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2007 research outputs found
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Fuzzy Bayesian Belief Networks Method on Risk Assessment of EPC Pipeline Project
No full textSubsea 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
Development of Airport Pavement Condition Evaluation Using Dominant Damage and Grid-Based Analysis
No full textAirport Pavement Condition Index (PCI) is a measure of pavement stability represented by an index ranging from 0 (failed) to 100 (best). The PCI evaluation procedure includes a series of steps, which are time-consuming and expensive. Therefore, this study aimed to propose an alternative PCI evaluation procedure that focused on major pavement damage using a grid-based system. The methods used in the analysis included discussions with expert panels and linear & nonlinear regression analysis. The results of the deduct value curve showed good statistical performance with an average RMSE of 1.80 and an average R² value of 0.85. The sample unit size with a grid system of 3í—5 m² produced good accuracy with an average standard deviation of 7.89 at the study locations of PKY, TJQ, and TKG airports. Additionally, the PCI value decline model as a function of pavement age produced an estimated PCI decline of 3.23 per year. Grid-based PCI analysis was further proven to improve the accuracy of PCI values and consequently increased the efficiency of runway condition investigation time and costs by 27.30% compared to standard methods. Future studies were recommended to integrate this PCI evaluation procedure with a classification algorithm for airport pavement damage. Doi: 10.28991/CEJ-2025-011-05-011 Full Text: PD
Retrofit Design for Climate Resilient Housing: Strategies for Architectural Adaptation to Climate Change
No full textThis study examines design flaws in single-family homes in the UAE, worsened by climate change-triggered rainfall and escalating maintenance requirements. The research focuses on three objectives: identifying existing weaknesses, analyzing building materials and construction methods, and proposing enhanced retrofit design standards. The methodology comprises both secondary data, gathered through literature reviews, and primary data obtained via site visits, participatory observation, and case studies. Examining multiple UAE regions, particularly six case studies in affected housing in Dubai, Sharjah, and Ajman, underscores widespread concerns in resilient housing, revealing deficiencies in drainage, waterproofing, and protective detailing. Notable problems include inadequate drainage slopes, subpar sealing around structural penetrations, and insufficient moisture barriers. These issues compromise structural integrity, inflate maintenance costs, and pose health hazards from mold and poor indoor air quality. By assessing current conditions, the study suggests various retrofit solutions, such as improved water-resistant coatings, slope modifications, drip edges, and overhangs. Findings emphasize rigorous detailing, robust materials, and periodic inspections to mitigate impacts from intensifying rainfall. Additionally, broader urban planning strategies, such as flood risk assessments and upgraded infrastructure, are crucial in minimizing future water intrusion. Collectively, these insights advocate novelty in research and set a blueprint for a fundamental shift in UAE housing design, prioritizing climate resilience, structural longevity, and occupant well-being in an era of rapidly changing environmental conditions. Doi: 10.28991/CEJ-2025-011-03-011 Full Text: PD
Assessment of Primary and Secondary Compression Parameters of Tropical Fibrous Peat Using Improved-CRS Consolidation Test
No full textPredicting 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
Nonlinear Finite Element Analysis of I-Steel Beam with Sinusoidal Web
No full textFor structural models, existing research frequently uses deterministic numerical analysis. Test findings, however, constantly point out uncertainties, especially about variables like the imposed load's amplitude, geometrical dimensions, material unpredictability, and inadequate experiential data. In response, scholars have focused more on probabilistic design models, realizing their importance for precisely forecasting structural performance. This research aims to incorporate reliability-based analysis into the numerical modeling of steel beams with sinusoidal webs. A steel welded plate beam with an I-section and a sinusoidal web has been taken into consideration in this study. The web height is 750 mm, the web thickness is 2.0 mm, the flange width is 300 mm, and the flange thickness is 5.0 mm. The beam's length, l = 1000 mm, has two 10.0 mm thick stiffeners positioned beneath the applied load to stop the flange from failing locally as a result of load concentration and end plate supports that are 5 mm thick. The commercial software application ANSYS ver. 2019 R3 has been used to perform a nonlinear finite element analysis in order to examine the failure modes and load capacities. In the first stage of this study, the changing of the amplitude/period ratio, A/P, was taken into consideration to examine the failure capacity loads and deformed shapes to optimize the amplitude/period ratio. In the second stage, the optimum amplitude/period ratio, A/P, was taken, and changing the period/span ratios, P/L, made the best use of the period/span ratios by examining the failure capacity loads and deformed forms. Doi: 10.28991/CEJ-2025-011-03-08 Full Text: PD
Consolidation Behavior of Soft Soil Treated with PVDs and Vacuum-Surcharge Preloading
No full textPrefabricated vertical drain (PVD) combined with vacuum-surcharge preloading is a widely used ground improvement technique to accelerate the dissipation of excess pore water pressure and reduce the soil compressibility. However, difficulties in the numerical simulations of water dissipation and equivalent permeability of soil with PVDs in three-dimensional (3D) and two-dimensional (2D) settings cause substantial deviation of numerical results from observational data. Moreover, the optimum length of PVDs has not been well documented. Accordingly, this work analyzes a project in Dong Nai, Vietnam, where a 37-meter-thick soft soil was treated with PVDs and vacuum-surcharge preloading. In this work, the field observations and finite element method with consolidation theory were used to analyze the ground settlements, lateral displacements, and excess pore water pressure. The observed and simulated data shows that (i) the rate of settlements in the first 60 days of increasing preloading pressure is about 2.1 times faster than that in the next 110 days of constant preloading pressure, (ii) at 170 days, the ground-surface lateral displacement at the toe of the embankment is around 50 mm and reaches its maximum value of 150 mm at 1.55 m depth, and (iii) the dissipation of pore water pressure is closely correlated with the settlement rate. Moreover, back analysis indicates that a permeability conversion ratio from 1.872 to 4.538 should be applied to achieve the same degree of consolidation between 3D and 2D models. Lastly, the optimum length of PVDs in this project is 28 m, around 76% of the fully penetrated length into the soft layer
Piezometer Time-Lag and Pore Pressure Ratio for Identification of Dam Internal Erosion
No full textEarth dams on complex geology without proper foundation treatment often face the risk of seepage problems. Sufficient installation and interpretation of field instruments are essential for monitoring dam behavior. Three indicators are introduced for assessment of seepage behavior: time lag (TL), pore pressure ratio (PR), and trigger water level (HW). The normalized TL reflects the washing out and plugging of rock cracks, as well as the progression of internal erosion. The foundation of the studied dam consisted of foliated rocks that were highly fractured, with the axis of the foliations aligned almost in the upstream-downstream direction, with a possible low-stress zone on the syncline axis. The existing crack easily opened in the concave section of the syncline when the reservoir had risen to a certain elevation, resulting in increased permeability and a higher flow to the downstream area, known as "hydraulic fracturing” (HF). The piezometer TL clearly indicated a shorter response time as the operating period progressed. The study dam showed the possibility of HF in the foundation, as observed during 2003–2024. The progression of HF was also confirmed by the increase in PR levels toward downstream. This revealed that the ongoing progression of HF had occurred at sta.2+700, which agreed well with the location of the slip zone that had occurred in 1993. HWwas activated by the reservoir water level response also decreasing with time from 2003 to 2024, confirming that water infiltration through the rock crack progressed with time. These three indicators could act as good warning indices for seepage problems. This compiled knowledge could be transformed into a flowchart to identify the possible risks of hydraulic fracturing in the dam. If the three indices all showed the same trend, the potential for hydraulic fracturing and internal erosion would be very high. Doi: 10.28991/CEJ-2025-011-03-019 Full Text: PD
Shear Strength and Serviceability of GFRP-Reinforced Concrete Beams: A Study on Varying Reinforcement Ratios
No full textThis study investigates the behavior of GFRP-reinforced concrete beams with varying reinforcement ratios. The experimental program consists of five concrete beams tested under a simply supported four-point bending setup with a section of (250í—300) mm and a clear span of 1800 mm with a span-to-depth ratio of 2.3. The beams were reinforced longitudinally with GFRP bars with varying reinforcement ratios (Ï = 0.5, 0.9, 1.35, 1.8, and 2.25) for B1-B5, respectively. GFRP stirrups were used for the transverse direction with a spacing of 240 mm for all the beams. The results showed that raising the GFRP longitudinal reinforcement ratio to 1.35 enhanced load-carrying capacity performance and dropped at higher reinforcement ratios (1.8, 2.25) while offering better performance in controlling crack widths and deflection, which could be due to the limit of bonding with concrete. Increasing the GFRP longitudinal reinforcement ratio reduced the deflection at both service and ultimate loads with enhanced crack control. Lower reinforcement ratios of (Ï= 0.5) resulted in a brittle failure, wider cracks, and poor stiffness. Conversely, a 1.8 reinforcement ratio led to delayed crack initiation, smaller crack widths, and a balanced stiffness-to-ductility ratio being achieved. It was found that the dowel action of longitudinal GFRP bars greatly contributes to the shear strength of concrete beams, with a ratio of (Ï= 1.35) having the maximum load capacity along the tested beams. The ductility index ranged from 1.7 to 2.49. Higher reinforcement ratio beams resulted in a deeper neutral axis up to (Ï = 1.35), demonstrating improved stress distribution and reduced deformations. Doi: 10.28991/CEJ-2025-011-03-04 Full Text: PD
Flexural Behavior of Hybrid Fiber Reinforced SCC Beams with Longitudinal and Bubble Voids
No full textTo 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
Glow-Wire Analysis of Polypropylene Blends for Mechanical and Marine Engineering Applications
No full textPolymer materials are widely used due to their versatility; however, their vulnerability to fire is a significant concern, especially under electrical influences on engineered mechanical designs and marine structure applications. This study examines the fire resistance of a polypropylene (PP) blend using Glow-Wire Flammability Index (GWFI) and Glow-Wire Ignition Temperature (GWIT) tests. While previous research typically relies on flame-retardants to address flammability, this work proposes using a simple 1:1 weight ratio blend of two distinct PP types. This specific PP blend was selected to provide balanced material properties and improved processing consistency. The results from glow-wire tests were compared with previous findings to evaluate flammability performance. Our findings reveal that although the PP blend offers enhanced fire resistance compared to neat PP, it remains inferior to PP-containing flame-retardant additives. The outcomes suggest that this blended PP may be suitable for applications where mechanical properties, cost-effectiveness, and recyclability precede fire resistance, such as engineered automotive interiors, mechanical design of marine transportation, and low-risk electrical components in engineering infrastructure. This initial research contributes valuable insights into the fire behavior of PP blends. Moreover, it establishes a foundation for future investigations into polymer fire resistance, encouraging additional glow-wire testing on other polymer systems