2031 research outputs found
Sort by
Mechanical Performance of Volcanic Ash Concrete Showing Modulus Reduction with Strength Retention
No full textThis study aims to evaluate the mechanical behavior of concrete that incorporates 51.3% raw volcanic ash into its structure, focusing on its static elasticity modulus and compressive strength. Cylindrical concrete samples were prepared via the mix design commonly used in practice in Baños, Tungurahua, Ecuador. Three curing methods were applied: immersion, water spraying, and no curing. Compressive strength tests were conducted at 3, 7, 14, 21, and 28 days, whereas the static modulus was measured at 28 days following ASTM C469. Despite the high use of ash in the mixture, the mixtures achieved adequate compressive strengths for structural applications, reaching 28.05 MPa. However, a significant reduction in the static modulus was observed, with experimental values of approximately 7.06 GPa, whereas the value of 24.89 GPa was predicted by the equations given in ACI318. The use of raw volcanic ash in structural mixes requires modifications to deformation and stiffness calculations to ensure seismic performance, suggesting the need to review local regulations on traditional mixes. Based on the experimental data, an alternative empirical model, the VAM model, was proposed to better predict the elastic modulus of concrete with high volcanic ash content. The findings reveal a dual function of ash, acting as a pozzolanic material and as a low-density aggregate, highlighting the need to adjust the design equations when raw volcanic ash is used. This work contributes to the sustainable design of concrete mixtures in seismic regions
Combined Effect of Basalt Fibers and Bentonite Clay on Complex Mortar Properties
No full textThis study examined the effects of basalt microfibers and amorphous-structured bentonite clay on the properties of complex mortar mixtures composed of cement and quicklime, utilizing locally sourced raw materials. Bentonite clay was subjected to thermal treatments at 400, 600, and 1000°C, and a technogenic pozzolanic additive was incorporated to investigate its influence on mortar performance. Optimal results were observed for the clay treated at 600°C, which was subsequently used in the mortar formulations. The primary objective was to assess the effects of varying basalt microfiber dosages (0.5%, 1%, and 2%) and thermally treated bentonite clay concentrations (5%, 15%, and 25%) on the chemical composition, physico-mechanical properties, and structural development of the resulting multi-component systems. Advanced analytical techniques, including SEM/EDS, XRD, FTIR, XRF, DLS, and thermochemical analyses (TG/DTG, TG/DSC, and TG/MS), were used to evaluate the mineralogical composition, particle size distribution, microstructure, and thermal behavior. The findings show that the combined use of basalt microfibers and thermally treated bentonite clay significantly enhanced the mechanical strength and structural formation of the mortars. This study provides novel insights into the synergistic effects of these components, offering a promising approach for enhancing mortar performance using locally sourced materials
Optimal Placement of Vibration Control Systems in a Smart Civil Engineering Structure
No full textAdvancements in construction technologies have led to the development of lighter and more flexible structures, which pose new challenges in terms of seismic resistance. This study explores the effectiveness of integrating an Active Tendon (AT) control system to mitigate seismic-induced vibrations in tall buildings. The main objective is to identify the optimal placement of these active control devices to maximize structural performance. To this end, three optimization approaches are investigated: modal controllability analysis, controllability index evaluation, and genetic algorithm (GA)-based optimization. The methodological approach is based on the development of a comprehensive flowchart that integrates the optimization procedures alongside a comparative assessment of passive and active control strategies. Detailed simulations were carried out in MATLAB, enabling accurate time-history analyses and the implementation of customized control algorithms. This framework enables extensive parametric studies and supports a rigorous assessment of control system performance. The results clearly show that optimal tendon placement leads to a substantial improvement in vibration mitigation compared to uncontrolled cases. Comparative analyses underscore the respective strengths and applicability domains of each optimization method, confirming their effectiveness in identifying optimal actuator locations. The novelty of this study lies in the integration of modal and evolutionary optimization techniques within a unified framework, offering a systematic and versatile approach to the placement of control systems in civil engineering structures. The practical recommendations derived from this study provide valuable guidance for engineers and designers seeking to improve structural performance under seismic loading
Improving the Performance of Shallow Footing Subjected to Uplift Loading Using Structural Skirt
No full textThe increasing demand for internet and phone services had required the construction of transmission towers in various terrains, including loose sand, which was often found in desert areas and exposed to wind loads that can pull out these towers. This study aims to improve the uplift resistance of shallow footings subjected to pure uplift forces. In this research, a loading system with a data logger, a shallow footing model, and skirts with different shapes, lengths, and inclination angles was used. The performance and behavior of unskirted footing resting on loose sand with 30% relative density were analyzed and compared with skirted footing under uplift loads. The results showed that increasing the L/B (where L is the footing length and B is the footing width) up to 2 and the inclination angles up to 45° of the skirt gave a significant increase in uplift resistance for skirts with straight corners by 26 times and 19 times for chamfered corners, compared with unskirted footing. It is noted that increasing L/B has less effect than increasing inclination angles by recording 6 times with L=2B and 0°. Skirt footing with straight corners demonstrates better performance than chamfered corners
Sluice Gate Operation and Managed Water Levels Improve Predicted Estuarine Lake Water Quality
Get PDFSaemangeum Lake, an artificial estuarine lake, suffers from a pollutant load from an upstream watershed that is insufficiently mitigated by current load reduction measures. However, no studies have reported simulated flow direction and velocity for a lake. This study aimed to present an alternative solution based on managing water levels and sluice gate operation. Data were collected on water quality, sluice gate operation, water levels, tidal currents, and flow velocities. Next, the inflow and outflow volumes through the sluice gates were calculated. The Delft3D model was applied to predict water quality in a number of simulated scenarios. Finally, streamline and vorticity were calculated to evaluate hydraulic phenomena, while the ecology-based seawater quality index was employed to evaluate water quality. Analysis of flow characteristics revealed a large-scale clockwise vortex formed in the area where the Mangyeong River meets one of the sluice gates. It revealed a two-layer circulation with different flows in the surface and bottom layers. Evaluation of predicted water quality showed that one-way circulation, alternated in 15-day cycles, significantly improved major water quality items at most stations. Collectively, these findings demonstrate the effect that gate operation and managed water levels can have on the water quality of estuarine lakes. Doi: 10.28991/CEJ-2025-011-01-015 Full Text: PD
Impact of the Application of Smart Sensor Networks for the Construction Management of Geotechnical Activities
Get PDFThe primary objective of this study is to evaluate the impact of smart sensor networks on geotechnical data management, specifically enhancing accuracy, real-time monitoring, safety, and reliability. To achieve this, data was collected through a survey of 380 geotechnical professionals in Saudi Arabia, with 106 valid responses analyzed using Partial Least Squares Structural Equation Modeling (PLS-SEM). Principal Component Analysis (PCA) and Factor Analysis (FA) were employed to identify the key variables and underlying relationships among them. The findings demonstrate that smart sensor networks significantly improve the accuracy of geotechnical data (path coefficient = 0.662), real-time monitoring and early warning systems (path coefficient = 0.701), safety and risk management (path coefficient = 0.761), and data reliability (path coefficient = 0.410). This study introduces a novel framework integrating advanced statistical methods with smart sensor networks, offering a practical approach to optimizing geotechnical operations. The research highlights the importance of advanced data analytics in enhancing the full potential of smart sensors, presenting an innovative solution for improving decision-making and risk management in geotechnical engineering. These findings provide a significant contribution to sustainable and effective geotechnical practices. Doi: 10.28991/CEJ-2025-011-01-020 Full Text: PD
Influence of Resistance Spot Welding Parameters on Cold-Formed Steel Properties and Failure Modes
Get PDFLightweight steel structural systems such as built-up beams and trusses are efficient and easy to handle, but the joining technique between thin-walled cold-formed steel elements requires improved solutions. Conventional welding technologies are not suitable for connecting thin sheets due to several inconveniences. The study presents a novel technological approach to connect lightweight steel beams made of corrugated galvanised sheets for webs and back-to-back lipped channel profiles for flanges connected by spot welding, as resistance spot welding (RSW) is widely used in various industrial sectors, such as automotive. This study investigates the influence of RSW parameters on the microstructural properties of spot-welded low-carbon galvanised steel sheets, as well as on their mechanical properties. Two grades of base material were used with thicknesses in the range of 0.8 - 2 mm. RSW joints were manufactured using an automated welding source, and their microstructural characteristics were evaluated by optical and electron microscopy to emphasise the importance of using optimal welding regimes to reduce weld failure. Mechanical properties were evaluated using Vickers microhardness measurements and nanoindentation. Tensile tests were carried out to assess the force-displacement curves and identify the failure mode. The results of the study show that RSW is a promising method for fabricating lightweight steel structural systems when the current, time, and interelectrode forces of RSW are carefully selected
A Theoretical Pore Network Model for the Soil–Water Characteristic Curve and Hysteresis in Unsaturated Soils
Get PDFThis study presents a novel approach to modeling the soil–water characteristic curve in unsaturated soils, employing Monte Carlo simulations to capture the complex behavior of the pore network. The primary objective is to develop an alternative method to represent the hysteretic nature of the soil–water characteristic curve, which is critical for understanding unsaturated soil behavior in various engineering applications. The proposed approach conceptualizes soil as a network of interconnected pores, where each pore interacts with its nearest neighbors. Monte Carlo simulations are used to model the pore-filling distribution as a function of pressure differences during drying and wetting cycles. The model effectively reproduces the characteristic hysteresis curves associated with the hydraulic and mechanical processes in unsaturated soils. A key finding is that the simulated soil–water characteristic curve captures the impact of pore-scale interactions and reflects the complex hysteresis effects observed in experimental data. The novelty of this work lies in integrating pore network modeling with Monte Carlo simulations, addressing limitations of traditional models and offering a more accurate representation of unsaturated soil behavior. While the model has not yet undergone experimental validation, it provides valuable insights into the dynamics of soil moisture retention and serves as a foundation for future experimental testing and refinement of soil–water models. Doi: 10.28991/CEJ-2025-011-02-021 Full Text: PD
Shape Functions Development for Beam-Column Element with Semi-Rigid Connections in Second-Order Steel Frame Analysis
Get PDFThe objective of this paper is to provide a novel method for developing the shape functions of a beam-column element with semi-rigid connection ends, thereby establishing a static analysis method for semi-rigid steel frames. This method takes into account the influence of the P-Delta effect, according to the finite element method based on displacement (FEM). The shape function is established directly from a third-order Hermitian displacement function polynomial combined with the bending element deflection differential equation. The linear elastic stiffness matrix, the geometric stiffness matrix of a semi-rigid connection beam-column, and the equilibrium equation of the element in a local coordinate system are simultaneously obtained by applying Castigliano's theorem (Part 1) for elastic deformation potential energy expression. The computational program was developed using Matlab software, and the calculation results are verified against published research results, showing that the derived shape functions and the steel frame analysis method are reliable and trustworthy. In addition, this article also derives stiffness matrices and an equivalent nodal load vector for specific cases where the semi-rigid connection is fully rigid (FR) or a pin connection. The derived shape functions are polynomial expressions with coefficients that are simply calculated from the connection stiffness and the geometric and material characteristics of the element, making them highly convenient to use. Doi: 10.28991/CEJ-2025-011-01-021 Full Text: PD
Smart Roundabout Coordination Systems for Sustainable Urban Mobility
Get PDFTraffic signal coordination control is a smart approach used in urban networks to relieve the congestion by increasing corridor throughput and minimizing overall traffic delay. Previous studies have investigated various signal coordination challenges; however, integrating roundabouts into a coordinated signalized corridor without compromising their operational distinctiveness remains underexplored. This study introduces an adaptive traffic signal offset strategy incorporating a platoon compaction factor to address the dispersion effects caused by roundabouts, ensuring the preservation of platoon movement along the coordinated corridor. The method was evaluated using the PTV VISSIM micro-simulation software. The results show improvements in sustainability indicators at roundabouts, with average corridor-level delays minimized by 17%, delays associated with vehicle stops reduced by 28%, fuel consumption reduced by 16%, and emissions reduced by 9% and 16% for NOâ‚“ and CO₂, respectively. These improvements were statistically significant, affirming the robustness of the proposed method. The findings underscore the potential benefits of implementing this framework in real-world traffic scenarios, contributing to making urban transportation systems more efficient and sustainable. Doi: 10.28991/CEJ-2025-011-02-013 Full Text: PD