Search Results (162)

As the construction industry seeks to reduce carbon emissions, timber has emerged as a key material due to its capacity for biogenic carbon storage and end-of-life (EoL) reuse. However, assessing the practical circularity potential of timber structures remains challenging. This is largely because recovered components suffer geometric and material losses at their connection points. This study evaluates the EoL reuse and recycling potential of a multi-storey timber building by combining Building Information Modelling (BIM) with Life Cycle Assessment (LCA). A digital model was used to quantify structural elements (beams, columns, and walls), explicitly accounting for material losses at connections to calculate the net recoverable timber. The recovered material (837.39 m³) was assigned to various cascading use scenarios based on material strength: structural reuse, non-structural reuse, engineered wood production, and energy recovery. To align with ISO 14044 principles, a functional equivalence factor (Q-factor) was applied to measure the environmental benefits of substituting new materials. Results indicate an overall material loss of 16.62% due to connections. Among the evaluated EoL pathways, structural reuse yielded the greatest net carbon benefit (−128.7 tCO₂e), significantly outperforming lower-value alternatives such as energy recovery (−29.3 tCO₂e). Additionally, a Design for Disassembly (DfD) sensitivity analysis showed that reducing connection losses by 50% could increase net global warming potential (GWP) savings by up to 19.7%. In conclusion, connection design is a critical factor in enabling timber circularity. Furthermore, combining BIM material tracking with LCA methods offers a practical approach to quantifying the long-term carbon benefits of timber reuse strategies. Full article

Accurately predicting the production dynamics of multi-stage fractured horizontal wells in high-water-cut tight gas reservoirs remains challenging due to complex nonlinear flow regimes. This research aims to quantify dynamic threshold pressure gradients (TPGs) and their impact on well performance. A high-temperature, high-pressure flow testing system was utilized to measure dynamic TPG under varying water saturations in ultra-low-permeability cores. A dynamic mathematical model was established to characterize the exponential evolution of TPG. Furthermore, a comprehensive flow model was constructed using a coupled dual continuum–discrete fracture model. An entirely implicit numerical model utilizing a non-structured 3D tetrahedral mesh and a control volume finite element method enabled accurate numerical solutions. Key parameters such as water saturation, stress sensitivity, and fracture spatial asymmetry were systematically analyzed. Results: The threshold pressure gradient induces distinct dynamic boundary characteristics in pressure propagation, significantly reducing the wave propagation range compared to conventional models, with pressure drops concentrated near hydraulic fractures. Lower permeability (below 0.05 mD) and higher water saturation exponentially intensify the TPG amplification effect (exceeding 0.12 MPa/m), causing substantial reductions in both daily and cumulative gas production. The established simulation framework accurately captures the non-Darcy flow dynamics of fractured horizontal wells in high-water-cut tight gas reservoirs. It provides a reliable theoretical basis and computational tool for optimizing efficient gas field development. Full article

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

The current research evaluates the potential of incorporating shredded end-of-life tires as recycled aggregate in traditional earth blocks, proposing a sustainable alternative for the managing and valorization of this waste. Shredded tire particles at the upper granulometric limit, according to applicable regulations for this type of block, were used in various volume replacement percentages. The results reveal that the bulk density remains almost constant, increasing by 2.12% after 20% replacement, while the porosity increases progressively with reduced content, reaching a maximum of 17.63% for the same replacement. Although the mechanical properties decrease with higher replacement percentages, reaching 2.061 MPa with a 31.83% reduction in compressive strength and a 30.18% reduction in flexural strength compared to the control samples, these values still exceed regulatory requirements. In contrast, there is an optimization of thermal properties, with a minimum conductivity value of 0.66 W/m·K and improvements in erosion resistance, including reductions of up to 42.71%. Through Thermogravimetric Analysis and Optical Image Analysis tests, complementing the feasibility analysis, it is determined that this type of block is viable for masonry applications for light or non-structural loads. Likewise, the material exhibits significant improvements in erosion resistance and highlights its thermal behavior as a potential insulating element. However, polymer degradation when exposed to high temperatures limits its application due to the loss of mechanical stability and the potential risks associated with matrix degradation. Full article

Earthquake risk communication often remains centered on event parameters and structural collapse, while local site effects, building response and non-structural elements vulnerability shape how earthquakes are experienced and what people can do to reduce risk. This study examines whether a multi-modal, experience-based strategy focused on these dimensions, which are referred to as “last mile” of seismic risk, can improve public understanding and support actionable preparedness behaviors. The case study is the exhibition “Terremoti: Attenti agli Elementi!—Dettagli che salvano la vita” (Earthquakes: Beware of the Elements!—Details that Save Lives), designed for school audiences and the general public. Its effectiveness was assessed through five multiple-choice questions administered before (N = 183) and after (N = 174) the visit to the Genoa Science Festival; responses were analyzed overall and by topic and demographic group. Correct answers increased significantly from pre- to post-visit, with the largest gains concerning local site effects (+43.29%) and household prevention measures (+49.45%), whereas building vulnerability (+14.97%) and building dynamic response (+0.49%) showed more limited improvement. These exploratory results suggest that seismic risk communication is more effective when abstract concepts are translated into observable, manipulable, and everyday experiences, and support a shift toward a “last-mile” framework of seismic risk communication. Full article

The piping systems are critical non-structural elements (NSEs) whose seismic performance directly affects the post-earthquake functionality of essential facilities. However, current seismic design provisions for such systems remain largely empirical, and behavioural factors are rarely calibrated using performance-based methods. This study implements an FEMA P695-inspired framework to calibrate the behaviour factor $\left(q_a\right)$for the installation of sway-braced suspended piping restraint systems in following the force-based requirements specified in Eurocode 8. The representative piping archetypes were developed and analysed using non-linear time history analyses under multiple seismic intensity levels derived from the floor response spectra (FRS) of prototype-reinforced concrete buildings. Fragility curves for two limit states were derived with displacement ductility adopted as the engineering demand parameter (EDP) and peak floor acceleration (PFA) used as the intensity measure (IM). The results show that increasing $\left(q_a\right)$ systematically shifts the fragility curves towards lower median PFA values, indicating higher seismic vulnerability at larger behaviour factor values. The effect of piping layout configuration was of secondary importance compared to the applied reduction factor. The implemented approach provides a rational basis for selecting behavior factors consistent with explicit performance objectives and supports further development of performance-oriented seismic design procedures for non-structural systems. The results show that increasing the behaviour factor $\left(q_a\right)$ leads to a systematic shift in the fragility curves towards lower median PFA values and a noticeable increase in the dispersion of the response. A quantitative analysis shows that increasing the behaviour factor $\left(q_a\right)$ from 1 to 4 results in a reduction of up to approximately 60% in median PFA, highlighting a significant increase in seismic vulnerability at higher behaviour factor values. Full article

Rapid population growth is increasing housing demand and accelerating the expansion of the built environment in Egypt. However, practical and sustainable residential building decarbonization remains constrained by limited supplies of supplementary cementitious materials, limited structural timber resources, code restrictions on cement reduction, and cost sensitivity. This study evaluates two Egyptian multi-unit residential case studies—one affordable housing project and one middle-class housing project—to assess whether wall-system substitution can reduce both embodied and operational carbon under local material, code, and cost constraints. An integrated BIM-based digital twin workflow was used to link quantity takeoff, finite-element structural assessment, and whole-building energy simulation. An architectural BIM model was used for material quantification, wall-system definition, and energy-model inputs. A structural model was used to assess the effects of reducing wall density on reinforcement and concrete demand under gravity and seismic load combinations. Operational performance was assessed through cooling-focused energy simulations under hot-arid climatic conditions representative of Egypt’s new desert cities. Alternative wall systems were then evaluated through scenario- based material substitution and revised structural and energy assessments. The results show that reinforcement, concrete, and wall- core materials account for about 80% of total embodied carbon, while cooling accounts for about 72% of operational emissions. Non-structural cement uses, mainly mortars and finishes, account for 36% of total cement demand, ranging from 161 to 229 tons per building across the two case studies. Replacing conventional partition walls with lightweight, energy-efficient alternatives reduced embodied carbon by up to 35.2%, operational carbon by about 15.7% to 16.5%, and total life-cycle carbon by about 17.4% to 17.5% over a 60- year service life. The average savings per building corresponded to avoiding about 30 tons of steel, 165 m³ of ready-mix concrete, and 191 m³ of mortar, with net cost savings of about 3.15 million EGP per building. These results identify a practical pathway toward more sustainable, lower-carbon Egyptian residential buildings without increasing project cost. Full article

This paper presents the application of a structural finite element model (FEM) of a light patrol aircraft for numerical flutter analysis. The thin-walled structure was developed using 2D shells and additional 1D beam elements. The virtual structure was supplemented with additional point elements imitating lumped masses of non-structural on-board components. The model was subjected to validation for qualities such as the mass distribution, its CG location, the structural stiffness of its airframe units, and the similarity of natural modes. The comparative analyses showed satisfactory consistency of the mass and stiffness properties of the FEM with the actual aircraft. Numerical flutter analysis was then performed with the MD Nastran for an integrated aeroelastic model consisting of the FEM and the simplified aerodynamic model. The critical velocities of basic flutter modes were determined. Using simplified kinematic models of flight control systems built into the FEM, an analysis of the sensitivity of control surface flutter due to the pilot’s influence was carried out. The stick grip and the support of control pedals with the pilot’s legs cause specific conditions related to the imposition of additional stiffness and mass on the control manipulators. These conditions directly affect the natural frequencies of control surface modes, which translates into a change in the critical flutter speed of the tail. For the established range of changes in stiffness and mass added to the stick and pedals, a series of analyses of natural vibrations and flutter were carried out. The influence of the change in the support conditions of control manipulators was illustrated in graphs. Full article

Recent earthquakes have underscored the significant seismic vulnerability and poor energy performance of existing reinforced concrete (RC) buildings, with particular deficiencies observed in non-structural components such as masonry infill walls. Conventional retrofit strategies typically address seismic and thermal deficiencies separately, often leading to increased costs and invasive interventions. This study explores the development of an innovative plaster that combines seismic strengthening with thermal insulation. The proposed plaster is produced using natural raw materials of local Calabrian origin and reinforced with broom fibers to enhance both ductility and mechanical strength. Experimental investigations included mechanical characterization through compressive and flexural strength tests, toughness, and ductility evaluation, as well as thermophysical analyses and further complementary tests. The results demonstrate that fiber reinforcement ensures adequate strength and significantly improves deformability, making the material suitable for seismic retrofitting of infill walls. In fact, the results show that the fiber insertion improves the post-critical behavior of the plaster through a significant increase in its ductility. Moreover, the thermal tests confirm a notable reduction in heat transfer, enhancing the energy performance of building envelopes. The complementary tests have demonstrated the suitability of the designed plasters for the intended applications. Full article

Indoor space segmentation is essential for indoor navigation, 3D reconstruction, and Building Information Modeling (BIM). However, reliable segmentation from unstructured 3D point clouds remains challenging due to structural voids caused by occlusion and noise, as well as the difficulty of distinguishing permanent structural elements from dense non-structural clutter. To address these issues, this paper proposes a semantic-grid structural completion method for indoor space segmentation from 3D point clouds. The method first integrates RandLA-Net-based semantic segmentation with geometric similarity correction to improve structural consistency. Subsequently, a semantic-grid structural completion algorithm detects and fills structural voids under height constraints; this process employs dual-grid structural marking with a 2D semantic occupancy grid and a 3D voxel grid to identify missing observations and generates synthetic points with inherited semantic labels to restore structural integrity within the scene. A density-aware height difference filtering method is then applied to remove non-structural clutter and clearly separate structural elements from the rest of the scene. Finally, indoor spaces are delineated through connectivity-based segmentation and inverse distance-weighted label propagation. Experiments on public datasets, including S3DIS, UZH and Structured3D, demonstrate that the proposed method consistently outperforms existing approaches, achieving a mean F1 Score of 0.99, an Intersection over Union (IoU) of 0.98, and a Segmentation Error Rate (SER) of 0 in most scenarios, particularly in occlusion-affected and structurally complex indoor environments. Full article

Drought stress profoundly affects plant growth and survival, but comparisons of integrated adaptive strategies across multiple tree species remain unclear. In this study, seedlings of Elaeagnus angustifolia (E. angustifolia), Populus euphratica (P. euphratica) and Xanthoceras sorbifolium (X. sorbifolium) were subjected to well-watered (CK), mild (T1), moderate (T2), and severe (T3) drought treatments. Leaf microanatomical traits, non-structural carbohydrates (NSCs), stoichiometric elements, biomass allocation, and key stress indicators were measured. The results showed that P. euphratica seedlings thickened leaves and vascular tissues and accumulated soluble sugars (SSs) and starch (ST) under T1–T2, but under T3, they prioritized root investment (root biomass +26.0%); their antioxidant enzymes were activated only under mild-to-moderate stress and declined under severe stress. E. angustifolia seedlings exhibited moderate leaf structural thickening, sharply increased root biomass (+97.2% under T3) while maintaining stem biomass, continuously elevated activities of superoxide dismutase (SOD) and peroxidase (POD) as well as osmoregulatory substances (soluble protein SP, proline Pro), and showed the lowest malondialdehyde (MDA) content; their leaf carbon (C), nitrogen (N), and phosphorus (P) contents decreased the least, and their stoichiometric ratios remained stable. In contrast, X. sorbifolium seedlings progressively reduced leaf thickness and vascular area, depleted NSC reserves, exhibited unstable antioxidant responses, showed a significant decrease in Pro under severe drought, accumulated the highest MDA, and had the lowest N/P ratio, indicating the strongest nitrogen limitation. These results demonstrate that E. angustifolia combines structural plasticity, efficient nutrient use, robust osmotic adjustment, and sustained antioxidant capacity, conferring the strongest drought tolerance; P. euphratica* shows moderate tolerance through transient structural and carbon investment but suffers under extreme drought; X. sorbifolium has the weakest drought tolerance. Full article

Decarbonizing the construction sector requires high-volume replacement of Portland clinker with non-calcined supplementary cementitious materials (SCMs). This study investigates white cement pastes incorporating raw Algerian diatomite—a silica-rich biogenic mineral—at substitution levels from 40% to 95% (5% increments) and a fixed water-to-binder ratio of 0.5. The target application is ultra-lightweight, multifunctional composites for non-structural uses such as decorative panels and partition elements. Increasing diatomite content progressively reduced bulk density from 1.483 g/cm³ (D40) to 0.557 g/cm³ (D95) and increased porosity. 28-day compressive strength decreased monotonically from 16 MPa (D40) to 2.4 MPa (D95) as clinker dilution intensified. Ultrasonic pulse velocity dropped from 6205 m/s to 1495 m/s, reflecting progressive pore development and confirming the material’s lightweight potential. Statistically significant strength gains beyond 28 days were recorded ($+25.87\%$ for compression, p-value $< 0.05$), evidencing delayed pozzolanic activity. These results confirm that raw, non-calcined diatomite is a viable SCM for eco-efficient, low-density construction systems. To overcome the extrapolation instability of purely data-driven approaches, a Meta-Avrami Hybrid Framework was developed. It anchors Gradient Boosting residual learning to a sigmoidal Avrami hydration kernel. The model achieved high predictive accuracy ($R^2\approx 0.999$, $\mathrm{RMSE}\approx 0.010$) under 10-fold cross-validation. Generalization was well-controlled, with a low overfitting gap ($\Delta R^2=0.0226$) and stable fold-to-fold performance ($\mathrm{Std}=0.0204$). These metrics confirm suitability for unseen mix designs. This is particularly relevant for service-life assessment of partition panels and lightweight façade elements, where long-term performance guarantees are required. The physics-informed architecture ensures asymptotic strength stabilization up to a 10-year horizon (amplification ratios 1.03–1.05). This prevents the non-physical divergence observed in polynomial and power-law hybrids (ratios 1.36–1.70). The framework provides a reliable and interpretable tool for service-life design of sustainable low-carbon cementitious systems. Full article

This experimental study investigates the influence of selected bed joint reinforcement systems on the evolution of damage and crack development in masonry elements subjected to axial compression. Autoclaved aerated concrete masonry samples reinforced with steel truss reinforcement, unidirectional carbon fibre mesh and steel cords embedded in a fibreglass matrix were tested and compared to an unreinforced reference specimen. Full-field deformation and strain localisation were monitored using digital image correlation (DIC). The results indicate that bed joint reinforcement does not lead to a measurable increase in compressive load-bearing capacity, as differences in ultimate load remain within experimental uncertainty. However, clear differences in the evolution and spatial distribution of damage were observed. Steel truss reinforcement promoted strain redistribution and delayed localisation of tensile strains, while the remaining reinforcement systems exhibited only limited influence on crack morphology. The findings confirm that bed joint reinforcement in compressed masonry should be classified as a nonstructural solution and demonstrate the diagnostic value of full-field deformation monitoring for assessing damage evolution and crack control in masonry structures. Full article

This study investigates the seismic performance limitations of a newly constructed reinforced concrete building that collapsed during the 6 February 2023 Kahramanmaraş–Elbistan earthquake despite formal compliance with current seismic design requirements. Beyond the specific earthquake event, the study addresses a broader scientific problem: the limited understanding of the relationship between observed damage mechanisms and nonlinear dynamic response in mid-rise reinforced concrete buildings. The first part classifies recurring structural and non-structural damage patterns identified in newly constructed RC residences. The second part presents a nonlinear fiber-based static and dynamic analysis of a collapsed mid-rise building. Nonlinear dynamic analyses were conducted using ground motion records scaled to match the site-specific elastic design spectrum defined by TBDY 2018, corresponding to predefined seismic performance levels rather than an incremental dynamic analysis framework. The results indicate that an extremely low shear wall–to–floor area ratio (0.0357%) combined with asymmetric vertical element distribution significantly amplified torsional response and local shear demands. Nonlinear dynamic analyses showed that critical shear walls exceeded Collapse Prevention limits under DD2-level excitation, while system-level shear contribution limits remained within code-defined thresholds. Dynamic base shear demand corresponded to approximately 30% of the maximum nonlinear capacity obtained from pushover analysis, indicating that localized member failure rather than global strength deficiency governed the collapse mechanism. The analytically identified critical members were consistent with the observed collapse configuration, particularly at the soft ground story. The findings demonstrate that prescriptive code compliance alone may not ensure satisfactory seismic performance when structural irregularities, torsional amplification, and detailing deficiencies coexist. The results are consistent with damage patterns reported in other recent destructive earthquakes and contribute to improving the understanding of collapse mechanisms in code-compliant RC buildings. Full article

The seismic vulnerability of existing reinforced concrete buildings is often exacerbated by the inadequate mechanical performance of non-structural components, such as masonry infill walls, which may exhibit brittle behavior and limited deformation capacity under seismic actions. This issue highlights the need for innovative and compatible strengthening materials capable of improving ductility and damage tolerance while maintaining adequate mechanical strength. This study presents an experimental investigation aimed at developing a sustainable fiber-reinforced plaster manufactured exclusively from locally sourced natural materials from the Calabria region, including cork granules, broom fibers, and natural hydraulic lime. Following a preliminary experimental phase, the mixture containing 30% cork granules was selected as the reference matrix due to its favorable mechanical performance and deformability. In the present phase of the research, several composite formulations incorporating broom fibers were produced and experimentally characterized. Uniaxial tensile tests were conducted on broom fibers to assess their reinforcing potential, while compressive and flexural tests were performed on the plaster matrices. The experimental results show that the incorporation of broom fibers significantly enhances flexural behavior and post-cracking ductility, while maintaining compressive strength levels compatible with structural retrofit applications. The study demonstrates that the combined use of cork and broom fiber effectively enhances the mechanical performance of the plaster by promoting ductility, improving flexural behavior, and limiting crack initiation and propagation. The high tensile strength of the fibers promotes effective crack-bridging mechanisms and improved energy dissipation capacity. Overall, the combined use of cork aggregates and broom fibers results in a mechanically balanced plaster composite characterized by enhanced deformability and reduced brittleness. These features make the proposed material particularly suitable for the strengthening of masonry infill walls and for applications where improved ductility and damage tolerance are required, such as seismic retrofitting and restoration of existing buildings. Full article