2031 research outputs found
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Fuzzy Bayesian Belief Networks Method on Risk Assessment of EPC Pipeline Project
Get PDFSubsea gas pipeline projects are experiencing significant technical and managerial challenges across Engineering, Procurement, and Construction (EPC) phases. To address the challenges, effective risk management in the early project phases is essential to mitigating cascading failures that cause significant schedule delay and cost overrun. Therefore, this study aimed to apply the Fuzzy Bayesian Belief Networks (FBBNs) method to model risk assessment during EPC phases. The findings showed that FBBNs made it possible for a new way to evaluate risks, find interdependencies, and guess what would happen next, which created a strong framework for reducing risk. Based on probabilistic analysis as supported by expert elicitation, risks from the early phase of engineering and procurement showed high probabilities of occurrence, including Incompetent Personnel, Project Mismanagement, Unsupportive Stakeholder, Corruption, and Design Inaccuracies. A significant impact was also observed on Construction Rework, Material Quantity Increase, Construction Delay, and Cost Overrun. The results showed the importance of addressing systemic issues early in the EPC project lifecycle, emphasizing personnel competency, design accuracy, strategic and project management planning, procurement management, stakeholder management, and constructability preparation to reduce vulnerabilities. This integrated method aimed to enhance accuracy predictions by determining causal risk probability relationships in high-risk offshore environments of EPC subsea gas pipeline projects. Doi: 10.28991/CEJ-2025-011-03-013 Full Text: PD
An Experimental Study on Steel Fiber Effects in High-Strength Concrete Slabs
Get PDFThis study investigated the impact of varying steel fiber ratios by volume on the performance of HSC slabs. Incorporating steel fibers into high-strength concrete (HSC) has been shown to significantly enhance its mechanical properties, particularly by improving its load-bearing capacity. Furthermore, the addition of steel fiber reduces the reliance on traditional reinforcement bars, leading to a more efficient use of materials. This not only simplifies the construction process but also contributes to a reduction in overall construction costs. This study investigated the behavior of HSC slab specimens under loading and elevated temperatures. Three groups of specimens were created based on their thickness (8 cm, 12 cm, and 16 cm) using a single high-strength concrete mixture and four varying steel fiber proportions (0, 37.5, 75, and 150 kg/m³). Two-point monotonic loading was applied to each slab specimen until failure. To determine the splitting tensile strength, 12 cylinders were cast. Additionally, 84 cubes were cast to assess the effects of elevated temperatures and different cooling techniques on compressive strength (fcu). The results revealed that incorporating steel fibers into high-strength concrete slabs has a negligible effect on the concrete's density and compressive strength. However, it notably enhanced the splitting tensile strength and modulus of rupture. These improvements significantly boosted the material's resistance to cracking, making it more durable and better suited for applications requiring superior tensile performance. This is particularly important in structures subjected to dynamic or cyclic loading, where the risk of cracking and failure is greater. Doi: 10.28991/CEJ-2025-011-01-013 Full Text: PD
SEM-Based Decision Support Model for Cost-Quality Impact Analysis on a Fast-Track Project’s Duration
Get PDFThe fast-track technique was introduced to mitigate time overruns and meet project deadlines; however, limited understanding exists regarding how cost and quality-related decisions influence the duration of such projects. This study aims to analyze the impact of cost and quality variances on project duration, ultimately proposing a decision support model tailored for fast-track high-rise building projects. Data were collected from 159 respondents and analyzed using Structural Equation Modeling (SEM), through which four hypotheses were formulated. The findings reveal that both cost and quality variances significantly affect project duration, with quality variance also exerting a notable influence on project cost. Mediation analysis further demonstrated that cost variance serves as a statistically significant mediator between quality variation and project duration. The R² values of the proposed model indicate that 78.4% of the variation in project duration can be attributed to changes in cost and quality, while 72.9% of the variation in project cost is linked to quality changes. The Importance–Performance Map Analysis (IPMA) identified the early procurement of long-lead-time items, the adoption of a scope-freeze approach during the early design phase, and the over-design of facilities as the most critical and best-performing decisions. The model introduces novel β-values and confirms the statistically significant relationships among cost, quality, and time. Additionally, model validation metrics—including Q², RMSE, MAE, and CVPAT—demonstrated strong out-of-sample predictive power of the proposed framework
Assessment of Primary and Secondary Compression Parameters of Tropical Fibrous Peat Using Improved-CRS Consolidation Test
Get PDFPredicting the long-term compression behavior of peat using conventional Oedometer tests is challenging. This soil exhibits an unusual compression curve shape under conventional load-increment tests. Meanwhile, conducting the conventional single-load test can disrupt specimens due to its sudden load. Alternatively, a constant rate of strain (CRS) test provides a rapid consolidation method by gradually loading the specimen at a small constant strain rate. However, the inability of the conventional CRS test apparatus to measure compression under a constant load limits its applicability in providing the secondary compression curve, which is essential for predicting the long-term compression in peat. To address this issue, an improved-CRS test apparatus was developed to measure compression under a constant load. Tropical fibrous peat was collected from Palangkaraya, Indonesia. The compression curves obtained from the CRS test, which are comparable to those from the conventional Oedometer test, were used to suggest appropriate strain rate ranges for conducting CRS tests on tropical fibrous peat. The results show that the improved-CRS consolidation test provides accurate primary and secondary compression parameters of tropical fibrous peat by using appropriate strain rates, which were categorized based on the coarse fiber content (CFc). Doi: 10.28991/CEJ-2025-011-05-03 Full Text: PD
Correlation of Methylene Blue Value with the Behavior of Natural and Stabilized Expansive Soils
Get PDFThis study investigates the expansive nature of soils from various regions in Indonesia, focusing on their natural and post-stabilization characteristics. The research aims to bridge the gap in understanding the relationship between Methylene Blue Value (MBV) and soil expansivity, both in natural and stabilized states. Soil samples were systematically collected from seven locations across three Indonesian islands and subjected to a range of laboratory tests, including X-ray diffraction analysis, to determine their properties and mineral composition. Compaction and swell tests were conducted to establish Maximum Dry Density (MDD) and Optimum Moisture Content (OMC), as well as swell pressure and free swell parameters. The study further explored soil improvement techniques using cement and lime stabilizers at varying concentrations from 5% to 15%. The results indicated that both cement and lime significantly reduce swell pressure and free swell, with a 15% additive concentration being optimal for mitigation. The analysis revealed a strong correlation between MBV and soil expansivity, with higher MBV values indicating greater expansivity. Regression analysis showed a non-linear relationship between MBV and swell pressure, explaining 97.8% of the variation in swell pressure. Additionally, a linear relationship between MBV and the expansive mineral content was identified, suggesting that the Methylene Blue Test can serve as a cost-effective and rapid substitute for identifying expansive minerals in the soil. The findings highlight the reliability of MBV as an indicator of soil behavior and its potential application in predicting soil expansivity. Doi: 10.28991/CEJ-2025-011-05-020 Full Text: PD
Flexural Behavior of Hybrid Fiber Reinforced SCC Beams with Longitudinal and Bubble Voids
Get PDFTo investigate the flexural behavior of self-consolidating hybrid fiber-reinforced concrete beams containing voids experimentally, six RC beams were tested, one solid without fiber and the others containing hooked-steel and macro-polypropylene fibers with a volume fraction of 1 and 0.5%, respectively. One of the five fibrous beams was solid; two contain a series of recycled plastic balls of diameters 110 and 120 mm, and another two contain a single longitudinal circular void created by PVC pipes of diameters 90 and 110 mm. The flexural behavior of the beams was assessed depending on the load-deflection curve, load-strain curve, ductility, toughness, stiffness, and crack patterns. The experimental outcomes showed that all the tested specimens (solid and voided) failed in a flexural mode. Hybrid fiber inclusion in the solid beam improved the load capacity at different loading levels, enhanced the stiffness by 38.3%, and increased the absorbed energy by 29.55%. The presence of voids in fibrous beams decreased the loads at cracking, yielding, and ultimate stages and enhanced the ductility. The ductility index, depending on deflection and energy methods, showed higher values for voided beams. The toughness of voided beams at the ultimate stage was enhanced by 1.1% to 28%. The voided beams exhibited lower values of stiffness, and their values decreased when the diameter of the voids increased. The outcomes also indicated that the incorporation of hybrid fiber significantly minimized the strain in steel reinforcing bars at the post-cracking stage, and the presence of voids minimized the reduction effect of steel strain according to void size and shape. Doi: 10.28991/CEJ-2025-011-04-08 Full Text: PD
Hydraulic Conditions Created by Passing Flow Through and Over a Combined Weir
Get PDFIn this study, a novel broad-crested weir was designed to investigate the effect of varying rectangular gate widths (vertical slots) on the discharge coefficient and free surface profile of a compound weir. Six weir models with vertical slots were theoretically and experimentally examined in a laboratory flume under uniform flow conditions. Each weir model measured 9.5 cm in height, 30 cm in length, and 10 cm in width. The vertical slots were uniformly 7.5 cm in height, with six different widths ranging from 0.5 cm to 3.0 cm, corresponding to a range of opening area ratios (OAR) from 10% to 60%. Under different head conditions, six flow rates between 10 and 35 m³/hr were tested. Dimensional analysis and multivariable regression techniques were applied to derive a formula relating the discharge coefficient to key influencing variables. These variables include the ratio of total energy head to flume width (Ht/B), the ratio of upstream water head to flume width (Hw/B), and the ratio of slot width to flume width (Bg/B). The results indicated that the discharge coefficient (Cd) of the compound weir increases with both Ht/B and Hw/B, and with increasing slot width (Bg/B). The proposed model, which describes the relationship between measured and computed discharge coefficients, demonstrated excellent accuracy, with R²= 0.998. Furthermore, the findings showed that the width of the weir openings has a significant impact on upstream water depth, downstream free surface profiles, and the hydraulic characteristics of the resulting flow transitions. Doi: 10.28991/CEJ-2025-011-05-016 Full Text: PD
Shear Performance of ULCC and PCC: Experimental and Numerical Insights Using DIC and FEM
Get PDFThis study investigates the shear behavior of reinforced concrete beams constructed with high-calcium fly ash-based Ultra-Low Carbon Concrete (ULCC) as a sustainable alternative to conventional Portland Cement Concrete (PCC). The objective is to assess ULCC’s structural performance under shear and its potential as a low-carbon substitute. Using a dry-mix method with dry activators, six beams (five ULCC, one PCC) of identical dimensions (150 × 250 × 1800 mm) were tested under four-point bending, with variations in shear reinforcement, flexural reinforcement, and shear span-to-depth (a/d) ratios. Digital Image Correlation (DIC) was employed to monitor crack propagation and strain development, while Finite Element Modeling (FEM) provided numerical validation. Results show that increasing shear reinforcement enhanced capacity by 12.05%, whereas higher (a/d) ratios decreased it by 22.63%; increased flexural reinforcement improved shear resistance by 31.27%. FEM closely matched experimental outcomes, with a load-deflection ratio of 1.01. ULCC outperformed PCC in shear capacity and exceeded ACI 318-19 predictions. The integration of DIC and FEM offers a comprehensive analysis framework, and the findings demonstrate ULCC’s viability as a structurally efficient, environmentally sustainable alternative for shear-critical applications
Effects of H₂SO₄, HCl, and MgSO₄ Attack on Porcelain-Based Geopolymer Concrete
No full textThis study examined the durability of porcelain-based geopolymer concrete when exposed to strong acids, chlorides, and sulfates. Specimens prepared with a 14M NaOH solution and initially cured at 105°C for 24 hours were submerged in acidic and alkaline solutions for varying durations—3, 7, 14, 21, 28, 60, and 90 days. Compressive and splitting tensile strength tests were conducted to assess material performance. The results showed that immersion in H₂SO₄, HCl, and MgSO₄ solutions led to weight loss and reductions in both compressive and splitting tensile strengths. Strength deterioration was more pronounced in the early stages, with a peak weight loss rate of 15.32 g/day. After 90 days in 20% H₂SO₄, 20% HCl, and 20% MgSO₄ solutions, the residual compressive strengths were measured at 2.80, 14.19, and 3.29 N/mm², respectively, while splitting tensile strengths were recorded at 0.40, 1.21, and 0.51 N/mm². The ratio of splitting tensile strength to compressive strength (fsp/f’c) was influenced by molar concentration and immersion duration. Experimental findings revealed that a high molarity NaOH solution and elevated curing temperature enhanced resistance to HCl attack more effectively than H₂SO₄ and MgSO₄. Moreover, the experimental data closely aligned with the ACI 318 design code, though it tended to overestimate tensile strength
A Novel Approach to Selecting Rational Supports for Underground Mining Workings
Get PDFThe goal of this study is to examine the stress-strain state and stability of rock massifs to select a rational type of support for underground workings in challenging mining and geological conditions. The primary aims include increasing the speed of mine workings, reducing capital expenditure, and enhancing safety. Established and novel theoretical methods for mining, geomechanics, and rock massif management were employed. These methods involve analyzing factors affecting the mine working speed, studying the physical and mechanical properties of rocks, developing stratigraphic profiles, and assessing the stress-strain state and stability using Bieniawski's Rock Mass Rating (RMR), Barton's Q-rating, and construction norms and rules. Numerical modeling with the Rocscience RS2/RS3 software was utilized to identify failure-prone areas and determine rational support types and parameters. This study provides comprehensive insights into the stress-strain state of the massif, identifying high-risk zones, and recommending suitable support types. The findings contribute to accelerating the progress of underground work, enhancing safety, and reducing construction costs. The developed support systems for challenging mining and geological conditions were designed to increase the speed, safety, and profitability of underground workings. Additionally, this research emphasizes the significance of selecting appropriate support systems to ensure the longevity and stability of underground structures, thereby optimizing operational efficiency and cost-effectiveness. Doi: 10.28991/CEJ-2025-011-03-022 Full Text: PD