Current Issue : January-March Volume : 2024 Issue Number : 1 Articles : 5 Articles
As concrete is one of the most commonly used construction materials, there is a massive production of cement, which causes cement manufacturing to be an energy-intensive industry. A significant amount of the cost of cement production, ranging from 20% to 25%, is attributed to thermal energy. In addition, the action of mining and burning fossil fuels results in the unfavorable emission of hazardous compounds into the environment. Therefore, the switch from conventional fossil fuels to alternative fuels (AFs) in the cement manufacturing business has attracted attention due to environmental and financial concerns. In this paper, four commonly used AFs are discussed, which are waste tires, municipal solid waste, meat and bone meal, and sewage sludge. It is found that each AF has a unique calorific value and properties, attributed to its source, treatment, and technology. Furthermore, the availability of AF is important as the amount varies depending on the location. In addition, their effects on gaseous emissions from the cement plant and the quality of clinker are found to be inconsistent. Thus, there will not be a single best type of AF option to be used in the cement industry. A good AF should be able to provide sufficient thermal energy while reducing the environmental impacts and costs. A careful analysis and multicriteria decision-making approach are always vital when employing AFs in order to prevent environmental problems, cost increases, as well as clinker quality degradation....
Aluminum has a bright future as a structural material due to its excellent corrosion resistance, durability, lightweight, and complete recyclability. However, it is necessary to fully understand its mechanical behaviour under various loading conditions to make it competitive with other materials, such as concrete or steel, for civil engineering applications, especially as primary load-bearing structural members. To develop an in-depth knowledge on the behaviour of extruded aluminum sections of various shapes, an extensive experimental study was undertaken with specific emphasis on analyzing the buckling response of rectangular and square hollow sections (RHS and SHS) with 6061-T6 aluminum alloy under compressive loads. In this regard, six stub column tests were performed under axial compression, while eleven short beam-column tests under eccentric compression are currently in progress. Additionally, six tensile coupon tests were performed to obtain the full material stress–strain curve, and initial geometrical imperfections were measured mechanically and using a 3D scanner. Finally, the results of the stub column tests were compared to the resistances calculated using the Canadian standard CSA S157, which were generally conservative compared to the experimental observations....
Concrete was made with four different types of coarse aggregate, i.e., natural stone aggregate concrete (NSAC), crushed virgin clay brick aggregate concrete (VBAC), crushed recycled brick concrete aggregate concrete (RBAC), and crushed recycled stone concrete aggregate concrete (RSAC). Beam specimens prepared from these four types of concrete were subjected to pure torsional moment up to failure. From this experimental procedure, ultimate torque at failure along with twisting angle were observed. From the torque vs. twisting angle curves, torsional stiffness and torsional toughness were also evaluated for these four types of concrete. It was observed that ultimate torque of VBAC and RBAC was 95% and 90% of that of NSAC, respectively. The torsional toughness of VBAC was found to be 68%–72% of that of NSAC. In addition, experimental torques were compared with predictions of torsional strength as per five commonly used models. For VBAC, the ultimate torque prediction made by skew bending theory was found to be the closest to the experimental findings....
Automatic semantic segmentation of point clouds in railway bridge scenes is a crucial step in the digitization process and is required for a variety of subapplications including digital twin reconstruction and component geometric quality verification. This paper details a method for reliably and effectively segmenting point clouds acquired from complex railway bridge scenes by unmanned aerial vehicles (UAVs). The method involves segmenting seven common infrastructure elements in railway bridge point clouds using an improved DGCNN after processing low-quality point clouds from UAVs with a score-based denoising algorithm. The segmentation performance of the network is measured by averaging the intersection to union ratio between the segmentation results and the true labels of different elements, i.e., the mean intersection over union (mIoU).Theproposed method is evaluated on three different scenes of railway bridges and achieved mIoU values of 99.18%, 90.76%, and 85.84%, respectively, at three levels of complexity ranging from easy to difficult. The results demonstrate that the proposed method captures the most discriminative features from low-quality point clouds, allowing for the accurate and efficient digital representation of railway bridge scenes....
The various components of fully prefabricated metro stations are mainly connected using grouted tenon and mortise joints. Therefore, studying the mechanical properties of the joint locations is of significant importance for the overall safety and stability of the station. This paper focuses on the single tenon-long joint as the research object and applies an orthogonal experiment plan to investigate the relationship between the lower bottom length, upper bottom length, and height of the joint and its flexural load carrying capacity. After comparing various loading methods, uniformly distributed loads are chosen as the method for applying axial forces and bending moments. The objective is to determine the dimensions of the tongue and groove that exhibit optimal mechanical properties based on the law of opening displacement and maximum deflection variation with bending moment. The influence of geometrical parameters on the flexural strength of tenon joints is analyzed by means of range analysis in order to find the combination of geometrical parameters with the best mechanical properties. The degree of influence of each geometrical parameter was also ranked. Using these insights, the authors proposed a modified cross-shaped tenon based on the optimal combination of geometrical parameters, which was verified by comparing the M–θ curves of the optimal combination and the optimum working condition. The main conclusions are as follows: (1) the ranking of the geometric parameters of the joint in terms of their influence on the flexural capacity is as follows: height has a greater impact than the bottom length, and the bottom length has a greater impact than the top length. Among these parameters, the influence factor of the height is significantly greater than the other two. (2) The optimumgeometry for the tenon and mortise joint is 385mmfor the lower bottom length, 230mmfor the upper bottom length, and 200mm for the height; the joint’s ratio of height to total width should be 25%, the ratio of lower bottom length to total width should be 48%, and the ratio of upper bottom length to total width should be 29%. (3) The load carrying capacity of the cross-shaped tenon is significantly higher than that of the optimal combination and optimum working condition, providing a significant improvement. This research’s results will serve as a valuable reference for designing assembly nodes in prefabricated assembly metro stations....
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