC systems. Moreover, such structural systems remain the most used in Albania even nowadays, almost five years after the aforementioned strong earthquake. This paper aims to review the seismic performance of buildings with concealed wide beams in light of the new field data gathered following the 2019 Albania and 2023 Türkiye earthquakes. Data from field visits in Albania and Türkiye are described and discussed. It was found that damage in Albania to the joisted slabs and concealed beams was limited, but the disadvantages of the system were expressed through damage mostly concentrated in other structural elements such as columns or non-structural masonry infill. Damages in Türkiye were more extensive. An investigation of the possible explanations for these observations is presented based on nonlinear analyses performed on two case study buildings. Finally, the implications of the results of the analyses for the seismic performance of RC buildings are discussed and confronted with earthquake damage observations
Application of geophysical and multispectral imagery data for predictive mapping of a complex geo‑tectonic unit: a case study of the East Vardar Ophiolite Zone, North‑Macedonia
No full textThe Random Forest (RF) and K nearest neighbors (KNN) machine learning (ML) algorithms were evaluated for their ability to predict ophiolite occurrences, in the East Vardar Zone (EVZ) of central North Macedonia. A predictive map of the investigated area was created using three data sources: geophysical data (digital elevation model, gravity and geomagnetic), multispectral optical satellite images (Landsat 7 ETM + and their derivatives), and geological data (distance to fault map
and ophiolite outcrops map). The research included a comparison and discussion on the statistical and geological findings derived from different training dataset class ratios in relation to a testing dataset characterized by significant class imbalance. The results suggest that the precise selection of a suitable class balance for the training dataset is a critical factor in achieving accurate ophiolite prediction with RF and KNN algorithms. The analysis of feature importance revealed that the Bouguer gravity anomaly map, total intensity of the Earth’s magnetic field reduced to the pole map, distance to fault map, band ratio BR3 map obtained from multispectral satellite images, and digital elevation model are the most significant features for predicting ophiolites within the EVZ. KNN showed poorer results compared to RF in terms of both the evaluation
metrics and visual analysis of prediction maps. The methods applied in this research can be applied for predictive mapping of complex geo-tectonic units covered by dense vegetation, and may indicate the presence of these units even if they were not previously mapped, particularly when geophysical data are used as features
Direct laser dynamic displacement measurement of structural response during testing
Full text linkThe paper presents part of the conducted research on laser-displacement sensors for the
measurement of structural response in civil engineering applications. Usually, the level of
displacement in laboratory or on-site testing is in small to mid-range levels of 1.00 to 25.00 mm
and in the frequency range of up to 100 Hz. Appropriate sensors were selected and used
according to performance in the sense of resolution/accuracy.
Experiments are conducted on steel model beam in the laboratory and on-site real bridge
structure. In both analysed cases, data analysis was carried out in the sense of modal frequencies
and damping estimation with comparison with numerically computed values.
Presented are the results of two experiments, a laboratory-tested model of steel beam and an onsite
tested real bridge structure. In both cases have achieved good argument of test results,
estimated modal frequencies and damping of tested model/structure.
Data analyses conducted used a developed MATLAB script, while the numerical computation
conducted used SAP2000_v14 FEM package for structural analysis.
Excellent agreement of extracted results was achieved in the case of the laboratory-tested
structural model, as well as of extracted results of on-site tested real-world structure in the sense
of extracted modal frequencies and modal damping.
Finally, the conclusion is that laser-displacement sensors are quite appropriate for small to midrange
of expected displacement and are quite appropriate for such applications according to the
possibility of installation so that such sensors could be applied for structural testing, particularly
for dynamic testing of such structures because of their possibility of high sampling frequency
and high resolution/accuracy
Modelling flow in evacuators for large dams - comparison of scale- and numerical models
No full textThe application of scale-models is a helpful during the design of important hydraulic structures. It enables designers to verify their assumptions and provide additional insight into complex flow field, and also enables additional optimization of the designed solution and risk assessment. However, changing individual parts
of a scale-model might be time-consuming and costly. Also, it is important to estimate the effects of the designed solution as accurately as possible before building the physical model in the first place. The constant increase in computational capacities enables the application of complex numerical models during design, which, to a certain extent, can predict the behavior of the object, that is, the results that will later be obtained from a scale-model. Applying the VOF (volume-of-fluid) method using the FLOW-3D HYDRO, in this paper the macroscopic hydraulic characteristics of the designed solution of the spillway dam with a smooth fast flow and a stilling basin were analyzed. Based on the physical model project, an uncalibrated three-dimensional numerical model was created and analyzed to compare calculated and measured flow characteristics: (1) rating-curves for the weir, (2) depth and velocity in the stilling basin, (3) pressures on bottom of the stilling basin and (4) forces on stabilizing elements in the stilling basin. Comparison with the results of the physical model indicate satisfactory accuracy in the estimation of the overflow flow curve (1-3%), acceptable accuracy in the estimation of time-averaged depths (1-5%) and local velocities and pressures (5-15%), but also limited possibilities of evaluating fluctuating components of pressures and velocities. Despite the optimistic results, the importance of physical modeling is evident, while the application of numerical models is the most adequate as support in the phases of conceptualization and optimization of the designed variant
Project management using the developed AHP–VIKOR method with the fuzzy approach
No full textThere are many factors to consider when designing a sewerage pumping station (SPS), such as sizing the system, pump type, cooperation
between pumps, SPS elevation, wastewater discharge location, system venting, correct number of inflows into the pumping station (PS)
reservoir, and chemical resistance of the installations. In this study, we developed a multi-criteria-decision-making (MCDM) fuzzy AHP–
VIKOR method with the aim to contribute to the improvement and development of MCDM methods. By combining and improving the existing
AHP and VIKOR methods with the application of fuzzy logic theory, a novel fuzzy AHP–VIKOR method is for easier and clearer obtaining of
optimal solutions. The new method was applied to obtain the findings in the analysis of four complex design solutions for canalisation, treatment, and pumping of atmospheric wastewater in the SPS in Makiš, an urban neighbourhood of Belgrade in Serbia. The analysis was carried
out in relation to the stability of the solution by way of considering the use of different methods of MCDM optimisation, while taking into
account ways of channelling, treatment, and evacuation of wastewate
Optimization of bridge maintenance policies based on semi-Markov decision process
No full textBridge networks are an essential part of transportation assets. Effective bridge maintenance
reduces bridge operation costs and extends its service life. A system that includes several tools
for managing the bridges is called a bridge management system (BMS). The state-of-the-art
Bridge Management Systems (BMS’s) feature tightly coupled deterioration and preservation
optimization model that enable determining the most cost-effective maintenance strategies at
both the project and network levels. BMS’s comprise a deterioration model to predict condition
development and a preservation optimization model to determine the optimum preservation
policy. That implies making decisions in selecting the most cost-effective maintenance strategies
at both the project and network levels. To solve optimization problems in BMS at network level,
mathematical models are employed in computer programs such as PONTIS in USA or KUBA
in Switzerland. In order to improve deterioration model, many authors suggest the application of
Weibull distribution for the sojourn time in condition states. Consequently, one has to solve
semi-Markov decision process to determine the optimum preservation policy. It can be shown
that the long-run optimal policies obtained using semi-Markov model doesn’t differ from those
of time homogenous Markov chains for average cost criteria if the expected sojourn times in
each condition state are same for both model. However, financial needs differ between the
models depending on distribution parameters of sojourn time in each condition state. It is
therefore that the estimation of these parameters is crucial for the realistic estimation of the
financial needs. In this paper, the semi-Markov decision process is briefly presented and
recommendations regarding its practical applications in bridge management are given
3D štampani betoni u Srbiji – realnost ili daleka budućnost?
Full text linkGrađevinska industrija ima značajan uticaj na bruto domaći proizvod svake zemlje kako kroz direktnu građevinsku aktivnost, tako i kroz povezane industrije poput mašinstva, elektrotehnike, proizvodnje materijala i slično. Građevinska industrija je kroz vekove podložna stalnim promenama i inovacijama u skladu sa razvojem nauke i tehnologije. Pored toga, građevinarstvo ima spor porast produktivnosti u poređenju sa ostalim granama industrije. Jedan od mogućih pravaca razvoja produktivnosti ove oblasti jeste primena tehnologije 3D štampe betona. Digitalizacija procesa izgradnje objekata značajno smanjuje potrebno vreme za izgradnju, rastur materijala i greške koje se javljaju prilikom izvođenja. U okviru ovoga rada predstavljena je tehnologija 3D štampe betona i sam 3D štampani beton kao inovativna metoda i materijal u savremenom građevinarstvu. Prikazan je dosadašnji razvoj u ovoj oblasti sa navedenim prednostima i izazovima, sa posebnim osvrtom na stanje u Republici Srbiji. U okviru zaključaka odgovoreno je na postavljeno pitanje: da li će u skorije vreme tehnologija 3D štampe betona postati široko rasprostranjena u savremenom konstrukterstvu
Generalized Plasticity Model for Nonlinear Analysis of Steel Frames at Elevated Temperatures
No full textThe paper presents a nonlinear steel frame analysis at elevated temperatures,
using a recently developed 3D beam/column element. The element belongs to the concentrated
resultant plasticity type and is based on the relations of the Generalized Plasticity material
model. It has two plastic hinges at the element ends and accounts for the interaction of the
axial force and the bending moments about the principal axes of the cross-section and the gradual
yielding of the cross-section. The nonlinear geometry under large displacements is taken into
account with the corotational formulation. The element has shown high computational efficiency
and numerical accuracy for modeling 3d steel frames under fire conditions
Advanced ANN regularization-based algorithm for prediction of the fundamental period of masonry infilled RC frames
No full textThe fundamental period (TFP) of vibration is the time required for a structure to complete one full cycle of vibration, and it is one of the main features of the structural system. It highly influences the behavor of structures under earthquake excitation. Therefore, its determination is of highest importance for the seismic design of buildings. This is a complex task in a case of masonry infilled RC frames, due to high stiffness of infill walls and their interaction with the surrounding frame. In this study, using Artificial Neural Network (ANN) algorithms, the fundamental (natural) period of vibration of fully or partially masonry infilled Reinforced Concrete (RC) frame structures was evaluated. Accurate prediction of TFP has a key role in ensuring the safety and resilience of structures, which is particularly expressed in seismic-prone regions. The collected database from open literature contains 4026 samples which cover a wide range of RC frames. For practical reasons, the database is divided in the preprocessing phase into two parts that contain either bare frames or fully/partially infilled frames. The authors compared first and second-order ANN paradigms, and conducted feature importance analysis. The proposed models were validated and verified by comparison with the experimental data, seismic design codes, and derived equations by other researchers. In addition to the superiority that the BRA model has shown in comparison with other solutions, it also enables simpler approach for the calculation of TFP, unlike the proposals of other authors. Based on the results from best ANN model, multi-objective optimization genetic algorithm was employed for additional optimization of TFP which include investigation of the most optimal solutions between two conflicting objective functions
Inovativna rešenja za popločavanje gradova u cilju smanjenja efekata poplava primenom strategije „Nultog otpada“
No full textU okviru ovog istraživanja primenjuju se principi koncepta nultog otpada, kao i principi cirkularne ekonomije (CE) kod ugroženih urbanih područja u cilju razvoja područja otpornih na kišne poplave. Navedeni principi se ogledaju kroz modifikaciju konvencionalnih sistema za odvođenje vode usled urbanih poplava. Fokus projekta je na: a) valorizaciji i karakterizaciji otpadnog recikliranog materijala (letećeg pepela iz termoelektrana) pogodnog za porozne kolovoze, pomoću savremenih metoda i tehnika; b) razvoj dizajna modifikovanih poroznih kolovozam sa unapređenim performansama; c) identifikacija jaza između vrednosti i primene otpadnih recikliranih materijala u građevinskoj industriji; d) analize tržišta za implementaciju i mapu puta za industrijske potrebe