2031 research outputs found
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Post-Earthquake Liquefaction Vulnerability Mapping by Swedish Weight Sounding and Standard Penetration Test
Get PDFOn September 28, 2018, a 7.5-magnitude earthquake struck Palu City, Sigi Regency, and Donggala Regency in Central Sulawesi. It triggered liquefaction in different locations, including Balaroa, Petobo, Jono Oge, and Sibalaya; Typically, a significant number of studies conducted in the Balaroa region relied on a small amount of field test data to cover a rather large area. This research aims to map the liquefaction vulnerability by analyzing the data from both the Swedish Weight Sounding (SWS) and the Standard Penetration Test (SPT) in the Balaroa area. The SWS data was acquired through mapping using a systematic grid sampling method at ten different locations. The liquefaction potential was analyzed based on the N values by converting the SWS data (Nsw and Wsw) to Nvalues using the Inada equation (1960). Afterward, the analysis findings were verified by comparing them with the SPT data obtained from the same area. Based on the SWS and SPT data analysis results, all locations, including the adjacent areas, exhibited very high liquefaction vulnerability. In contrast, the SPT data indicated that the areas further from the spots exhibited low and very low liquefaction. The findings indicated that the occurrence of post-earthquake liquefaction in Balaroa and other regions within Palu City is prone to recurrence following earthquakes of specific magnitudes. Doi: 10.28991/CEJ-2024-010-07-09 Full Text: PD
Multi-Objective Optimization of Stress Concentration Factors for Fatigue Design of Internal Ring-Reinforced KT-Joints Undergoing Brace Axial Compression
Get PDFStress concentration factors are important to determine fatigue life based on the S-N curve methodology, where the lower the stress concentration factor, the higher the fatigue life. In this work, we developed internal ring-reinforced KT-joints, one of the most commonly used joints in the offshore industry, for the most practical ranges with the least stress concentration factors, followed by the formulation of a novel set of parametric equations for determining the stress concentration factors of internal ring-reinforced KT-joints. Using numerical investigation based on a finite element model and a response surface approach with 8 parameters (λ, δ, ψ, ζ, θ, Ï„, γ, and β) as input and eleven outputs (SCF 0° to SCF 90° and peak SCF), the stress at ten locations around the brace was evaluated, since efficient response surface methodology has been proven to give comprehensive and accurate predictions. The KT-joint with the following parameters: λ=0.951515, δ=0.2, ψ=0.8, ζ=0.31, θ=45.15°, Ï„=0.60, γ=16.25, and β=0.40 had the least stress concentration factor. The KT-joint with the optimized parameters was validated through finite element analysis. The resulting percentage difference was less than 6%, indicating the applicability of the response surface methodology with high accuracy. Doi: 10.28991/CEJ-2024-010-06-03 Full Text: PD
Spatial and Temporal Analysis of Surface Water Pollution Indices Using Statistical Methods
Get PDFThis study was conducted to evaluate surface water quality using pollution indices including the organic pollution index (OPI), comprehensive pollution index (CPI), and water quality index (WQI), cluster analysis (CA), with the support of one-way analysis of variance (One-way ANOVA), and principal component analysis (PCA). Water quality data at 42 locations, with 22 water quality parameters including temperature, pH, turbidity, salinity, chloride, total dissolved solids, electrical conductivity, sulfate, dissolved oxygen, total suspended solids, biological oxygen demand, chemical oxygen demand, nitrite, nitrate, ammonium, orthophosphate, coliform, E. coli, arsenic, cadmium, lead, and copper, were used for the evaluation. The results showed that all the pollution indices fluctuated spatially and temporally. The OPI index ranged from slight organic pollution to heavy organic pollution, and the OPI values in February and April were higher than those in other months. OPI values were classified as moderate with 54.76% of the locations and heavily polluted with 45.24%. Assessment based on the CPI revealed that 16.7% and 83.3% of locations were classified as moderately contaminated and heavily contaminated, respectively. The WQI classified 45% of the locations as poor and 55% of the locations as having average water quality. In particular, the water quality in August, October, and December was better than that in other months. PCA results showed that eight polluting sources were responsible for 77.1% of the water quality variation. The main surface water polluting sources could be natural sources (riverbank erosion, rainwater runoff), wastewater (domestic, agricultural, and industrial), water discharge from the national park, and livestock areas. Local environmental management agencies need to have appropriate solutions to improve water quality. Future research should focus on the contribution sources to surface water degradation. Doi: 10.28991/CEJ-2024-010-06-07 Full Text: PD
Groundwater Quality Assessment in the Middle-Upper Pleistocene Aquifer
Get PDFThe study was conducted to assess groundwater quality and identify the main pollution sources of groundwater in Hau Giang province, Vietnam. Groundwater samples were collected at five locations (GW1-GW5) at qp2-3 aquifer in May and October 2022. Principal component analysis (PCA), cluster analysis (CA), water pollution index (WPI), and groundwater quality index (GWQI) were applied in the study. The results revealed that the groundwater quality was influenced by TDS, NH4+-N, permanganate index, and Fe. On the basis of WPI, GW2 and GW3 had the lowest water quality, exceeding a value of 1. The results of GWQI showed that groundwater quality was divided into three categories (excellent, poor, and unsuitable for drinking) in May and four categories (good, poor, very poor, and unsuitable for drinking) in October. The study also revealed seasonal variations in groundwater quality, particularly in GW5 (Vi Thuy district, Hau Giang, Vietnam). The CA results formed four water quality groups in both periods based on the similarity of groundwater parameters. PCA results presented that the three PCs explained 79.55% of the variation in groundwater quality. Three potential sources of pollution are derived from the discharge of wastewater (domestic, industrial, and agricultural), landfilling, and seawater intrusion. Doi: 10.28991/CEJ-2024-010-07-018 Full Text: PD
BIM Maintenance System with IoT Integration: Enhancing Building Performance and Facility Management
Get PDFThe rapid growth of technology worldwide in different ways drives the construction sector to take the same path. Smart cities, Digital Twins, Building Information Modeling (BIM), and the Internet of Things (IoT) are the trends in this way today. Also, integrating Building Information Modeling (BIM) and Internet of Things (IoT) technologies has revolutionized how buildings are designed, constructed, maintained, and managed. On the other hand, the complexity, high cost, need for expertise, and other things make the maintenance process and facility management by human inspections, commercial software, and different tools not suitable for the growth of the technology. This paper presents a proposal for a workflow of integration between BIM, and an algorithm of Maintenance System with IoT and highlights its potential to enhance building performance and facility management. The paper explores this innovative system's underlying principles, benefits, challenges, and implementation strategies. Furthermore, it discusses the implications of BIM, and the proposed algorithm of Maintenance System with IoT integration on various stakeholders, including building owners, facility managers, and occupants by using a case study. The findings collected by a questionnaire for some experts emphasize the importance of adopting this integrated approach to optimize building operations, improve maintenance practices, and create sustainable and intelligent built environments. Doi: 10.28991/CEJ-2024-010-06-015 Full Text: PD
Evaluation of Hydraulic Structures for Agricultural Discharge Optimization
Get PDFThe objective of the research was to evaluate the hydraulic structures on the Al-Gharraf River in southern Iraq and their ability to achieve the required discharge for agricultural areas that depend on them. Al-Gharraf head regulator discharges unstable volumes of water, ranging from 280 m3/s in winter to 100 m3/s in summer. The research aimed to determine whether the operational discharges are achievable for the offtakes branching from the Al-Gharraf River when the river's discharge ranges from 60% to 100% of the operational discharge. The researchers utilized a simulation of the irrigation channel (SIC) model to simulate river flow. The researchers used hydraulic indicators such as Delivery Performance Ratio (DPR), Discharge Deviation (∆Q), and Sensitivity (S) to evaluate the work of the hydraulic structures (regulators), determine the more and less efficient regulators in delivering water to the offtakes, and determine the reasons for inefficiency. Depending on the discharge values for each offtake from simulation results by SIC and calculating the hydraulic indicators, it is observed that some offtakes exceed their operational discharges, such as Al-Zydia and Al-Sabila. Also, some offtakes do not receive their operational discharge (Al-Dawaiya, Shatt Al-Shatra, and Al-Basra) projects, which failed to reach even 10% of their operational discharges. The researchers suggest redesigning some offtakes and ensuring reasonable control of gate openings for other offtakes to make the water distribution proportional. Doi: 10.28991/CEJ-2024-010-05-010 Full Text: PD
Upgrading of Precast Roof Beam–Column Connections with Seismic Safety Key Devices
Get PDFTo meet the increasing demands for innovations in precast systems with high seismic resistance, in this study, we introduced a novel seismic upgrading technique for roof beam-column (RBC) connections, termed the targeted seismic upgrading (TSU) method, incorporating the innovative seismic safety key (SSK) devices we developed. These devices significantly enhance seismic resilience, offering a substantial improvement over traditional pin-based RBC connections in precast structures, which are known to have limited effectiveness. Our experimental tests on half-scale models of conventional RBC connections, coupled with comprehensive refined finite element method-based nonlinear analytical studies, conclusively demonstrated the enhanced seismic retrofitting capabilities of RBC connections augmented with SSK devices. The paper delineates a technical procedure for applying the SSK, our proprietary innovation, for the targeted seismic upgrading of RBC connections within modern precast systems. Notably, the SSK-upgraded RBC connections exhibited a marked increase in safety, as evidenced by results from experimentally validated nonlinear three-dimensional micro-analytical models. The incorporated flexible design elements in the TSU method ensure its high effectiveness and general applicability for seismic upgrading of both existing and new precast industrial hall structures, offering a significant advancement in this specific seismic engineering topic. Doi: 10.28991/CEJ-2024-010-05-06 Full Text: PD
Artificial Intelligence Using FFNN Models for Computing Soil Complex Permittivity and Diesel Pollution Content
Get PDFSoil pollution caused by hydrocarbons, such as diesel, poses significant risks to both human health and the ecosystem. The evaluation of soil pollution and various soil engineering applications often relies on the analysis of complex permittivity, encompassing parameters such as dielectric constant and dielectric loss. Various computational models, including theoretical physics-based models, mixture theory models, statistical empirical models, and artificial neural network (ANN) models, have been explored for computing soil complex permittivity and predicting water and pollutant content. Theoretical models require detailed data that is often unavailable, and thus have limited applicability. Mixture models tend to underestimate soil characteristics due to inaccuracies in permittivity estimation of soil phases. While empirical models are widely used, their applicability is restricted to specific soil types, datasets, and locations. ANN models offer promising predictions, accommodating nonlinear phenomena and allowing for missing information and variables. In this study, capacitive electromagnetic electrode sensors were utilized to determine the complex permittivity of soil contaminated with varying levels of diesel at different moisture levels. Theoretical mixture, empirical, and Feed Forward Neural Network (FFNN) models were employed to compute the permittivity of polluted soil based on its phases and to predict the level of diesel pollution. A comparison of these modeling approaches revealed that the FFNN model exhibited the best performance. The ANN model demonstrated superior performance metrics, including a high correlation coefficient and lower mean square error. Specifically, the correlation coefficients for the FFNN model were 0.9942 for training samples, 0.9967 for validation samples, and 0.9977 for test samples. Additionally, the ANN model yielded the lowest mean square error compared to the other three models. Doi: 10.28991/CEJ-2024-010-09-018 Full Text: PD
Evaluation of Skirt-Raft Foundation Performance Adjacent to Unsupported Excavations
Get PDFThe continuous demand for urban development, along with the construction of new buildings, highways, and infrastructure, creates an increasing necessity for excavation activities. Deep excavation near existing buildings can lead to ground instability, potentially causing structural damage to nearby properties. This research aims to investigate methods for enhancing buildings stability from the initial stages of construction, focusing on protecting structures from potential future adjacent excavations. This study utilizes a skirt-raft foundation system, modeled using the finite element software PLAXIS 3D, to evaluate its effectiveness in improving stability and protection. The study analyzed the behavior of raft foundations in clay soil adjacent to excavations ranging from 1 m to 10 m and compared this with the performance of raft foundations with added skirt foundations. The comparison focused on settlement, rotation, and lateral movement of the excavations to assess potential building damage. The results showed that incorporating a skirt foundation significantly enhanced structural stability and reduced excavation-related damage. The implementation of a skirt foundation to a depth of 0.5B (where B is the foundation width) for excavations of similar depth has been shown to significantly reduce damage levels from medium or high to light while also decreasing differential settlement by 80%. It is recommended that adjacent excavation depths should not exceed 0.25B. However, if a skirt foundation is constructed at a depth of 0.5B, the excavation depth can be safely extended to 0.75B. Doi: 10.28991/CEJ-2024-010-12-018 Full Text: PD
Seismic Performance Assessment of Sustainable Shelter Building Using Microtremor Method
Get PDFThe increasing intensity of earthquakes in West Sumatra could trigger megathrust earthquakes and tsunamis at the inter-plate in the Mentawai Islands. Building assessments are necessary to determine their vulnerability to predicted earthquakes. The target is a four-story building that serves as an education building and vertical evacuation. This research proposes a complete vulnerability assessment method using single microtremor observations, and the results are used to determine seismic building performance. The natural frequency is derived from the spectral analysis of the horizontal components (NS and EW) for each level, and we considered the largest earthquake peak ground motion (PGA) in this region to be the September 30, 2009, Padang earthquake (PGA 380 gals as ground motion input). We calculated the resonance index, seismic vulnerability index, and damping ratio. The results show that the resonance index of the structure is less than 1, the vulnerability index of the UNP Faculty of Economics building ɤ > (1/100-1/200) and is 1/234 to 1/699 for the x direction and 1/207 to 1/709 for the y direction; the average damping ratio is <5% for both directions (x, y) and RDM and FSR relationship is 0.78 and 0.69 for x and y respectively. The overall findings indicate that the structural response of the evaluated buildings falls within the 'slight' damage category during seismic events. Doi: 10.28991/CEJ-2024-010-11-06 Full Text: PD