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2007 research outputs found
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Performance of Treated Date Palm Leaf Fiber as a Sustainable Reinforcement for Different Soil
No full textThe use of sustainable materials in geotechnical applications has increased in recent years due to their positive impacts on geo-environmental and future generations. This paper contributes to existing knowledge on geocell reinforcement of soil by proposing a new inexpensive product: cells made from natural materials, Date Palm Leaf fiber coated with Bitumen (DPLB), to improve its durability, as an alternative to commercially available high-density polyethylene (HDPE) geocells. A physical laboratory model was designed to examine the performance of the DPLB cell and HDPE cell reinforced base layer under repeated loading. The study tested different infill materials gravel, sand, and recycled asphalt pavement (RAP) in DPLB cells and HDPLE geocell-reinforced granular layers and compared them to unreinforced layers. The reinforcement's performance was assessed using elastic deformation, permanent deformation, traffic benefit ratio, and rut depth reduction. Results showed that both DPLB cell and geocell reinforced sand decreased the cumulative permanent deformations compared to the unreinforced layer. DPLB reinforcement cells improved the permanent deformation behavior by 30% due to the lateral restriction provided by the DPLB pockets on the infill materials, while the geocell improved it by 7%. The traffic benefit ratio (TBR) of geocell-reinforced RAP is 26% greater than that of the DPLB cell-reinforced RAP section, although both geocell and DPLB cell exhibited similar TBR values in the case of gravel infill materials. The experimental results showed that DPLB cells are a cost-effective and environmentally friendly substitute for commercially available HDPE geocells in soil reinforcement applications. Doi: 10.28991/CEJ-2024-010-10-018 Full Text: PD
Analyzing the Future Climate Change Impacts on Meteorological Parameters Using the LARS-WG Model
No full textThis research aims to evaluate the impacts of climate changes and reveal the future trends on meteorological parameters, i.e., precipitation and temperature effects, in three major cities in Iraq, namely Baghdad, Wasit, and Maysan, which are located along the Tigris River basin. The LARS-WG8.0 model was employed, and five GCMs were used within CMIP6 under three different scenarios, i.e., SSP126, SSP245, and SSP585, for the period 2021-2100. The observed and simulated data were tested by the statistical criteria R, R2, NSE, and RMSE through the baseline period 2003-2022. In addition, using the K-S test for validation of the LARS-WG8.0 model resulted in accuracy and reliability. The future projections indicate that the average temperatures will increase until the end of the current century, with a difference of 1.86, 2.85, and 5.36°C. The fluctuations in precipitation occur throughout the winter, spring, and autumn months. The highest precipitation was recorded in December and January. Therefore, all GCMs give a unified indicator of future climate forecasts. Rising temperatures and fluctuations in precipitation negatively impacted water and food security. As a result, this will impact the water resources and agricultural sectors. This research contributes to exploring the future climate behavior of the study area. Doi: 10.28991/CEJ-2024-010-11-019 Full Text: PD
An Investigation of Dynamic Soil-Structure Interaction on the Seismic Behavior of RC Base-Isolated Buildings
No full textSoil-structure interaction (SSI) can significantly influence earthquake responses in base-isolated (BI) buildings, yet it is often overlooked in practice due to the high computational demands of complex analyses. This study investigates SSI effects on reinforced concrete (RC) base-isolated buildings, idealizing SSI with a cone model. Three BI building models of varying heights and soil characteristics were analyzed using modal and nonlinear time history analysis. The base isolation system incorporated elastic sliding bearings, lead rubber bearings, natural rubber bearings, and oil dampers. The SSI model was idealized considering hard, medium, and soft soils. To simulate earthquake input, three artificial ground motions with different phase characteristics were generated to match the design response spectrum according to the Japanese code. The seismic responses of the base-isolated building models with SSI were compared to those of models without SSI. Modal analysis showed that the natural period increased with softer soil profiles. In the first and second modes, the natural period lengthened as the building's aspect ratio increased. Conversely, in the higher modes with a rocking pattern, the building with the lowest aspect ratio exhibited the longest natural period. Overall, implementing SSI generally reduced seismic responses, notably lowering story drift, acceleration, and force, particularly for buildings on soft soil. However, the SSI effect significantly increased the base rotation angle in high aspect ratio buildings on soft and medium soils. These findings indicate that including SSI in analysis is essential for more realistic seismic response predictions, especially for tall, slender base-isolated buildings. Doi: 10.28991/CEJ-2024-010-11-01 Full Text: PD
Comparison of Structural Response Utilizing Probabilistic Seismic Hazard Analysis and Design Spectral Ground Motion
No full textIndonesia is seismically active due to tectonic plate convergence south of Java Island. In the examination of earthquake-resistant structures, Indonesia possesses the SNI 1726-2019 rule; however, it requires re-evaluation in conjunction with other seismic motions, specifically the PSHA method. The PSHA approach is employed in probability-based seismic hazard analysis, taking into account uncertainties related to earthquake magnitude, location, and frequency to provide a comprehensive assessment of a location's hazard level. To demonstrate the impact of ground motion induced by earthquakes on structural reaction, it is essential to study the structure using the time history of SNI and PSHA artificial earthquake shaking. Spectrum matching with target spectra derived from probabilistic seismic hazard analysis can build artificial time histories. Consequently, the time history obtained from the analysis can be considered to be derived from the probabilistic methodology. Both analytical methods, SNI and PSHA, indicate that the structural reaction of the Alana Hotel is not markedly different, and the structure remains secure against seismic activity. Doi: 10.28991/CEJ-SP2024-010-012 Full Text: PD
Dynamic Buckling Analysis of Ductile Damage Evolution for Thin Shell With Lemaitre's Model
No full textThin-shell structures are used in several fields of construction and are often exposed to severe dynamic environments, making them susceptible to dynamic instabilities. These instabilities are typically preceded by varying degrees of damage to the shell, justifying the need to incorporate this behavior in the formulation of the finite elements used. The objective of this work is to evaluate the different dynamic instability criterion in the presence of damage, afterward, evaluate the influence of this behavior on the stability of shells subjected to the dynamic excitations. The methodology of this project is essentially numerical, based on the finite element method. We are asked to program the introduction of damaging behavior and Lemaitre's model criteria in the DYNCOQ program developed locally. To examine the results, two examples extracted from the literature were presented. The first model aimed to confirm the proper functioning of the program and the convergence of the plasticity criterion (Lemaitre's model). As for the second model, it allows us to test the dynamic instability. A comparison was made with experimental data from previously published literature, revealing a strong agreement between the calculated and experimental results. The obtained results prove the utility of considering this behavior in the shell analysis. Doi: 10.28991/CEJ-2024-010-03-012 Full Text: PD
Effectiveness of Grouting and GFRP Reinforcement for Repairing Spalled Reinforced Concrete Beams
No full textCorrosion of steel reinforcement from chloride exposure can compromise the strength of reinforced concrete structures. Rust formation expands, applying pressure on concrete, resulting in cracks and spalling. Prompt repair is crucial for severe cases of spalling. This research assessed the efficacy of repair strategies for reinforced concrete beams post-spalling, including grouting and different techniques involving Glass Fiber Reinforced Polymer (GFRP) reinforcement. The research examined four variations of reinforced concrete beams, each sized at 150 mm í— 200 mm í— 3300 mm. Results showed that the standard beam (BK) had an average maximum load capacity of 29.74 kN. In contrast, the grouted beam (BGR) demonstrated a reduced maximum load of 14.39 kN, along with decreased steel and concrete strain compared to BK. This suggests that the grouting repair did not fully restore the beam's flexural capacity after spalling. Incorporating GFRP strips (BGRS) led to a marginal increase in the beam's maximum load, albeit remaining below BK, with lower steel and concrete strain than BK. However, the steel and concrete approached their yield points, indicating enhanced flexural performance. The full-wrap GFRP beam (BGRSF) experienced an 8.08% increase in maximum load compared to BK, with concrete strain surpassing BK, suggesting an enhancement in flexural stiffness. Doi: 10.28991/CEJ-2024-010-07-05 Full Text: PD
Assessing Air Quality Using Multivariate Statistical Approaches
No full textThe purpose of the current study was to evaluate air quality in Dong Thap province, Vietnam. The air quality data was collected during 2019–2020, representing the time of pre- and mid-COVID-19. Twenty-seven air quality samples (in the areas of urban, residential-administrative, hospital-schools, and industry-craft village areas) were used for the evaluation. Air quality was evaluated using national technical regulations on air quality, including QCVN 26:2010/BTNMT and QCVN 05:2013/BTNMT. The difference of mean air quality between the areas was examined using a one-way ANOVA followed by the Duncan test at a significant level of 5%. The relationship between air quality parameters and microclimate factors was tested using Pearson correlation. Principal component analysis (PCA) was utilized to identify critical variables and potential sources of air variation. Cluster analysis (CA) was applied to group similar air quality sites, thus recommending air monitoring site selection. The results show that the air quality in the study area is not polluted. The concentrations of noise, TSP, SO2, and NO2in the mid-COVID-19 pandemic were significantly lower than those in the pre-COVID-19 pandemic due to the social distancing policy. There was a close correlation among air quality parameters, except for air humidity. PCA identified two to four potential sources of air variation, explaining 84.3%, 100%, 100% and 89.7% of the total air quality variance at urban, residential–administrative, hospital-schools, and industry-craft villages, respectively. CA divided the 27 sampling sites into eight groups by the differences, mainly in humidity, wind speed noise, TSP, and CO. Eight sampling sites could be potentially reduced from the current monitoring program for representativeness and cost-effectiveness purposes. All air parameters in the current study are significant for monitoring, and the potential sources of air quality variation are traffic activities, industrial production, craft village activities, and daily life using fuels in residential areas. The results of the current study provide useful information for air quality monitoring and management. Future monitoring programs should include toxic air pollutants in air quality monitoring programs. Doi: 10.28991/CEJ-2024-010-02-012 Full Text: PD
Upgrading of Precast Roof Beam–Column Connections with Seismic Safety Key Devices
No full textTo 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
Frictional Axial Resistance of Clamped Split Pocket Mechanism Steel Structural Joint: An Experimental Study
No full textThe Clamped Split Pocket Mechanism (CSPM) prefabricated joint system was developed for a single-story steel instant house, designed to be compact and rapidly constructed without modifying the end of the beam and column element member. The CSPM bolted joint system was proposed as an optimal solution for post-disaster housing, especially after earthquakes. Despite its potential, the frictional tensile resistance behavior of the CSPM bolted joint system has not been previously studied, necessitating experimental investigation. This study examined the frictional tensile resistance behavior of the CSPM joint system by monitoring the effective friction coefficient under axial tension force. The experiments considered both the strong and weak axes of the joint and utilized two configuration types of specimens (L and T) with varying bolt pretensions of 2.5, 5, 7.5, and 10 kN. Results indicated that the effective friction coefficient of the CSPM bolted joint system ranged from 0.19 to 0.26, correlated to bolt pretension. Increased bolt pretension resulted in larger surface deformation of the split pocket, triggering a not uniform frictional tensile resistance across the steel surfaces of the split pocket joint. From this study, the achieved effective friction coefficients could guide the design of minimum pretension forces for clamps in prefabricated steel instant houses. Doi: 10.28991/CEJ-2024-010-09-07 Full Text: PD
Effect of the Stepped Spillway Geometry on the Flow Energy Dissipation
No full textIn this research, flume experiments were conducted on stepped weirs to investigate the effect of step shape on the energy dissipation of flow. Four configurations with a constant number of steps were considered, namely, horizontal steps, inclined steps, horizontal steps with rounded sills, and "Žinclined steps with rounded sills. The slopes of inclined steps were 13% and 23%, and the diameters of the rounded sills of the step ends were 10 and 15 cm. The majority of previous studies focused on energy dissipation in stepped weirs in horizontal and inclined steps. In this research, new step geometries were used, such as horizontal steps with rounded sills and inclined steps with rounded sills. Dimensional analysis was applied to correlate the different variables affecting the flow hydraulics. Flow rates in the range of 0.61-9.12 lit/sec were used with each step shape. Results showed that the inclined steps with rounded sills had the highest flow energy dissipation in comparison to the other types. Rounded sills at the end of steps had more effective energy dissipation than did the horizontal step. However, the 23% inclination slope with rounded sills of a 7.5 cm radius was the most effective in dissipating flow energy. Doi: 10.28991/CEJ-2024-010-01-09 Full Text: PD