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Moment-resisting beam-to-column joints in reusable building structures
No full textGiven the increasing emphasis on sustainable development, circular construction strategies, particularly structural reuse, are becoming more prominent within the industry. In contrast to conventional building design, the design-for-reuse paradigm prioritises the creation of structures engineered for efficient disassembly, transpor-tation and reassembly at the conclusion of their life cycles. Another reuse approach involves integrating materials reclaimed from existing structures into new buildings. This paper advances reusable building practices by introducing an innovative beam-to-column joint designed for reusable moment-resisting steel frames. The proposed joint is fully demountable, utilising bolted connections instead of welds to enhance the ease of reusing structural components. Additionally, the joint is designed to allow the reuse of reclaimed steel, featuring an adaptable connecting link that ex-tends the service length of existing steel members and adjusts them to the de-signed span of a new structure. Experimental testing was conducted to evaluate the joint’s performance, including failure modes, moment resistance, rotation ca-pacity and stiffness. Furthermore, finite element models were created to simulate the mechanical behaviour of the tested joint and further investigate its structural performance
Numerical study of RC frames with decoupled masonry infills with and without openings under in-plane seismic loads
No full textThis study presents an innovative decoupling solution designed to improve the seismic performance of infilled reinforced concrete (RC) frame structures. Previous experimental research by the authors confirmed the effectiveness of the decoupling system through a series of full-scale separate and combined in-plane and out-of-plane tests. In the present work, a simplified micro-model developed and realised in Abaqus is validated against three experimental tests and then employed in a comprehensive parametric study investigating the in-plane behaviour of RC frames with decoupled masonry infills featuring various opening types (windows, doors and partial infills) of different sizes and locations. The results demonstrate that the decoupling system successfully reduces adverse frame-infill interaction effects across all configurations. The first cracks in the decoupled masonry infills are typically observed at in-plane drifts exceeding the maximum design in-plane drift of 2.0 %. Meanwhile, the inplane response of the frames remains largely unaffected. Finally, based on the comprehensive findings of the study, and in accordance with the second generation of Eurocode 8, practical guidelines are proposed for the design of the novel decoupling system to ensure efficient decoupling of masonry infills from the RC frames
Dynamic stiffness–based free vibration study of moderately thick circular cylindrical shells
No full textThis paper presents an advanced application of the dynamic stiffness method for the free vibration analysis of moderately thick circular cylindrical shells, based on a generalized Flügge shell theory accounting for shear deformation, rotary inertia and effects of initial stresses. Unlike previous studies, the governing differential equations are solved exactly for each frequency of interest, eliminating the need for numerical approximations in the solution process. An exact dynamic stiffness matrix derived from the strong-form solution is developed for a fully free cylindrical shell element and implemented in a genuine MATLAB code to efficiently compute natural frequencies and mode shapes. The numerical study includes examples featuring stepwise thickness variations, intermediate supports, and initial stresses, providing insights into a wide range of structural applications. The results are validated through comparison with finite element analysis and published data, demonstrating the accuracy, reliability, and computational efficiency of the proposed approach for complex cylindrical shell structures. Additionally, the proposed method addresses limitations of previous studies by capturing all relevant natural frequencies. Finally, numerous high-accuracy results are provided to serve as benchmark solutions for validating future research in this field
Time-Frequency Characteristics of Morlet/Gabor and Cauchy Wavelets for Continuous Wavelet Transform
No full textThe paper presents time-frequency characteristics of two different types of mother wavelets. Wavelets used for the continuous wavelet transform. The continuous wavelet transform is used to analyze continuous functions also be interpreted numerically. Numerical interpretation of the continuous wavelet transform is appropriate for time-frequency analysis of recorded acceleration responses of civil engineering structures (or other mechanical dynamic systems) in the sense of modal properties determination, such as natural frequencies, damping, and mode shapes. Likewise, the analysis has the advantage of the classical Fourier method for determining those values from a short-recorded signal. Small sensitivity to noise is also an advantage.
Morlet wavelets (one specific case of the Gabor wavelet) and Cauchy wavelets are considered, and their comparison made. The mentioned wavelets belong to a large family of complex wavelets defined by analytic functions. The Morlet wavelet is only an approximate analytic function, but it represents a specific wavelet because it achieves the best time-frequency resolution. The Cauchy wavelet is an analytic function and it adopted for analysis because it can represents by relatively simple functions in both, frequency and time domains.
The Heisenberg box area for Morlet/Gabor wavelets remains constant as its parameters change. It has the minimum possible value according to the Heisenberg uncertainty principle. The Heisenberg box area for the Cauchy wavelet varies with its parameter. In accordance with this change, the instantaneous frequencies and Wigner-Ville distribution also change in such a way that the Cauchy wavelet becomes more and more similar to the corresponding Morlet and Gabor wavelet
Geometry and stress resilience of medieval portals
No full textThis paper investigates the geometric design and structural performance of medieval church portals. The research focuses on two marble portals from the Studenica Monastery in Serbia, completed before 1209. Unique incised drawings of the archivolts of these two portals, preserved on the church walls, offer authentic and rare evidence of medieval design practices. Using 3D modeling and stress simulations in SolidWorks and Diana FEA software, the study demonstrates how geometric configurations influence load distribution, stability, and resilience. The findings highlight the critical role of geometry in construction of Romanesque portals and provide a methodological framework and protocols applicable to similar structures. These protocols support preservation and conservation strategies for medieval architectural heritage by combining historical analysis with engineering technologies and advanced computational methods
Lessons learned in institutional preparedness and response during the 2022 European drought
No full textDroughts in Europe are becoming increasingly frequent and severe, with the 2022 drought surpassing previous records and causing widespread socio-economic impacts. Using a Europe-wide survey (n = 481 across 30 countries) combined with hydroclimatic data (i.e., Standardized Precipitation Evapotranspiration Index; SPEI), we quantify how forecasting systems and Drought Management Plans (DMPs) affected response timing and perceived effectiveness. It specifically assesses the role of forecasting systems and Drought Management Plans (DMPs) in improving preparedness and in facilitating more effective and timely responses. Our findings show that organisations with forecasting systems or DMPs in place implemented drought response measures on average two and one months earlier respectively than those without, and rated their effectiveness higher. Additionally, the study investigates how drought management practices and awareness have evolved as a consequence of the 2018 European drought and how recent experiences shape water managers' perceptions, with 35 % of the respondents indicating introducing or updating their DMPs after the 2018 drought. The findings emphasize the necessity of a standardized, continent-wide drought risk management coordination to address the multifaceted nature of drought risk by integrating climatic and societal factors, and advocates for a Drought Directive as a means to achieve this. This research aims to inform policy development towards sustainable and holistic drought risk management, highlighting the crucial roles of preparedness, awareness, and adaptive strategies in mitigating future drought impacts.This study and its companion paper The 2022 drought needs to be a turning point for European drought risk management are the result of a study carried out by the Drought in the Anthropocene (DitA) network, an IAHS initiative
Long-Term strain measurements on Long-Span RC roof beams of Hangar 2 on airport Nikola Tesla in Belgrade
No full textStructure of Hangar -2 facility on airport Nikola Tesla in Belgrade erected a 40 years ago with 135.80m long span posttensioned with cables outside of exceptional structure during period of construction, on several occasions, carried out inspections and different type of measurements, particularly on main roof beams. Measurements included posttensioned cable force measurement, strain measurement on RC section, deflections of main roof beams, etc.
Paper considers strain state in main RC roof beams in the last inspection carried out in 2025 and comparison with available data of strain state in cross section at measuring points establish in previous period, which reported in available inspection reports.
For initial state are assumed strain state after so-called II phase of posttensioning 1985 with presence of approx. 90-95% dead load, which reported in inspection report from 2018. From the report dated on 2018 (so-called Main inspection report) reported actual strain state in measuring sections at measuring points on the same positions as in 1985. Furthermore, during the last inspection of structure 2025, established corresponding strain state at measuring points in main roof beams in all three main roof beams, as in the previous period.
Finally, after comparison of available data of strain measurements on RC cross section carried out comparison of such data, and made conclusions, which show adequate and expected strain state during a long-term period
Numerical analysis of the seismic response of a confined masonry system
No full textThe seismic performance of a confined masonry (CM) technology using novel hollow clay blocks with large cavities for thermal insulation, and polyurethane glue rather than thin-layer mortar was analysed. Shear compression tests on two CM walls have revealed a specific type of damage at the interface between the tie-column and masonry due to the difference in thickness between the tie-columns (25 × 25 cm) and the masonry (38 cm). This motivated further research into the mechanisms behind this type of damage as well as the seismic response of the system as a whole. A simplified 3D micro-model was developed to replicate the observed phenomenon and analyse all aspects of the seismic response. A parametric study was then performed to explore the influence of longitudinal and transversal reinforcement, tie-column size, toothing, compressive strength of masonry, and bed joint reinforcement. The reinforcement detailing had little effect on the seismic response, though numerical simulations showed that the spacing of the transverse reinforcement should not be larger than 15 cm. The tie-column size had the largest effect on seismic response. If appropriately used, toothing and bed joint reinforcement could mitigate issues involving the shear failure of the tie-columns. However, if the tie-columns were reinforced by at least 1 % longitudinal reinforcement as required by the code, then the overall response was adequate regardless of whether the tie-columns experienced shear failure or not
Full gravity gradient tensor modeling by normal gravity field and digital terrain models
No full textThis paper examines the possibility of modeling Earth’s gravity gradients using only the
normal gravity field and the masses located above the reference ellipsoid. The contribution
of the ellipsoidal mass was computed based on the normal gravity field and the second
derivatives of the normal gravity potential. The remaining part was modeled by discretiz
ing the topographic masses and approximating their gravitational effects using prisms as
regular geometric bodies. The practical study was conducted over the territory of Serbia.
The computed gradients were compared with torsion balance measurements taken at a
test area near Novi Sad. A root mean square value of 17 E (1.7 μGal/m) was obtained
for the gradient differences. Gradient values from a global geopotential model were also
computed, and it was found that, over extremely flat terrain, they exhibit similar or slightly
better agreement with the measurements than the modeled values. The results demonstrate
that the proposed concept enables modeling of gravity gradients with an overall deviation
that is comparable to the accuracy of the measurements or, at most, within one order of
magnitude