2031 research outputs found
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Optionally Reinforced Columns Under Simulated Seismic and Time Varying Axial Loads: Advanced HYLSER-2 Testing
Get PDFSteel- and composite-reinforced columns (SRC and CRC columns) provide alternative solutions for common and harsh environments. Although extensive research has been conducted on these columns, direct comparative studies of SRC and CRC columns under seismic conditions, with consistent testing and realistic load simulations, remain limited. This study examined the nonlinear seismic responses of nine ordinary steel-reinforced concrete column models constructed alternatively with normal-strength and high-strength concretes under simulated earthquakes and time-varying axial loads. A developed advanced HYLSER-2 seismic testing system was employed to conduct seismic tests. Spiral transversal reinforcement with pitches of 6.0 and 9.0 cm was used to explore the effects of concrete confinement. The HYLSER-2 seismic tests, conducted under various interactively simulated earthquake intensities and time-varying axial loads, yielded crucial experimental results. Additionally, an extensive complementary analytical study was conducted to provide comparative insights between steel-reinforced columns (SRC) and composite-reinforced columns (CRC) with novel glass fiber-reinforced (GFRP) bars. The analytical study was conducted using experimentally proven advanced nonlinear analytical micromodels. The analytical results highlight the hysteretic behavior of columns reinforced with ordinary steel and novel GFRP reinforcing bars under the simulated combined effects of reversed cyclic bending and time-varying axial loads. The findings form a critical basis for advancing seismic design strategies for SRC and CRC columns exposed to strong earthquakes and high-time variations in axial loads. Doi: 10.28991/CEJ-2024-010-10-09 Full Text: PD
Measuring Belt and Road Initiative Perceptions: A Comparative Analysis of Thai Border and Non-Border Regions
Get PDFThis study aims to analyze and compare perceptions of the Belt and Road Initiative (BRI) between border and non-border regions in Thailand, addressing a gap in understanding how geographic proximity influences BRI project views. Using a sample of 3,200 respondents, this study employed confirmatory factor analysis and measurement invariance techniques to examine perceptions across eight key constructs related to BRI impacts. The findings reveal significant structural differences in BRI perceptions between border and non-border regions. Non-border regions generally showed more consistently positive perceptions across all constructs, while border regions demonstrated more varied and nuanced views. Notable differences were observed in perceptions of economic benefits, logistics improvements, and social impacts. This study contributes to the field by providing a comprehensive comparative analysis of BRI perceptions across different geographical contexts within a single country, employing advanced statistical methods to ensure valid comparisons. The results suggest the need for tailored approaches to BRI implementation and communication in different regions, implementing inclusive policy-making processes, and establishing robust monitoring and evaluation systems to address the varied perceptions and potential impacts of BRI projects in Thailand. Doi: 10.28991/CEJ-2024-010-12-010 Full Text: PD
Comparison of Structural Response Utilizing Probabilistic Seismic Hazard Analysis and Design Spectral Ground Motion
Get PDFIndonesia 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
Unfired Bricks Mixed with Para Rubber Latex for Sustainable Construction Materials
Get PDFThis paper aims to study the development of bricks without burning, mixing para rubber latex, and compressing them with the technology of interlocking block production. The ratio of cement, lateritic soil, and water used in the mix was 1:6:11, while the percentage of para rubber latex (PRL) added was 2.5, 5, 7.5, 10, and 12.5% of the cement weight. The optimal PRL content (2.5%–7.5% by cement weight) enhances compressive strength, reduces water absorption, and improves durability, meeting the Thai industrial standard (TIS 77-2545). The PRL7.5 mixture achieved the highest performance, with a compressive strength of 21.42 MPa and a water absorption rate of 7.55%. These advancements are credited to the polymer film network formed from PRL during the hydration process, which strengthens particle bonds and reduces porosity. However, PRL content exceeding 7.5% leads to performance reductions, attributed to thicker polymer films and particle aggregation, which create larger voids within the material. Furthermore, the modified unfired bricks demonstrated enhanced crack resistance, increased ductility, and superior thermal insulation properties. Thermal tests of masonry walls confirmed that unfired bricks provide better thermal insulation. Temperature measurements revealed that houses constructed with unfired bricks consistently maintained cooler indoor temperatures compared to those made with fired bricks, indicating improved thermal efficiency. Environmentally, unfired bricks eliminate carbon emissions from firing processes and offer simpler, more energy-efficient production methods. These bricks provide sustainable alternatives to fired bricks, promoting both environmental and economic benefits for brick-making communities. Doi: 10.28991/CEJ-2024-010-12-05 Full Text: PD
Evaluating the Importance of Ecosystem Services in University Campus
Get PDFUniversity campuses provide a variety of ecosystem services (ES) that play an important role in both physical and mental benefits for students. However, the importance and actual service performance of ES in universities were not clearly perceived in Vietnam. This study was conducted to fill these gaps with the objectives of (1) assessing students' perceptions of the importance of ecosystem services on their university campus and (2) assessing students' satisfaction with these ecosystem services. Using the interview method, the study collected research data from 210 students at Can Tho University (CTU), a large university in Vietnam. The results of the study have confirmed the importance of ecosystem services such as trees, lawns, water bodies, and buildings on CTU's campus. With modern design, buildings play an important role in creating space to organize formal classes, self-study, and group work for students. Green spaces not only improve air temperature and bring high aesthetic value, but they are also habitats for many species of animals and plants. Most students were very satisfied with the ES provided by the CTU's campus. However, the functions of the grass and water bodies ecosystem need to be improved, as the student satisfaction with these ES was significantly lower than the value they expected. The results of analyzing the importance and satisfaction of ES will be a useful basis for making decisions on planning and developing ecosystems. This is a new research direction in Vietnam that needs continued research and application. Doi: 10.28991/CEJ-2024-010-01-015 Full Text: PD
The Application of Neural Networks to Predict the Water Evaporation Percentage and the Plastic Shrinkage Size of Self-Compacting Concrete Structure
Get PDFThis article presents a solution using an artificial neural network and a neuro-fuzzy network to predict the rate of water evaporation and the size of the shrinkage of a self-compacting concrete mixture based on the concrete mixture parameters and the environment parameters. The concrete samples were mixed and measured at four different environmental conditions (i.e., humid, dry, hot with high humidity, and hot with low humidity), and two curing styles for the self-compacting concrete were measured. Data were collected for each sample at the time of mixing and pouring and every 60 minutes for the next ten hours to help create prediction models for the required parameters. A total of 528 samples were collected to create the training and testing data sets. The study proposed to use the classic Multi-Layer Perceptron and the modified Takaga-Sugeno-Kang neuro-fuzzy network to estimate the water evaporation rate and the shrinkage size of the concrete sample when using four inputs: the concrete water-to-binder ratio, environment temperature, relative humidity, and the time after pouring the concrete into the mold. Real-field experiments and numerical computations have shown that both of the models are good as parameter predictors, where low errors can be achieved. Both proposed networks achieved for testing results R2 bigger than 0.98, the mean of squared errors for water evaporation percentage was less than 1.43%, and the mean of squared errors for shrinkage sizes was less than 0.105 mm/m. The computation requirements of the two models in testing mode are also low, which can allow their easy use in practical applications. Doi: 10.28991/CEJ-2024-010-01-07 Full Text: PD
Experimental and Numerical Study of Soil Strata for Underground Transportation System: A Case Study
Get PDFIn 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
An Empirical Formula for Assessing the Characteristic Strength of Unreinforced Laterite Stone Masonry
Get PDFThis study aims to determine the needed coefficients for evaluating the uniaxial compressive strength characteristic value for masonry structures made of Laterite Stone (LS) and cement mortar, resulting from experiments conducted in the laboratory evaluating the compressive strengths of the laterite stone and mortar separately in masonry. It proposes calculation coefficients for the completion of Eurocode 6 data that fit the behavior of laterite stone-based masonry. The laterite stone blocks are extracted from three quarries in southern Burkina Faso. The dimensions of the masonry samples tested are 800 mm í— 800 mm í— 135 mm (±5 mm) with a cement mortar joint of 20 mm (±5 mm) thick. The different failure modes of masonry were also explored. The tests carried out on the masonry showed that the failure is initiated by vertical cracks through the block-mortar interface at a quarter of the width of the walls, generally at 40 to 60% of their maximum strength. The statistical analysis made through a linear regression from the standard model of approximation of the characteristic strength of masonry in Eurocode 6 was used to set out parameters for the empirical relation. The proposed formula considers the intrinsic properties of the block and the mortar, the thickness of the mortar, the dimensions of the masonry block, and the geometry of the masonry itself to evaluate its compression strength. The adequacy between the model and the experimental values is evaluated through the coefficient of determination and the standard error of 0.94 and 0.041 MPa, respectively. Doi: 10.28991/CEJ-2024-010-04-07 Full Text: PD
Lateral Displacement Behavior of IBS Precast Concrete Elements Reinforced with Dual System
Get PDFThroughout history, the construction industry has been a significant contributor to construction waste, presenting an ongoing challenge in efficiently managing this waste to mitigate environmental pollution. The Industrialized Building System (IBS) stands out as a construction approach that utilizes prefabricated components made from various waste materials, implemented with machinery and formwork, leading to minimal waste production. The potential failure of IBS blockwork columns under lateral loads is a significant concern, and the deformation of these columns is crucial in assessing overall structural performance against lateral forces. This study focuses on examining the deformation and flexibility of components in IBS blockwork columns when subjected to lateral loads. Using Finite Element Modeling (FEM), a 1:5 scale prototype model of the dual-reinforced system IBS Block Work Column is analyzed. The IBS Block Work Column, comprising four prefabricated components assembled in the form of a crucifix plan to enhance lateral stability, is subjected to FEM analysis and experimental investigations. The study aims to explore the impact of four different shapes of reinforcement on deformation resistance. The findings suggest that employing a dual-reinforced system in the IBS Block Work Column enhances its resistance to lateral loads compared to a column with conventional reinforcement. Moreover, the assembled IBS Block Work Column exhibits greater stiffness than a single prefabricated component when subjected to lateral loads. Doi: 10.28991/CEJ-2024-010-01-020 Full Text: PD
Influence of Shear Strain on the Deflection of Girders
Get PDFNumerical calculations are a standard part of modern structural design. Engineers remain particularly interested in real problems where analytical and numerical solutions can be compared with experimental results. Such cases are typical examples of benchmarks because they are used to verify the assumptions introduced. This study shows in detail how shear stresses affect the deflection of a relatively short and high cantilever when the span-to-height ratio of the cross-section is less than five. Such models are frequently used in the design of cantilevers that support heavily loaded beams, for example in the cement industry (e.g., often as structural elements for a heat exchanger system) or for the assessment of short cantilever limit states that appear during excavation in rock sediments. The models are also suitable for designing the various details and joints in the industry of prefabricated elements. This work analyzes in depth the analytical solutions for the displacement field of the linear elastic plane stress theory with two displacement boundary conditions. Also, the solutions were compared with the beam, two-, and three-dimensional numerical models using SAP2000. The results highlight the fundamental principles and solutions behind plane stress and beam theories, with an insight into the advantages and limitations of such models. Doi: 10.28991/CEJ-2024-010-05-04 Full Text: PD