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2007 research outputs found
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Enhancing Risk Assessment in Toll Road Operations: A Hybrid Rough Delphi-Rough DEMATEL Approach
No full textThis study aims to identify significant risks and their relationship to the successful operation of the Trans-Sumatra toll road in Indonesia. The research utilizes the Delphi and DEMATEL methods, along with rough set analysis, to identify and evaluate 28 risks associated with toll road operations in Sumatra. The research identifies 13 dominant risks, including policy changes, government intervention, inflation, financial distress, fluctuation of interest rate, fluctuation of currency, high cost of maintenance, low volume of traffic, competitive routes, overloading vehicles, many infrastructure defects, and natural disasters. In this case, natural disasters, inflation, and vehicles with excessive loads are the most dominant cause factors because those risks have the highest cause value based on the cause-effect diagram. Furthermore, the prominence diagram reveals that income risk, policy changes, and financial distress have notable implications for operational activities. The study presents a MCDM risk assessment approach that incorporates rough set analysis, providing a comprehensive understanding of the critical risk relationship factors for toll road operations. By integrating rough set analysis, this research contributes to the field of toll road operations and risk assessment. The identified risks and their relationships serve as a foundation for developing effective strategies for toll road operational management. Doi: 10.28991/CEJ-2023-09-09-03 Full Text: PD
Evaluating Willingness to Pay for E-Waste Recycling in Vietnam
No full textE-waste is generating rapidly, potentially causing risks to the environment and public health. Formal collection and recycling are necessary to reduce risk and exploit the value of e-waste. This study was conducted to assess factors affecting the willingness to hand over (WTH) and the willingness to pay (WTP) for the recycling e-waste cost of young consumers in Vietnam. The methods of descriptive statistics, regression analysis, and ANOVA were used to analyze the data of 403 interviewed students. The research results show that a high percentage of students were willing to hand over and willing to pay the cost of recycling. According to the results of the regression analysis, WTH was mainly influenced by the attitude towards recycling. Students highly assessed the importance of environmental considerations, recycling costs, convenience, and information security. Meanwhile, students seriously lack knowledge about policies, legal regulations, and information about e-waste collection and treatment programs. This knowledge factor had a major impact on students' willingness to pay for recycling costs. This study makes a meaningful contribution to the scarce data source on electronic waste in Vietnam. Dissemination of information and establishment of e-waste collection points are essential solutions that need to be taken to promote participation in e-waste recycling. Doi: 10.28991/CEJ-2023-09-10-03 Full Text: PD
Effect of Openings on the Torsional Behavior of SCC Box Beams Under Monotonic and Repeated Loading
No full textRepeated Torsional loading occurs in many concrete structures, such as offshore structures, freeways, multistory parking garages, and other structures; however, repeated torsional loading is still poorly understood. This study aims to investigate the effect of openings on the ultimate and cracking torques, angle of twist, and modes of failure of self-compacted R.C. box beams under monotonic and repeated loading. Two groups of eight half-scale box beams with different numbers of circular openings in the web with a diameter of about 30% of the hollow box dimension were investigated. The first group (I) included four beams: one was the control box beam without openings, whereas the rest of the beams were hollow with one, two, or three openings in the web tested under monotonic loading. The second group (II) consisted of the same details as the first one tested under repeated loading. The range of the repeated loading was about 30% and 60% of the ultimate load of the monotonic tests. The study showed that the cracking and ultimate torques and the angle of twist of the tested beams were significantly reduced due to openings in the web. Results revealed a more pronounced effect for monotonic loading, with a maximum reduction of 20% and 26.8% in cracking and ultimate torsional strength, respectively, compared to monotonic loading. Moreover, results revealed that repeated loading causes inelastic deformations in proportion to the number of loading cycles. Doi: 10.28991/CEJ-2023-09-09-015 Full Text: PD
Influential and Intellectual Structure of Geopolymer Concrete: A Bibliometric Review
No full textThe objective of this bibliometric review is to deliver an in-depth examination of the dynamic field of geopolymer concrete, revealing its evolution, current trends, and possible future trajectories. The method involves a rigorous bibliometric analysis of research output since the field's inception in 2003, underlining key milestones and mapping research patterns. Findings show a consistent surge in geopolymer concrete research, exemplified by over 1360 annual publications, with notable contributions predominantly from Australia and India. The paper also uncovers the increasing practical applications of geopolymer concrete, especially in construction processes, underpinned by a wealth of research on fly ash, a crucial manufacturing component. Additionally, prevalent research themes include compressive strength, fly ash, and geopolymer itself. The review's novelty lies in its comprehensive overview of geopolymer concrete research, elucidating past and present trends and identifying potential future research areas. It thereby serves as a firm foundation for further studies, fostering continued growth in this promising field. Doi: 10.28991/CEJ-2023-09-09-017 Full Text: PD
A Green Way of Producing High Strength Concrete Utilizing Recycled Concrete
No full textMultiple studies have investigated the influence of recycled aggregates derived from concrete waste on the efficacy of structural concrete manufactured in recent times. By utilizing recycled aggregates obtained from construction and demolition debris, it is possible to safeguard natural aggregate resources, reduce the demand for landfill space, and promote the utilization of sustainable building materials. However, compared to natural aggregate, bonded cement mortar on recycled concrete aggregate exhibits higher porosity, greater water absorption capacity, and lower strength. The mechanical and durability characteristics of freshly poured and hardened concrete made from recycled concrete aggregate are adversely affected as a result. This study presents comprehensive experimental research aimed at examining the residual mechanical properties and resistance to acid attack of normal and high-strength mixes of recycled aggregate concrete (RAC) using the compressible packing model. Recycled aggregate was employed as both coarse and fine aggregate. The recycled concrete samples were prepared in a manner that corresponded to the proportions of both the coarse and fine aggregates. Twelve mixtures were designed and cast, and their performance was evaluated based on various strength parameters (compressive strength, splitting tensile strength, and flexural strength) as well as acid attack resistance properties (porosity and ultrasonic pulse velocity). The findings indicate that recycled concrete aggregate can be utilized in the production of high-strength concrete, with mechanical property values that are significantly acceptable compared to concrete containing natural aggregates. Moreover, the addition of Silica Fume as a cement replacement in concrete plays a crucial role in enhancing sulphate resistance. In terms of concrete product utilization, recycled concrete and its significance in this study played a crucial role in environmental preservation. Doi: 10.28991/CEJ-2023-09-10-08 Full Text: PD
A Case Study on Reducing Traffic Congestion–Proposals to Improve Current Conditions
No full textTraffic congestion has been considered one of the most serious global issues confronting all nations in recent years. Basrah City's highways in general, and particularly the highways surrounding and leading to the University of Basrah, the campus of Bab Azzubair, and the college complex, have experienced traffic congestion and higher delays. The focus of this study is to propose some solutions to mitigate traffic congestion and higher delays on these highways. Field traffic data and questionnaires where SPSS was used to analyse the collected data, and Highway Capacity Software (HCS 2010) was used to assess the level of service (LOS) on the highways. The results showed that the LOS reaches level F on Baghdad Street, while other streets range from level B to level C. Two proposals have been suggested to improve the LOS on Baghdad Street: (1) applying a park-and-ride system; and (2) widening Baghdad Street by adding two lanes in each direction. The LOS for both proposals has been evaluated, and the results showed that the first proposal performed better. The analysis of the collected data also showed that public transportation services are very limited on the highways surrounding and leading to the Bab Azzubair campus. Therefore, public transportation services should be promoted and enhanced in Basrah City. Doi: 10.28991/CEJ-2023-09-10-07 Full Text: PD
Investigation on Existing Tunnel Response to Piles Construction: A Numerical Study
No full textDeep foundations are frequently built close to existing tunnels in the urban environment. Tunnels can only withstand very small movements. The construction of bored piles and/or the subsequent loading of the piles may result in unbearable movements or stresses that could result in cracking of the tunnel linings, which worries obstacles to the tunnel structure. This research presents an understanding of the interaction issue and investigates and evaluates various geometric factors that determine the effect of the construction of the pile on the existing tunnel. However, numerical modeling was established utilizing a modified Mohr-Coulomb constitutive model for the soil strata. Numerous factors have been examined, including different locations of the pile tip to the tunnel centerline as well as variable pile diameters and lengths. The numerical analysis results revealed that the bending moment decreases as the distance from the tunnel increases from 8 to 12 m and then remains constant, while the shear stress is not affected considerably. In addition, the shear stress and bending moment increase with pile diameter and length due to the increased confinement caused by the pile. The spacing has a considerable effect on the horizontal displacement with very little effect on the vertical displacement. Moreover, there is an increase in the shear force developed in the tunnel lining with pile diameter for different spacings between the tunnel and pile. This increase becomes smaller as the pile length increases. At small spacing between the pile and tunnel (8.3 m and 12.5 m), the bending moment in the tunnel lining decreases as the pile length increases. Doi: 10.28991/CEJ-SP2023-09-016 Full Text: PD
Development of a Flow-Measuring Hydropneumatic Bench for Testing Pipeline Valves
No full textPipe fittings are an important element of any pipeline network, ensuring stable and safe operation by regulating the flow of the working medium. To control the performance of pipeline valves, it is necessary to conduct various tests, the main ones of which are hydraulic and pneumatic. It is important to expand testing capabilities and reduce time costs. The purpose of this work is to combine hydraulic and pneumatic tests into one test complex, which will reduce the time of the test complex due to the absence of the need for reinstallation and reconfiguration. The subject of the study is the determination of the design, technical, and operational characteristics of such a stand, as well as the simulation of operating conditions to confirm its operability. During the development, methods of solid and surface modeling, the finite element method, and analytical calculation methods were used. The results of the stand design are presented, and the features of the process of its development are described, including the analysis of the stress-strain state and the analysis of reliability and durability indicators. The obtained values of the distribution of equivalent stresses, deformations, and displacements of the structure elements do not exceed the maximum allowable values and do not lead to destruction. The analysis shows that the developed stand has improved capabilities compared to those previously used. Doi: 10.28991/CEJ-2023-09-01-013 Full Text: PD
Evaluation of Liquefaction Potential based on Cone Penetration Test (CPT) and Semi-empirical Methods
No full textThe phenomenon of soil liquefaction can be an induced effect of earthquake shaking where the saturated soil loses some or all of its bearing capacity and stiffness. Likewise, the increase of water pressure in the soil pores under the seismic wave causes a decrease of the shear strength. As a result, the soil becomes liquefied and susceptible to producing permanent deformations. The phenomenon of liquefaction is generally unpredictable, and neglecting it can influence the stability of structures and infrastructure foundations. Since the 1964 Alaska and Niigata earthquakes, more research works have been conducted to assess land liquefaction vulnerability. This study is undertaken in this field, whose objective, on the one hand, is to signal the phenomenon of liquefaction in the north of Morocco as a geo-technical part known for its instability and, on the other hand, to study the semi-empirical methods to adequately evaluate the liquefaction potential while specifying the most appropriate method for our case study. Similarly, the study is based on data derived from experimental results of in-situ tests applied to the embankment crossing the valley of "Oued Gharifa" on a high-speed rail line section from KP 228+400 to KP 229+375. Moreover, this research aims to show and discuss the evaluation of liquefaction potential of the experimental results of the CPT (cone penetration test) using three semi-empirical methods, namely the Juang method, the Olsen method, and the Robertson method. In doing so, we are going to compare the application results of the three semi-empirical methods in light of evaluating the liquefaction likelihood of the studied area, taking into account the nature of the soil, the variation of the safety coefficient, and the liquefaction potential for each method as well. Doi: 10.28991/CEJ-2023-09-02-013 Full Text: PD
Using FEM-AI Technique to Predict the Behavior of Strip Footing Rested on Undrained Clay Layer Improved with Replacement and Geo-Grid
No full textThe objective of this research is to predict how strip footings behave when rested on an undrained clay layer enhanced using a top replacement layer with and without a geo-grid. The study was conducted in several stages, including collecting load-settlement curves from "Finite Element Method" (FEM) models with different clay strengths, replacement thicknesses, and axial stiffnesses of the geo-grid. These curves were then idealized using a hyperbolic model, and the idealized hyperbolic parameters were predicted using three different AI techniques. According to the numerical results, the ultimate bearing pressure of pure clay models was found to be five times the undrained strength of the clay. These findings align with most established empirical bearing capacity formulas for undrained clays. The results also suggest that the initial modulus of the subgrade reaction is solely influenced by replacement thickness. Additionally, the enhancement in subgrade reaction due to the replacement layer decreases with increasing clay strength. However, the percentage of improvement decreased with higher clay strength. Moreover, the impact of the geo-grid was significant for settlement beyond 50mm, and it was more impactful in soft clay than in stiff clay. Finally, the research proposed predictive models employing the "Genetic Programming" (GP), "Artificial Neural Networks" (ANN), and "Evolutionary Polynomial Regression" (EPR) techniques, and these models exhibited an accuracy of about 88%. Doi: 10.28991/CEJ-2023-09-05-014 Full Text: PD