Search Results (291)

This study aims to develop a reliable method for predicting power plant construction costs during the early planning stages using ensemble machine learning techniques. Accurate cost predictions are essential for project feasibility, and this research highlights the strength of ensemble methods in improving prediction accuracy by combining the advantages of multiple models, offering a significant improvement over traditional approaches. This investigation employed the Random Forest (RF) algorithm to estimate the overall construction cost of a power plant. The RF algorithm was contrasted with single-learner machine learning models: Support Vector Regression (SVR) and k-Nearest Neighbors (KNN). Performance measures, comprising the coefficient of determination ($R^2$), Mean Absolute Error (MAE), and Root Mean Squared Error (RMSE), were used to evaluate and contrast the performance of the implemented models. Statistical measures demonstrated that the RF approach surpassed alternative models, demonstrating the highest coefficient of determination for testing ($R^2=0.956$) and the lowest Root Mean Square Error (RMSE = 29.27) for the testing dataset. The Shapley Additive Explanation (SHAP) technique was implemented to explain the significance and impact of predictor factors affecting power plant construction costs. The outcomes of this investigation provide crucial information for project decision-makers, allowing them to reduce discrepancies in projected costs and make informed decisions at the beginning of the construction phase. Full article

Structural research teams face significant challenges when conducting studies with explosives, including the costs and inherent risks associated with field detonation tests. This study presents a replicable method for loading spherical and bare TNT-based cast explosive charges, offering reduced costs and minimal risks. Over eighty TNT and Composition B charges (comprising 60% RDX, 39% TNT, and 1% wax) were prepared using spherical molds made of thin aluminum, which are low-cost, off-the-shelf solutions. The charges were bare, meaning they lacked any casing, as the molds were designed to be easily removed after casting. The resulting charges were safer due to their smaller dimensions and the absence of hazardous metallic debris. Composition B charges demonstrated promising results, with their performance characterized through blast and thermochemical experiments. Comprehensive data are provided for Composition B charges, including TNT equivalence, pressures, velocity of detonation, DSC/TGA curves at four different heating rates, activation energy, peak decomposition temperatures, X-ray analysis, and statistics on masses and densities. A comparison between detonation and deflagration processes, captured in high-speed footage, is also presented. This explosive characterization is crucial for structural teams to precisely understand the blast loads produced, ensuring a clear and accurate knowledge of the forces acting on structures. Full article

The surface settlement of railroad tunnels is dynamically updated as the construction progresses, exhibiting complex nonlinear characteristics. The accuracy of the on-site nonlinear regression fitting prediction method needs to be improved. To prevent surface settlement and surrounding rock collapse during railroad tunnel construction, while also ensuring the safety of the tunnel and existing structures, we propose a recursive prediction model for the long-term trend of surface settlement utilizing a singular spectrum analysis (SSA), improved sand cat swarm optimization (ISCSO), and a kernel extreme learning machine (KELM). First, SSA decomposition, known for its adaptive decomposition of one-dimensional nonlinear time series, reorganizes the early surface settlement data. The dynamic sliding window method is introduced to construct the prediction dataset, which is then trained using the KELM. ISCSO is used to optimize the key parameters of the KELM to obtain the long-term trend curves of surface settlement through recursive time series prediction. The superiority and effectiveness of ISCSO and the model are verified through numerical experiments and simulation experiments based on engineering cases, providing a reference for the early warning and control of surface settlement during the construction of similar tunnels. Full article

PC steel material inside pre-stressed concrete bridges is prone to corrosion due to the effect of salt, which leads to cross-sectional losses and fractures if proper maintenance is not carried out, affecting the girders’ structural performance. In Japan, pre-tensioned girders incorporating small-diameter PC steel material with a span length of 13 m or less were used until the early 1980s. Thus, it is essential to understand the fracture conditions of PC steel material and the factors affecting section loss due to corrosion, in order to properly assess the residual strength of salt-affected pre-tensioned girders. Hence, the current research clarifies the accuracy of techniques used for detecting deterioration in a pre-tensioned PC girder that had been out of service for about 40 years, caused by exposure to the severely saline environment of the Okinawa coast. Visual and hammer-tapping investigation of the actual bridge in addition to fracture investigation of the PC steel material using the triaxial magnetic method and destructive investigation of the concrete cover on the bottom of the girder were carried out and correlated. The final results confirmed that the triaxial magnetic method could detect PC steel material fractures accurately, and valuable information was obtained regarding fracture-detection technology for application in PC girders via non-destructive testing. Full article

Rising industrialization and population growth contribute to the increasing generation of plastic waste, which poses significant environmental and health challenges. Despite its potential as a resource, plastic waste is often discarded without proper treatment. Repurposing it in road construction offers both economic and environmental benefits, providing a sustainable waste management solution. This paper thoroughly examines various types of plastic waste used in asphalt mixtures, considering both wet and dry processing methods and their impact on bituminous binders and asphalt performance. Overall, incorporating waste plastics into asphalt mixtures has been shown to improve fatigue resistance, rutting resistance, moisture resistance, and high-temperature performance. However, challenges related to compatibility and low-temperature performance persist in plastic-modified asphalt applications. To address these issues, modified approaches, such as the use of chemical additives, have been identified as effective in enhancing the bonding between waste plastics and bituminous binders while also increasing the amount of plastic that can be incorporated. While plastic-modified asphalt shows significant promise, overcoming these challenges through targeted research and careful implementation is essential for its sustainable and effective use in asphalt mixtures, ensuring long-term performance. Full article

The construction of highway bridges using continuous precast prestressed concrete girders provides an economical solution by minimizing formwork requirements and accelerating construction. Different ways can be used to integrate bridge continuity and enable the development of negative bending moments at piers. Continuous bridge connections enhance structural integrity by reducing deflections and distributing loads more efficiently. Research has led to the development of various continuity details, categorized into partial and full integration, to improve performance under diverse loading conditions. This review summarizes studies on both partial and fully integrated continuous bridges, highlighting improvements in connection resilience and the incorporation of advanced construction technologies. While extended deck reinforcement presents an economical solution for partial continuity, it has limitations, especially in longer spans. However, full integration provides additional benefits, such as further reduced deflections and bending moments, contributing to improved overall structural performance. Positive-moment connections using bent bars have shown enhanced performance in achieving continuity, though skewed bridge configurations may reduce the effectiveness of continuity. Ultra-High-Performance Concrete (UHPC) has been identified as a superior material for joint connections, providing greater load capacity, durability, and seismic resistance. Additionally, mechanical splices, such as threaded rod systems, have proven effective in achieving continuity across various load types. The seismic performance of precast prestressed concrete girders relies on robust joint connections, particularly at column–foundation and column–cap points, where reinforcements such as steel plates, fiber-reinforced shells, and unbonded post-tensioning are important for shear and compression transfer. Full article

Airport facility management requires innovative and coordinated techniques due to the infrastructure’s complexity, stakeholders’ diversity, and the necessity of safety. Adopting building information management (BIM) as an advanced technology has several benefits, including increased productivity, lower cost, and higher quality of service. This study seeks to determine the strategies for using BIM in airport facility management. In this vein, two questionnaires were developed to collect data based on a literature review. The first questionnaire was used to collect data for identifying and ranking the main criteria, and the second questionnaire was used to identify the practical strategies. The experts of this study answered five strengths, four weaknesses, five opportunities, and five threats using a standardized questionnaire. An integrated AHP-SWOT approach was used to identify and examine the practical strategies. Furthermore, a sensitivity analysis was used to ensure the results were correct. The findings showed that smart maintenance management, with a weight of 0.363, was the most important strength in the SWOT analysis. Resistance to change was the most important weakness, with a weight of 0.455. The increasing need for smart airports with a weight of 0.358 was the most important opportunity, while cybersecurity issues with a weight of 0.385 were the most important threat. Integrating BIM into the aviation sector can enhance efficiency and sustainability in airport facility management while addressing potential opportunities and shared hazards that extend beyond airport operations. Full article

Corrosion in steel girder ends, progressing from localized thinning of the web and the lower flange to severe perforation in severe cases, can significantly affect structural integrity. This study evaluates the effects of severe corrosion, including web–lower flange disconnection and transverse flange perforation combined with web damage, on the residual shear strength of steel girder end web panels through experimental and numerical methods. Results indicate that when only the web is affected, post-buckling strength starts to decline by corrosion damaging the plastic hinge on the tension flange, disrupting the tension field action. Conversely, in cases involving simultaneous web and lower flange damage, localized yielding at fracture points near the flange damage leads to the abrupt rotation of the tension field inclination angle, causing an earlier and more pronounced decline in post-buckling strength compared to web-only damage scenarios. Full article

Shells are significant structural components that are extensively utilized in numerous engineering fields, including architectural and infrastructural projects. These components are employed in the construction of domes, water tanks, stadiums and auditoriums, hangars, and cooling towers. Significant research efforts have been dedicated to the analysis of vibrations and dynamic behaviors of shells, due to their distinctive capacity to efficiently bear loads through their geometry rather than mass. Additionally, a vast array of shell theories and computational methods have been proposed and developed by researchers. This paper represents a continuation of research initiated begun in a 2009 paper by Elishakoff, wherein the suggestion was made to disregard an energetic term in the dynamic analysis of Timoshenko–Ehrenfest beams, wherein the suggestion was made to disregard an energetic term in the dynamic analysis of Timoshenko–Ehrenfest beams. The resulting reduced theory was found to be both more straightforward and more reliable than the complete, classical approach. While the original idea was heuristically justified, a more sound variationally consistent theory was proposed in the papers of De Rosa et al. concerning the dynamic analysis of the Timoshenko-Ehrenfest beams and later extended to the case of the Uflyand-Mindlin plates. In accordance with the proposal put forth in those works, we initially delineate the classical shell theory and subsequently propose two alternative hypotheses that give rise to two distinct aspects of the energy terms. By employing the variational approach, we derive two novel boundary problems, which are direct generalizations of those previously considered. Both theories can be readily specialized for beams and plates, and the theory can also be specialized for the case of cylindrical shells. Full article

The rapid progression in concrete technology and the emphasis on improving the mechanical characteristics and durability of concrete, as well as the need for skilled workers, were key factors that led to the fabrication of self-consolidating concrete (SCC). The primary advantage of SCC is the elimination of vibrations during construction. This experimental study investigates the effect of nano-silica, nano-clay, and micro-silica with ratios of 2% and 4% on the properties of SCC. To reach this aim, rheological tests (flow slump, V-shape funnel, U-shaped box, and L-shaped box tests), mechanical tests (compressive strength, tensile strength, and flexural strength test), and durability tests (freezing, abrasion, and permeability tests) were carried out. The results demonstrated that the mechanical characteristics and durability of the concrete were enhanced by increasing the nano-silica content up to 4% of the cement weight. Also, the increase in the nano-clay content produced suitable results for SCC in terms of mechanical and durability aspects. However, as the nano-material ratio increases, the amount of superplasticizer also increased to ensure the proper workability of the SCC. Full article

The productivity of the construction industry is about half that of the manufacturing industry, and the labor shortage in the construction industry is serious; therefore, improving productivity using information and communication technology (ICT) is an urgent issue. In addition, in civil engineering works, the number of projects that handle multiple types of soil and sand is increasing due to the recycling of construction waste soil; thus, traceability management is important to ensure quality. This paper presents a system that uses sensing on soil-transporting dump trucks and ICT to record which soil was piled up where with the aim of improving the efficiency of traceability management in earthwork construction. This system automatically creates traceability data by linking sensing data and data from the compaction management system via an application. This eliminates the need to record and manage the earthwork location, which was previously required manually to create traceability data, and reduces the labor and manpower required for traceability management. The created traceability data are automatically assigned attribute information such as the construction date and soil information; consequently, they can be used to check the construction history in the future. Full article

The employment of automated non-destructive testing (NDT) methods for crack characterization in concrete, needs calibration and benchmarking in a controlled environment. This requires test specimen with comparable and ideally reproducible cracks. To this end, in this paper a method is presented that aims to mimic cracked concrete specimens with a high degree of control over the resulting crack parameters width, depth and length for material testing and calibration of automated (NDT) methods. The method comprises 3D-printing of formwork with integrated crack patterns. The obtained crack width accuracy is tested by comparing printed cracks and resulting cracks in the concrete with the desired width from the print file. This procedure enables the realization of crack widths ≥ 0.2 mm with a deviation in the range of 25% between desired and resulting crack width. Further, the proposed methodology is independent of intrinsic material properties which enables this accuracy. Full article

Currently, the demand for environmental sustainability options in the construction industry is increasing, especially those related to the correct use of water. The aim of this work is to study different sustainable alternatives that minimize the use of water in cured hydraulic concrete, analyzing the effect of curing on hydration, microstructure, and compressive strength of hydraulic concrete exposed to different curing techniques: Manual Curing, Standard Curing, Vinipel, and Uncured. An experimental study was conducted using 180 cylindrical hydraulic concrete specimens, which were compression-tested at 7, 28, and 56 days. A Scanning Electron Microscope equipped with an Energy Dispersive X-ray Spectrometer analysis was carried out to examine the microstructural and compositional changes under the different curing techniques. The results indicate that the Vinipel technique is the best alternative, showing a compressive strength of 35 MPa after 56 days of curing. In general, Vinipel > Standard Curing > Manual Curing > Uncured is the order of strength from highest to lowest. The formation of hydration products was observed in all curing techniques. The presence of ettringite, complementing by abundant portlandite in Vinipel, shows the dominance of an important product in the strength of concrete. The best strength capacity under load and the lowest percentages of vacuum are likely to be favorable for the durability of the processes. Full article

Topographical data are essential for hydrological analysis and can be gathered through on-site surveys, UAVs, or remote sensing methods such as Digital Elevation Models (DEMs). These tools are crucial in hydrological studies for accurately modeling basin morphology and surface stream network patterns. Two different DEMs with resolutions of 0.13 m and 5 m were used, as well as tools which carry out urban basin delineation by analyzing their morphometric parameters to process the hydrography of the study area, using three Geographic Information Systems (GIS): ArcGIS, GlobalMapper, and SAGA GIS. Each piece of software uses different algorithms for the pre-processing of DEMs in the calculation of morphometric parameters of the study area. The results showed variations in the quantity of delineated stream networks between the different GIS tools used, even when using the same DEM. Similarly, the morphometric parameters varied between GIS tools and DEMs, which tells us that the tools and topographic data used are important. The stream network generated using ArcGIS and the DEM obtained with UAV offered a more precise description of surface flow behavior in the study area. Concerning ArcGIS, it can be observed that between the resolutions of the INEGI DEM and the UAV DEM, the delimited area of micro-basin 1 presented a minimum difference of 0.03 km². In contrast, micro-basin 2 had a more significant difference of 0.16 km². These discrepancies in results are attributed to the different algorithms used by each piece of software and the resolution of each DEM. Although some studies claim to have obtained the same results using different software and algorithms, in this research, different results were obtained, and emphasize the importance of establishing procedural standards, as they can significantly impact the design of stormwater drainage systems. These comparisons will allow decision-makers to consider these aspects to standardize the tools and topographic data used in urban hydrological analyses. Full article

Rib–deck (RD) welded joints in orthotropic steel bridge decks are prone to different fatigue crack mechanisms. Standard fatigue design methods are inadequate for some of these mechanisms under multiaxial non-proportional loading conditions. This study presents a framework to assess fatigue damage at RD welded joints, considering the different crack mechanisms based on the equivalent structural stress method and its extension to multiaxial non-proportional fatigue, which is the path-dependent maximum stress range (PDMR) cycle counting algorithm. The method is validated for uniaxial loading by using experimental data from the literature. Additionally, non-proportional fatigue damage at RD welded joints of a suspension bridge girder is investigated under simulated random traffic loading. The analyses reveal the limitations of the nominal stress approach to account for complex stress field variations. The PDMR method, more suited to capture the stress path dependency of non-proportional fatigue damage than the hot spot and critical plane-based methods, predicts higher fatigue damage. A comprehensive fatigue test campaign of full-scale RD welded joints is necessary to better understand their fatigue behaviour under multiaxial loading. Until more experimental data are available, the PDMR method is recommended for fatigue verifications of welded RD joints as it yields safer predictions. Full article