2031 research outputs found
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Modeling of the Full-Scale Secondary Sedimentation Basin Using the GPS-X Model
Get PDFThe secondary sedimentation basin is being modeled in this study for the first time using the GPS-X model instead of the computational fluid dynamics (CFD) model. This study was conducted in the extended-aeration Al-Hur treatment plant that struggles with unstable sedimentation in its sedimentation tank. After collecting and entering the data into the GPS-X model, the model was calibrated and validated, and the results were statistically examined based on R and RMSE. To determine the efficiency of the sedimentation tank, the following scenarios were investigated: 1) testing the efficiency in removing pollutants; 2) conducting state point analysis (SPA); and 3) measuring the concentration of sludge in the layers of the sedimentation basin. Six factors were considered during the sensitivity analysis, namely sludge volume index (SIV), surface area, underflow rate (RAS), pumped flow (WAS), maximum settling velocity, and liquid temperature. The calibration and validation results were within the specified limits, and the secondary sedimentation basin demonstrated high efficiency in removing pollutants, with the analysis point (SPA) obtaining the highest MLSS concentration of 3000 mg/L. The sludge concentrations in the lower layers were 7000 mg/L, while those in the upper layer were 18 mg/L. These results suggest that a lower (100 ml/g) sludge volume index corresponds to a better sedimentation basin efficiency. Increasing the surface area of sedimentation basins can positively affect their efficiency, while increasing waste-activated sludge, maximum settling velocity, and liquid temperature may reduce pollutants and improve the sedimentation process. The GPS-X model is demonstrated as an excellent tool for understanding and predicting the work behavior of sedimentation basins, making this model particularly valuable for the management of sewage treatment plants. Doi: 10.28991/CEJ-2024-010-09-017 Full Text: PD
Enhancement of Expansive Soil Properties by Water Treatment Sludge Ash in Landfill Liners
Get PDFThis study aims to enhance the suitability of expansive clayey soils for use as landfill liners by incorporating water treatment sludge ash (WTSA). Expansive soils, prone to swelling and desiccation cracking, compromise landfill liner integrity, increasing the risk of groundwater contamination. Local soils often do not meet the requirements for hydraulic conductivity and stability, prompting the use of additives like bentonite. However, bentonite-treated soils still face challenges in tropical regions due to moisture loss and cracking. This research investigates the effects of adding WTSA to bentonite-treated soils to mitigate swelling and shrinkage issues. Several geotechnical tests were conducted, including hydraulic conductivity, free swell percentage, swelling pressure, volumetric shrinkage, and desiccation cracking. Results show that WTSA significantly reduces hydraulic conductivity, free swell percentage, and swelling pressure, meeting the standard requirements for liners (hydraulic conductivity of at least 1í—10-9m/s and volumetric shrinkage of at least 4%). Moreover, WTSA addition reduces desiccation cracking to acceptable levels, demonstrating its potential as an effective reinforcement material. This study introduces an innovative approach to using WTSA, a waste product, as a sustainable alternative to conventional liner materials, reducing environmental impact and enhancing landfill liner performance. Doi: 10.28991/CEJ-2024-010-11-04 Full Text: PD
Impact of Vertical Vibration on Group Piles During Earthquake Loading: Experimental Findings
Get PDFThis study presents novel research on the impact of vertical vibration on the dynamic response of pile groups embedded in stratified soil under seismic loading conditions. An experimental setup was employed wherein the piled machine foundation was subjected to vertical vibrations at three operating frequencies (10, 20, and 30 Hz) and subsequently exposed to four levels of seismic acceleration (0.1 g, 0.34 g, 0.77 g, and 0.82 g). Piles with a length-to-diameter ratio of 25 were embedded in a stratified soil profile, with an upper loose layer (30% relative density) and a lower dense layer (80% relative density) acting as end-bearing. Measurements and analyses of horizontal and vertical accelerations, and amplification factors were conducted using the Fast Fourier Transform (FFT), spectral acceleration (Sa), and variation of acceleration with depth. The results demonstrated a significant reduction in horizontal acceleration, with a peak ground acceleration (PGA) reduction of up to 64% in average, particularly at higher frequencies such as 30 Hz. The mitigation efficiency at 30Hz improved with increasing PGA, showing reductions of 42, 68, 75, and 63% for seismic accelerations of 0.1 g, 0.34 g, 0.77 g, and 0.82 g, respectively. The analysis further revealed harmonic resonance and higher mode effects at lower frequencies, with nonlinear soil behavior affecting the resonance and amplification patterns. Additionally, the results demonstrate that the far-field accelerations exceeded the near-field accelerations within the pile group, particularly in the surface layer. The results indicated that the initial vibration amplitudes exceeded the safe operating limits outlined in ACI 351.3R-18 under seismic loading, particularly at higher seismic acceleration levels and lower frequencies. Additional modified charts were presented to account for these conditions. The results presented promising evidence for using vertical vibrations as an earthquake-mitigation strategy. However, avoiding operating at frequencies less than 10 Hz is recommended because of the potential resonance and interaction with horizontal accelerations during earthquakes. Doi: 10.28991/CEJ-SP2024-010-010 Full Text: PD
Assessment of Fluid Forces on Flooded Bridge Superstructures Using the SPH Method
Get PDFThis paper presents a numerical simulation utilizing the Smoothed Particle Hydrodynamics (SPH) methodology to analyze the impact of water flow on bridge superstructures. The focus of the study is the Canh Nang bridge, which experienced significant damage during a severe flood in Vietnam. The SPH model accounts for flow morphology, velocity fields, and flow pressure around the submerged superstructure, providing insights into areas of high flow pressure and the water resistance coefficient (Cd). By employing modified dynamic boundaries for solid surfaces and the inflow-outflow conditions, the model effectively addresses fluid-bed and fluid-structure interactions. The results highlight elevated flow pressure on specific surface locations of the superstructure, while lower pressures are observed on the bottom surfaces and between adjacent girders. The calculated Cd values are evaluated against those from various bridge design standards, including the Indian code, Eurocode, AS5100, and TCVN 11823. This comparison reveals discrepancies and suggests the potential for refining current design practices. Future research directions include the experimental validation of SPH model results and the exploration of how structural parameters influence superstructure response during flood events. Doi: 10.28991/CEJ-2024-010-12-019 Full Text: PD
Flexural Behavior of Repaired Reinforced Concrete Beams Due to Corrosion of Steel Reinforcement Using Grouting and FRP Sheet Strengthening
Get PDFOne of the common causes of damage to the concrete structures close to the sea line is corrosion on the steel reinforcement in the concrete, which may cause spalling on the concrete cover. This paper presents the results of the simulation of the corroded reinforced concrete beams, which were repaired using the grouting method and FRP strengthening. The concrete cover of the beam specimens on the tensile side was filled with grouted concrete instead of filled with normal concrete to simulate the repair of concrete spalling. Three types of beam specimens were prepared and tested under a monotonic loading. BG and BPF were the specimens for beams with grouting only and beams with grouting and flexural strengthening using FRP sheets, respectively. Flexural strengthening using FRP sheets was carried out to restore the flexural capacity. As a comparison, control beams were also prepared in the form of normal reinforced concrete (BN). The results showed that the BG beam had a capacity of only about 50% compared to the control beam (BN). However, applying flexural strengthening using FRP sheet as on the type BGF beams showed that it had approximately the same capacity as BN specimens. This indicated that the repair method using grouting on damaged concrete covers and strengthening using FRP sheets was an effective alternative to repairing the corroded reinforced concrete beams. Doi: 10.28991/CEJ-2024-010-01-014 Full Text: PD
Cost Efficiency of Retrofitting Green Chemical Industrial Buildings
Get PDFClimate change is a threat and crisis that hit the world today. The green industry is widely implemented in the manufacturing sector as an effort to reduce negative impacts on the environment. The implementation of the green industry is influenced by various factors. The Chemical Industry is one sector that faces challenges in implementing green industry practices. The objective of this paper is to create an innovative conceptual framework that combines blockchain technology and building information modeling. This research examines the concept of green retrofitting in the chemical industry using an assessment based on the Ministry of Public Works and Housing Regulation No. 21 of 2021. The study was conducted in a chemical industry located in Cilegon, Banten, Indonesia. The research method combines Blockchain-Building Information Modeling (BIM) to analyze the cost efficiency of green retrofitting and Structural Equation Modeling-Partial Least Squares (SEM-PLS) as a tool to process data from questionnaires and identify influential factors. The results indicate that the use of Blockchain-BIM can reduce retrofitting costs by 4.42% for low-level, 4.45% for medium-level, and 4.40% for high-level categories. This demonstrates that Blockchain-BIM has a significant impact on improving cost performance in the retrofitting process. Doi: 10.28991/CEJ-2024-010-03-04 Full Text: PD
Evaluation of the Mechanical Behavior of Soil Stabilized with Asphalt Emulsion Using Multi-Stage Loading
Get PDFThe objective of this research was to assess the mechanical response (resilient and plastic) of soil stabilized with petroleum asphalt concrete using asphalt emulsion under multi-stage loading. To enhance the adhesion of the asphalt film to the soil grains, the stabilized soil underwent air-drying curing for seven days. Dosage was conducted through the indirect tensile strength test using diametral compression. With the optimum content determined in the dosage (2% emulsion), additions and removals of 0.5% asphalt emulsion from this content were performed. Consequently, three specimens were molded with concentrations of 1.5%, 2%, and 2.5% of slow-setting cationic asphalt emulsion. These specimens were then subjected to drained triaxial tests under multi-stage loading, using 5 different stress pairs, totaling 50,000 cycles. Analyzing the regions defined by the total and permanent deformation curves allowed studying the plastic and elastic response, the proportionality between these regions, and the increase in elastic and plastic regions of the soil and stabilized soil in a single test, providing a more accurate interpretation. Regarding the measured deformations, as the deviator stress was increased with each loading cycle, the stabilized samples exhibited an increase in plastic deformations compared to the natural soil (control). It was also observed a proportional increase in the resilient region, indicating that the addition of asphalt made the soil less rigid but provided cohesion that was absent before stabilization. Doi: 10.28991/CEJ-2024-010-01-02 Full Text: PD
Macroscopic Traffic Characterization Based on Distance Headway
Get PDFAccurate traffic characterization is essential for congestion mitigation. In this paper, a traffic model is proposed that incorporates distance headway in the well-known Lighthill, Whitham, and Richards (LWR) model. Velocity is influenced by the headway distance between vehicles. When this distance is small, the velocity is low, and when it is large, the velocity is high. The proposed and LWR models are implemented in MATLAB, and the performance is evaluated for different values of distance headway. The results show that traffic with the proposed model evolves with smaller changes that are more accurate and realistic than with the LWR model. Doi: 10.28991/CEJ-2024-010-12-016 Full Text: PD
Numerical Modeling the Rock Mass Stress-Strain State Near Vertical Excavations in Combined Mining
Get PDFIn recent years, the development of the mining industry in the Republic of Kazakhstan has been accompanied by the commissioning of new underground levels for many existing mineral deposits, which were initially developed through open-pit mining. As the depth of open-pit mining increases, the volume of overburden rises sharply, making open-pit mining unprofitable due to the significant amount of additional mining work required. For this reason, most open-pit mines in Kazakhstan are transitioning to underground mining, or combined mining. Many researchers have examined the timing of this transition and have worked on optimizing it to determine the best economic efficiency and manage risks. However, there is limited information available on how to determine the optimal location for a vertical mine shaft when transitioning from open-pit to underground mining. The purpose of this study is to identify a safe location for a vertical shaft in combined mining operations. Specifically, the study assesses the impact of the open-pit mine on the selection of the mine shaft's location, considering the stress-strain state of the rock mass during combined mining methods. To address these objectives, numerical modeling of the stress-strain state around vertical excavations during combined mining was performed. The results provide a solution to the critical issue of determining the location of the mine shaft in combined geotechnology and lay the groundwork for further research on shaft placement in Kazakhstan. The novelty of this study lies in identifying the shaft location by considering the geometric shape of the open-pit mine and the depth of development. Doi: 10.28991/CEJ-2024-010-09-010 Full Text: PD
Unveiling Effectiveness of Lean Construction Practices: A Comprehensive Study through Surveys and Case Studies
Get PDFConstruction projects frequently encounter challenges such as stagnant productivity, excessive waste, cost overruns, and delays, contributing to sustainability issues. In response to these issues, Lean Construction (LC) has emerged as a methodology aimed at eradicating inefficiencies and wasteful practices. However, the construction industry has been slow to embrace LC, primarily due to a lack of comprehensive evaluations regarding its real-world effectiveness. This study seeks to thoroughly assess the effectiveness of LC when implemented in construction projects in Pakistan. The research involved conducting a survey among experts in the construction industry, utilizing a comprehensive questionnaire to evaluate the extent of LC adoption and its impact on construction project performance. The collected data underwent rigorous statistical analysis to ascertain the influence of LC practices on project outcomes. To validate the survey results, the study selected five case study projects for in-depth analysis. These case studies assessed how well the projects adhered to LC principles and examined the resulting effects on project delays, cost overruns, quality issues, rework, and health-related concerns. The findings consistently confirmed that a higher level of adherence to LC principles led to significant reductions in project delays, cost overruns, quality issues, and health-related problems. This analysis strongly supports the notion that a more extensive adoption of LC practices results in substantial improvements in project performance. By presenting these compelling results, this study offers valuable insights to the construction industry, providing a clearer path for the effective integration of LC practices. Doi: 10.28991/CEJ-2024-010-04-09 Full Text: PD