2031 research outputs found
Sort by
Pre- and Post-Cracking Resistance of Steel Fiber Reinforced Concrete Flexural Members with GFRP Bars
No full textThis research investigates the pre- and post-cracking resistance of steel fiber-reinforced concrete specimens with Glass Fiber Reinforced Polymer (GFRP) bars subjected to flexural loading. The purpose is to modify the ductility and cracking resistance of GFRP-reinforced beams, which are prone to early cracking and excessive deflections instigated by the low modulus of elasticity of GFRP. Six self-compacting concrete specimens (1500×240×200 mm), incorporating steel fibers of two lengths (25 mm and 40 mm) with varying distribution depths, were tested to assess their structural performance. The results indicate significant enhancements in cracking resistance, stiffness, energy absorption, ductility, and flexural strength. Tested beams reinforced with 40 mm-long steel fibers exhibited a 23.9%–24.2% development in the ultimate moment capacity associated with the steel-reinforced specimens, whereas those with 25 mm fibers showed smaller increases (2.7%–3.1%). The cracking resistance improved by up to 33.3% in beams with 40 mm-long fibers and by 16.67%–20% in those with 25 mm-long fibers, associated with a non-fibrous GFRP specimen. Additionally, the inclusion of 40 mm hooked-end steel fibers significantly enhanced ultimate deflection, with peak deflections increasing by 30.2%–44.8% compared to steel-reinforced beams. Fibrous GFRP-reinforced beams exhibited up to 154% higher energy absorption under ultimate load than a non-fibrous GFRP beam. All fibrous GFRP-reinforced beams achieved deformation-based ductility indices between 4.2 and 6.9, exceeding the minimum threshold of 4 for adequate deformability. These findings confirm that incorporating 40 mm steel fibers significantly improves the structural behavior of GFRP-reinforced concrete specimens, offering valuable insights for optimizing their design
Investigating the Influence of Functional Units on the Life Cycle Assessment of Asphalt Pavements
No full textThe Life Cycle Assessment (LCA) of asphalt pavements is an essential tool for reducing environmental impacts. The definition of the functional unit (FU) within LCA can significantly influence the results, affecting the assessment of greenhouse gas (GHG) emissions and, consequently, the selection of asphalt mixtures. In this context, this study aims to analyze the impact of different functional units on the selection of asphalt mixtures for road pavements, considering the phases of raw material extraction, material production, mixing, and construction. To this end, the mechanical behavior of two distinct asphalt mixtures was evaluated under two different loading conditions, and their contributions to climate change were assessed using three functional units: t CO₂ eq/km of roadway, kg CO₂ eq/t of HMA, and kg CO₂ eq/m³ of HMA. The results indicated that asphalt mixtures with a higher resilient modulus require thinner pavement layers, leading to lower GHG emissions. However, when asphalt mixtures are analyzed individually and compared, no clear pattern in GHG emissions is observed, reflecting the specific characteristics of each production process. Additionally, it was found that the environmental impact varied according to the adopted functional unit, demonstrating that this choice can significantly influence decision-making regarding the selection of asphalt mixtures in terms of their contributions to climate change. It was concluded that the selection of the FU in pavement LCA should be aligned with the study's objective and the context of the analysis, as an inadequate choice may compromise the selection of asphalt mixtures
A Model to Estimate the Level of Passenger Satisfaction With the High-Speed Train
Get PDFPassenger satisfaction must be measured by operators providing high-speed train services, as it is directly related to passenger loyalty, which in turn ensures the business's sustainability. This study aims to measure passenger satisfaction with the Jakarta-Bandung high-speed train by developing a model that considers various factors significant in influencing user satisfaction. The quantitative method was developed by distributing questionnaires to 300 respondents, and the results were analyzed using SEM. The results of this study prove the existence of a model built from 5 (five) dimensions: the availability of information, accessibility, train comfort, emergency actions, and responses to complaints. The results of this study are expected to provide recommendations to the operator of the Jakarta-Bandung High Speed Train to evaluate the factors of 5 (five) dimensions that are considered important in forming a user satisfaction model for the service using a performance analysis matrix (IPA Diagram). According to the results of the IPA diagram, it is evident that the most urgent task for the operator is to consolidate with third parties related to the availability of modes to serve passengers who will continue their journey to Bandung, particularly for work and tourism purposes
Numerical Analysis of Ground Motion Topographic and Geological Effect: A Case Study of MOXI Platform
Get PDFThe ground motion amplification effect influenced by diverse topographic and geological conditions was investigated to enhance the seismic design standards for mountain structures. A comprehensive series of two-dimensional and three-dimensional numerical simulations was conducted. These simulations utilized idealized and real-world topographic models, meticulously considering various critical parameters, such as platform height, width, slope, surface angle, and soil properties. The results reveal that topographic and geological factors both significantly impact the ground motion amplification effect, with the maximum amplification factors frequently surpassing those stipulated by the current Chinese seismic code. Based on these findings, a refined and modified formula was developed for calculating the ground motion amplification factor that integrates the influences of height, width, slope, and geological conditions. The validity and feasibility of this modified formula were substantiated thoroughly through detailed comparisons between the actual observed values and the suggested values, demonstrating its potential to improve the safety and reliability of seismic design in mountainous regions substantially
Groundwater Quality and Irrigation Suitability Assessment Using Geochemical and GIS-Based Approaches in Arid Regions
Get PDFIn arid and semi-arid climates, such as Iraq's Salah Al-Din Governorate, the availability of surface water is much lower than demand, so groundwater becomes a vital resource. Groundwater is one of the basic needs for agricultural irrigation, and therefore this study presents a suitable groundwater suitability assessment for agricultural irrigation based on a comprehensive assessment of groundwater geochemical properties and spatial distribution using the kriging technique within Geographic Information Systems (GIS). Key water quality parameters, including EC, TDS, pH, Cl⁻, Na⁺, K⁺, NO₃⁻, HCO₃⁻, CO₃²⁻, SO₄²⁻, Ca²⁺, and Mg²⁺, were determined in a total of 51 wells across the study area. In addition, two wells located in the Al-Alam District of Salah Al-Din Governorate were remeasured in 2025 to assess changes in water levels. These measurements were compared to the static water levels recorded in 2014 for one well and in 2008 for the other. To determine irrigation suitability, the Water Quality Index, Sodium Adsorption Ratio, Residual Sodium Carbonate, and Total Hardness were calculated and analyzed. Groundwater quality was spatially variable, but several areas exceeded the FAO limits for safe agricultural use at all groundwater depths considered owing to salinity, sodicity, and anthropogenic contamination. Spatial mapping using GIS identified the risk zones and assisted in recommending appropriate management practices for sustainable groundwater development. Such findings emphasize the importance of regular monitoring together with appropriate irrigation management and remediation measures to reduce groundwater degradation and maintain agricultural development in Salah Al-Din Governorate
Three-Dimensional Finite Element Evaluations of H-Steel Beams Strengthened with Various Types of Steel Stiffeners
Get PDFThree-dimensional finite element analyses were carried out to assess the impact of various types of lateral stiffeners on the response of steel beams. Hot-rolled simply supported H-steel beams were modeled in Abaqus and strengthened with centrally located vertical, V-shaped, inverted V-shaped, single X-shaped, or doubled X-shaped stiffeners. All these stiffeners possess a similar quantity of steel by varying the length and thickness of the stiffeners. The behavior of beams was studied in the elastic phase, hardening phase, necking phase, and failure. The yield stress, ultimate load, deflection value, and hardening in the three phases were also examined. It has been found that the findings indicate that altering the configuration of the stiffener, while maintaining its location and steel volume, can influence the response of the strengthened beam either favorably or adversely. Two stiffeners raised the yield load by 9.6%, the ultimate load by 10.8%, and elastic storage energy by 70% above the reference beam. One kind of stiffener increases in the plastic region, two types drop somewhat, and two others decrease significantly. The necking region shows a rise of 237% in one threshold and 36% to 90% for the other beams compared to the reference beam. Furthermore, the software provides a definitive indication of the kind of stiffener and the degree of its advantage, while simultaneously revealing the type of stiffener that is not advantageous
Geopolymer Mortars from Tuff Waste: A Circular Approach
No full textThis study explores the potential use of volcanic tuff mining waste in geopolymer mortar formulations, aiming to enhance recycling and promote sustainable construction. Two filler-to-binder ratios (70/30 and 65/35) were developed using a geopolymer binder composed of tuff waste, dolomite powder, and sodium silicate. The mortars were subjected to heat treatments at 200, 350, 500, and 650°C for 8.5 hours. Compared to natural tuff (reference sample), water absorption decreased from 16.8% to 7.7%, with the lowest absorption observed in the 65/35 composition. Flexural strengths increased by 0.97% to 117.1%, and compressive strengths improved by 17.8% to 97.1%, reaching their maximum at 500°C; at 650°C, strengths declined due to water evaporation, shrinkage, and microcrack formation. Softening coefficients increased by over 10%, indicating enhanced resistance to water-induced softening. The study demonstrates that incorporating dolomite powder improves water resistance, while tuff waste serves effectively as both filler and binder component. Moreover, geopolymer mortars produce significantly lower CO₂ emissions (0.133 t/m³) compared to ordinary Portland cement mortars (0.415 t/m³), highlighting their environmental advantage. These results underscore the potential of tuff-based geopolymer mortars for sustainable construction applications
Enhancing AA6061–Bottom Ash Composites: Role of Heat Treatment on Properties and Dimensional Stability
No full textAluminum matrix composites (AMCs) reinforced with industrial by-products have attracted attention as lightweight, sustainable materials, yet most research has focused on fly ash. The higher density of bottom ash compared to fly ash makes bottom ash suitable for use as reinforcement in AMC. This study investigates the combined effect of BA reinforcement (0, 3, and 6 wt%) and T6 heat treatment (aging at 175, 200, and 225 °C) on the microstructure, mechanical performance, thermal expansion, and dimensional stability of AA6061 composites. Mechanical testing, thermomechanical analysis (TMA), and coordinate measuring machine (CMM) evaluations were conducted to establish correlations between microstructure and macroscopic reliability. The results show that aging plays a decisive role in strengthening and stabilizing the alloy. The unreinforced AA6061 achieved peak hardness (69.43 BHN) and tensile strength (274.60 MPa) at 200 °C, but exhibited the largest distortion due to high thermal expansion. BA addition significantly reduced the mean coefficient of thermal expansion, with the 3 wt% BA composite aged at 200 °C demonstrating the most balanced behavior: stable CTE response, minimal distortion (0.1–0.4 mm²), and improved mechanical reliability. In contrast, 6 wt% BA composites, despite their lowest mean CTE (≈25 ppm/K), suffered from local instabilities due to particle agglomeration and porosity, leading to reduced toughness and higher geometric irregularities. Overall, this work highlights the novelty of employing BA as a sustainable reinforcement distinct from fly ash, showing that moderate BA addition coupled with optimized heat treatment can enhance dimensional stability and mechanical performance. The findings provide new insights into the design of cost-effective, environmentally friendly AMCs for structural applications
A Semantic-Enabled Common Data Environment for Real-Time Digital Twin Applications in Small-Scale Construction Projects
Get PDFThe integration of Building Information Modeling (BIM) and Digital Twin (DT) systems has reshaped construction project delivery, but their application remains concentrated in large, resource-intensive developments. Small-scale projects, which dominate the built environment in many regions, often lack access to advanced digital platforms due to financial constraints, insufficient infrastructure, and limited technical capacity. Existing Common Data Environment (CDE) frameworks are typically monolithic and costly, making them unsuitable for the flexible and affordable deployment needed in these contexts. A persistent barrier is semantic fragmentation: without interoperable data exchange across BIM, Internet of Things (IoT) devices, and Geographic Information Systems (GIS), project information remains siloed and underutilized. This study introduces a modular, semantic-enabled CDE architecture designed specifically for small-scale projects. The framework incorporates lightweight ontologies, microservices, and knowledge graphs to deliver scalable and semantically coherent integration of BIM–IoT–GIS datasets. To validate its applicability, the research applies the model to a three-storey educational building, demonstrating how real-time DT functionality can be achieved with minimal infrastructure demands. The case study highlights improvements in data exchange, operational monitoring, and sustainability analysis, showing how the architecture supports predictive maintenance and decision-making. By synthesizing insights from literature and practical demonstration, the paper proposes a blueprint for democratizing DT adoption, enabling affordable, adaptable, and interoperable solutions for small-scale construction projects
Assessment of Urban Changes at the Residential Neighbourhood Level Based on Satellite Imageries
Get PDFOngoing urban expansion leads to the steady loss of green spaces. Residential units' gardens and green open spaces are a vital part of city life, contributing considerably to urban green infrastructure and ecological services. However, these areas are diverse, making it difficult to assess their changes over time to take advantage of their benefits and contribution to sustainable urban development. This study proposes a new methodology that combines survey data with high-resolution image analysis to construct maps and statistics of change in two residential neighbourhood areas in the Iraqi city of Baqubah. Three change detection techniques utilising very high-resolution multispectral Pléiades images were used to evaluate the changes: pixel value differencing, band index differencing, and categorical change detection. Then, a unique strategy employing geo-processing processes by the ModelBuilder tool was applied to the evaluation outcomes to assess the changes in a final manner. In addition to survey data that supported the final change detection outcomes, study validation was conducted through field verification, and the mean accuracy was 93%. The final results indicated that open or green spaces decreased over a period of seven years at rates of 24% and 14% of the total of both areas assessed. Policymakers and urban planners see such privately owned land as difficult to affect. However, reducing vegetative cover areas and turning them into impermeable surfaces may result in the areas becoming inefficient in the development of urban sustainability. Our developed method demonstrates the capability of utilising Very High Resolution (VHR) imagery with local survey data to accurately infer changes in urban vegetation within residential neighbourhood regions. Doi: 10.28991/CEJ-2025-011-01-05 Full Text: PD