Search Results (764)

During a severe earthquake, the violent shaking causes freestanding non-structural elements to sway and overturn, potentially injuring occupants or causing the elements themselves to break apart. This study investigates how freestanding contents (FSCs) in buildings respond to various earthquake intensities, detailing their movement through extensive analysis of dynamic performance. The stability of the FSCs on each floor varies depending on the earthquake’s intensity, the building’s structural mode shape, the FSCs’ geometry, and the chosen performance assessment method. A series of multi-level seismic excitation assessments of FSCs were conducted using 30 earthquake records, classified into 50%, 10%, and 2% probabilities of exceedance in 50 years. The floor’s responses, including absolute peak floor acceleration and relative peak floor velocity from both elastic and inelastic analyses, provided the seismic demand. The Ishiyama criterion made it difficult to evaluate FSCs’ seismic capacity because of the ambiguous distinction between rocking and overturning movements. A new criterion, specifically developed to differentiate between rocking and overturning of FSCs, has been proposed to address this issue. The results translate into practical guidance for design and protection: because the demand-to-capacity ratios for overturning are governed by the floor level, content slenderness, and the elastic-versus-inelastic modeling assumption, the proposed criterion identifies which floors and which content geometries are genuinely at risk, allowing anchorage, restraint, or relocation measures to be targeted where they are most needed rather than applied uniformly. This supports more reliable and economical seismic protection of non-structural building contents. Full article

While place attachment (PA) is an important concept that varies across built environments, empirical research directly examining it in student dormitories remains limited. This study aims to investigate students’ levels of PA to their dormitories across variables including gender, age, field of study, class level, degree level, campus location, family’s region of residence, dormitory of residence, duration of residence, and floor level. The research scope encompasses five Ministry of Youth and Sports (GSB) dormitories in Kırklareli, Turkey, and their residents. Data were collected via a questionnaire from 450 participants selected using a stratified sampling method. The independent samples t-test and one-way ANOVA were utilized for data analysis. The results indicate that PA levels differ significantly according to gender, field of study, degree level, campus location, dormitory of residence, and floor level. In contrast, age, class level, family’s region of residence, and duration of residence in the dormitory do not show significant differences. These findings highlight that socio-spatial dynamics are significantly associated with students’ PA. Accordingly, to better accommodate the different needs related to these socio-demographic and spatial variables, dormitory designs might benefit from prioritizing human-scaled, context-integrated environments offering flexible personalization rather than uniform architectural solutions. Full article

We present a novel method for deriving radially resolved dynamical chronometers from galaxy rotation curves, allowing galaxy assembly histories to be reconstructed directly from kinematic data. In the Nexus Paradigm, the baryonic Tully–Fisher relation is used to estimate the dynamical mass profile. We compare this profile with independently derived intrinsic baryonic mass distributions obtained from stellar Sérsic fits and gas surface-density measurement yields. This yields a radial ratio that maps to formation redshift with radial resolution. Inverting this ratio within a standard cosmological framework produces a radial lookback-time profile, representing the time since each radial shell last experienced dynamical reconfiguration. Applying the method to a pilot sample of seven SPARC galaxies, including both high- and low-surface-brightness systems as well as the Milky Way, reveals diverse age structures: stratified profiles associated with inside-out growth and flatter profiles consistent with coherent disk assembly. The method requires no dark-matter halo fitting and offers a kinematic chronometer that complements stellar population and chemical evolution approaches. The NP rotation-curve parameters were determined by minimizing the chi-squared statistic between the observed and predicted velocities using a two-stage optimization consisting of a global differential-evolution search followed by nonlinear least-squares refinement. Observational uncertainties were taken from the published rotation-curve data, supplemented by a 5 km s⁻¹ systematic error floor added in quadrature to account for non-circular motions and other unresolved systematics. We also show that the governing dynamical equation admits a gravitoelectromagnetic interpretation, in which a velocity-dependent term generates disk-wide torques that regulate angular momentum transport. This leads to a unified stability framework in which galaxy morphology emerges from a single parameter regime: balanced conditions favor a coherent spiral structure, whereas dynamically hot regimes naturally produce diffuse and ultra-faint systems. The cosmological scaling of the effective gravitomagnetic field further suggests that the spiral structure is partly regulated by cosmic time. Although the inferred ages depend on the accuracy of the baryonic mass reconstruction and on the local validity of the evolving baryonic Tully–Fisher relation, our results show that rotation curves encode time-resolved dynamical information. This establishes the radial dynamical chronometer as a new observable for studying galaxy evolution and testing gravitational frameworks. Full article

This study addresses the technical, environmental, economic, and systemic role of multi-apartment residential buildings as hydrogen consumption nodes within urban energy systems. A representative five-story building comprising 30 apartments and 2400–2800 m² of heated floor area, located in a cold European climate, was modelled with an annual heat demand of approximately 185,000 kWh. Four heating configurations were assessed: a conventional natural gas/biomethane boiler (baseline), a hydrogen boiler, a hydrogen-fuel-cell combined heat and power (CHP) system, and a hybrid heat-pump–hydrogen solution. Dynamic simulations indicate that all hydrogen-based systems can fully satisfy space heating and domestic hot water demand without modifications to the internal hydronic distribution network. The fuel cell CHP achieved an overall efficiency of 93%. It generated approximately 54,000 kWh/year of on-site electricity, while the hybrid configuration reached a seasonal efficiency of 108% and the highest primary energy reduction (46%). Operational CO₂ emissions decreased from 37,800 kg/year (gas baseline) to 1900 kg/year (green hydrogen boiler), 1200 kg/year (fuel cell CHP), and 900 kg/year (hybrid system), corresponding to reductions of up to 98%. Peak-load analysis demonstrated improved operational stability in CHP and hybrid systems, characterised by reduced cycling frequency and enhanced thermal resilience through hydrogen storage integration. Capital expenditure (CAPEX) ranged from 41,000 EUR (gas baseline) to 101,000 EUR (fuel cell CHP), reflecting additional storage, safety, and control requirements. Over a 20-year lifecycle (5% discount rate), the hybrid system achieved the lowest levelized cost of heat (0.076 EUR/kWh), followed by fuel cell CHP (0.081 EUR/kWh), compared to 0.087 EUR/kWh for gas. Payback periods ranged between 9 and 13 years, depending on configuration and hydrogen pricing assumptions. Sensitivity analysis identified a break-even hydrogen price of approximately 0.085 EUR/kWh, while carbon pricing above 100 EUR/t CO₂ significantly improves economic competitiveness. District-scale aggregation modelling suggests that hydrogen-equipped multi-apartment buildings can reduce grid electricity imports by 30–40% through on-site generation and seasonal storage. The findings confirm that multi-apartment buildings offer structural and economic advantages for early hydrogen deployment compared to dispersed housing typologies. By combining high demand density, centralised infrastructure, and compatibility with sector-coupling strategies, such buildings can function as distributed energy hubs within decarbonized urban systems. Full article

The influence of debonding in concrete-filled steel tube (CFST) columns on the dynamic characteristics of super high-rise buildings is a common concern that remains insufficiently understood. The abnormal vibration incident of the SEG Plaza on 18 May 2021, also known as the 5·18 incident, serves as a typical case highlighting this issue. After two decades of service, the first-order bending frequency of the building decreased by approximately 6.1%, and extensive CFST column debonding was observed, with the maximum debonding rate reaching up to 97% on certain middle floors. To investigate the influence of CFST column debonding on structural dynamic characteristics, this study first derives a theoretical relationship between debonding parameters, namely angle and distance, and the equivalent bending stiffness of CFST columns. This analytical formulation is then implemented and validated through finite element simulations at multiple scales, including planar frame analysis in ABAQUS, a thin-interlayer simulation method in ANSYS, and full-building modeling in ETABS. Results show that for a planar frame, when a CFST column debonds at 270°, the structural natural frequency decreases by 0.984%; when the debonding angle is 180° with a 2 mm gap, the first-order frequency decreases by 0.141%. Numerical simulation of the SEG Plaza structural model predicts a reduction in the first-order frequency of 0.987% under the observed debonding conditions, confirming that debonding impairs force transmission, reduces structural stiffness, and alters natural frequencies. This study provides a mechanistic basis for evaluating stiffness degradation in long-service super high-rise buildings. Full article

Fire protection remains one of the key challenges in the field of architectural heritage conservation, particularly for heritage buildings dominated by timber structures, which face greater difficulties in fire prevention and risk assessment. To systematically evaluate the fire safety performance of high-rise timber heritage buildings, this study takes the Shengjin Pagoda, a typical brick–timber pavilion-style ancient tower in Jiangxi Province, China, as the research object. A three-dimensional performance-based fire assessment framework was developed using Fire Dynamics Simulator (FDS) and PyroSim. Based on field survey data and historical documentation, the geometric characteristics, material properties, and vertical circulation system of the pagoda were reconstructed. Three representative fire scenarios, including bottom-floor ignition, simultaneous multi-level ignition, and wind-driven top-floor ignition, were established to investigate smoke propagation, thermal insulation degradation, and the thermal response of critical timber components under different fire conditions. The results show that brick walls provide effective thermal insulation during the early stages of fire, with efficiency exceeding 90%, but this decreases to approximately 55% in upper regions due to chimney-effect-driven smoke accumulation. Under wind-driven top-floor ignition, exposed dougong components can reach temperatures of 782 °C, resulting in a progressive “top-down and outside-in” failure mechanism. The study reveals the dominant smoke-driven heat transfer pathways and the failure sequence of critical load-bearing elements. Based on these findings, a performance-based fire protection strategy incorporating vertical virtual smoke control zoning and fire-resistance enhancement of key structural components is proposed to support the sustainable conservation of historic high-rise timber structures. Full article

With deep coal mining in China, high in situ stress frequently causes severe floor deformation, bolt-cable support failure, and excessive floor heave, which critically threaten mine safety. In this study, we use physical experiments, numerical simulation, and theoretical analysis to explore how hydraulic fractures with different azimuth angles affect stress transfer in roadways under floor dynamic pressure. Prefabricated fractures simulate weak planes induced by hydraulic fracturing. Uniaxial compression tests and PFC2D fluid–solid coupling simulations analyze mechanical properties, failure modes, acoustic emission behavior, and stress distribution. Results show that fracture azimuth significantly controls rock damage and failure modes. As the angle increases from 0° to 90°, failure changes from gradual degradation to sudden instability. Peak strength first decreases then increases, reaching the minimum at 22.5°, while roadway damage is minimal at 45°. Small-angle fractures lead to shear failure with clear precursors, and large-angle fractures cause sudden tensile failure. Hydraulic fractures form directional stress-relief zones and enable effective stress transfer and pressure relief. The results support parameter optimization of hydraulic fracturing and stability control for deep roadways under floor dynamic pressure. Full article

To address the “3R” issues (resistance, resurgence, and residue) associated with chemical control of the sea buckthorn fruit fly (R. batava obscuriosa), this study proposes a novel physical barrier technology aimed at reducing pesticide application intensity, mitigating environmental pollution, and enhancing fruit quality. Yellow sticky traps were deployed to monitor adult occurrence dynamics and delineate the critical control window, while black polyethylene (PE) ground cover was installed on the orchard floor around the base of sea buckthorn trunks to prevent adult emergence from the soil. Control efficacy was evaluated by comparing adult trap catches and fruit infestation rates between the black PE ground cover treatment and the untreated control. Monitoring results revealed that adult emergence commenced on 29 June, entered the peak period on 9 July, attained maximum trap catch on 24 July, and persisted into the late emergence phase through mid-to-late August. Control data demonstrated that mean trap catches in the black PE ground cover treatment were lower than those in the control. From 2024 to 2025, fruit infestation rates declined from 74.5% and 62.3% in the control plot to 19.0~22.0% and 16.2~19.3% in the treatment plots, respectively, with control efficacy consistently exceeding 65%. This study demonstrates that black PE ground cover reduces adult abundance and fruit infestation rates of R. batava obscuriosa, with control efficacy consistently exceeding 65%. The observed effects are consistent with a soil-surface barrier effect and likely attributed to dual physical mechanisms: it may reduce adult emergence from the soil into the canopy and may obstruct mature larvae from entering the soil to pupate. This technology represents an environmentally sound, sustainable green control option suitable for integration into IPM programs for the sea buckthorn industry. Full article

Gob-side roadways driven along the floor while retaining top coal in thick soft coal seams are prone to instability under strong mining-induced dynamic loading. To clarify the instability mechanism and develop an effective control method, the 1609 return airway of Jiulishan Mine was investigated using field survey, borehole imaging, FLAC3D numerical simulation, industrial testing, and field monitoring. The results show that, under the combined effects of large mining height, insufficient filling of the gob by the caved immediate roof, weak retained top coal, and low coal strength, shear failure planes tend to develop within the narrow coal pillar and extend from the gob-side roof toward the floor. Once the dominant shear plane cuts through the pillar, the overall bearing structure is destroyed, leading to shear slip, asymmetric rib deformation, roof subsidence toward the coal-pillar side, and rib–roof coupled instability. Based on a multi-index evaluation of pillar load-bearing capacity, plastic zone development, stress concentration, roadway deformation, and coal recovery, a 3 m coal pillar was determined as the rational width. A coordinated “narrow coal pillar + cross-rib anchorage” scheme was proposed, and field verification confirmed its effectiveness in controlling roof separation, roadway surface displacement, and internal surrounding-rock damage. Full article

In provinces where the dynamics of industrialization and urbanization are intensifying, migration flows from rural settlements to urban centers are transforming the socio-cultural structure and physical fabric of rural spaces, leading to the gradual weakening of the unique rural identity and, consequently, a decline in its sustainability. This study examines the population loss occurring in rural areas as a result of industrialization and urbanization processes, along with the accompanying issue of cultural heritage preservation, using the village of Akkoy in Bilecik as a case study. Akkoy is considered worthy of preservation due to its geographical location and its architectural fabric, which has survived largely intact to the present day. Within the scope of the research, the architectural typology of 134 traditional dwellings in Akkoy was analyzed in detail based on parameters such as plot relationships, number of floors, construction systems, material usage, and facade characteristics. The findings show that the structures in the village are examples of sustainable architecture, built using local materials (adobe, stone, wood) and adapted to the sloping terrain. However, it was determined that due to intense migration, a large portion of the structures are abandoned and at risk of losing their original identities. The study emphasizes that a comprehensive conservation and management plan covering not only the buildings but also socio-economic activities (silkworm farming, agriculture, etc.) must be implemented urgently to preserve Akkoy’s rural heritage. Full article

In post-socialist countries, the transition from state-controlled housing provision to market-driven residential development has significantly reshaped urban housing production. This transformation has introduced new development dynamics associated with increasing pressures toward economic efficiency and affordability, which may influence the implementation of spatial standards. In this context, this paper examines the extent to which newly built apartments comply with national minimum housing standards in Serbia. The study is based on an empirical dataset comprising 31 multifamily housing projects and 1155 apartment units designed in Niš in the period from January 2024 to April 2025. Each apartment is classified according to its typology and analysed in relation to the minimum floor area prescribed by national regulations. The results reveal a selective pattern of compliance, with the lowest levels observed in two-room apartments, which represent the dominant segment of housing production. This suggests that spatial optimization may be most pronounced in the lower segment of medium-sized dwellings, where dominant housing typologies and regulatory thresholds converge. The findings are interpreted within the framework of post-socialist housing transition, highlighting the uneven relationship between regulatory standards and contemporary housing production patterns. Full article

This paper presents an extended combined experimental and numerical study on the vibration comfort assessment of a modern timber-framed public utility building. The research focuses on a lightweight skeleton floor system, representing a typical high-frequency floor. In situ vibration measurements were conducted under various walking excitations (single and multiple pedestrians) to determine key vibration parameters. Post-processing, which yielded root mean square accelerations and velocities, was performed using a custom-developed code in the Mathematica package. A finite element model was prepared in Dlubal RFEM 6 using shell and beam elements with offsets. The dynamic characteristics obtained from the FE modal analysis showed high consistency with the experimental data, with a relative error of approximately 5 % for the fundamental frequency. The vibration comfort was assessed using two distinct methodologies: the JRC report and the SCI P354 guide. Both approaches positively verified the floor’s vibration comfort, confirming its suitability for the intended use. The study demonstrates that the JRC methodology is more straightforward and unambiguous for engineering practice. Furthermore, the results indicate that simplified FE models provide a reliable basis for predicting vibration modes and calculating mode shape factors, which are essential for the correct interpretation of local measurements in existing buildings. Full article

This study aimed to model the growth trajectories of Denizli chickens under different production systems and to identify the most appropriate nonlinear growth function within a Bayesian framework. A total of 156 birds were monitored weekly from hatch to 26 weeks of age under conventional cage, conventional floor, and enriched floor systems. Eight candidate nonlinear growth models were evaluated using Bayesian model comparison criteria, including leave-one-out cross-validation (LOO) and the widely applicable information criterion (WAIC). Among the evaluated models, the Gompertz function showed the best predictive performance, with the lowest LOOIC (225.16) and superior predictive accuracy across fit statistics. The selected model was subsequently extended to a Bayesian nonlinear mixed modelling framework to evaluate the effects of sex and production system on growth dynamics while accounting for between-animal variability. Males exhibited substantially higher asymptotic weights than females, whereas females showed faster early growth and earlier stabilization. Birds reared under the conventional floor system, particularly males, exhibited the highest asymptotic growth potential and later inflection ages, indicating a more prolonged growth phase. In contrast, enriched systems appeared to have promoted greater variability in growth responses, possibly due to increased behavioral activity and energy expenditure. The findings demonstrated that production system and sex jointly influenced both the scale and timing of growth in Denizli chickens. Beyond statistical model comparison, the Bayesian nonlinear mixed modelling approach provided biologically meaningful information that could support breeding, housing, and management decisions for indigenous and dual-purpose poultry production systems. Full article

To examine the dynamic response of tunnel floor slabs subjected to blasting under varying stress conditions, a numerical model was developed to simulate blasting effects at different tunnel depths. This model integrated Hopkinson bar experiments conducted under confining pressure with the Riedel–Hiermaier–Thoma (RHT) constitutive framework. The study subsequently investigated the effects of geostress fields, tunnel depth and tunnel inclination on the propagation characteristics of stress waves. Additionally, the mechanisms stress wave transmission and the damage evolution within the rock mass were analyzed. Results from the numerical simulations reveal that increasing the charge depth diminishes the dissipation of post-blasting stress waves toward the free surface, thereby concentrating stress wave propagation within the rock mass and substantially amplifying shock wave intensity and impact loading. Moreover, elevated stress levels in the surrounding rock increase the peak stress wave amplitude, constrain damage propagation on the tunnel’s upper side, and redirect more stress waves toward deeper regions of the model. Increasing tunnel inclination was also found to intensify stress concentration and augment stress wave intensity. Notably, at a tunnel inclination of 5°, stress wave intensity attains its maximum; beyond this angle, the development of stress waves exhibits irregular patterns. Full article

Public goods provision is vulnerable to free riding, making sustained cooperation a central challenge in economics. Fehr and Schmidt’s inequity-aversion model explains how fairness concerns can support cooperation, but it treats preferences as fixed. Motivated by Kimbrough and Vostroknutov’s norm-sensitivity framework, this paper develops a reduced-form dynamic framework in which observed norm violations erode normative commitment over time. As normative commitment declines, the model maps this change into Fehr–Schmidt-style fairness parameters: guilt weakens and envy rises. These parameters provide an interpretive representation of norm erosion, while behavior is generated through a tractable contribution-scaling rule. The framework is calibrated illustratively to the public goods experiment of Fischbacher and Gächter. The calibration is not causal evidence of preference change and does not directly identify inequity-aversion parameters. It shows that a context-dependent preference channel can reproduce the observed aggregate decline in cooperation and generate testable implications. When no free-rider exposure is present, cooperation does not decline within the model. The model also predicts a nonlinear relationship between population-level free-rider prevalence and cooperation. Finally, because the model imposes a lower bound on normative commitment, this institutional floor determines long-run cooperation. The findings should be interpreted as model-based hypotheses for future experimental and field research. Full article