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2007 research outputs found
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Innovative Method for Reinforcing Beams with Different Types of Concrete Using Cross-Rod Steel Bracing Under Pure Torsion
No full textThis study aimed to investigate the effectiveness of an innovative way to reinforce the concrete beams using cross-rod steel bracing under pure torsion. The experimental program consists of casting and testing eighteen concrete beams made of three types of concrete in the form of three groups, with the same dimensions for all beams (200í—200í—2000) mm. The parameters of the study included concrete types (normal strength, high strength, and steel fiber), as well as the number of internally cross rods (4, 8, 12, 16, 20). The experimental results showed that the number of internally cross-rod reinforcements and concrete type had an effect on ultimate torque, crack width, toughness, and stiffness. The torsional capacity of all concrete beams increased with the increase in internally cross-rod reinforcement. The ultimate torque of normal-strength concrete beams, high-strength concrete beams, and steel fiber concrete beams reinforced with twenty internally cross rods increased (88.34%, 53.20%, and 40.60%), respectively, compared to beams without cross rods in each type of concrete beam. Increasing the internally cross rod in all concrete beams effectively inhibited the development of crack width and improved torsional stiffness, especially in fibrous concrete beams that contained steel fiber. The torsional toughness of all concrete beams increased with the increase of internally cross-rod reinforcement, and it was higher in steel fiber concrete beams. The steel fiber concrete beams reinforced with internally cross-rod steel bracing have better torsional properties compared to ordinary concrete beams and high-strength concrete beams. Doi: 10.28991/CEJ-2024-010-04-06 Full Text: PD
Effect of Non-Class Fly Ash on Strength Properties of Concrete
No full textDeveloping of green construction and reducing CO2emissions in the environment is a priority for industry in the coming years. Recycling fly ash in the concrete industry is a well-known way to reduce environmental impact. Aside from this benefit, there are numerous other positive effects of incorporating fly ash into concrete; however, in this research, the objective is to replace cement with a different percentage of non-class fly ash with high CaO, more than 42%. The analyzed variables are non-class fly ash properties, the effect of fly ash presence on the main properties of concrete and examining the optimum of non-class fly ash in ordinary concrete C-25/30 and high-performance concrete C-50/60. All investigations took place in the laboratory by producing 24 different mix designs and more than 1000 specimens to examine: consistency, setting time, shrinkage, and compressive strength in the short and long terms of curing. Recycling industrial waste in new construction, especially fly ash because of its non-uniform properties, still has some obstacles and is not a practical issue, but the future must be environmentally friendly, and this research proves that the objective of producing sustainable ordinary and high-performance concrete was achieved by replacing 40% of cement with non-class high CaO content fly ash. Doi: 10.28991/CEJ-2024-010-03-02 Full Text: PD
Quality of Harvested Rainwater from a Green and a Bitumen Roof in an Air Polluted Region
No full textA one-year study was conducted to evaluate the impact of air pollution and roof coating on runoff quality. An existing 440 sq meter bitumen roof of a single-story building was coated with an extensive green roof layer on one half. Rainfall and runoff samples from both roofs were collected during 11 rainfall events after the separation of the first flush. The study monitored several key parameters, including pH, electrical conductivity (EC), turbidity, chemical oxygen demand (COD), ammonium nitrogen, nitrate nitrogen, and phosphates. The study revealed that both types of roofs altered the rainfall quality, but the changes caused by the green roof were more substantial. Although the retention of runoff from green roofs has a widely acknowledged positive impact on collecting systems, our study shows that green roofs also result in a 7.5-fold increase in COD concentrations, a 5.4-fold increase in the sum of ammonium and nitrate nitrogen, and a 2.3-fold increase in phosphates compared to bitumen roofs. A clear link between the quality of rainwater/runoff and air pollution was not established. The study's findings will aid in the development and management of local rainwater harvesting systems and enhance global understanding of the primary quality parameters of various roof types, particularly in regions with air pollution. Doi: 10.28991/CEJ-2024-010-05-015 Full Text: PD
Optimizing Gene Expression Programming to Predict Shear Capacity in Corrugated Web Steel Beams
No full textCorrugated web steel systems, such as corrugated web girders (CWG) and beams (CWSB), have the potential to influence the modern construction industry due to their unique properties, including enhanced shear strength and reduced necessity for transverse stiffeners. Nevertheless, the lack of a rapid and accurate design approach still limits its wide applications. Recently, gene expression programming (GEP) has been employed to predict the shear capacity of cold-formed steel channels, demonstrating superior predictive accuracy and compliance with established standards. This study applies GEP to predict the shear capacity of sinusoidal CWSBs and optimizes its predictive performance by employing a systematic grid search to explore combinations of chromosomes, head sizes, gene counts, and linking functions. The process involved testing 19 different parameter combinations and more than 60 developed models. The findings include the sensitivity of the model's performance to gene count and the critical role of the linking function. The optimal model in the study, GEP13, achieved R² of 0.95, an RMSE of 100.5, and an MAE of 86.6 in the testing dataset with 150 chromosomes, a head size of 12, and four genes using a multiplication linking function. Doi: 10.28991/CEJ-2024-010-05-02 Full Text: PD
XGBoost-SHAP and Unobserved Heterogeneity Modelling of Temporal Multivehicle Truck-Involved Crash Severity Patterns
No full textThis paper aims to address the critical issue of multivehicle truck crashes in developing regions, with a focus on Thailand, by analyzing the factors that influence injury severity and comparing the effectiveness of predictive models. Utilizing advanced random parameters and the XGBoost machine learning algorithm, we conducted a comprehensive analysis of injury severity factors in multivehicle truck-involved accidents, contrasting weekdays and weekends. Our findings reveal that the XGBoost model significantly outperforms the heterogeneous logit model in predicting crash severity outcomes, demonstrating superior accuracy, sensitivity, specificity, precision, F1 score, and area under the curve (AUC) in both model training and testing phases. Key risk factors identified include motorcycle involvement, head-on collisions, and crashes occurring during late night/early morning hours, with environmental elements like road lane numbers and weekend hours also playing a significant role. The study introduces XGBoost as a novel and improved method for truck safety analysis, capable of capturing the complex interactions within multivehicle crash data and offering actionable insights for targeted interventions to reduce crash severity. By highlighting specific risk factors and the effectiveness of XGBoost, this research contributes to the development of data-driven strategies for enhancing truck safety in developing countries. Doi: 10.28991/CEJ-2024-010-06-011 Full Text: PD
The Influence of Customer Relationships on Supply Chain Risk Mitigation in International Logistics
No full textAdequate transportation and administration of products and resources across borders are crucial in the logistics industry, particularly in locations such as the China-Pakistan Economic Corridor (CPEC). However, other hazards are associated with this, including global disputes, geopolitical tensions, trade battles, natural catastrophes, terrorist threats, and security breaches, all of which can disrupt the supply chain. These hazards highlight the need for robust supply chain risk management (SCRM) strategies to ensure the seamless distribution of products and services in the face of adversity. To address these challenges, this study examines the impact of customer relationships (CR) on supply chain risk management in the CPEC logistics sector. A survey conducted across various transportation and logistics firms' sites obtained data from 500 staff members. After removing 50 partial replies, 450 total responses were considered. The information also includes reactions for operational supply chain risk management (OSCRM), organization performance (OP), strategic supply chain risk management (SSCRM), and customer relationship (CR). To evaluate the respondents of the survey questionnaire using the Likert scale. Partial least squares structural equation modeling (PLS-SEM) is utilized to validate the hypothesis, which is used for statistical analysis, validation of structural models, and measurement models. The measurement model established the measure's validity and reliability, while other approaches demonstrated discriminant validity. The structural model is employed to identify the significant relationships between CR and SCRM in the logistics sector. The findings emphasize CR's importance in managing the supply chain's inherent constraints, contributing to CPEC's sustainability. Overall, this research attempts to enhance understanding of the complex relationship between CR and SCRM in the dynamic world of global logistics. Doi: 10.28991/CEJ-2024-010-06-010 Full Text: PD
Utilizing Recycled Sand from Excavation Wastes for Sustainable Cement Mortar Production
No full textThis research investigates the feasibility of using recycled sand produced from excavation waste as natural sand alternative for sustainable cement mortar production. Two different types of recycled sand, namely limestone powder (RS1) and scalping powder (RS2), were collected and characterized. Thorough characterization encompassed particle size distribution, morphology, specific gravity, water absorption, and chemical composition. The recycled sands are then utilized to replace natural sand in mortar compositions, with varying proportions reaching up to 20%. The properties of the produced mortars were examined using the following tests: compressive strength, workability, density, water absorption, and thermal stability via thermogravimetric analysis (TGA). The results revealed that the inclusion of RS in cement mortar led to a decrease in compressive strength and workability, coupled with an increase in water absorption for both types of recycled sand. The decline in strength became more pronounced with higher RS proportions, with RS1 demonstrating superior compressive strength compared to RS2. Despite these effects, the thermal stability of cement mortar was only marginally impacted by the presence of RS. This research underscored the promise of recycled sand from excavation waste in cement mortar production, highlighting performance characteristics and suggesting further investigation, especially regarding thermal behavior under elevated temperatures. Doi: 10.28991/CEJ-2024-010-06-012 Full Text: PD
Use of Recycled Ceramic Powder as a Green Alternative in Mortar-Based Cementitious Composites
No full textRecognizing material waste as a significant global concern has influenced both the environment and the construction industry. The utilization of ceramic waste as a recycled material in construction projects has gained attention as an effective and sustainable approach to address environmental issues. This study examines the use of waste ceramic tile powder (WCTP) as a supplementary material in cement mortars to decrease the amount of cement required. WCTP was used in place of cement at percentages of 5%, 10%, and 20%. Four different mix designs were created and tested for the study, yielding a total of 48 specimens. Numerous investigations were carried out, including flow table evaluations, measures of dry density, assessments of compressive and flexural strengths, X-ray diffraction, and SEM-EDX testing. The objective of these investigations was to evaluate the specimens' mechanical and physical characteristics as a whole. The findings showed that using ceramic powder in place of some cement might enhance the properties of the mortar. The compressive and flexural strengths of the mortar were notably impacted by replacing 10% of the cement content with ceramic powder. The inclusion of ceramic powder significantly enhanced the mortar's microstructure interface, according to SEM-EDX studies. In the end, the utilization of ceramic powder was found to have a substantial positive impact on the environment by reducing waste. Doi: 10.28991/CEJ-2024-010-10-03 Full Text: PD
Flood Hazard Assessment Due to Changes in Land Use and Cover
No full textThis study aimed to investigate the influence of land use changes on the occurrence of flood hazards in the Pondok Karya area, Jakarta, Indonesia. Landsat OLI 8 and 7 from 2002 to 2023 were analyzed with a supervised classification tool using Envi and ArcGIS to investigate land use changes over the period. Additionally, the HEC-HMS and HEC-RAS tools were utilized for hydrological and hydraulic assessments under 25 discharge return periods (Q25), using a daily rainfall dataset from 2004 to 2021. The flood hazard index was produced using statistical and GIS methodologies and was based on Neighbourhood Associations (NAs) after qualified hydraulic model performance, indicating a Nash 0.65–Nash-Sutcliffe model efficiency (NSE) value. The analysis revealed considerable alterations in land use and cover within the Pondok Karya watershed. Consequently, the percentage of urban areas surged 30%, whereas vegetative cover declined 24%. Additionally, bare land decreased 9%, and water bodies marginally increased 3%. This indicates a 10% increase in the peak flood river flow of Mampang, from approximately 90 m³/s to 100 m³/s within this period. Subsequently, the percentage of high-risk areas increased from 42.85% (six NAs) to 57.14% (eight NAs), whereas the percentage of low-risk areas decreased from 14.29% (two NAs) to 7.14% (one NAs). Moderate-risk areas also decreased from 42.85% (six NAs) to 35.71% (five NAs). The study found that despite vegetative cover exceeding 30%, the capacity of the Mampang River remained inadequate, and the risk of flooding increased with the impact of its conversion. Additionally, the soil properties and social intervention factors contributed to the performance of the inundation model. Our study underscores the need for further research to mitigate flood risks and advocate interventions such as reservoir construction or river normalization in the upper Mampang catchment area. This study is useful for both local and central governments, which act as decision-makers to reduce the risk of flooding. Doi: 10.28991/CEJ-2024-010-12-04 Full Text: PD
Durability of Fiber-Reinforced Polymer (FRP) Bars: Progress, Innovations and Challenges Based on Bibliometric Analysis
No full textThis review systematically examines the literature on the Fiber-Reinforced Polymer (FRP) bars durability in concrete matrices using bibliometric analysis to understand progress, innovations, and challenges. The objective is to explore the durability of FRP bars, which are recognized for their strength-to-weight ratio, corrosion resistance, and non-conductivity, as a potential substitute to conventional steel reinforcement. Methods involved employing bibliometric tools such as Biblioshiny and VOSviewer to analyze trends, collaboration patterns, and the global distribution of publications. Findings reveal an increase in research activity over the past two decades, significant international collaboration, and leading contributions from key countries. Critical environmental factors like alkalinity, thermal conditions, and chemical aggressors affecting the interface of fiber-matrix mechanical properties were highlighted. Advances in predictive modeling for long-term behavior conditioned FRP bars are studied, steering future research towards improved durability and sustainable construction practices. This study contributes novelty by providing a comprehensive bibliometric perspective on FRP bar durability, identifying emerging trends, and suggesting areas for future suggested research to enhance the reliability and application of FRP bars in construction. Doi: 10.28991/CEJ-SP2024-010-09 Full Text: PD