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2007 research outputs found
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Evaluation of Skirt-Raft Foundation Performance Adjacent to Unsupported Excavations
No full textThe 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
Evaluation and Restoration of Corrosion-Damaged Post-Tensioned Concrete Structures
No full textThis study addresses the pressing issue of chloride-induced corrosion in post-tensioned (PT) concrete structures, known for their strength and flexibility yet vulnerable to durability issues in extreme climates. The objective is to evaluate corrosion mechanisms in a PT building in the United Arab Emirates and develop a robust restoration strategy. Using a combination of nondestructive and semi-destructive testing methods, this research identifies severe deterioration in critical structural elements, such as steel tendons, PT ducts, and concrete surfaces, largely due to high chloride exposure and aggravated by environmental factors like acid rain and fluctuating temperatures and humidity. The findings reveal serious inadequacies in current maintenance practices, often overlooking long-term corrosion risks in harsh climates. In response, this study proposes a comprehensive repair strategy, including removing damaged materials and applying advanced repair products, protective coatings, and waterproofing measures to enhance the structure's durability. This case study highlights significant concerns regarding structural integrity and provides practical insights into effective maintenance and repair strategies for PT structures. By offering a targeted, sustainable intervention approach, this research contributes to developing PT maintenance protocols, particularly in regions prone to aggressive corrosion, ensuring the longevity and safety of these critical structures. Doi: 10.28991/CEJ-2024-010-12-02 Full Text: PD
Macroscopic Traffic Characterization Based on Distance Headway
No full textAccurate traffic characterization is essential for congestion mitigation. In this paper, a traffic model is proposed that incorporates distance headway in the well-known Lighthill, Whitham, and Richards (LWR) model. Velocity is influenced by the headway distance between vehicles. When this distance is small, the velocity is low, and when it is large, the velocity is high. The proposed and LWR models are implemented in MATLAB, and the performance is evaluated for different values of distance headway. The results show that traffic with the proposed model evolves with smaller changes that are more accurate and realistic than with the LWR model. Doi: 10.28991/CEJ-2024-010-12-016 Full Text: PD
Influence of Filler Materials on Bituminous Mastic Rheology at High Temperatures
No full textThe mixing and compaction temperatures of the bituminous mixture are determined by the viscosity of the binder. It was always a concern to understand the influence of the type of filler on the workability of the bituminous mixture. The interaction of the filler with the bitumen plays a key role in this. The inert filler has a physical interaction with the binder, and the active filler will have both a physical and chemical interaction. Based on the type of interaction, the viscosity and shear thinning characteristics of the mastic (binder + filler) change, which will hence influence the workability of the bituminous mixture. An experimental investigation is conducted to measure the viscosity of the mastic with two types of filler, one chosen from the active filler category (hydrated lime) and another from the inert filler category (quarry dust). A shear rate sweep experiment was carried out within the temperature range of 100 to 160 °C to analyze the Newtonian and shear thinning responses of the mastic. Results indicate that, for an equivalent weight proportion of the filler, mastic containing quarry dust exhibited elevated Newtonian viscosity and zero-shear viscosity (as predicted using the Carreau Yasuda Model). Additionally, quarry dust mastic demonstrated a higher rate of shear thinning. Consequently, the beneficial effect of shear thinning during the compaction of bituminous mixtures has the potential to enhance workability and streamline the compaction process. Doi: 10.28991/CEJ-2024-010-02-013 Full Text: PD
Valuation of Urban Green Open Spaces Using the Life Satisfaction Approach
No full textThis study conducts the valuation of the urban Green Open Spaces (GOS) in Jakarta (Indonesia) using the life satisfaction approach (LSA). We integrated the important elements of the LSA, such as housing structure and environmental facilities, into a comprehensive valuation model (using hedonic variables). By explicitly acknowledging the limited application of these methodologies in developing nations, this study endeavors to provide a context-specific understanding of the economic value of GOS in Jakarta. The LSA model, a novel non-market valuation tool, employs community life satisfaction as its primary metric. In this study, we analyzed the satisfaction levels of residents of Jakarta based on a 10-point scale; the responses of a total of 1,592 participants were collected through online questionnaires in 2021 (during the pandemic). We considered various independent variables, including socioeconomic factors, housing attributes, environmental facilities, location amenities, and the presence of GOS. The analysis involved LSA and ordinary least squares (OLS) models in the Statistical Package for the Social Sciences (SPSS). The results indicate that several variables, such as longer residence duration, good employment status, high income "over 20 million Indonesian Rupiah (IDR); approximately USD 1281.56”, and access to more shopping centers, positively influenced the life satisfaction of the residents, which is in line with the studies conducted in western countries. Surprisingly, the economic evaluation of urban GOS portrayed a limited impact on the residents' life satisfaction, while negative aspects, e.g., the presence of cemeteries around residential areas (19.1%), impacted the residents significantly. Urban parks did not portray statistical significance in influencing the residents' life satisfaction, despite having a positive impact across all radii of urban regions. Urban forests exhibited a positive impact, mainly within the 100–500-m radius, with a significant impact on resident life satisfaction. Our attempt to assess the values of landscape amenities in Jakarta using LSA marks a pioneering effort in the field of environmental science with respect to community preferences. Consequently, this study contributes significantly to the evolving yet limited literature in this domain. The results differ from those of the Global North research, emphasizing the need for context-specific urban planning strategies. Our study offers valuable insights for urban planners and government entities and can guide GOS development to enhance urban sustainability and community satisfaction. The implications extend to urban centers in Indonesia and other developing countries, emphasizing the importance of optimizing limited urban spaces based on community preferences. Doi: 10.28991/CEJ-2024-010-04-010 Full Text: PD
Numerical Analysis of Time-Dependent Strength and Stiffness in Palm Oil Fuel Ash-Stabilized Soil: Early and Long-Term Effects
No full textOver the years, investigating the behavior of soft soil, stabilized using different techniques, has been recognized as a critical priority for geotechnical engineers. Numerous soil constitutive models have been utilized to simulate stabilized soil behavior, improve strength and ductility, and analyze load-deformation responses. However, further investigation is required to study stabilized soil's time-dependent strength and stiffness, especially at an early curing age. Early strength and stiffness development is crucial in engineering construction for improving building quality and efficiency and minimizing crack risk. Furthermore, estimating UCS from an early age aid in safety evaluation and ground-improvement analysis. Researchers are increasingly recognizing palm oil fuel ash (POFA) as an eco-friendly alternative to traditional soil stabilizers due to its abundant availability. This study proposes an advanced concrete constitutive model to simulate the time-dependent strength and stiffness of POFA-stabilized and cement-stabilized soil due to pozzolanic interactions. The model accurately measures strength and stiffness improvement from an early curing age to 28 days using finite element analysis (FEA) before then comparing the experimental results. Based on the experimental results, the UCS values of palm oil fuel ash-stabilized soil grew to 3.18 MPa and 3.89 MPa after seven and 28 days with an optimum content of 30% (POFA): 10% Magnesium Oxide (MgO). It exhibited a significant increase in early strength with 64.02% compared with cement-stabilized soil. For stiffness results, a slight increment of 9.26% was observed. Employing FEM, the sensitivity of the parameters to stress-strain behavior was investigated. Finally, the validity of the concrete constitutive model to predict the time-dependent strength and stiffness of stabilized soil was proved. Doi: 10.28991/CEJ-SP2024-010-05 Full Text: PD
Development of a Conservative Hamiltonian Dynamic System for the Early Detection of Leaks in Pressurized Pipelines
No full textIn this study, we propose an innovative approach for real-time leakage detection in pipelines by integrating conservative Hamiltonian equations and experimental Internet of Things (IoT) technologies. The proposed method combines a hybrid model that utilizes sensors and IoT devices to acquire real-time data and solves the coupled system of Hamiltonian equations using the ODE45 numerical integration method. Spectral frequency analysis is an essential part of this method, as it reveals specific patterns in the pressure and flow signals. The findings highlighted 95% accuracy in leak detection, which was validated through a comparison of the theoretical and experimental data. The novelty of this approach lies in its ability to maintain constant total system energy, thereby enabling continuous monitoring for early leak detection. As an improvement, the proper handling of sensor signals is emphasized, underscoring its contribution to the efficient management of water resources in potable water distribution systems. Doi: 10.28991/CEJ-2024-010-04-01 Full Text: PD
Performance Index Model of Raw Water Infrastructure
No full textThis research intends to build a performance index model of raw water infrastructure mathematically by considering technical, non-technical, and environmental aspects. The research location is in Lombok and the Sumbawa Islands. Data is collected by field surveys and questionnaires that are distributed to 160 respondents related to raw water infrastructure in 21 locations. The methodology consists of Partial Least Squares (PLS) and Generalized Reduced Gradient (GRG). The results show that technical, non-technical, and environmental aspects have a significant influence on the performance index of raw water infrastructure. The structural analysis shows that the technical, non-technical, and environmental variables have a positive and significant influence on the performance index. The performance index of raw water infrastructure is successful enough to be developed and tested by using field data and GRG. The evaluation result shows that the model gives an accurate estimation of raw water infrastructure performance in Nusa Tenggara Barat province. The performance index model for raw water infrastructure is as follows: 0.521 IKTK + 0.305 IKNT + 0.174 IK Liwith the sum of square residual (SSR) is 83.21, the root mean square error (RMSE) is 0.44, the mean square error (MSE) is 3.97, and the accuracy level is 95.25%. This research provides the development of an evaluation method for raw water infrastructure performance and a valuable outlook for policymakers in managing and maintaining raw water infrastructure to support sustainable water resources in the future. Considering some aspects of this, it is hoped the efforts to increase the quality of raw water infrastructure can be more directed and effective, contributing to increasing society's prosperity and a sustainable environment in the region. Doi: 10.28991/CEJ-2024-010-06-014 Full Text: PD
Refining Low Strain Pile Integrity Testing for Minor Flaw Detection with Complex Wavelet Transform
No full textThe structural integrity of pile foundations is critical for the safety and longevity of buildings and infrastructure. Low strain impact testing is a widely used non-destructive method for assessing pile length and identifying significant defects; however, its sensitivity to minor flaws remains limited. This study aims to enhance the detection capabilities of low strain testing for minor defects by proposing an improved methodology. We conducted field tests on ten piles with small, artificially introduced flaws and complemented these tests with three-dimensional numerical simulations. Initial time-domain analyses of both field and simulated data, using low-frequency wave excitation, did not reveal distinct signal features indicative of defects. To address this limitation, we employed a set of hammers with varying weights and head materials for wave excitation, simulated with different input force pulse durations. We further applied Complex Continuous Wavelet Transform (CCWT) for time-frequency analysis of the acquired signals, which effectively identified minor defects through characteristic changes in wavelet coefficient phase angles at expected timestamps. The consistency of CCWT phase spectrum features across signals from different hammers, considering the varying sensitivities of wave excitations, facilitates the differentiation of genuine flaw-induced phase shifts from noise. The study's findings were integrated into an improved low strain pile integrity testing workflow, enhancing the method's accuracy in detecting minor flaws. Doi: 10.28991/CEJ-2024-010-10-05 Full Text: PD
Influence of Temperature on the Viscoelastic Behavior and Durability of Flexible Pavements
No full textThis study meticulously examines the impact of temperature variations on the viscoelastic characteristics of flexible pavements composed of mineral aggregates and bituminous binders. The primary objective is to understand how temperature fluctuations affect the structure and durability of these pavements, designed to withstand traffic loads while absorbing stresses induced by weather conditions. The methodology involves a thorough analysis of a range of temperatures from T1 to T4, assessing their effects on road rutting and the longevity of pavement infrastructure. Through a detailed analytical approach, the research investigates the viscoelastic behavior of bituminous mixes, which display viscous and elastic properties that change with temperature. The findings reveal significant correlations between temperature variations and the performance of flexible pavements, offering insights into their structural resilience and durability under different climatic conditions. This research introduces a novel approach to managing flexible pavement infrastructure by enhancing our understanding of the temperature-induced viscoelastic response. The improvement lies in the precise quantification of temperature impacts, which can inform better maintenance and design strategies for flexible pavements. Ultimately, this leads to more resilient and long-lasting road surfaces, addressing the critical need for durable infrastructure in changing weather patterns. Doi: 10.28991/CEJ-2024-010-07-06 Full Text: PD