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2007 research outputs found
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Study on Solutions for Early Dismantling of Aluminum Formwork Systems in High-Rise Building Construction
No full textThis paper evaluated the impact of early aluminum formwork (AF) removal on the structural integrity of reinforced concrete (RC) beam-slab systems, specifically focusing on punching shear capacity, deflection, and crack width. The study provided a comprehensive analysis of the AF system, detailing its erection and dismantling sequences while examining its advantages and disadvantages. Moreover, safety principles for early formwork removal were proposed in accordance with the Vietnamese code (TCVN 5574:2018). By utilizing calculation examples based on actual high-rise building constructions and employing the finite element method, the study offered practical guidelines for the safe and effective use of AF systems, balancing rapid construction with structural safety. The findings emphasized the importance of assessing punching shear, deflection, and crack width criteria at the time of formwork removal to ensure structural safety. Results indicated that RC beam-slab systems remain safe in terms of punching shear capacity, deflection, and crack width if the shoring span does not exceed 1.6m when the concrete reaches its design strength. Furthermore, early removal of AF was feasible when the concrete achieved a strength grade of B12.5, with a shoring span of up to 1.6 m and a minimum slab thickness of 200mm. This study also contributed novel insights into optimizing construction efficiency by offering practical guidelines for the safe and effective use of AF systems, thus providing valuable recommendations for construction professionals and engineers. Doi: 10.28991/CEJ-2024-010-10-07 Full Text: PD
The Behavior of Enlarged Base Pile Under Compression and Uplift Loading in Partially Saturated Sand
No full textThe aim of this paper is to study the behavior of enlarged base piles embedded within partially saturated soils under compression and uplift loading. This type of pile is rarely excavated and cast on-site. Accordingly, to construct an enlarged base pile model, an excavator was designed and manufactured to give appropriate shape through drilling and casting in the laboratory through the design and manufacture of an excavator to produce piles with a shaft of 35 mm in diameter, 500 mm in length, and a base of 80 mm in diameter inclined at an angle of 60 degrees. Three different partial saturation soils were achieved by lowering the water level below the soil surface 20, 40, and 60 cm and measuring the suction force of each stage using a Tensiometer. The average matrix suction results were 6.4, 7.6, and 9.1 kPa for each lower water level, respectively. The test results showed that the bearing capacity of the enlarged base piles under compression load in partially saturated soil was higher than that in the case of full saturation because of matrix suction, with an improvement rate of 2.5–4.5 times compared with the case of fully saturated soil. Additionally, test results showed that the enlarged base piles subjected to uplift loading in partially saturated soil were significantly improved compared with the fully saturated condition, with an improvement rate of 1.5 - 3 times. The reason for this is the apparent surface cohesion of the sandy soil, which increases the bearing capacity of the sandy soil. This study sheds light on the phenomenon of apparent surface cohesion of sandy soil and the extent of its effect on increasing the soil's resistance to the loads placed on it. Doi: 10.28991/CEJ-2024-010-10-08 Full Text: PD
Effect of Climate Change on Wetland Areas in West Iraq Using Satellite Data and GIS Techniques
No full textIraq is considered to amongst those countries in the Middle Eastern region that are most exposed to the effects of climate change, which will have notable effects on wet areas and lakes. Natural or industrial water resources must be paid particular attention due to their importance in preserving environmental and biological systems, in addition to their economic and social importance. As a result of the effects of climatic change, water resources in Iraq have seen a multitude of changes. The aim of this study is to determine changes in the wetland area around AL-Razzaza Lake, Karbala province, Iraq, during the years 2000, 2005, 2010, 2015, and 2023. Landsat 5 satellite data from 2000, 2005, and 2010, and Landsat 8 and 9 data for 2015 and 2023, respectively, were used in this analysis, which was conducted using NDWI as a free, open-source program (ArcMap 10.8) to detect these changes; NDWI is a natural water anisotropy index used to detect the surface area of bodies of water in satellite images. The results revealed a clear decrease throughout the study period, as the wetland area of the lake in 2000 was 1189.7 km2, which represents a decrease of 34.3% compared to the total area of the lake (1810 km2); it decreased by 52.7% in 2005 (855.5 km2) and continued to decrease for 2010, 2015, and 2023, by 79.2%, 80%, and 85%, (376.5 km2, 362.9 km2, and 270.4 km2, respectively). The wetland area of Al-Razzaza Lake decreased between 2000 and 2023 by 919.3 km2, that is, an average of 40 km2per year. It was found that the lake wetland area sharply declined over the study period due to a lack of water surface resources via the Euphrates River, as well as climatic changes and poor water resource management. It is anticipated that the lake will lose more than half its current wetland area by 2040 if the current decline continues. These results are considered important in terms of preparing a strategic plan to preserve water bodies and wet areas in Iraq, including Al-Razzaza Lake. Remote sensing and GIS technologies have played a major and essential role in detecting such changes. Doi: 10.28991/CEJ-2024-010-09-013 Full Text: PD
Experimental and Numerical Study of Soil Strata for Underground Transportation System: A Case Study
No full textIn the current capital of Yemen, Sana'a, a time-efficient and economical transportation system is one of the greatest challenges to overcome the increasing urbanization for many years. Rapid transport systems use tunnel structures to reach the city's most inaccessible areas. Given the Gulf's geopolitical unrest, these structures could also serve as emergency shelters. Consequently, this research conducted an experimental soil exploration investigation in Sana'a, Yemen, to identify potential tunneling sites for the city's rapid transit system. The field exploration, in-situ, and laboratory soil testing at the four locations were performed with the collaboration of the Ministry of Public Works & Highways, Yemen. Further, to calculate the geotechnical parameters for tunnel design, numerical analysis has been carried out using the finite element package ABAQUS, and two-dimensional plane-strain numerical models of underground tunnel structure have been developed to conduct the parametric study in different soil types and boundary conditions under static loading. The material behavior of soil strata has been incorporated into the well-known Mohr-Coulomb constitutive model. The field investigation found that the geotechnical properties of the soil strata in Sana'a have a lot of variation. The numerical study shows that the maximum deformation in the concrete liner of the tunnel was observed at the crown of the tunnel. The ovalling effect in tunnel concrete liner was also seen in all the tunnel models, and the maximum ground settlement at sites 1, 2, 3, and 4 was estimated to be approximately 4, 25, 17, and 11 mm, respectively. Doi: 10.28991/CEJ-2024-010-01-03 Full Text: PD
Effect of Breach Parameters and Progression Curves on Dam Failure Hydrograph
No full textUnderstanding the failure mechanisms of embankment dams due to overtopping is vital for flood protection, covering planning, design, and flood defence zone management. Typically, dam failure-induced flood wave propagation is modeled in 1D using Saint-Venant's equations. The breach itself is often simplified as a trapezoid defined by its final height, average width, side slopes, and the time required for complete formation. Often overlooked is the dynamic process of breach formation and its correlation with the outflow hydrograph during dam failure. This research scrutinizes the impact of breach parameters and progression curves on the outflow hydrograph. Two approaches were formulated: one crafting new equations for average breach width and formation time using global dam failure data and regression analysis, and the other employing these equations in 2D HEC-RAS dam failure modeling, comparing them with literature recommendations. The derived equations yield results similar to those in the literature. This study introduces a novel aspect by examining the mutual influence of results and floodplain areas on the outflow hydrograph, offering a comprehensive perspective on dam failure dynamics and its hydraulic consequences. Doi: 10.28991/CEJ-2024-010-02-08 Full Text: PD
Stress Concentration Factors in KT-Joints Subjected to Complex Bending Loads Using Artificial Neural Networks
No full textFatigue analysis of tubular joints based on peak stress concentration factor (SCF) is critical for offshore structures as it determines the fatigue life of the joint and possibly the overall structure. It is known that peak SCF occurs at the crown position for in-plane bending (IPB) and at the saddle position for out-of-plane bending (OPB). Tubular joints of offshore structures are under multiplanar bending, comprising IPB and OPB. When a joint is subjected to IPB and OPB loads simultaneously, the peak SCF occurs somewhere between the crown and the saddle. However, existing equations estimate SCF at the crown and saddle only when a joint is subjected to IPB or OPB. It was found that the position and magnitude of peak SCF under simultaneous IPB and OPB depend on the relative magnitudes of these uniplanar load components. The crown and saddle position SCF can be substantially lower than the cumulative peak SCF. Empirical models are proposed for computing peak SCF for KT-joints subjected to multiplanar bending. These models were developed through regression analysis using artificial neural networks (ANN). The ANN training data was generated through 3716 ANSYS finite element simulations. The empirical model was validated using models available in the literature and can determine peak SCF with an error of less than 1.5%. Doi: 10.28991/CEJ-2024-010-04-04 Full Text: PD
Examining Soil Microplastics: Prevalence and Consequences Across Varied Land Use Contexts
No full textIn an extensive exploration of microplastics within soil environments, our study aims to investigate the presence, spread, and ecological impact of microplastics in soil, focusing on Makassar City, Indonesia. Using a Sinher binocular digital microscope, we visually examined soil samples in Petri dishes, measuring microplastic sizes with Image-J software. Fourier-transform infrared (FTIR) spectroscopy was also employed for additional identification and analysis of polymer compositions. Our research uncovered a widespread presence of microplastics across diverse soil types and land uses, including residential, fishpond, agricultural, landfill, coastal, and bareland areas. The concentration of these microplastics was found to be between 16.6 to 21.9 particles/gram, showing consistency across most land uses, with some variations in coastal areas. We noted a significant variety in microplastic forms, predominantly fragments and films, across the different land uses. A wide range of colors was observed, including blue, green, red, and transparent. Polyethylene (PE) and polypropylene (PP) were identified as the predominant polymers. Our study highlights the non-uniform distribution of microplastics in soil, suggesting potential significant impacts on soil organisms and the wider ecosystem. These findings underscore the critical need for more comprehensive research on the ecological implications of microplastics in soil environments. Doi: 10.28991/CEJ-2024-010-04-017 Full Text: PD
Properties and Microstructure of Treated Coal Bottom Ash as Cement Concrete Replacement
No full textSustainable construction is a rapidly growing area of research focused on using industrial waste to replace Portland cement in concrete. This approach not only reduces CO2emissions from cement production but also serves as an effective way to diminish the environmental impact of concrete production. This study aims to investigate the properties of Coal Bottom Ash (CBA) after undergoing two different treatments: flotation and burning. It also evaluates the impact of CBA as a cement replacement in concrete with different replacement percentages (5%, 10%, 15%, and 20%). Chemical analysis of CBA has revealed that it can be classified as a pozzolanic material due to its high content of silicates, aluminates, and iron oxides. The microstructure of CBA showed a porous, angular, and irregular surface with many voids. The findings of this study revealed that the optimum mix was 10% CBA, resulting in a 2% increase in compressive strength compared to the control mix after 56 days of curing. Additionally, the study evaluated the effects of sulfate and chloride on concrete. It was found that the mix with the burning treatment showed an overall increase in strength, while the flotation treatment did not reach the control mix's strength in any of the curing periods. Furthermore, the results demonstrated that CBA has significant potential as a cement replacement material, and the burning treatment showed improvement in concrete's overall properties compared to the raw material in terms of mechanical and chemical properties while reducing greenhouse gas emissions and enhancing the environment. Doi: 10.28991/CEJ-2024-010-04-08 Full Text: PD
BIM Adoption in MENA's Construction Industry: A Contractor's Perspective
No full textThis study delves into the multifaceted landscape of Building Information Modeling (BIM) adoption and implementation across the Middle East and North Africa (MENA) region's construction industry. Employing an online survey methodology, the research scrutinizes the varied profiles of contractors. Through regression analysis, the study investigates the impact of institutional pressures on the contractors' BIM adoption, implementation, encountered barriers and challenges, expected benefits and outcomes, and related expertise and training. The analysis then extends to evaluate the interrelationships among such BIM variables. The key findings reveal significant influences of institutional pressures on BIM adoption and benefits as well as their expected benefits and outcomes but less impact on overcoming BIM barriers and challenges and enhancing expertise and training. The research highlights the limited role of BIM expertise and training in the adoption, implementation, and realization of its benefits and outcomes within the MENA construction sector. Furthermore, the study concludes that barriers, challenges, benefits, and outcomes don't have a significant effect on BIM's adoption and implementation. The study also evaluates the primary benefits and outcomes of BIM alongside the main barriers and challenges encountered. Crucially, the research identifies and dissects the salient barriers to BIM deployment, such as awareness and expertise deficiency, financial and human resource constraints, training shortages, and resistance to change. This study not only provides a detailed snapshot of the BIM landscape but also lays the groundwork for addressing the persistent challenges and harnessing the full potential of BIM in revolutionizing construction methodologies in the MENA region. Doi: 10.28991/CEJ-2024-010-08-015 Full Text: PD
The Behavior of the Tunnel Reinforced with Geogrid in Soft Soil Under the Effect of Axial Load
No full textThe soft soil's poor tensile strength requires reinforcing to increase bearing capacity, improve stability, and reduce settlements. This study assessed the efficacy of using geogrid layers to enhance and secure the soil surrounding tunnels. enabling the tunnel to endure pressure, particularly during excavation. The utilization of geogrids in soil reinforcement has experienced a substantial rise as a result of their consistent dimensions and exceptional tensile strength. To quantify the exerted force transferred to the tunnel, during this study utilized various testing tools, including a soil container, a steel loading frame, data loggers, a 0.5-ton load cell, and a miniature pressure cell. The vertical loads are applied by utilizing a hydraulic jack. A series of eleven tests were conducted on the tunnel at two depths of 1.5D and 2.5D, where D is the tunnel's diameter. The different models of geogrid layers showed that using two layers of geogrid at the first dimension, 0.5B and 1B from the base, led to a significant increase in tunnel stability. Two layers of reinforcement were used in both directions, giving the soil a high bearing capacity for the loads applied to the tunnel. This resulted in an improvement, a 1.65 in 1.5D and a 1.82 in 2.5D. The pressure above the pipe decreased by approximately 7.1kPa at the first tunnel depth and about 3.5kpa at the second depth. In conclusion, the study found the geogrid improves the stability of the tunnel by equally distributing loads and minimizing stress concentrations, hence decreasing the chances of collapses or deformations. Doi: 10.28991/CEJ-2024-010-08-04 Full Text: PD