Point clouds are essential for 3D spatial analysis and widely used in geodesy, photogrammetry, and remote sensing. While modern technologies simplify their collection, processing remains challenging due to data size, irregularity, and noise. Classification is critical for object identification and noise removal. This paper explores geometric features of points derived from their local 3D neighbourhoods. It examines neighbourhood definitions, feature computation via principal component analysis (PCA), and their impact on real dataset classification. Using a test point cloud with natural and anthropogenic features, we analyze feature dependencies, identify redundancies, and highlight key metrics. Additionally, we propose new approaches for noise filtering, contributing to more efficient point cloud processing and practical applications. Received: 02.12.2024 Received in revised form: 20.01.2025 Accepted: 14.02.2025
The study evaluates the effectiveness of various ecological slope protection strategies for riverbank stabilization by systematically analyzing several critical factors: slope coefficient, durability, impact resistance to flow, biodiversity index, biochannel fluency, vegetation coverage, construction and maintenance costs, landscape aesthetics, and recreational function. The Fuzzy Set Pair Analysis Assessment Method was utilized to create a comprehensive evaluation model, employing normalized benefit-type indices and incorporating the Analytic Hierarchy Process (AHP) with an Accelerated Genetic Algorithm (AGA) to determine the weight of each evaluation index. This model assesses the linkage degree of single indices and uses a confidence criterion to classify evaluation samples across different risk tolerance levels. The results show that plant berms are most effective at a confidence level of 0.50, while gabion revetments perform best at levels of 0.60 and 0.70. The findings suggest that plant berms are suitable for higher risk tolerance, while gabion revetments are better for risk-averse decisions. This methodology offers a novel and robust tool for scientifically assessing and selecting optimal river slope protection strategies.
This paper introduces a set of new criteria for assessing the energy-efficiency potential of multilayered building envelopes, focusing on physically measurable aspects of dynamic thermal performance and LCA parameters. Based on EN ISO 13786:2023, the study considers thermal transmittance (U-value), internal areal heat capacity (k1), and decrement factor (f) as thermal performance parameters, along with assembly mass (m) and embodied energy (EE) as additional LCA objective indicators. Five wall assemblies common in the Ukrainian market-hempcrete, AAC + Rockwool, Porotherm brickwork + Rockwool, wood-chip cement-bonded blocks (Woodcrete) and ICF systems were evaluated through numerical modelling and comparative analysis. To eliminate subjectivity in criteria weighting, three new interconnected criteria were proposed: Dynamic Thermal Performance Efficiency per mass (DTPEm), per embodied energy (DTPEEE), and per both (DTPEm&EE). Results indicate that AAC + Rockwool (Wall B) consistently ranks as the most efficient assembly according to the DTPEm&EEcriteria. At the same time, Wall E (ICF) aligns with the recommended thermal inertia ranges but exhibits the highest embodied energy, resulting in the lowest DTPEm&EE. The study highlights the complexity of MCDA in envelope design and provides physically grounded criteria that can support more objective predesign decision-making.
In the context of modern architecture, glass is widely regarded as a fundamental design element, representing a material of increasing interest to architects and engineers. The fundamental challenge in using glass is to design convenient connections. Adhesive joints are more convenient connections compared to mechanical fixings due to ensuring uniform stress distribution. This study focuses on small glass-to-glass specimens: (i) bonding of the specimens, (ii) artificial ageing, and (iii) shear tests. Two different transparent adhesives were tested, 2-component epoxy and UV-cured acrylate. Proper specimen bonding is essential. Two-component epoxy required careful sealing during curing to prevent leakage. The UV-cured acrylate adhesive needed a careful curing process to avoid bubble formation due to shrinkage of the adhesive. To determine resistance to environmental effects, a combination of DVS 1618 procedure and UV radiation was used for artificial ageing of specimens. Shear tests on the reference set showed excellent results for the acrylate adhesive, which achieved an average shear strength of 10.17 MPa. Problems with adhesion appeared after artificial ageing. Epoxy adhesive achieved an average shear strength of 4.55 MPa in the reference set. Two specimens had problems with adhesion to glass. After ageing, the specimens achieved a higher average shear strength (4.86 MPa) than in the reference set. The aged specimens failed only by glass breakage. Both adhesives showed high potential for use in glass construction joints.
In this study, to investigate the cracking resistance of UHPC-strengthened simply-supported-to-continuous concrete box beams in the negative moment zone, a total of nine specimens were designed: one reinforced concrete box beam (comparison beam), seven UHPC-RC composite box beams (reinforced beams), and one prestressed concrete box beam (prestressed beam). The research focuses on evaluating the influence of key parameters-including reinforcement ratio, UHPC casting length in the negative moment zone, UHPC thickness, and the joint configuration between UHPC and ordinary concrete-on the cracking resistance of these beams. The results demonstrate that, under the same reinforcement ratio, UHPC strengthening in the negative moment zone significantly enhances the cracking performance of the test beams, with the cracking load increasing by 46%. As the UHPC casting length increases, the maximum crack width at the vertical interface between the full normal concrete (NC) section and the UHPC-NC composite section decreases markedly. Additionally, increasing the UHPC thickness leads to a substantial reduction in the maximum crack width at both the UHPC-NC composite section and the intermediate diaphragm section.
Cable-stayed bridges have become one of the fastest growing and most competitive bridge types in modern bridge engineering due to their large spanning capacity and novel structure. Rapid economic development has led to a gradual increase in the number of vehicles transporting flammable and explosive products, as well as an increase in the incidence of bridge fires. Cable-stayed cables are usually close to the carriageway, and a fire will inevitably cause varying degrees of harm to the cable-stayed cables of a bridge in the event of a fire, leading to significant economic losses. Dynamic performance of cable-stayed bridges after fire is investigated by different simulation analyses of fire-induced damage to the tension cables. Results show that different tie damage has different effects on the dynamic characteristics of the whole bridge, and the tie damage has the greatest effect on the vertical symmetric bending formation, and almost no effect on the longitudinal drift, transverse bending and torsion formations. Damage to the outer cables near the transition span and side spans has a large effect on the low-order frequency variation of cable-stayed bridges, especially when the damage to the outermost back cables of S13+N13 occurs, it has the largest effect on the 2nd and 3rd order frequency variation, with a maximum value of 9.6%. Different levels of damage to the tension cables affect the dynamic performance of the bridge in terms of quantitative changes, with the frequency of a certain order formation increasing as the level of damage increases. It is particularly important to quickly and accurately analyze and evaluate the mechanics of overfire cable-stayed bridges to provide an accurate basis for decision-making.
This study examines the impact of a country's macroeconomic and political stability on the construction duration of nuclear power plant (NPP) projects. Despite extensive research into technical and managerial causes of delays, the role of national stability remains underexplored. This research develops the Macroeconomic and Political Stability Score (MAPSS), a composite risk assessment index designed to quantify national-level risks affecting project delivery. A stratified sample of 96 NPP projects was analysed using Pearson correlation, Welch's t-tests, and multiple linear regression to evaluate the relationship between key economic indicators, political events, and construction timelines. The results show that national economic crises, international crises, government collapses, and armed conflicts are significantly associated with extended construction durations, whereas factors such as inflation and international sanctions showed no meaningful effect. The MAPSS index demonstrated a statistically significant correlation with project duration (r = -0.390, p < 0.001), confirming its practical value for early-stage risk assessment. The findings underscore that external macroeconomic and political factors are critical determinants of nuclear project delivery. This research offers a novel framework to support policymakers, investors, and planners in evaluating stability-related risks prior to committing to nuclear infrastructure investments.
The disposal of bottom ash from municipal solid waste incineration (MSWI) in landfills may lead to ecological contamination and inefficient land resources utilization. The investigation assessed whether MSWI bottom ash could serve as a substitute for sand and supplementary binder components in concrete production. Multiple analytical techniques were employed to characterize the MSWI bottom ash and its recycled powder. X-ray fluorescence (XRF) and laser particle size analysis were used to determine chemical composition and particle size distribution, respectively. Microscopic morphology and pore structure were examined with scanning electron microscopy (SEM) and nitrogen adsorption analysis. Phase composition was identified by X-ray diffraction (XRD), complemented with simultaneous thermal analysis (TG/DTG) and Fourier transform infrared (FTIR) spectroscopy. Results show that incineration bottom ash is coarse-grained and even exceeds the gradation range of Zone I sand stipulated by the Chinese standard. Soaking and sieving treatment yields coarse bottom ash particles with clean surfaces, while fine bottom ash particles contain organic contaminants that are difficult to treat. The soaked bottom ash showed low Cl and SO3 content, containing mainly quartz, calcite, gypsum, and hematite. The particles of bottom ash-derived powder are gravel-shaped, with pore sizes ranging from 1 nm to 70 nm and a high specific surface area. The pores are mainly mesopores, accounting for 73.83% of the total pore volume. BET measurements revealed a specific surface area six times greater than that of cement. Except for Cr, all heavy metal leaching levels comply with Chinese regulatory limits. MSWI bottom ash shows potential for partial replacement of natural sand or cement in construction applications.
In many studies on the compressive properties of engineering cement-based composites (ECC), there are relatively few mesoscopic studies on the dosage and length of PVA fibers. To explore the influence of internal fibers of ECC on its compressive performance, this paper established a two-dimensional distribution model of PVA fibers in the matrix through random placement and generation algorithms. Firstly, an overview of previous experiments was provided. The ECC finite element (FE) model was developed using ABAQUS, and the simulation outcomes were contrasted with the experimental stress-strain curves to validate the model's viability. On this basis, parameter analysis was carried out to study the impact of different PVA fiber content and length in ECC on its compressive characteristics under vertical axial compression, and the characteristic values of the stress-strain curves of ECC with differing PVA fiber content and length under vertical axial compression were analyzed. The findings indicate that the ECC containing 2% PVA fiber with a length of 12 mm exhibits optimal compressive strength, and the yield stress and peak stress can reach 47.25 MPa and 54.96 MPa, respectively. When the fiber content is below 2% and the length ranges from 10 mm to 12 mm, the yield stress and peak stress of ECC progressively rise with increasing fiber content and length. Conversely, when the fiber content exceeds 2% within the same length range, the yield stress and peak stress of ECC exhibit a declining trend as fiber content increases. This research offers a reference for the judicious choice of fiber content and length to enhance the compressive capabilities of ECC.
The article focuses on the possibilities of modifying the window assemblies of apartment buildings from the 19th and early 20th centuries. The issue is illustrated through a case study of a building constructed in 1873, located in Prague in the heart of & Zcaron;i & zcaron;kov and protected as a cultural monument. It examines restoration, renovation, and maintenance strategies for historic window assemblies, addressing the methods of their repair as well as current technical and material possibilities for their renewal. The study concentrates on options for improving the technical performance of existing window structures, their comparison, and their adaptation to present-day standards required of modern window assemblies. The issue is evaluated from technical, economic, thermal, and hygrothermal perspectives.
With the continuous increase in traffic loads, the insufficient bearing capacity of existing bridges has become increasingly prominent, necessitating effective strengthening technologies to enhance their performance. This study focuses on bonded prestressed strengthened hollow slab beams. A finite element analysis method was employed to establish a discrete model comprising concrete (SOLID65 elements), composite mortar (SHELL41 elements), and prestressed tendons (LINK8 elements), with nonlinear spring elements used to simulate the interaction at the bonding layer. A three-point loading method was adopted to analyze the stress distribution characteristics of the strengthened beam under 10 kN and 80 kN loads, with emphasis on the stress responses in the anchorage zone, mid-span cross-section, and reinforcement. The results indicate significant stress concentration in the anchorage zone, requiring reinforcement in engineering design. When the crosssection approaches the destressed state (stress range: 0.1 MPa to -0.2 MPa), there is a notable discrepancy between finite element simulation results and material mechanics theoretical values. However, good agreement is observed in non-destressed states. Additionally, the stress variation trend of prestressed tendons under increasing loads aligns with theoretical predictions, with an error margin below 0.8%. This research provides theoretical and numerical references for the engineering application of bonded prestressed strengthening techniques.
In order to solve the problem of poor bonding and easy peeling of reinforced concrete structure strengthened by steel wire mesh and polymer mortar (SWM-PM). In this paper, a steel wire mesh and polyurethane cement (SWM-PUC) composite strengthening technique is presented. The flexural properties of one unreinforced beam, two SWM-PM strengthened beams and four SWM-PUC composite strengthened beams were studied experimentally. The experimental results show that the SWM-PUC composite reinforcement layer can improve the load carrying capacity and rigidity of reinforced concrete beams and limit the unfolding cracks significantly. The SWM-PUC composite strengthened beams have pure bending damage and peeling damage between the strengthening layer and the concrete has not occurred. However, SWM-PM strengthened beams with the same SWM reinforcement ratio occurred with peeling damage between the reinforcement and the concrete. On basis of an experimental study, the theoretical formulas for cracking load, ultimate load, deflection and width of crack of SWM-PUC composite strengthened beams are proposed by the simplified stress-strain constitutive relation of the material and the theoretical formulas are deduced with the code. By contrasting the test results with the theoretical computation results, the accuracy of the experiment results and the reliability of the theoretical formulas were verified. Received: 21.10.2024 Received in revised form: 09.04.2025 Accepted: 17.06.2025
In this paper, the flexural performance of seven steel wire mesh and polyurethane cement (SWM-PUC) composite strengthened beams was investigated experimentally. The variation law of flexural performance of reinforced beams is clarified. Based on the experimental research, the deflection and stress analysis of SWM-PUC composite strengthened reinforced concrete beams was conducted using finite element analysis software ABAQUS. The Bending properties of reinforced beams with different steel wire mesh (SWM) reinforcement rates and different polyurethane cement (PUC) thickness parameters were researched. The reinforcement ratios of SWM are 0.064%, 0.087%, 0.114%, 0.144%, and 0.178%, respectively. The PUC thickness is 20mm, 25mm, 30mm, 35mm and 40mm. The finite element analysis shows that as the reinforcement ratio of the SWM increases, the yield and ultimate loads gradually increase and the deflection then gradually decreases. When the reinforcement ratio reaches a certain level, the increase in yield load decreases with the increase of reinforcement ratio. In the case of 0.114% increase in the reinforcement ratio of the SWM, the ultimate load of the simulated beams was increased by 47% compared to the simulated beams with 0.064% reinforcement ratio of the SWM. As the thickness of the PUC increases, the yield limit and ultimate load gradually increase, and the deflection value decreases continuously. The ultimate load of the reinforced beam with PUC at 40mm thickness was increased by 20.5% compared to the reinforced beam with 30cm thickness. The optimum configuration of the SWM -PUC composite reinforcement layer was given through the finite element analysis. Received: 01.10.2024 Received in revised form: 05.12.2024 Accepted: 27.01.2025
The stay cable is usually close to the carrieway. Once the fire occurs, it will inevitably cause different degrees of damage to the cable of the bridge. Rapid and accurate mechanical analysis and evaluation of fire-damaged cable-stayed bridges is very important to provide accurate basis for decision makers. Taking Sifang Tai Bridge fire accident as the engineering background, this paper uses damage theory and finite element theory to simulate the fire damage of different cable-stayed cables and different fire damage degrees of the same cable, and analyzes the change characteristics of the static parameters of the main beam and cable force caused by fire damage of the cable-stayed bridge. The results show that the fire damage of back cable and mid-span cable has a global effect on the alignment and cable force of the whole bridge. However, the damage caused by other cable fires is localized, with only the deflection near the self anchored main beam position and the significant influence of 3-4 cable forces nearby. It is similar to the support stiffness change or support failure of multi-point elastic supported continuous beam. The fire induced fusing damage occurred on the outermost back cable, which caused the cable force of the nearby cable not to reach the warning value, but the surplus was very small. The results of the study can provide implications for similar projects. Received: 8.2.2025 Received in revised form: 24.7.2025 Accepted: 30.8.2025
Few studies have been conducted on the use of machine learning (ML) techniques to predict the volume expansion (Ve) of cement paste when fly ash (FA) and MgO expansive addition (MEA) are present. Utilizing a set of data that contained 170 experimental results that were obtained from previous research, the purpose of this study was to develop and evaluate ML algorithms for the assessment of Ve. To achieve this, the Extra tree regression (ETR) was created. The technique uses FA, Portland cement (PC), MEA, and sample age (Age) as input parameters. The Red-Tailed Hawk Algorithm (RTHA) and the Electric Eel Foraging Algorithm (EEFA) establish the hyperparameters of ETR, which greatly affect its effectiveness. The variation percentages of the two models developed for these measures are a minimum of 13%; in some cases, this variation decreases by 53%, illustrating the ETR (R)'s predictive reliability and efficacy. For instance, for the RMSE index, ETR (R) achieved values of 0.0053 and 0.01 during the training and testing phases, which are about 28% and 14% lower than the corresponding values of ETR (E) at 0.0068 and 0.0114, correspondingly. The ETR (R) model is somewhat superior to the alternative model regarding its purpose. Received: 21.10.2025 Received in revised form: 13.2.2025 Accepted: 1.9.2025
Due to a lack of foresight by designers during bridge planning, outdated specifications that have not been updated in a timely manner, or construction errors during the building process, bridge structures may be overloaded, ultimately leading to excessive deflection in the main span of continuous rigid frame bridges. Therefore, it is urgent to study the causes of downward deflection in continuous rigid frame bridges and explore their reinforcement methods. This paper conducts parametric analysis by using the finite element method to explore the influence degree of different factors on deflection. This paper addresses the issue of severe mid-span deflection in a specific continuous rigid frame bridge and investigates the impact of various factors, including internal prestress loss, stiffness reduction, shrinkage and creep, over-excavation (possibly referring to excessive excavation or over-dimensioning in construction), shear deformation, external prestress loss, and overloading, on the downward deflection of continuous rigid frame bridges. The study identifies the most significant factor contributing to this deflection. Upon comprehensive comparison of all factors, stiffness reduction is found to be the primary cause of mid-span deflection. When the stiffness is reduced by 10%, the deflection difference plot shows that the maximum decrease in deflection near the mid-span is 8.76mm. For reinforced bridges, external prestress loss and overloading are the most critical factors. In calculations for continuous rigid frame bridges, shear deformation cannot be neglected.
This paper systematically analyzes the parameters of prestressed steel wire rope strengthened concrete beams using finite element software ANSYS, aiming to explore the influence of different reinforcement parameters on the flexural performance of the beams. Seven 2.4m concrete beam models with different reinforcement methods were established, including comparisons of factors such as the number of prestressed tendons, tensile control stress, and composite mortar protection. Through simulated loading tests, the deflection changes, stress distribution, and force characteristics of steel bars and steel strands were examined. The results indicate that prestressed reinforcement significantly improves the stress state of the beams: an increase in prestress can effectively reduce the tensile stress at the beam bottom and decrease the stress in the main reinforcement, but has no significant impact on structural stiffness. An increase in the cross-sectional area of prestressed tendons significantly enhances the beam's stiffness. Composite mortar protection, although increasing self-weight, reduces prestress loss and optimizes the stress distribution of the steel strands. In contrast, the steel plate bonding method fails to fully utilize its effectiveness under low loads and even increases the stress in the steel bars. Additionally, excessively high prestress values may lead to excessive tensile stress at the beam bottom, necessitating reasonable design in practical engineering. This study provides a theoretical basis and parameter optimization directions for the engineering application of prestressed steel wire rope strengthened concrete beams, verifying the effectiveness of this technology in enhancing bridge load-carrying capacity and extending service
The use of ultra-high performance concrete (UHPC) for strengthening deficient reinforced concrete T-beam bridges has gained popularity in recent years. Despite its growing application, the failure mechanisms of UHPC-reinforced T-beams under flexural loads, along with corresponding design methods, require further exploration. This study aims to investigate the flexural performance of T-beams enhanced with thin UHPC layers through a combination of theoretical analysis and experimental testing. An analytical model is proposed to estimate the cracking and ultimate resistances of UHPC-strengthened T-beams subjected to bending moments. To validate this model, three concrete T-beam specimens with varying UHPC thicknesses were fabricated and tested to failure. The observed failure modes, load-displacement responses, and strain distributions of the T-beams are presented and analyzed. Results indicate that the incorporation of UHPC layers markedly improves the flexural performance of the T-beams: increasing the layer thickness from 0 mm to 50 mm resulted in a 167.8% enhancement in flexural stiffness, a 241.0% increase in initial cracking load, and a 40.8% rise in ultimate flexural capacity. The relative error between predictions from the developed model and experimental outcomes was found to be less than 10%, underscoring the model's validity and indicating sufficient safety margins. These findings offer significant insights for the design of flexural strengthening techniques employing thin UHPC layers in defective concrete T-beams, contributing to enhanced structural integrity and longevity.
To investigate the stress and deformation behavior of the mushroom-shaped assembly tunnel, intelligent monitoring and numerical simulation were employed. The mechanical behavior variation during different construction stages, the longitudinal and cross-sectional distribution characteristics, and the deformation control effect of the support on the surrounding rock were analyzed. Comparative analysis assessed the applicability of different excavation methods, and theoretical comparisons discussed the bearing characteristics, providing engineering suggestions. The results indicate that excavation of the lower section has minimal impact on the mushroom head arch but continuously affects the side wall. The arch support of the mushroom head enhances the restraint ability of the lower section support on surrounding rock deformation. In the corner of the wall, the support appears to deviate from the tunnel, where the bolt is compressed. The contact stress of mushroom head increases first, then decreases and then increases from the position near the centroid to both sides. The stress in the transition area between the arch and the straight wall on both sides increases locally, and the stress concentration occurs at the corner of the wall. The deformation of the initial support and the bolt axial force on both sides of the lower section increase first and then decrease from top to bottom, while the law of the contact stress is opposite. Engineering focus should be on arch foot and side wall stress and deformation characteristics for combined flat arch and vertical straight wall support.
Based on the study of the flow around finite-length cylinders, an analysis of the flow resistance characteristics of commonly encountered variable diameter cylinders at high Reynolds numbers was conducted. A comprehensive relationship equation for the flow resistance within the subcritical region, the drag crisis region, and the drag recovery region was obtained. Additionally, the influence of end effects on the flow resistance characteristics of finite-length cylinders and variable diameter cylinders was analyzed using large eddy simulation (LES), and a comprehensive formula describing the range of end effect influence was obtained. The results indicate that the flow resistance coefficients at both ends of the variable diameter cylinder are influenced by the aspect ratio lambda, Reynolds number ( Re ), and included angle theta. As theta and lambda increase, the distance affected at the top of the cylinder increases. As Re decreases, the affected distances at the top and bottom increase. The comprehensive formula for the influence range can be used to modify the relationship equation for the drag coefficient. These findings have important implications for the study and application of the flow characteristics of finite-length variable diameter cylinders.
