Civil Engineering Journal
Not a member yet
2007 research outputs found
Sort by
Short-, Medium-, and Long-Term Prediction of Carbon Dioxide Emissions using Wavelet-Enhanced Extreme Learning Machine
Get PDFCarbon dioxide (CO2) is the main greenhouse gas responsible for global warming. Early prediction of CO2 is critical for developing strategies to mitigate the effects of climate change. A sophisticated version of the extreme learning machine (ELM), the wavelet enhanced extreme learning machine (W-EELM), is used to predict CO2 on different time scales (weekly, monthly, and yearly). Data were collected from the Mauna Loa Observatory station in Hawaii, which is ideal for global air sampling. Instead of the traditional method (singular value decomposition), a complete orthogonal decomposition (COD) was used to accurately calculate the weights of the ELM output layers. Another contribution of this study is the removal of noise from the input signal using the wavelet transform technique. The results of the W-EELM model are compared with the results of the classical ELM. Various statistical metrics are used to evaluate the models, and the comparative figures confirm the superiority of the applied models over the ELM model. The proposed W-EELM model proves to be a robust and applicable computer-based technology for modeling CO2concentrations, which contributes to the fundamental knowledge of the environmental engineering perspective. Doi: 10.28991/CEJ-2023-09-04-04 Full Text: PD
Analysis of Barrier Factors for Collaboration in Handling Used Cell Phones for Second-hand Market Actors to Implement e-waste Management
No full textWaste management is an activity to manage residues, by-products, and used items. Handling used cell phones is one form of waste management activity. In developing countries, used cell phones are mostly handled by informal actors, where second-hand market actors for cell phones act as collection points. Some of these activities often affect the environment and the actors' health due to a lack of adequate technology. Hence, a collaboration between informal and formal actors is necessary to handle the used cell phones and reduce the adverse effects. However, several obstacles faced by informal actors can hinder such collaboration. This study explores the inhibiting factors for the collaboration between the informal and formal actors in handling used cell phones. The respondents were 424 informal actors in five areas of the Special Region of Yogyakarta (DIY Province), Indonesia. The results showed that the unavailability of infrastructure and insufficient organization significantly hindered collaboration in the Yogyakarta municipal area. As for the areas of Gunungkidul, Bantul, Kulonprogo, and Sleman regions, there were no significant factors hindering the collaboration. The results of this study can contribute for stakeholders' consideration related to e-waste handling, primarily used cell phones in Indonesia; thus, the management of used cell phones is safe for the environment and provide economic benefits for the informal actors. Doi: 10.28991/CEJ-2023-09-03-011 Full Text: PD
Historical Arch Bridges-Deterioration and Restoration Techniques
No full textHistoric buildings are the most valuable evidence of cultural heritage. They play an essential role in establishing a tangible link between the past and the present by understanding, interpreting, and tracing the epoch of civilization. Unfortunately, the high costs of restoration, vandalism, and arson take their toll. However, new technologies are having a positive impact on the restoration process and are becoming a suitable alternative to labor-intensive, expensive, and unsafe traditional inspections. Therefore, the role of non-destructive testing (NDT) as a new method is becoming more evident. Faro laser scanning, impact echo, impulse sound testing, and geoelectric tomography as non-destructive methods are leading to the inspection of historic structures to preserve their character. These new methods are representative of the development of non-contact techniques for the examination and documentation of structures. Non-destructive testing examines the internal and external structure of complex building components as well as defective areas, quantifies cracks, and detects near-surface moisture. The objective of this work is to identify new adventurous and traditional methods for the reconstruction of the Turkish arch bridges Dara-1 and Halilviran to determine the appropriate rehabilitation methods and their deterioration of construction materials, damage, and failure patterns. Bridge dimensions were measured using a Faro laser scanner, which allows inspectors to capture and evaluate data from bridges and structural components without permanently altering them. The laser captures bridge dimensions by scanning cross-sections of the structure in the horizontal and vertical planes. The data is exported in the form of point clouds that represent all visible aspects and actual dimensions of the bridge in 2D and 3D models. In comparison between traditional and laser scanning methods, the main advantages of the applied method are the time savings on-site and the creation of a three-dimensional model of the structure, which can be used to collect precise and accurate surface data of objects in a non-destructive manner. Doi: 10.28991/CEJ-2023-09-07-010 Full Text: PD
Effect of Class F Fly Ash on Strength Properties of Concrete
No full textReducing the amount of CO2 emissions in the environment is one of the priorities of the EPA and other environmental agencies. A way to reduce CO2 emissions is by using fly ash in the concrete industry. Aside from environmental benefits, fly ash has numerous quality advantages; some of the positive effects were recognized earlier; however, in this research, the objective is to replace cement with a different percentage of class F fly ash with a low CaO content to produce sustainable concrete. Laboratory tests were performed to examine the rational percentage of cement replaced by class F fly ash in ordinary concrete C–25/30 and high-performance concrete C–50/60. In total, twelve different mix designs were prepared to examine consistency, setting time, shrinkage, and compressive strength in different periods of curing for more than 600 days. Using recycled material in new buildings still has some obstacles, but the future of construction must be green, so this research indicates that the objective of producing ordinary and high-performance concrete was achieved by replacing 30% of cement with class F fly ash. Doi: 10.28991/CEJ-2023-09-09-011 Full Text: PD
Post Fire Behavior of Structural Reinforced Concrete Member (Slab) Repairing with Various Materials
No full textOne of the most significant building materials used to build a variety of infrastructure, military, and civil structures is concrete. It can effectively withstand fire mishaps for a long period of time. This study employs a finite element simulation approach in Three steps: the first involves applying mechanical loading, the second involves applying mechanical and thermal loading; and the third involves strengthening the damaged model. Two different strengthening procedures were used to evaluate the performance of the fire-damaged slab. Two types of strengthening techniques”carbon-fiber-reinforced polymer (CFRP) sheet and slurry-infiltrated fibrous concrete (SIFCON) jacketing”were used. Studying the performance of SIFCON and CFRP together and in two different thicknesses of each for repairing both normal and high-strength concretes after fire exposure is considered limited. An investigation of their behavior can provide insights into how effective the restoration of strength is. The study aims to assess how well various repair materials perform in restoring the durability and strength of reinforced concrete members after being exposed to fire. This will assist in determining the best materials for concrete repair after a fire. Results show that the enhancements by SIFCON with a thickness of 30 mm significantly improved many indices, including load displacement behavior, ductility, and absorption energy of the slab. Doi: 10.28991/CEJ-2023-09-08-013 Full Text: PD
Enhancing Sustainability and Economics of Concrete Production through Silica Fume: A Systematic Review
No full textThis review article addresses the problems associated with the carbon footprint of the cement industry. The PRISMA framework methodology was for data extraction from published studies. In-depth research has been done in the literature on using silica fume as a cement replacement in concrete production, considering environmental, engineering, and economic (EEE) factors. The strength, durability, and economic parameters results revealed a positive variation of up to 5–20% substitution of silica fume. However, most past studies reported the threshold at a 10% replacement ratio. A novel benefit-cost ratio analysis was also done in this review study. The benefit-cost ratio analysis reveals the economically beneficial effects that can be achieved in sustainable silica fume-based concrete with a (5–20%) silica fume combination. The benefit-cost ratio showed positive effects, up to 20% cement replacement with silica fume. Hence, the higher cement replacement with silica fume is also beneficial in terms of the benefit-cost ratio. Further research has been proposed based on the findings of this review study. Doi: 10.28991/CEJ-2023-09-10-017 Full Text: PD
Land Readjustment Model for Transit-Oriented Development (TOD) Projects: Generating Optimal Financial Benefits
No full textTransit-Oriented Development (TOD) projects are increasingly recognized as vital components of sustainable urban planning, aiming to create compact, walkable, and mixed-use communities centered around high-quality public transportation systems. However, implementing TOD projects poses significant challenges, especially in land acquisition and redistribution. This research addresses these issues in the context of the MRT Jakarta project and proposes a land readjustment approach as a potential solution. The study combined qualitative and quantitative methods to compare existing and ideal land use in the TOD area and benchmark successful TOD models from different countries. A comprehensive financial analysis was performed to assess the potential financial impacts of the proposed model. The analysis reveals differences between the existing land use in the Fatmawati TOD area and the ideal TOD model, suggesting the need for adjustments to achieve better land use diversity and economic vibrancy. The financial analysis demonstrates positive feasibility for the TOD project, surpassing the minimum attractive rate of return (MARR) threshold. However, the potential value of the reserved area covers only 16% of the total land readjustment (LR) costs, indicating the necessity for further measures to enhance financial feasibility. The study proposes leveraging existing apartment buildings as temporary relocation sites, optimizing resources, and increasing overall financial viability to address substantial relocation costs. Exploring different property redistribution scenarios reveals the importance of balancing landowners' benefits with the developer's financial feasibility for a successful TOD project. Overall, this research provides valuable insights and a comprehensive framework for implementing thriving and sustainable transit-oriented communities in Jakarta. Further research and collaboration among stakeholders are essential to refine the proposed model and ensure successful TOD project implementation in the future. Doi: 10.28991/CEJ-2023-09-10-012 Full Text: PD
Seismic Risk Assessment and Rehabilitation Method of Existing RCC Structures Using Micro Concrete
No full textAging reinforced concrete (RC) building structures typically experience more severe damage and are prone to collapse during earthquakes, constituting a primary factor in casualties and direct economic losses. To enhance the seismic performance of these old structures, this paper proposes a seismic risk assessment and a micro-concrete restoration method. It applies the process to an existing three-story reinforced concrete structure. A practical framework for mitigating structural vulnerabilities in seismic-prone regions was proposed. Then an as-built survey was conducted to create as-built architectural and structural drawings. Concrete core tests, ferroscans, and rebar tests were also performed. Based on field surveys and test data, nonlinear static and dynamic analyses have been used to evaluate structural safety. Concrete column jacketing was used to strengthen weak existing columns with micro-concrete. In assessing the structural response of retrofitted buildings, a comparison was made to their initial state. The comparison shows that applying concrete column jacketing with micro concrete can reduce other structural elements' demand capacity ratio (DCR), minimize maximum displacements, and enhance overall stiffness. The results indicate that the proposed method effectively evaluates the seismic risk of aging structures and enhances seismic resilience in existing buildings. Moreover, the application to the actual structure demonstrates that micro-concrete is highly durable and compatible with parent-concrete. Doi: 10.28991/CEJ-2023-09-12-04 Full Text: PD
Consideration of Temperature Factors when Designing Butterfly Check Valves for Hazardous Production Facilities
No full textThe safety of hazardous production facilities is directly related to the reliability of pipeline systems, which must be ensured regardless of environmental conditions. Accidents on pipeline sections can have catastrophic consequences associated with damage to human health and the environment. Damage to the metal of pipeline elements during operation due to internal corrosion occurring under the influence of the working fluid is one of the main reasons for failure. This study aims to develop an improved butterfly check valve (BCV), which is a pipeline element. For this purpose, various structural materials used in the production of check valves were analyzed, and the changes in their mechanical properties under the influence of temperature were also considered. Based on this material, a butterfly check valve was developed. The stress-strain state of the developed structure was assessed using the finite element method (FEM). Strains, stresses, and displacements were calculated to evaluate valve performance. These calculations are necessary to determine the most loaded elements of the BCV at the maximum and minimum ambient temperatures. The following conclusions were obtained: X6CrNiTi18-10 stainless steel grade is the most suitable material for piping systems transporting liquids in production facilities. On the basis of the simulation results, the values of equivalent stresses, maximum strains, and displacements were obtained. The research results confirmed the performance of the improved design, the unhindered motion of the working fluid in the working direction, and the convenient connection to horizontal and vertical sections of the pipeline. Doi: 10.28991/CEJ-SP2023-09-020 Full Text: PD
Relationship of Rainfall Intensity with Slope Stability
Get PDFThe impact of rainfall on landslides is not an uncommon issue worldwide, including in Malaysia. It is a major challenge for geotechnical engineers to ensure the constructed slope is safe and can sustain longer periods of time, including during heavy rainfall. Kota Belud, Sabah, has been selected as the study area to meet the study objectives. Heavy rainfall has been recorded every year within Kota Belud, which has caused a repetition of landslide occurrences within the hilly areas, especially during the monsoon season. Presently, there is no local procedure for determining the rainfall intensity value for slope stability analysis. This study utilized the rainfall intensity value from Hydrology Procedure 26. Seepage analysis conducted shows rainwater infiltration has caused the groundwater level to increase from rainfall starts until 0.5 m below ground level and decrease after rainfall stops, creating fluctuations in the groundwater level during the wet and dry conditions within the wetting front. The factor of safety of the slope shows a decreasing trend, with a reduction of around 27 to 33% after 24 hours of rainfall in conjunction with the changes in groundwater level. However, the factor of safety increased by around 3% from the initial condition after 48 hours. The objective of this study is to identify the factor of safety of a rainfall-induced slope within Kota Belud utilizing the rainfall intensity design limits from Hydrology Procedure 26. Doi: 10.28991/CEJ-SP2023-09-06 Full Text: PD