• Structural Engineering and Mechanics
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• v.86 no.6
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• pp.793-815
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• 2023

The current study looks at the experimental and numerical performance of ferrocement RC channel slabs reinforced with welded steel mesh, expanded steel mesh, and fiber glass mesh individually. Ten RC channel slabs with dimensions of 500 mm×40 mm×2500 mm were subjected to flexural loadings as part of the testing program. The type of reinforcing materials, the number of mesh layers, and the reinforcement volume fraction are the key parameters that can be changed. The main goal is to determine the impact of using new inventive materials to reinforce composite RC channel slabs. Using ANSYS -16.0 Software, nonlinear finite element analysis (NLFEA) was used to simulate the behavior of composite channel slabs. Parametric study is also demonstrated to identify variables that can have a significant impact on the model's mechanical behavior, such as changes in slab dimensions. The obtained experimental and numerical results indicated that FE simulations had acceptable accuracy in estimating experimental values. Also, it's significant to demonstrate that specimens reinforced with fiber glass meshes gained approximately 12% less strength than specimens reinforced with expanded or welded steel meshes. In addition, Welded steel meshes provide 24% increase in strength over expanded steel meshes when reinforcing RC channel slabs. In general, ferrocement specimens tested under flexural loadings outperform conventional reinforced concrete specimens in terms of ultimate loads and energy absorbing capacity.

• Computers and Concrete
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• v.31 no.2
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• pp.163-171
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• 2023

Face gear transmission is widely used in aerospace shunt-confluence transmission system. Tooth wear is one of the main factors affecting its bearing transmission performance. Furthermore, the installation errors of face gear are inevitable. In order to study the wear mechanism of face gear tooth surface with installation errors, based on tooth contact analysis numerical method and Archard wear theory, the UMESHMOTION subroutine in ABAQUS is developed.Combining with Arbitrary Lagrangian-Eulerian adaptive mesh technology, the finite element mesh wear model of abraded face gear pair is established.The preprocessing conditions are set to generate the inp files.Then,the inp files for each corner are imported and batch processed in ABAQUS.The loading tooth contact problem at each rotation angle is solved and the load distribution coefficient among gear tooth, tooth root bending stress, tooth surface contact stress and loaded transmission error are obtained. Results show that the tooth root wear is the most serious and the wear at the pitch cone is close to 0.The wear law of tooth surface along tooth width direction is convex parabola and the wear law along tooth height direction is concave parabola.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1D
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• pp.53-60
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• 2010

The objective of this paper is to evaluate a performance-based load zoning procedure in flexible pavements. Long-term performance in flexible pavements will be evaluated using VESYS type rutting model and Miner s theory on fatigue cracking. Permanent deformation properties such as alpha and gnu, and fatigue cracking properties such as k1 and k2 in asphalt concrete were used respectively. The data from the literatures were also used in predicting performance in flexible pavements for evaluating load restrictions as well as parametric study. Finally, a performance-based load zoning procedure and a simple load limit procedure for load zoning were assessed.

• International conference on construction engineering and project management
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• 2017.10a
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• pp.52-61
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• 2017

Considering its significant impact on the cost and schedule of construction projects, formwork as one part of temporary facility categories in construction should be arranged precisely. Current practice in the formwork planning is often conducted manually and repetitively, causing low efficiency and time waste. This study proposes an automated framework to generate more accurate and detailed formwork plans by utilizing information from building information modeling (BIM) considering the adequate geometric and semantic information provided by the BIM model. The dimensions and quantities information of elements in a building can be extracted automatically. Then, a rule is prepared for calculating the required forms erected around elements based on the contact areas. Finally, an algorithm of integrating first fit decreasing (FFD) with coordinated bottom left (CBL) is applied to automatically generate the formwork plan. The BIM-based automated planning framework is demonstrated by an illustrative example. The results show that the proposed framework can generate the formwork plan accurately and automatically, and significantly improve the efficiency in the formwork plan and reuse.

• Steel and Composite Structures
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• v.44 no.4
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• pp.545-555
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• 2022

Empirical relationships that capture the nonlinear behavior of headed steel shear stud anchors have been derived from standard push out tests, where the specimens are comprised of large wide flanged steel sections attached to flat concrete slabs via the anchors. However, many composite systems used in practice utilize much smaller steel members and/or steel decking as part of the slab system. Composite open web steel joist systems generally include both of these elements and consequently the nonlinear performance ofthe anchor is not accurately represented by existing models. In this paper, a new empirical relation is presented for open web steel joist systems based on experimental results from a modified push out test that more realistically represent a composite open web steel joist system. The methodology for obtaining the proposed nonlinear function where the response of the system is characterized by two parameters(α and β) is presented. The two-step process for obtaining the two parameters is described and the empirical relation is calibrated with the experimental data. In comparison with existing expressions, the new proposal herein more accurately predicts the high initialstiffness of the system and overall nonlinear system performance.

• Korean Journal of Artificial Intelligence
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• v.11 no.4
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• pp.15-20
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• 2023

Machine learning is comprised of supervised learning, unsupervised learning and reinforcement learning as the type of data and processing mechanism. In this paper, as input and output are unclear and it is difficult to apply the concrete modeling mathematically, reinforcement learning method are applied for crawling robot in this paper. Especially, Q-Learning is the most effective learning technique in model free reinforcement learning. This paper presents a method to implement a crawling robot that is operated by finding the most optimal crawling method through trial and error in a dynamic environment using a Q-learning algorithm. The goal is to perform reinforcement learning to find the optimal two motor angle for the best performance, and finally to maintain the most mature and stable motion about EV3 Crawling robot. In this paper, for the production of the crawling robot, it was produced using Lego Mindstorms with two motors, an ultrasonic sensor, a brick and switches, and EV3 Classroom SW are used for this implementation. By repeating 3 times learning, total 60 data are acquired, and two motor angles vs. crawling distance graph are plotted for the more understanding. Applying the Q-learning reinforcement learning algorithm, it was confirmed that the crawling robot found the optimal motor angle and operated with trained learning, and learn to know the direction for the future research.

• Structural Engineering and Mechanics
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• v.88 no.1
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• pp.67-81
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• 2023

The reinforced concrete (RC) structures might need strengthening or upgradation due to adverse environmental conditions, design defects, modification requirements, and to prolong the expected lifespan. The RC beams have been efficiently strengthened using the near surface mounted (NSM) approach over the externally bonded reinforcing (EBR) system. In this study, the performance of RC beam elements strengthened with NSM-steel rebars was investigated using an experimental program and nonlinear finite element modeling (FEM). Nine medium-sized, rectangular cross-section RC beams total in number made up for the experimental evaluation. The beams strengthened with varying percentages of NSM reinforcement, and the number of grooves was assessed in four-point bending experiments up to failure. Based on the experimental evaluation, the load-displacement response, crack features, and failure modes of the strengthened beams were recorded and considered. According to the experimental findings, NSM steel greatly improved the flexural strength (up to about 84%) and stiffness of RC beams. The flexural response of the tested beams was simulated using a 3D non-linear finite element (FE) model. The findings of the experiments and the numerical analysis showed good agreement. The effect of the NSM groove and reinforcement on the structural response was then assessed parametrically.

• Structural Engineering and Mechanics
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• v.89 no.4
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• pp.363-374
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• 2024

Significant changes have been made to estimate the punching shear capacity for edge column-slab joints in the latest editions of most current codes. The revised equations account for axial forces as well as moments conveyed to columns from slabs, which have a substantial impact on the punching resistance of such joints. Many key design parameters, such as reinforcement-ratio, concrete strength, size-effect, and critical-section perimeter, were treated differently or even ignored in various code provisions. Consequently, wide ranges of predicted punching shear strength were detected by applying different code formulas. Therefore, it is essential to assess the various current Codes' design-equations. Because of the similarity in estimated outcomes, only the ACI, EC, and SNiP are used in this study to cover a wide range of estimation ranges from highly conservative to unconservative. This paper is devoted to analyzing the techniques in these code provisions, comparing the estimated punching resistance with available experimental data, and finally developing efficient models predicting the punching capacity of edge column-slab connections. 63 samples from past investigations were chosen for validation. To appropriately predict the punching shear, newly updated equations for ACI and SNiP are provided based on nonlinear regression analysis. The proposed equations'results match the experimental data quite well.

• Computers and Concrete
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• v.33 no.5
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• pp.481-496
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• 2024

Internal erosion around pipes can lead to the failure of earth dams through various mechanisms. This study investigates the displacement patterns in earth dam models under three different failure modes due to internal erosion, using digital image correlation (DIC) methods. Three failure modes—erosion along a pipe (FM1), pipe leakage leading to soil erosion (FM2), and erosion in a pipe due to defects (FM3)—are analyzed using two- and three-dimensional image- processing techniques. The internal displacement of the cross-sectional area and the surface displacement of the downstream slope in the dam models are monitored using an image acquisition system. Physical model tests reveal that FM1 exhibits significant displacement on the upper surface of the downstream slope, FM2 shows focused displacement around the pipe defect, and FM3 demonstrates increased displacement on the upstream slope. The variations in internal and surface displacements with time depend on the segmented area and failure mode. Analyzing the relationships between internal and surface displacements using Pearson correlation coefficients reveals various displacement patterns for the segmented areas and failure modes. Therefore, the image-based characterization methods presented in this study may be useful for analyzing the displacement distribution and behavior of earth dams around pipes, and further, for understanding and predicting their failure mechanisms.

• Computers and Concrete
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• v.33 no.1
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• pp.13-25
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• 2024

In this study, contact analysis in a functionally graded (FG) layer loaded with two circular punches is solved using the finite element method (FEM). The problem is consisted of a functionally graded layer that resting on an elastic semi-infinite plane and is loaded with two rigid punches of circular geometry. External loads P and Q are transferred to the layer via two rigid punches. The finite element model of the functionally graded layer is created using the ANSYS package program and a 2-dimensional analysis of the problem is analyzed. The contact lengths, obtained as a result of the analysis are compared with the analytical solution in the literature. In the study, the effects of parameters such as distances between punches, loads, inhomogenity parameter on contact zones, initial separation loads and distances, normal stresses, stresses across depth and contact stresses are investigated. As a result, in this study, it can be said that the magnitude of the stresses occurring in the FG layer is less than the homogeneous layer, therefore the life of FG materials will be longer than the homogeneous layer. When the distance between the punches is 2.25, the initial separation distance is 6.98, and when the distance between the punches is 4, the initial separation distance decreases to 6.10. In addition, when the load increased in the second punch, the initial separation load decreased from 55 to 18. The obtained results are presented in the form of graphs and tables.