2031 research outputs found
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Experimental and ANN Analysis of Shearing Rate Effects on Coarse Sand Crushing
Get PDFThe present study analyzes laboratory experiments on how shearing rate affects the shear strength and crushability of natural coarse sand, employing artificial neural network (ANN) analysis. This study tested three different coarse sands obtained from the crushing of natural rocks: Black Virgin Tuff, weathered Zeolitic Tuff, and calcareous limestone. The behavior of crushed sand specimens with consistent grading, which passed through sieve #4 and were retained on sieve #8, was analyzed using a direct shear box. The specimens were subjected to varied normal loads and shearing speeds to examine their behavior at different relative densities. The test results were analyzed using ANN to investigate the significance of shearing rates on shearing strength parameters, specifically internal mobilized peak friction, the constant volume (residual) internal friction angle, and the consequence of shearing rate on the particle's breakage index. The selected normal (Gaussian) rate significantly affected both the shear strength parameters and breakage. The loading rate increased both shear strength parameters and particle breakage. Therefore, it's highly recommended to maintain secure sets of shear strength values and comprehensive test data for assessing parameters at typical strain rates, prioritizing using slower rates whenever possible. Doi: 10.28991/CEJ-2024-010-03-011 Full Text: PD
Seismic Performance of Infilled Reinforced Concrete Frame with Crumb Rubber Mortar Wall Panel
Get PDFIn this paper, the seismic performance of reinforced concrete (RC) frames with crumb rubber mortar wall panels is reported. The tests of the crumb rubber mortar were conducted to obtain model parameters for equivalent diagonal compression struts. With a higher percentage of sand replacement by crumb rubber, the unit weight, the compressive strength, the tensile strength, and the modulus of elasticity of the crumb rubber cement mortar are decreased. Nonlinear pushover analysis of a simple frame shows that the RC frame with a wall panel with less crumb rubber demonstrates lower lateral deformation ability. The failure modes are affected by the amount of crumb rubber and are dependent on the modeling choice of the equivalent compression strut as the wall panel representative. Finally, the seismic performance of the RC building was studied by the equivalent static approach to explore the influence of the crumb rubber mortar wall panels on internal forces and deformations of the frame. With a higher percentage of crumb rubber, the weight of the infill wall panels and the overall weight of the building are reduced, which meets lower seismic base shear demand. This benefit is, however, traded off with higher lateral deformation and also higher inter-story drift of the studied building frames. Doi: 10.28991/CEJ-2024-010-02-09 Full Text: PD
Quality of Harvested Rainwater from a Green and a Bitumen Roof in an Air Polluted Region
Get PDFA one-year study was conducted to evaluate the impact of air pollution and roof coating on runoff quality. An existing 440 sq meter bitumen roof of a single-story building was coated with an extensive green roof layer on one half. Rainfall and runoff samples from both roofs were collected during 11 rainfall events after the separation of the first flush. The study monitored several key parameters, including pH, electrical conductivity (EC), turbidity, chemical oxygen demand (COD), ammonium nitrogen, nitrate nitrogen, and phosphates. The study revealed that both types of roofs altered the rainfall quality, but the changes caused by the green roof were more substantial. Although the retention of runoff from green roofs has a widely acknowledged positive impact on collecting systems, our study shows that green roofs also result in a 7.5-fold increase in COD concentrations, a 5.4-fold increase in the sum of ammonium and nitrate nitrogen, and a 2.3-fold increase in phosphates compared to bitumen roofs. A clear link between the quality of rainwater/runoff and air pollution was not established. The study's findings will aid in the development and management of local rainwater harvesting systems and enhance global understanding of the primary quality parameters of various roof types, particularly in regions with air pollution. Doi: 10.28991/CEJ-2024-010-05-015 Full Text: PD
The Consequence of the Involvement of Flexural, Compression, and Punching Reinforcement Upon Punching Strength
Get PDFFlat slabs have an important role in concrete buildings due to their architectural flexibility and speed of construction. Punching shear is one of the most important phenomena to be considered during the design of reinforced concrete flat slabs, as this type of failure is brittle and does not predict previously raised alarms before failure. The main factors that affect punching strength in concrete are compressive strength, flexural reinforcement, and punching reinforcement in the form of stirrups, shear studs, or other shapes. This paper is part of a research program operated at the reinforced concrete laboratory of the Faculty of Engineering, Cairo University, to evaluate the contribution of horizontal flexural reinforcement, horizontal compression reinforcement, and vertical punching reinforcement on the punching strength of reinforced concrete flat slabs. In this research, fifteen half-scale specimens are cast and tested. The specimens had dimensions of 1100í—1100 mm and a total thickness of 120 mm. All specimens were connected to a square column of dimensions 150í—150 mm and loaded at the four corners with a supported span of 1000 mm. The main parameters considered in this research included spacing between stirrups, width of the stirrups, number of stirrup branches, ratio of the compression reinforcement, and ratio of the tension reinforcement. During testing, ultimate capacity, steel strain, cracking pattern, and deformation were recorded. The experimental results were analyzed and compared against values estimated from different international design codes. Doi: 10.28991/CEJ-2024-010-09-014 Full Text: PD
Analysis of Traffic Safety Factors and Their Impact Using Machine Learning Algorithms
Get PDFThe safety of road traffic is facing increasing challenges from a range of factors, and this study aims to address this issue. The paper describes the development of a model that assesses both the quantitative and qualitative aspects of the current traffic situation and can also predict future trends based on monthly data on traffic accidents over a period of years. The dataset is composed of the number of accidents that occurred in the Pristina region over a 10-year period, and these are categorized based on the type of accident and safety factors, including human, vehicle, and road factors. By using machine learning algorithms, a model has been developed that determines the factor with the greatest impact on traffic safety. To create the model, the algorithms Multiple Linear Regression (MLR), Artificial Neural Network (ANN), and Random Trees (RT) were used. The model evaluates the contribution of human, road, and vehicle factors to traffic accidents, using machine learning algorithms and 36 types of traffic accidents to analyze the relevant statistics. The results indicate a very good fit of the model according to the MLR algorithm, and this model also identifies the road factor as the main influencer of the traffic safety level. Doi: 10.28991/CEJ-2024-010-09-06 Full Text: PD
Adaptive Seismic Upgrading of Isolated Bridges with C-Gapped Devices: Model Testing
Get PDFThe seismic safety margins of seismically isolated bridges have not been thoroughly studied or comprehended due to a lack of actual on-site data observations. This study introduces a newly validated method for the efficient seismic protection of bridges that may be exposed to extremely strong, multidirectional near-source and critical far-source earthquakes. The isolated system was improved by incorporating innovative adaptive horizontal C-multigapped (HC-MG) energy dissipation devices to overcome the safety limitations associated with solely using isolated bridges under seismic loads. The newly developed adaptive C-gapped (ACG) bridge system was systematically validated through extensive experimental seismic tests on bridge models and additional analytical studies. The new ACG bridge system represents an advanced technical solution that integrates the benefits of seismic isolation and energy dissipation. The seismic isolation system for the large-scale ACG bridge prototype was designed using double spherical rolling seismic bearings (DSRSB). The seismic performance of the system was enhanced with adaptive HC-MG energy dissipation devices. The improved seismic performance of the system was demonstrated through extensive seismic shaking-table tests on the ACG bridge prototype, simulating selected seismic inputs characteristic of typical near- and far-source earthquakes. Doi: 10.28991/CEJ-2024-010-09-01 Full Text: PD
The Effects of Seismic Behavior on High Ground Stress Soft Rock Tunnel: A Review
Get PDFThe purpose of this review is to critically assess seismic activity's effects on soft rock tunnels under high ground stress scenarios. The paper seeks to identify key novelties and research gaps in the existing literature, offering new insights into analytical techniques, excavation methods, support systems, and monitoring technologies. A comprehensive review of recent studies was conducted, focusing on seismic behavior, analytical techniques, and mitigation strategies for soft rock tunnels. Case studies were selected based on their relevance to high ground stress conditions and their contribution to understanding seismic resilience. Significant findings include the identification of specific geological conditions that exacerbate seismic risks and the comparative effectiveness of various analytical techniques and support systems. Novel insights into the interaction of structural reinforcements and monitoring systems are also discussed. The review highlights new analytical techniques and advanced monitoring systems that improve predictive accuracy and early detection of seismic risks. It also proposes a refined approach to integrating mitigation strategies for enhanced tunnel resilience. Doi: 10.28991/CEJ-2024-010-09-020 Full Text: PD
Study on Pull-Up Behavior of Double Fold Anchor with Field Full Scale Test
Get PDFSeveral studies have been conducted on the use of anchors, including numerical analysis, experimental testing, and field-scale testing. These studies have provided insights into anchor behavior in terms of pull-up capacity and soil failure models under tensile loading. Specifically, for the use of anchors in cohesive or soft soils, it is possible to innovate by using anchor elements with various dimensional or surface area changes. This research aims to design anchors for cohesive soils that can be easily applied in the field and have high tensile capacity, determine the pull-up capacity of double-fold type ground anchors, and analyze the effect of the depth of double-fold anchors. The results of pullout and tensile capacity testing on double-fold anchors showed significant variations at each test location. At the first location, Sungai Kariango, high tensile capacity occurred at relatively shallow embedment depths, influenced by the type and bearing capacity of the soil at the test site. At the second location, although the soil was relatively soft, the tensile capacity was similar to the first location but with deeper embedment depths. At the third location, the consistency of soil type and soil strength at the two test points resulted in similar tensile capacities. This indicates that the type and strength, or bearing capacity, of the soil at the test site, as depicted by cone resistance parameters (qc), significantly affect the tensile capacity of the anchor. The better the soil strength and bearing capacity at the test site, the greater the tensile capacity of the anchor that can be achieved. A deep understanding of soil characteristics through CPT is essential in determining the design and embedment depth of anchors to achieve optimal tensile capacity. Through this research, it is expected to obtain optimal tensile capacity results for anchors and develop a double-fold type ground anchor model that is easy to install in the field, suitable for various structures with high tensile loads, and susceptible to uplift in soft soil layers. Doi: 10.28991/CEJ-2024-010-12-012 Full Text: PD
Optimizing Mortar Mixtures with Basalt Rubble: Impacts on Compressive Strength and Chloride Penetration
Get PDFThis research aims to establish a theoretical framework for developing binders from waste materials to reduce cement use in mortar production. It specifically examines the potential of ground basalt rubble (BS) as a supplementary binding material for partially replacing Portland cement Type 1 (OPC) in mortar mixtures. Various substitution ratios of BS, specifically 0%, 10%, 20%, 30%, and 40% by binder weight, were tested while maintaining a constant water-to-binder ratio (W/B) of 0.45. Superplasticizers (SP) were utilized to ensure consistent workability and flow of the mixtures. The SEM-EDS analysis was conducted to examine the microstructure of the cement paste, confirming the presence of calcium silicate hydrate (C-S-H) phases resulting from the pozzolanic reactions of BS. The findings showed that, at the 7-day test, replacing cement with 10% and 20% basalt rubble (BS) by weight of the binder yielded compressive strengths of 97% and 92% compared to the control (CT) mortar. In contrast, replacements of 30% and 40% BS resulted in compressive strengths of 72% and 60% of the CT mortar, respectively. Results from 28-day tests showed that replacing 10% of OPC with BS not only increased the compressive strength but also significantly decreased chloride penetration compared to the control mortar (CT). This enhancement suggests that BS can effectively replace 10%-20% of cement, with the compressive strength of the mortar ranging from 92% to 107% of that of the control. The findings accentuate the potential of using industrial by-products such as ground basalt rubble to reduce waste, alleviate environmental impacts, and promote the development of sustainable construction materials. Doi: 10.28991/CEJ-2024-010-12-013 Full Text: PD
Strength Assessment of Stiffened-Panel Structures against Buckling Loads: FE Benchmarking and Analysis
Get PDFThis research endeavors to examine the effect of stiffener shapes on the structural capacity of stiffened-plate structures, specifically focusing on Tee (T), Angle (L), and Flat (I) stiffened plates. The primary objectives are threefold: firstly, to quantify the critical load values during the buckling phenomenon for T, L, and I stiffened plates; secondly, to assess model deformation upon failure; and thirdly, to investigate whether the buckling behavior of T, L, and I stiffened plates correlates with distinct failure patterns. Employing numerical simulation through the finite element method, this study sheds light on previously unexplored aspects of structural behavior. The findings indicate that angle stiffeners exhibit superior load-bearing performance compared to flat bars. Notably, the research reveals a substantial increase in maximum compressive load by at least 15.90% with Tee bar and 8.25% with angle bar stiffeners when the stiffened panels undergo a 5 mm displacement, presenting a potential avenue for structural enhancement. Additionally, the study demonstrates that T bars outperform in terms of resisting buckling. Noteworthy is the novel approach of examining the combined effect of transverse frame, longitudinal frame, and hull girder under buckling scenarios, a facet not explored in previous research. Furthermore, the utilization of steel S355JR-EN10210 as a material introduces a unique dimension not previously considered in these scenarios. Doi: 10.28991/CEJ-2024-010-04-03 Full Text: PD