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Human-induced vibrations of cross-laminated timber floors
Get PDFThis paper discusses vibration serviceability assessment of cross-laminated timber (CLT) floors
induced by human activities, with special emphasis on vibrations induced by walking. In the first
part current design criteria for vibration serviceability check of timber and CLT floors were analyzed
in line with the more general vibration performance-based approach applicable to any floor structure regardless of the material used. The second part focuses on the ongoing research achievements in the design of vibration resistant CLT floors carried out at the Faculty of Civil Engineering, University of Belgrade. In addition, challenges for future research were formulated as well
Multi-aging Impact on Rheological and Chemical Properties of Recycled Binder Blends with Asphalt Recycling Agents
No full textAsphalt recycling is becoming a regular activity in road construction,
benefiting the economy, the environment, and circularity while preparing for a
world less dependent on fossil resources. Therefore, asphalt recycling agents
(ARAs) have been identified as important components for producing asphalt
mixtures with high reclaimed asphalt (RA) content. As there are many ARAs
on the market, as well as many other alternative products, it is essential to
ensure that their long-term performance, compatibility, and recyclability are
not compromised. In this chapter, two ARAs, one tailored asphalt additive and
one waste cooking oil, were used. Blends with 50% of virgin and rejuvenated
RA binder were subjected to different aging levels: short (rolling thin-film
oven test), long [20 h in pressure aging vessel (PAV)], and prolonged (60 h
in PAV) and compared to a reference blend without additive. Rheological and
chemical properties were then evaluated after each level, addressing their aging
behavior. Fourier Transformed Infra-Red spectroscopy was used to explore
the chemical characteristics of binders. More specifically, the ketone peaks
(between 1800 and 1650 cm−1) were investigated. Rheological properties were
assessed by determining crossover temperature at 1.59 Hz, crossover shear
modulus, Glover–Rowe parameter, equi-modulus temperature, and phase
angle. The rheological and chemical properties of binder blends containing
ARAs were found to be comparable, with no negative effects after long-term
aging. However, these properties were still not quite as near to those of virgin
binder
Fatigue of wire arc additively manufactured components made of unalloyed S355 steel
No full textToday, wire arc additive manufacturing (WAAM) can be used to fabricate critical structural steel components. The process allows to fabricate sophisticated shapes, thereby achieving very high levels of material capacity utilization. Key welding parameters inevitably influence the mechanical resistance of components made by WAAM, submitted to static or cyclic loading. In this research, the fatigue behaviour of wire arc additively manufactured carbon steel elements is investigated. Firstly, samples are manufactured by cold metal transfer (CMT) welding process using carbon steel 3Dprint AM 35 (S355) grade and following a welding procedure optimised to limit the welding-induced imperfections. A series of microstructural investigations and mechanical experiments are carried out on milled samples including: (i) hardness tests, (ii) static tensile tests, and (iii) cyclic fatigue tests. Both transverse and longitudinal directions are tested. The obtained fatigue test results are then compared against existing research on equivalent details. A database containing all similar test results and own experimental results is then used to calculate the fatigue detail categories, and to assess the applicability of the current Eurocode and IIW provisions for fatigue. The reliability levels of the proposed fatigue classes are then validated through the use of Weibull models, commonly used in survival analysis
Investigation of the long-term changes in sediment load along a free-flowing transboundary Middle Danube reach
No full textThe presented study aims at the indirect estimation of the long-term sediment transport along the sand-bed reach of the free-flowing Middle Danube River based on the surveillance cross-sections’ data. A decreasing trend in water levels and an increasing trend in cross-sectional areas are persistent, while longitudinal changes in long-term sediment transport rates indicate the existence of both degrading and aggrading riverbed reaches
3Dprint AM35 wire arc additively manufactured milled specimens under fatigue
No full textToday, wire arc additive manufacturing (WAAM) can be used to fabricate critical structural steel components. The process enables the fabrication of sophisticated shapes, achieving high levels of material capacity utilisation. Key welding parameters inevitably influence the mechanical resistance of WAAM-fabricated components subjected to static or cyclic loading. This study specifically examines the fatigue behaviour of WAAM carbon steel elements. Firstly, samples are produced by cold metal transfer (CMT) welding process using carbon steel 3Dprint AM 35 (S355) grade, following an optimised welding procedure to minimise induced imperfections. A series of microstructural investigations and mechanical experiments, including static tensile and cyclic fatigue tests, are conducted on milled samples, in both transverse and longitudinal directions. The obtained fatigue test results are then assessed for reliability and validated using Weibull models, commonly employed in survival analysis
A reconstruction of flood hydrograph at the Prijedor gauging station
No full textРеконструкција хидрограма поплавних таласа на основу забележених нивограма у
профилима хидролошких станица није увек могућа, било због прекида у раду хидролошке станице током проласка поплавног таласа, било због непоуздане екстраполације криве протока у домену великих вода. Савремене, физички засноване методе, као што је метода размене количине кретања (МРКК), пружају могућност прецизније процене протока великих вода. Ова метода могла би да се примени за екстраполацију криве протока и реконструкцију таласа великих вода у профилима хидролошких станица. За хидролошку станицу Приједор на реци Сани постоје подаци забележени током поплавних таласа који су се догодили у последњих двадесет година. Ови подаци могу да се искористе за проверу МРКК у условима сложене геометрије корита за велику воду. Тако проверена метода може да се искористи за
реконструкцију хидрограма поплавних таласа у случајевима када екстраполација криве протока применом традиционалних метода није поуздана. У овом раду ће се искористити расположива крива протока за калибрацију МРКК, а нивограми снимљени током четири поплавна таласа из 2010. године за проверу модела. Након тога, МРКК ће се искористити за попуну недостајућих података на хидрограмима попалвних таласа из 2014 године.ABSTRACT: A reconstruction of a flood hydrograph based on recorded measurement data at a gauging station is not always possible, either due to interruptions in the operation of the gauging stations during the passage of the flood wave, or due to high uncertainties in the extrapolation of the stage-discharge curve for high flows. State-of-the-art, physically based methods, such as the exchange discharge model (EDM), allow for a much better estimation of discharges during high water flows. This method can be applied to extrapolate the stage-discharge curve and to
reconstruct the flood hydrograph at the gauging station. The gauging station Prijedor on the Sana
River has data records for flood waves from the last twenty years. The data will be applied to verify the EDM in a compound channel of a complex channel geometry. The verified method will be applied then to reconstruct the flood wave hydrograph in cases where extrapolation of the stage-discarge curve using traditional methods is uncertain. In this work, the available stage-discharge curve will be used for EDM calibration, and stage hydrographs, recorded during four floods in 2010, will be applied to verify the model. After that, EDM will be used to fill in missing data from flood hydrographs from 2014
Citizens Willingness to Embrace the Use of Industrial Waste in Porous Concrete Pavers: Preliminary Findings from the Ø-Waste-Water Project
No full textHighlights:
* Porous concrete pavers (PCP) utilize solidified WWTP sludge for urban stormwater management.
* The human factor strongly influences 0waste PCP implementation and self-sustainability.
* The approach to stakeholders should consider education/occupation role/relevant experience
Experimental Investigation and Numerical Analysis of the Axial Load Capacity of Circular Concrete-Filled Tubular Columns
Get PDFThis paper focuses on the experimental investigation of the axial load capacity of CFT
(concrete-filled steel tube) columns under actual construction conditions during building reconstruction. A total of four samples were loaded up to failure. The varied parameters were the column length and absence/presence of the concrete infill within the steel tube. Further, the analysis is extended to developing a numerical model in the finite element-based software ABAQUS version 6.9. This numerical model includes material and geometrical nonlinearities and was validated with the experimental results. The contribution of the concrete core to the column capacity and the concrete core confinement effect are discussed. Finally, the column capacity was calculated according to several design codes: the Eurocode 4 with and without considering the confinement effect, American specifications, Australian standards, the American Institute of Steel Construction, and the Architectural Institute of Japan. The Eurocode 4 considering the confinement effect provides the closest results to those obtained in the tests
Towards Quality Management Procedures in 3D Cadastre
Get PDFThe 3D cadastre presents a modern approach to the development of cadastral information systems, with the role of improving current cadastral systems and overcoming the challenges of a 2D-based approach. Technological advancements, standardization, and scientific research in recent decades have contributed to the development and definition of the 3D cadastre. This positioned the 3D cadastre as an integral part of the future of land administration. However, every country needs to define a solution for itself based on its own legal system and cadastral tradition, while at the same time relying on international standardization and research. Once a 3D cadastral system is developed, it is crucial to ensure the monitoring, evaluation, and maintenance of both the quality of the cadastral data and the system itself throughout its lifecycle. Since 3D cadastres involve geometric data, quality management procedures must address both geometric and alphanumeric data. In this paper, we analyze and present the quality management procedures that should be included during designing, implementing, and maintaining a 3D cadastral system. Some examples based on real cadastral data were used to emphasize the need for improvement in quality management. The presented quality management procedures require further development in order to meet country-specific requirements and to fully support the 3D cadastre information systems
Combining sewer discharge measurement methods for the reduction of in-situ measurement uncertainty
Get PDFPodaci o protocima u kanalizacionim sistemima su jedan od ključnih parametara za upravljanje radom sistema i planiranje daljeg razvoja. Usled prirode rada kanalizacionih sistema kao i specifičnih, nepovoljnih hidrauličkih uslova koji se javljaju u mreži, obezbeđivanje pouzdanih podataka o protoku je često veoma zahtevan zadatak. Na tržištu su dostupne različite merne metode, gde svaka od njih ima svoj opseg primenjivosti, koji je određen samim mernim principom i tehničkim karakteristikama konkretnih uređaja. Određivanjem merne nesigurnosti definiše se kvantitativni indikator kvaliteta rezultata merenja. Za određivanje nesigurnosti protoka izmerenog u kanalizacionoj mreži koriste se uglavnom preporuke iz odgovarajućih standarda i uputstava. Ispitivanjima korišćenih merila u kontrolisanim, laboratorijskim uslovima, definišu se vrednosti i funkcionalne zavisnosti za opisivanje komponenata merne nesigurnosti, koje se kasnije ekstrapoluju na terensku primenu ispitanog merila. Međutim, na kvalitet izmerenih podataka na terenu često značajno utiče i komponenta merne nesigurnosti koja se javlja usled uticaja lokalnih, specifičnih uslova strujanja na rad samog merila. Ova komponenta merne nesigurnosti se ne može opisati laboratorijskim eksperimentima, često se zanemaraje, dok sa druge strane ona može imati dominantan uticaj na kvalitet izmerenih podataka. U ovom radu se analizira jedan slučaj merenja protoka na ispustu kombinovanog kanalizacionog sistema u Beogradu gde su primenjena dva merila protoka koja rade na različitim mernim principima, zbog ekstremnih hidrauličkih uslova. Predstavljen je postupak kombinovanja podataka sa dva merila sa ciljem definisanja najbolje procene vremenske serije protoka, kao i određivanja vremenske serije komponente merne nesigurnosti usled lokalnih uslova strujanja.Discharge data is one of the key components for the successful sewer system management and development planning. Due to the sewer system nature, and specific, adverse hydraulic conditions in the network, obtaining reliable discharge data is a very complex task. Various measurement methods are available on the market, where each has its own application range defined by the measurement principles and technical characteristics of the particular devices. Computation of the measurement uncertainty allows for the quantitative indication of the measurement result quality. For sewer discharge measurements uncertainty assessment, usually the procedures from appropriate standards and guidelines are used. Laboratory tests and benchmarks are used to define the values and functional relationships for describing the measurement uncertainty components, which are later extrapolated to the field application of the analyzed instrument. However, the quality of the field data is often impeded by the measurement uncertainty component stemming from the effects of the local, specific flow conditions on the instrument operation. This measurement uncertainty components cannot be described by the lab experiments, is often neglected, while on the other hand can have a dominant effect on the measurement results quality. In this paper one example of the discharge measurements on the combined sewer outlet in the Belgrade, is analyzed, where the two different measurement methods were applied due to the adverse flow conditions. Data fusion procedure is shown, where the data from two instruments were combined to define the best estimate of the discharge time series, and the in-situ measurement uncertainty