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Methods for Life Extension of Multi-Storey Car Park Buildings
Get PDFMulti-storey car park buildings with steel–concrete composite floor structures are widespread in construction due to the distinct benefits of the implemented structural system. Although there are various possibilities for accomplishing composite action between a steel beam and a concrete slab, some solutions, such as friction-grip bolts commonly applied in the 1970s, did not show good durability. An example is the multi-storey car park building “Obilićev venac” in Belgrade. This case study presents two methods for life extension of the car park building structure. Both approaches focus on applying welded headed studs with the primary intention of providing a durable shear connection. While the first method has been applied during the structure’s reconstruction, the second method is proposed as a novel solution for implementation in steel–concrete composite floors. The application of the proposed connection is discussed and the results of the experimental and numerical research conducted are presented
Implementation of Hybrid ANN-GWO Algorithm for Estimation of the Fundamental Period of RC-Frame Structures
Get PDFThe fundamental period (TFP) of vibration is one of the most important parameters in structural design since it is used to assess the dynamic response of the structures. It is the time taken by a structure or system to vibrate back and forth in its most natural way, without any external forces applied. Simultaneously, TFP depends on the mass distribution and stiffness of the structure, which is largely influenced by infill walls in RC frame structures, and which is why their careful design is necessary. This study aims to develop a fast, accurate, and efficient machine learning (ML) method for the prediction of the fundamental period of masonry-infilled reinforced concrete (RC) frame structures. Hybridization of the stochastic gradient descent (SGD) based artificial neural network (ANN), and meta-heuristic grey wolf optimization (GWO) algorithm is proposed as an effortless computational method. This approach provided even more reliable solutions than robust second-order procedure based on single ML models. A total of 2178 samples of infilled RC frames were collected from available literature, where the number of storeys (NoSt), number of spans (NoSp), length of spans (LoSp), opening percentage (OP), and masonry wall stiffness (MWS) were considered as input parameters for predicting the output TFP results. The accuracy and exploration efficiency of the proposed ANN-GWO paradigm have demonstrated superiority over existing seismic design codes and other conventional ML methods
Primena kamera i tehnika obrade video zapisa za procenu protoka u kanalizacionim sistemima - iskustva merne kampanje Novi Banovci
Get PDFTehnike merenja u hidrotehnici zasnovane na upotrebi kamera i naknadnoj obradi video zapisa u trendu su poslednje dve decenije. Odlikuju ih tehnička jednostavnost, niska cena i prilagodljivost hardvera i softvera. Međutim, primena za merenje protoka u kanalizacionim sistemima nije analizirana u literaturi. Tim Građevinskog fakulteta Univerziteta u Beogradu osmislio je, konstruisao i postavio merni uređaj, baterijski napajan mikroračunar sa IC kamerom u kanalizacioni šaht u naselju Novi Banovci radi kontinualnog merenja dotoka upotrebljene vode. Rad prikazuje specifičnosti upotrebe mernog uređaja i tehnike obrade video zapisa. Preliminarni rezultati pokazuju potencijal razvijene metodologije, posebno tamo gde konvencionalna oprema nije primenjiva
Dynamic calibration in hydrologic and hydraulic modelling: exploring the potential of data assimilation for estimation of models' parameters
No full textHydrological and hydraulic models used for forecasting and providing reliable inputs are essential for effective water management. Throughout their application, models might produce results of unsatisfying accuracy due to many uncertainty sources. Considerable uncertainty stems from model parameters values, which are usually obtained through calibration, i.e., iterative adjustment of the parameter values to achieve the best possible fit between simulated and observed variables. Model calibration yields time-invariant parameter estimates, which can lead to poor-quality simulation outputs that cannot serve as decision support. Specifically, parameter values can be expected to vary due to secondary- or seasonal processes that are not explicitly accounted for in the model, or due to anthropogenic activity (e.g., land-use change). Therefore, models used for operational forecasting should be run with up-to-date parameter values. This necessitates frequent model recalibration, which can be quite impractical due to high time- and computational requirements of the calibration procedure. Therefore, developing fast(er) calibration algorithms could be a viable alternative. This paper explores the potential of control theory-based, tailor-made, data assimilation algorithm intended for continuous update of the parameters of hydrological and hydraulic models. The algorithm enables the parameter values to be regularly updated at each computational time step based on the dynamically assessed goodness-of-fit (GOF) performance indicator. This approach enables one-pass calibration procedure. Using this algorithm instead of traditional, iterative calibration procedure where models’ GOF is assessed at the end of the simulation, can improve efficiency and effectiveness of models’ calibration. The proposed one-pass calibration approach will be tested on two synthetic test cases, one example of a hydrological model and one example of a 1D hydraulic model
Mixed Spearman’s Correlation Suitability for Sine-Shaped Independent Variables in Natural Sciences
No full textPearson’s and Spearman’s methods are most often used in popular software packages to calculate the correlation coefficient between two variables in natural sciences. The (1) difference between them is that the Pearson’s method takes actual numerical values into account whereas the Spearman’s operates with their ranks. Ranking is often efficient in dealing with nonlinearities and outliers in the data. However, not both independent (x) and outcome (y) variable have to be suitable for this. We propose not to rank the independent variable in case it comes sine-shaped. Most notable example of such a variable in nature is the temperature. It is sine-shaped due to day-night and summer-winter transitions. It does not contain many outliers, not only due to the shape, but also because it is often sampled at multiple points and averaged (to be linked with a single outcome variable observation). The proposed method is evaluated in simulations and with experimental data obtained in South Adriatic zooplankton research. Practical advices on how to apply it using popular software tools are given
Reuse of Solid Brick Waste Mix in Geopolymerization – a Preliminary Investigation
Get PDFThe applicability of solid bricks waste in geopolymerization technique was considered. Waste samples were characterized in terms of mineralogical composition by XRD prior to mechanical testing. XRD analysis showed that both brick samples contained anorthite, wollastonite, and mullite as the main components. The compressive strength investigation was carried out by screening method with three geopolymer mixtures. Geopolymer mixtures were prepared with alkaline activators; the mixtures were poured into molds and air-dried for 28 days. The compressive strength of samples was measured according to the standard SRPS EN 12390-3:2010 for cubic samples. The compressive strength values ranged from 9.8 MPa for the newer solid brick, 10.2 MPa for the older solid brick, and 10.5 MPa for the solid brick mix waste geopolymer sample. The most likely underlying reason for the higher compressive strength results of the older solid brick and the mixed sample is their mineral composition, i.e. higher proportion of aluminosilicate. However, all samples showed satisfactory compressive strengths, and it represents an excellent basis for further research
Principal Component Analysis of Morphological Descriptors for Assessment of Surface Defects Induced by Extreme Conditions
Get PDFImplementation of statistical analysis for monitoring the formation and propagation of defects that occurred due to exposure of the material to thermal shock and cavitation is presented in this study. Results of two groups of materials are shown: refractory concrete sintered at three temperatures and ceramic materials based on cordierite and zircon. Alumina- based refractory concretes were subjected to thermal stability test, while the surface morphological changes regarding the defects were monitored after a certain number of thermal shock cycles. Cordierite and zircon based materials were initially subjected to cavitation testing while after specified time periods, morphological changes in the surface defects were analyzed. Besides the standardized methods, non-destructive testing of materials was applied for monitoring the surface changes. Cameras, microscopes, and numerous software enable recording images of sample surface with appropriate magnifications as well as monitoring and quantifying the surface damage degree with various image analysis tools. Thus, this approach offers the quantification of selected morphological descriptors regarding the defects. Obtained values were then subjected to pattern recognition method, the principal component analysis that can provide information on extracted morphological descriptors by describing the main difference among observed defects and identifying variations among them. As a result, a better insight into surface degradation that occurs during exposure to extreme conditions was obtained. The multivariate analysis provided grouping and thus reduction of the descriptors while maintaining the highest percentage of variance unchangeable. More precisely, the analysis extracted the most informative descriptors that should be observed for monitoring changes in surface defects and determining a degradation mechanism
Primena strategije nultog otpada - Upotreba mulja sa postrojenja za prečišćavanje otpadne vode u građevinskim materijalima
Get PDFU ovom radu ispitani su različiti tipovi kompozitnih materijala, koji su po sastavu većim delom od cementa, a jednim delom od recikliranog otpadnog praškastog materijala, neutrala. Ispitivanja su obuhvatila uticaj kompozitnih materijala na kvalitet vode u šaržnom sistemu. Ispitani su ključni parametri na osnovu kojih se može oceniti uticaj na promenu kvaliteta vode. Deo materijala čini i reciklirani otpadni materijal koji ima komercijalni naziv „neutral“. Neutral nastaje od sirovine koju predstavljaju različiti tipovi (često opasnog) otpada, koji se u reaktoru sa kalcijum-oksidom prevodi u prah koji se može koristiti kao beozopasan. Ovo istraživanje predstavlja preliminarna ispitivanja koaj će ukazati na mogućnost korišćenja neutrala kao materijal koji bi, u kontaktu sa vodom, otpuštao zagađujuće materije u ekološki prihvatljivom obimu i/ili ne
Thermally Activated ZnCr Layered Double Hydroxide Based Photocatalysts:Photocatalytic and Antibacterial Efficiency
Get PDFLearning while playing - Througie platform for creating models of spatial structures
Get PDFThe paper shows a way to create a set of tools that allows the construction of different models of spatial deltahedral structures as a result of the game. It is a set of accessories with which participants (school children, students) through play, experimenting with different layouts and combinations of elements of the whole, create spatial forms from uniform elements: sticks of length "a" and ringshaped joint connections. The game uses a STEM learning approach and the "learning by doing" method to provide knowledge about the spatial relationships of elements and static properties of the structure, in the process of playing. The process of forming structures via mentioned connecting elements uses the same principle of connecting supports and nodes as in the real space truss. A similar method is used by some other gaming platforms, such as Geomag, Magna-tiles, Picasso, or Blockaroo. Unlike them, our solution does not use magnets, but prestressing.https://mongeometrija2023.ftn.uns.ac.rs/?page_id=1