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Flexible joints for seismic-resilient masonry-infilled RC frames: Shaking table test results
No full textMasonry infills are among the most vulnerable components of reinforced concrete (RC) building frames, often sustaining significant damage even under low to moderate seismic intensities. Flexible joints are a very promising technique to protect these infills from damage, which could also offer an opportunity to enhance the global performance of infilled frames. To validate their effectiveness, it is essential to conduct full-scale shaking table testing on structural prototypes under realistic loading conditions. Additionally, it is important to evaluate whether these joints offer sufficient energy dissipation capabilities to support a resilient design of infilled frames.
The ERIES-FLEJOI project has addressed these research needs by examining two innovative flexible joint systems: one designed to increase the infills' compliance, and another intended to decouple the infills from the frame. These systems have been implemented in two identical RC frame prototypes with masonry infills, which have been successfully tested at the Dynamic Testing Laboratory of IZIIS in Skopje, North Macedonia. This paper describes the constructed prototypes and the preliminary results from the shaking table tests, highlighting differences in the performance achieved with the two joint systems
An efficient computational model for progressive failure analysis of cross-laminated timber panels
No full textThe paper introduces an efficient model for progressive failure analysis of cross-laminated timber panels under out-of-plane bending load. To provide the computational efficiency, the model kinematics is based on the full-layerwise plate theory of composite materials, providing 3D stress and strain fields necessary for accurate prediction of damage initiation and progression. Damage initiation and associated failure mode on the lamina level are determined using the 3D Hashin failure criterion, while the post-failure behaviour is described using a smeared crack band model introducing the bilinear strain-softening curves. The model allows capturing different timber response in tension (brittle) and compression (ideally plastic) in the entire considered (3D) domain. The computational analyses are performed using an original layered finite element framework, while the model validation is done through the extensive experimental testing programme on full-scale CLT specimens. Excellent agreement of obtained load–deflection curves and strain distributions verified that the proposed methodology can be efficiently applied in progressive failure analysis of mass timber, but also in other layered beam- and plate-like structures in bending
Poređenje poroznih i standardnih habajućih asfaltnih slojeva sa stanovišta količina i tretmana zagađujućih materija nataloženih dreniranjem atmosferske vode
No full textZbog svojih pozitivnih osobina sa stanovišta smanjenjena saobraćajne buke i efekta zapljuskivanja susednih vozila u koloni, porozni asfalti primenjuju se sve češće kao habajući slojevi kolovoza na gradskim saobraćajnicama.
Poseban ekološki aspekt predstavlja koncentracija zagađujućih materija u atmosferskoj vodi koja se prikuplja na površini kolovoza i dalje odvodi do recipijenta. Ove koncentraciije značajno se razlikuju tokom sušnog perioda i za vreme trajanja padavina, naročito kada su u pitanju gradske saobraćajnice. U ovom radu će biti predstavljena analiza primene poroznih asfalta u Evropi i SAD-u sa aspekta zadržavanja teških metala i drugih čestica koje se talože filtracijom kroz porozne
slojeve. Efikasnost poroznih asfalta za smanjenje koncentracije zagađujućih materija će se proceniti upoređivanjem koncentracija zagađivača u kišnom oticaju sa habajućih slojeva izgrađenih od poroznih asfalta i standardnih asfaltnih mešavina. Analizirano je takođe kako se sa starošću poroznog asfalta menja njegova sposobnost i efikasnost uklanjanja zagađujućih materija koncentrovanih u atmosferskoj vodi. Razmotreno je i kakav uticaj na promenu koncentracija
zagađujućih materija imaju primenjene tehnike za čišćenje i različiti tretmani održavanja poroznih asfalta
Research and development in construction industry
No full textProduktivnost predstavlja jedan od ključnih indikatora građevinske proizvodnje, kao i
faktor koji bitno utiče na visinu nepotrebnih troškova. Unapređenjem produktivnosti
stvaraju se preduslovi za smanjenje proizvodne cene, ostvarivanje visokog profita i
povećanje konkurentnosti firme. Zbog angažovanja velikog broja različitih resursa,
kontrola produktivnosti na građevinskim projektima je otežana, često zakasnela i
neefikasna. U radu je predložen pristup za identifikaciju ključnih resursa, koji mogu bitno
uticati na visinu produktivnosti na projektima. Na taj način stvaraju se preduslovi za
fokusiranu kontrolu, pre svega ključnih resursa, gde su greške najskuplje i gde treba
delovati preventivno, ciljano i efikasno. Predloženi pristup podržava lean principe. U radu
su analizirane najčešće korišćene metode za merenje produktivnosti i date su preporuke
za njihovu primenu na ključnim resursima, sa ciljem unapređenja poslovanja
Demountable connectors with parallel threaded coupler (PTC) and rebar anchor loaded in tension
No full textPrefabrication of reinforced concrete (RC) elements reduces construction time and costs for steel-concrete buildings, as well as precast RC buildings. The use of demountable connectors for dry connections between structural elements in these buildings can increase their potential for reuse at the end-of-life scenario. Although the use of most demountable connectors can assure the reuse of steel elements, the reuse of RC elements and embedded connectors remains relatively uncertain due to potential damage of connectors during disassembly stage.
The reuse of all structural components could be assured by using demountable connectors assembled from a demountable threaded bar (or bolt) and mechanical coupler with a rebar anchor embedded in concrete. This type of connector has been used for more than a decade in contemporary building structures, with various types of threaded mechanical couplers and, consequently, different local connection between coupler and rebar anchor. Parallel threaded couplers and taper threaded couplers are most widely used. Therefore, the type of mechanical coupler and corresponding threading at the end of rebar anchor can significantly affect the behaviour of the connector under tension load.
This paper presents preliminary experimental investigations of demountable connectors with parallel threaded mechanical coupler (PTC) and rebar anchor under tension load. Eight in-air tests on bare connectors were conducted in order to define the local behaviour of the connector. The influence of connector diameter (16 mm and 20 mm diameters) and the length of threaded part at the end rebar anchor on connector behaviour were discussed in terms of failure modes, resistance and deformation capacity. All specimens failed due to fracture of threaded part at the end of rebar anchor, albeit different locations of failure plane along the thread length. Ultimate tension resistance varied from 110.7 kN to 173.8 kN. Higher tension resistance and deformation capacity was obtained for specimens with shorter length of threaded part at the end of rebar anchor. Good match between existing analytical equations for the calculation of tension resistances and test results were obtained
Sixth Regional Symposium on Landslides in the Adriatic-Balkan Region: ReSyLAB 2024
No full textThe Sixth Regional Symposium on Landslides in the Adriatic-Balkan Region was held in Belgrade, Serbia,
from 15 to 18 May 2024. The Symposium was organised by the University of Belgrade, Faculty of Mining and Geology, as a member of the Adriatic-Balkan Network. The Adriatic-Balkan Network is one of eight regional and thematic networks of the International Consortium on Landslides (ICL). The Symposium started with workshops on May 15, 2024, followed by the Opening ceremony on the same day in the afternoon. The opening ceremony was started with welcome notes from ICL President Prof. Željko Arbanas from the University of Rijeka (Croatia) and ICL Vice President for Europe and a Dean of the Faculty of Mining and Geology Prof. Biljana Abolmasov (Serbia). Parallel scientific sessions continued from May 16 to May 17, 2024. The closing plenary session occurred on May 17, 2024, in the afternoon hours after the round tables’ discussion. The field trip excursion was held on May 18, 2024. A total number of 84 participants from 15 countries attended the Sixth ReSyLAB
Layerwise theory-based finite elements for static and dynamic analysis of CLT-concrete composites with partial shear connection
No full textThe paper presents a formulation of layered finite elements (based on Reddy’s full-layerwise-theory) for static and dynamic analysis of cross-laminated-timber concrete composites (CCC). A partial interaction between concrete and cross-laminated-timber (CLT), allowing for interlayer slip, is incorporated by using distributed elastic springs in the CLT-concrete interface. A linear discontinuous layer-wise interpolation of displacement components through the thickness is imposed to account for complex layerwise kinematics including partial shear connection.
The model is implemented using the original MATLAB framework, while the graphical user interface is developed in GiD environment. It is validated against the available data in the literature, and excellent agreement for static and dynamic simulations is obtained with computational cost savings. The complex 3D displacement/strain/stress fields and natural frequencies of the CCC with various interlayer slip moduli аre accurately predicted. The parametric study on the influence of partial shear connection on stress distribution within the CCC is provided as a benchmark for future investigations. The developed model can be applied for the analysis of timber-concrete (TCC) or other plate-like layered composites with partial shear connection and arbitrary geometry
Influence of Opening Size and Internal Tie-columns Around Openings on the Seismic Response of Confined Masonry Walls: A Numerical Investigation
No full textConfined masonry (CM) is one of the popular structural systems embraced by many countries as an earthquake-resistant and affordable solution for building construction. Despite this, there are still gaps in the knowledge about seismic response. This paper presents a comprehensive numerical investigation into the seismic response of CM walls with openings, utilizing a micro-modelling approach in Abaqus software. A finite element (FE) model, validated on two cyclic shear tests of full-scale CM wall specimens, is employed for a parametric study exploring the effects of varying wall aspect ratios and opening configurations (no opening, door opening, window opening). The primary objective is to examine the influence of opening size and on the lateral resistance of CM walls, focusing on in-plane behavior, stiffness, strength, and ductility.
The results from the numerical simulations demonstrate that the presence of tie-columns around openings and shape of the openings significantly affect the seismic performance of CM walls. As the opening size increases, the strength reduction becomes more evident, with walls having AR = 0.71 showing a substantial decrease in load-bearing capacity due to the amplified effect of larger openings. Furthermore, the size of tie-columns around openings is recognized as crucial in mitigating strength losses. These findings underscore the necessity of further experimental tests to fully validate these conclusions
Enhanced seismic safety of masonry infilled rc frame structures: INODIS connection
No full textAlthough they are famous for their fast construction and advantages in thermal insulation, reinforced concrete frame buildings with masonry infill walls frequently behave poorly during earthquakes. These buildings are vulnerable to out-of-plane infill failure and in-plane cracking, which can result in expensive repairs and high danger for those in the vicinity. Infill collapse results from the failure of conventional mortar-based connections between infills and frames under seismic loading. This was addressed by developing and testing a new decoupling/isolation connection between the RC frame and masonry infill using rubber strips. After two percent drift, tests revealed the first infill cracks. This was verified in shaking table test as well. This ground-breaking approach improves the seismic resilience of RC frame buildings by preventing infill damage, streamlining seismic design, and lowering repair costs. Because less concrete and reinforcement are required for RC structural elements, it also has financial advantages. Paper shows basic concepts of the INODIS connection, brief overview of the experimental results and some important findings of the numerical study that are used for the practical design
Geometry of bastion fortifications magistral line: influences and development
No full textIn the middle of the 15th century, the fortification system of medieval European cities underwent a transformation into a bastion fortification system. This system will dominate until the mid-19th century, experiencing its zenith by the late 17th century with the improvements of the French military engineer Vauban. A defining feature of this system is the distinct contour of the magistral line in the ground plan, with its geometry progressing from simplicity in the early stages, to comprehensive solutions that addresses dimensions of all elements within bastion fortifications, in the final ones. Our research encompasses the geometric principles used by four selected military engineers from this period (Marolois, de Ville, Pagan, Vauban) with the aim to identify the development of geometric procedures in the design of the magistral line. We explore the specifics and differences in their approaches and methodologies. Conducting a comparative analysis of the geometric principles employed by different builders, using the example of star fortresses, we follow the progression of theoretical framework and design aspirations underlying the key elements of the magistral line. We consequently consider whether the “Vauban style” is a spontaneous creation of a single genius, or an outcome that emerged from the collective contributions of numerous predecessors across Europe. This paper spotlights the principles of bastion fortress design based on geometry, offering a way to identify markers of influence in observed examples, and also to complement non-invasive methods of cultural heritage preservation with adapted 17th-century geometric procedures, making them more compatible with modern approaches