2031 research outputs found
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Numerical Analysis on Fatigue Performance in Fillet Weld Roots of Steel Bridge Bearings
Get PDFFillet weld roots near bridge supports are critical fatigue-prone details in steel bridges, particularly under high stress concentration. Fatigue cracks at these locations tend to be initiated internally, where detection and repair remain challenging with current techniques. Fatigue performance improvements are explored from the perspectives of structural design and epoxy insertion. Five actual bridges in the USA, China, and Japan were analyzed using a hybrid finite element modeling approach, employing low-precision girder models for load distribution and high-precision local support models with an introduced notch for Effective Notch Stress (ENS) evaluation. Both actual bridge case studies and numerical parametric analyses were conducted. Results indicate that increasing weld size effectively reduces ENS, while sole plate thickness has a limited effect. Bolts play a pivotal role in limiting relative displacement between the bottom flange and the sole plate, though their constraint range is localized. To address the limited effectiveness of structural adjustments, adhesive filling was introduced in areas beyond the bolt constraint range. Bonding-assisted welding with epoxy insertion achieved up to a 56% reduction in ENS and significantly improved fatigue performance. The findings confirm the potential of bonding-assisted welding for improving the durability of fillet weld roots in steel bridge supports and provide practical solutions to the difficult-to-detect root fatigue cracks
Spatial Variation of Shallow Soil Bearing Capacity Using SPT Data and MATLAB Analysis
Get PDFThe current research examines the spatial distribution of shallow bearing capacity in Al-Najaf City through the use of Standard Penetration Test (SPT) data supplemented with advanced computational tools in MATLAB. A high-quality geotechnical survey of 464 boreholes was carried out, with drilling performed at depths ranging from 18 m to 35 m below the current ground surface. To assess the shallow foundations, the top 12 m of the soil profile was analyzed. To measure in-situ soil resistance, SPT measurements were taken at specified depth intervals in every borehole. The raw SPT N-values were adjusted for overburden pressure, an energy-correction parameter, and groundwater effects; other minor adjustments were considered negligible based on their minimal impact on the final dataset. These corrected N-values formed the basis for calculating both ultimate and allowable bearing capacities using empirically developed correlations. MATLAB surface-interpolation procedures were used to generate georeferenced thematic maps that depict the lateral variation of bearing capacity within the 0–12 m depth interval. The resulting spatial analysis shows a significant increase in the bearing capacity of the northern and western regions of Al-Najaf, correlating with increases in urbanization and infrastructure density. The predictive geotechnical maps developed in this study can be considered a highly robust, cost-effective, and timely tool for initial subsurface engineering surveys to guide sustainable city development, infrastructure design, and optimization of foundation engineering
Development of Sustainable Self-Compacting Concrete Using Slag Sand and Expanded Clay Aggregates
No full textThe objective of this study is to develop a sustainable self-compacting concrete (SCC) by partially replacing natural aggregates with slag sand (SS) and lightweight expanded clay aggregate (ECA) in combination with a ternary binder system, thereby enhancing both performance and environmental sustainability. The methodology involved preparing thirty SCC mixes of M30 grade using 65% Ordinary Portland Cement, 25% fly ash, and 10% silica fume as binder, with slag sand replacing river sand at 20–100% and ECA replacing coarse aggregate at 20–100%. Fresh properties were evaluated through slump flow, T50, V-funnel, L-box, and U-box tests following EFNARC guidelines, while mechanical strength (compressive, split tensile, and flexural) was measured at 7, 28, and 90 days. Durability was assessed through sulphuric acid and magnesium sulphate exposure, and microstructural behavior was studied using FTIR and TGA. Results revealed that mixes with higher ECA content enhanced flowability, with A2B10 achieving superior workability (slump flow 694 mm, T50 2.9 s), while A2B6 (20% SS + 20% ECA) achieved optimum strength (45.21 MPa compressive) and durability retention under aggressive exposures. The novelty of this work lies in demonstrating the synergistic role of slag sand and ECA in producing SCC with enhanced performance, reduced natural aggregate usage, and improved sustainability compared to conventional SCC
Recycled Steel Fiber-Reinforced Mortar with Embedded Structural Health Monitoring for Sustainable Construction
Get PDFThe study examines the mechanical and microstructural performance of eco-friendly mortar mixes that incorporate Recycled Steel Fibers (RSF) derived from waste tires. Four mortar formulations with varying RSF content (0%, 0.5%, 1%, and 1.5% by volume) were evaluated for compressive strength, flexural strength, and electrical conductivity. Experimental results revealed that a 1.5% RSF mixture exhibited remarkable improvements in flexural strength, achieving a 67% increase compared to the control formulation while delivering a 12.6% enhancement in compressive strength. However, the 0.5% RSF mix showed reduced performance due to poor fiber dispersion, underscoring the importance of proper fiber distribution. Specific resistance decreased with RSF addition, indicating enhanced electrical conductivity, with the lowest specific resistance observed at 0.5% RSF on day 28. An empirical model using a fiber reinforcing index (ξ) was developed to predict strength behavior. A quadratic relationship was found to best describe compressive strength gains, while a linear model effectively captured the flexural strength trend. The models were calibrated using both experimental data and literature values, achieving high predictive accuracy. Electrical conductivity increased with RSF addition, and the slope of the specific resistance during loading correlated strongly with mechanical strength, highlighting its potential as a non-destructive structural health monitoring (SHM) indicator. SEM analysis confirmed improved matrix integrity and fiber–matrix interaction at the optimal 1% RSF content, which balanced strength gains and sensing capability. The study establishes RSF as a viable sustainable alternative to virgin steel fibers, providing both mechanical enhancements and self-sensing properties. This novel integration of electrical monitoring with mechanical testing and modeling provides new insights into recycled-fiber composites by enabling simultaneous enhancement of structural performance and real-time damage monitoring
Improving Thermal Comfort and Air Quality: PET and CO₂ Evaluation of School Courtyard’s Orientation
Get PDFThis study aims to investigate the thermal conditions related to the variations in the school courtyard’s orientation, focusing on mass temperature (Tm), outdoor air temperature, and Physiological Equivalent Temperature (PET). A qualitative methodology based on ENVI-met software was adopted. Simulations for the existing school building were performed in the four basic orientations on 21 March and 21 September to assess the thermal impact of the courtyard’s orientations. Results showed that orientation produced slight but meaningful differences in Tm, with variations of 0.16°C in September and 0.20°C in March. Though modest, these differences become significant when scaled to the large mass of the school buildings, where even small reductions affect energy demand and comfort. For outdoor air temperature, the south orientation achieved reductions of 0.53–1.13°C in September and 1.1–1.9°C in March compared to ambient conditions. PET and wind maps supported these findings, with the south orientation allowing better airflow and better thermal comfort. Furthermore, analysis of CO₂ concentration confirmed that the south-facing courtyard provided the healthiest air quality. The study highlights that courtyard orientation should not be overlooked in large educational buildings, as even slight orientation-driven improvements become critical, reinforcing the importance of integrating orientation into holistic passive design strategies
Real-Time Monitoring and Development of a Localized OTTV Equation for Building Energy Performance
Get PDFGlobal warming negatively impacts indoor environments, affecting human comfort. Despite global efforts, energy demand and greenhouse gas emissions continue to rise. As sustainable building designs become more critical, enhancing energy efficiency through real-time data analytics is essential. The Overall Thermal Transfer Value (OTTV) is a key metric for assessing a building's energy usage, considering factors like orientation, location, and climate. However, limited research has examined real-time data's impact on OTTV coefficients. Therefore, this research aims at developing and validating new OTTV coefficients using real-time data with the EQUEST simulation engine. The coefficients of OTTV (Equivalent Temperature Difference TDeq, Temperature Difference ∆T, and Solar Factor SF) were monitored in real-time using HOBO Temperature Data loggers and Delta Ohm Photometer for Solar Radiations. Focusing on UTM Eco-Home building, the study calculates heat gain components, including transmission through walls, windows, and radiation heat gain. The findings of the study suggest that the modified OTTV equation accurately determines a building's OTTV, enhancing energy efficiency evaluations. The novelty of the study lies in the development of a new OTTV equation for the specific climate of Johor, Malaysia, and the real-time monitoring of OTTV that helps the energy managers analyze the Thermal Transmittance of Building envelopes in real-time. Doi: 10.28991/CEJ-2025-011-02-09 Full Text: PD
Structural Assessment and Rehabilitation of an Existing Hydraulic Masonry Structure Supporting Railway
Get PDFOld hydraulic masonry structures are essential components of global road and rail infrastructures. Over decades of operation, these structures have experienced inevitable deterioration, necessitating evaluations of their structural conditions through comprehensive assessment and rehabilitation programs to ensure compliance with contemporary safety standards. This study focuses on a specific regulator as a case example to implement a rehabilitation strategy aimed at restoring its structural integrity after 190 years of continuous service. From 2015 to 2021, an extensive program was conducted to assess the condition of the construction materials. This program included mechanical and physical testing, as well as Finite Element Analysis (FEA), to identify areas of high stress and to analyze the distribution of stress throughout the structure. The findings revealed that the structure fails to meet current Egyptian standards, thereby underscoring the critical need for a strengthening program. Subsequently, a rehabilitation intervention was developed, which involved reinforcing the intrados of the arches and piers with a slender reinforced concrete jacket. These reinforcements were integrated with the existing structure using steel shear bar connectors. Following the rehabilitation, a re-evaluation of the analysis of the modified structure using FEA software confirmed compliance with Egyptian specifications. The proposed rehabilitation strategy offers a viable solution to the challenges associated with the examined masonry arch bridge. Doi: 10.28991/CEJ-2025-011-02-012 Full Text: PD
Artificial Recharge of an Unconfined Aquifer Using Treated Wastewater as a Climate Change Mitigation Strategy
Get PDFWorldwide groundwater extraction has increased dramatically during the past six decades. Water scarcity will affect 1.4 billion people in around 48 nations by 2025. Iraq is experiencing an unparalleled and severe water crisis due to various factors, including climate changes, insufficient rainfall, the policies of neighboring nations, and the increased demand resulting from population expansion. The research area (Dibdiba aquifer) is in Iraq, in the middle between Najaf and Karbala. It was observed that farmers had abandoned numerous wells as a result of the decline in their water levels. Groundwater is the water resource for the region, and due to high agricultural and industrial demand, the Dibdiba aquifer is facing groundwater depletion. This study utilized climatic datasets projected under two scenarios obtained from CMIP6 and the Groundwater Modeling System (GMS). The objective was to evaluate the effect of projected climate change on the quantity of groundwater. Artificial recharge of treated wastewater from the wastewater treatment plant (WWTP) in Kerbala into groundwater aquifers has proven to be an effective method of mitigating groundwater depletion while providing a sustainable water supply. Eleven wells are distributed randomly within the research area; each of them is located within the unconfined aquifer. The groundwater levels in these wells were measured in situ from July 2023 to April 2024. The model was run for steady and unsteady flow conditions, and calibration at steady state was carried out using the groundwater head data for (7) wells. These seven wells were selected to represent the whole research region as well as shorten the simulation run duration in the calibration process. On the other hand, the transient calibration was performed employing measurements of groundwater heads for four wells. Calibration and validation results indicated convergence between the observed and simulated heads. The modeling findings showed that the increment in groundwater level is about 1.0, 1.85, and 2.25 m with artificial recharge of about 6000 m³/day, 9000 m³/day, and 12000 m³/day, respectively. The above findings illustrate the ability of artificial recharge as a highly promising strategy for addressing the water depletion and environmental issues in the Dibdiba aquifer. Doi: 10.28991/CEJ-SP2024-010-016 Full Text: PD
Natural Frequency of Liquefaction Potential Based on Soil Investigation and Microtremor Observation Results
Get PDFThis study aims to identify the natural frequency threshold for liquefaction potential by comparing four assessment methods at 54 identical sites in Padang, Indonesia. Methods include: (1) safety factor calculations from soil investigation results (CPT and SPT) applying the 2009 Padang earthquake's peak ground acceleration as input for cycling stress ratio; (2) natural frequency measurements at the surface using microtremor single observations; (3) liquefaction potential assessment through vulnerability index; and (4) analysis of historical liquefaction events from the September 30, 2009 Padang earthquake documented in two previous research papers. The analysis focused on soil depths ranging from 1-4 m. Findings reveal that sites with natural frequencies exceeding 0.40 Hertz remain safe from liquefaction, while sites with frequencies between 0.20-0.39 Hertz demonstrate significant liquefaction potential. This research contributes to the field by establishing a clear correlation between measurable natural frequency thresholds and liquefaction risk, providing engineers and urban planners with a more accessible parameter for preliminary risk assessment. Integrating multiple assessment methods at identical sites enhances the reliability of the identified frequency thresholds, offering a more comprehensive approach to liquefaction hazard mitigation in earthquake-prone regions
Assessing Sediment Transport and Shoreline Dynamics in High-Energy Tropical Coasts
Get PDFThis research examines coastal erosion in North Galesong, Indonesia, by validating longshore sediment transport (LST) equations and predicting shoreline changes over ten years. To evaluate sediment movement and coastline alterations, it integrates field data on sediment grain size and wave characteristics with numerical modeling techniques, including the CERC equation and finite difference methods. Sieve analysis revealed a range of sediment textures (D50: 0.17–0.65 mm), predominantly medium-fine sand. Wave analysis indicated a dominance of moderate energy southwesterly waves (1.5 m height, 6.39 s period) that aid sediment transport. The empirical LST models, calibrated with local data, closely matched numerical simulations (error <20%), predicting an annual net northward sediment transport of 406,869 m³. Shoreline analysis across 15 segments showed significant spatial variability: severe erosion occurred in Cell 4 (Δy = -0.82 m), while Cell 3 saw accretion (Δy = +0.68 m), influenced by wave direction, sediment supply, and coastal morphology. This study underscores the value of hybrid empirical-numerical methods in data-scarce regions and emphasizes the need for local model calibration to enhance coastal resilience. The findings inform sustainable management practices, promoting adaptive strategies to address sediment imbalances and hydrodynamic changes due to climate factors