Evaluation of Internal Resistance in Asphalt Concretes

Zandi, Yousef,Akpinar, Muhammet Vefa Korea Concrete Institute 2012 International Journal of Concrete Structures and M Vol.6 No.4

Composites are somewhat more difficult to model than an isotropic material such as iron or steel due to the fact that each layer may have different orthotropic material properties. In finite element literature the asphalt mixes are represented by using rectangular meshes, not the actual picture of their cross-sections. Asphalt aggregate size and distribution in the asphalt concrete sample, aggregate shape, and fractured surface effects are ignored. In this research, the actual image of the sample including all these effects were directly considered in the finite element. The samples, were cut into cross-sections and were scanned. The image-processing toolbox of Labview was utilized in obtaining the rectangular gray images of the scanned images. In the rectangular sample the aggregates were white and the asphalt binders were black. The grayscale images were converted by LABVIEW into the format required by ANSYS as an input file, with the same dimensions. The nodes at the bottom of the model were constrained in both x and y directions. Left and right edges were symmetry and top was free. Certain amount of pressure was applied along the top surface to simulate the tire pressure.

Computational investigation of the comparative analysis of cylindrical barns subjected to earthquake

Yousef Zandi,Mahdi shariati,Aminaton Marto,Xing Wei,Zeki Karaca,Duy Kien Dao,Ali Toghroli,Mir Heydar Hashemi,Yadollah Sedghi,Karzan Wakil,Majid Khorami 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.4

The structural behaviors of cylindrical barns as a specific engineering structure have been considered as a complicated computing process. The structure design against the earthquake load, to protect by using the code, is an urgency avoiding unexpected damages. The situation has been subjected to the applied design method if there would be no failure across the construction procedures. The purpose of the current study is to clarify the behaviors of cylindrical reinforced concrete barns through the analytic methods across the mass and Lagrangian approaches through the whole outcomes comparison indicating that the isoparametric element obtained from the Lagrangian approach has been successfully applied in the barns earthquake analysis when the slosh effects have been discarded. The form of stress distributions is equal with <i>s_z</i> closed distributions to one another.

Evaluation of Internal Resistance in Asphalt Concretes

Yousef Zandi,Muhammet Vefa Akpinar 한국콘크리트학회 2012 International Journal of Concrete Structures and M Vol.6 No.4

Composites are somewhat more difficult to model than an isotropic material such as iron or steel due to the fact that each layer may have different orthotropic material properties. In finite element literature the asphalt mixes are represented by using rectangular meshes, not the actual picture of their cross-sections. Asphalt aggregate size and distribution in the asphalt concrete sample, aggregate shape, and fractured surface effects are ignored. In this research, the actual image of the sample including all these effects were directly considered in the finite element. The samples, were cut into cross-sections and were scanned. The image-processing toolbox of Labview was utilized in obtaining the rectangular gray images of the scanned images. In the rectangular sample the aggregates were white and the asphalt binders were black. The grayscale images were converted by LABVIEW into the format required by ANSYS as an input file, with the same dimensions. The nodes at the bottom of the model were constrained in both x and y directions. Left and right edges were symmetry and top was free. Certain amount of pressure was applied along the top surface to simulate the tire pressure.

Experimental investigation on UHPC beams reinforced with GFRP and steel rebars and comparison with prediction equations

Parvin, Yousef Abbasi,Shaghaghi, Taleb Moradi,Pourbaba, Masoud,Mirrezaei, Seyyed Saeed,Zandi, Yousef Techno-Press 2022 Advances in concrete construction Vol.14 No.1

In this article, the flexural and shear capacity of ultra-high-performance fiber-reinforced concrete beams (UHPFRC) using two kinds of rebars, including GFRP and steel rebars, are experimentally investigated. For this purpose, six UHPFRC beams (250 × 300 × 1650 mm) with three reinforcement ratios (ρ) of 0.64, 1.05, and 1.45 were constructed using 2% steel fibers by volume. Half of the specimens were made of UHPFRC reinforced with GFRP rebars, while the other half were reinforced with conventional steel rebars. All specimens were tested to failure in four-point bending. Both the load-deformation at mid-span and the failure pattern were studied. The results showed that utilizing GFRP bars increases the flexural strength of UHPFRC beams in comparison to those made of steel bars, but at the same time, it reduces the post-cracking strain hardening. Furthermore, by increasing the percentage of longitudinal bars, both the post-cracking strain hardening and load-bearing capacity increase. Comparing the experiment results with some of the available equations and provisions cited in the valid design codes reveals that some of the equations to predict the flexural strength of UHPFRC beams reinforced with conventional steel and GFRP bars are reasonably conservative, while Khalil and Tayfur model is un-conservative. This issue makes it essential to modify the presented equations in this research for predicting the flexural strength of UHPFRC beams using GFRP bars.

Buckling of porosity-dependent bi-directional FG nanotube using numerical method

Wang, Haiquan,Zandi, Yousef,Gholizadeh, Morteza,Issakhov, Alibek Techno-Press 2021 Advances in nano research Vol.10 No.5

This article focused on studying the buckling behavior of two-dimensional functionally graded (2D-FG) nanosize tubes, including porosity based on first shear deformation and higher-order theory of tube. The nano-scale tube is simulated based on the nonlocal gradient strain theory, and the general equations and boundary conditions are derived using Hamilton's principle for the Zhang-Fu's tube model (as higher-order theory) and Timoshenko beam theory. Finally, the derived equations are solved using a numerical method for both simply-supported and clamped boundary conditions. The parametric study is performed to study the effects of different parameters such as axial and radial FG power indexes, porosity parameter, nonlocal gradient strain parameters on the buckling behavior of di-dimensional functionally graded porous tube.

Analysis of leaking ratio of sealing device for the intake port of EMC closed integral structure turbine disk through soft computing

Cao, Yan,Zandi, Yousef,Rahimi, Abouzar,Fan, Qingming,Bai, Yu,Guo, Junde,Fu, Leijie,Khadimallah, Mohamed Amine,Jameel, Mohammed,Assilzadeh, Hamid Techno-Press 2021 Advances in nano research Vol.11 No.3

The rotor disk produces an azimuthal velocity component in the space between the rotor and stator of a turbine disk, also known as the rim seal cavity. As part of an empirically study, the rim seal cavity is subjected to a test aimed to count the number of unstable structures and evaluate their rotational speed. An Electronic Control Unit (ECU) has a leak test aperture that is sealed by a sealing device that is selectively disposed in the leak test aperture. Designing pump and compressor machines and units requires the development of dependable seal assemblies that maintain tightness over a long period of time and in a wide variety of pressures and temperature. In the field of electrochemical machining (ECM), heat-resistant and high-strength materials may be machined into complicated forms using this well-known technology. ECM presents some issues as the electrochemical copying of grooves, insulating groove features, slots and mini-holes can cause water leakage due to the poor sealing device of the closed integral structure turbine disk. Sealing devices of rotor turbine disks are heavy components with low-cycle fatigue analysis to their life curves. However, there is rare analysis to detect their defects in various rotor regions (temperature, considering stress, mission profile). This study by use of hydro-thermal loading has attempted to focus on the mechanical seals rings and basic productive and operating requirements. Taking the damage and wear, the clearance has been altered that cause a raising in leakage. Generally, the leakage grows more rapidly than linearly with the after-damage clearance. Also, damage and wear were related to the labyrinth seal itself, resulting that the bending curvature and the percentage of bent tooth length were also relevant in defining the leakage in the case of bending damage.

A review study of application of artificial intelligence in construction management and composite beams

Yan Cao,Yousef Zandi,Alireza Sadighi Agdas,Qiangfeng Wang,Xueming Qian,Leijie Fu,Karzan Wakil,Abdellatif Selmi,Alibek Issakhov,Angel Roco-Videla 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.6

This paper is aimed to review the use of artificial intelligence (AI) algorithms in diverse civil engineering applications such as predicting and evaluating the different parameters of composite beams and shear connectors and determining the compressive strength of concrete. Also, the application of AI methods especially artificial neural network (ANN) in construction engineering and management including prediction and estimation, decision-making, classification or selection, optimization and risk analysis and safety has been thoroughly discussed. Furthermore, the integration of Artificial Neural network (ANN) with other soft computing methods, such as Backpropagation (BP), imperialist competitive algorithm (ICA), support vector regression (SVR), back-propagation neural network (BPNN), Genetic Algorithms (GA) and Multilayer feed forward (MLFF) has been reviewed. It has been reported that the combination of ANN with other intelligence algorithms leads to providing more accurate results. Moreover, the performance of ANN with other soft computing techniques, such as BP, BPNN, SVR, GA, ICA, and MLFF in various fields has been compared and ANN in many cases had superiority over other models.

The compressive strength of concrete retrofitted with wind ash and steel slag pozzolans with a water-cement based polymers

Cai, Ting,Zandi, Yousef,Agdas, Alireza Sadighi,Selmi, Abdellatif,Issakhov, Alibek,Roco-Videla, Angel Techno-Press 2021 Advances in concrete construction Vol.11 No.6

Freeze and thaw phenomena in cold regions are the main cause of severe damage to concrete structures. Alkali-activated slag repair mortars, which are introduced as a suitable material for the replacement of Portland cement, can be used as the protective coating for these damaged structures. The mechanical properties and durability of this coating layer should be studied. In this study, the mechanical properties and durability of alkali-activated slag repair mortars with silica fume (SF) participation as inorganic additives against freeze-thaw and salt scaling attacks have been investigated. In order to evaluate the effects of alkaline activators type, the ratio of these solutions to Pozzolan (Pozz), and the use of SF as a substitute base material, these three factors were considered as the main variables to produce 12 alkali-activated slag mortar mixtures. To investigate their mechanical properties, compressive strength, tensile adhesion strength, and drying shrinkage tests were conducted. Also, mortar specimen length change, compressive strength loss, weight loss, and dynamic elastic modulus were measured to evaluate the durability features against freeze-thaw and salt scaling attacks. According to the results, in addition to higher compressive strength and adhesion resistance of alkali-activated slag repair mortars, these mortars showed at least 30% better durability against freeze-thaw and salt scaling attacks than cement-based repair mortar. Also, alkali-activated slag mixtures containing potassium hydroxide, alkaline solution (AS) to Pozz ratio of 0.7, and SF had the best mechanical properties and frost resistance among all mixtures.

Analysis of the superplasticizer demand using computer simulation

Heirati, Arian,Zandi, Yousef,Tafreshi, Shahriar Tavousi,Behruyan, Manuchehr Techno-Press 2021 Advances in nano research Vol.11 No.5

The merits of self-consolidating concrete (SCC) such as high deformability, excellent resistance to segregation, and usability without applying vibration is highly common. To gain an environment-friendly approach or improving SCC properties, cement in SCC can be partially replaced with other materials. However, identifying the most effective parameters on the Superplasticizer demand (SP demand) of SSC would not be easy after the replacement. The main aim of this study is to identify the most influencing approaches on SP demand prediction. Hence, five different approaches in SP demand prediction, including Jring test, V funnel test, Ubox test, 3-min slump value, and 50-min slump value have been considered. Then, different models of an artificial intelligence approach are developed and the most influential one in an accurate SP demand prediction was determined. In comparison with other methods, it was indicated that in estimating the SP demand, V-funnel can be a better technique because of producing the lowest RMSE.

Computer simulation for stability performance of sandwich annular system via adaptive tuned deep learning neural network optimization

Ming, Yan,Zandi, Yousef,Gholizadeh, Morteza,Oslub, Khaled,Khadimallah, Mohamed Amine,Issakhov, Alibek Techno-Press 2021 Advances in nano research Vol.11 No.1

In this article with the aid of adaptively tuned deep neural network (DNN), dynamic stability analysis of the sandwich structure has been investigated. Due to finding the design-points features, the numerical solution procedure called two-dimensional generalized differential quadrature technique has been applied to the ordinary differential equations of the current structure system acquired on the foundation of the kinematic theory with refined higher order terms. Also, the involved parameters with the optimum values in the fully-connected neural network mechanism are obtained via momentum-based optimizer. For modeling a moderately thick structure, higher order terms of shear deformation are chosen. For stability analysis of the current structure the design points considering the method of adaptive learning is presented. For analysis of the current structure 'accuracy (used for determining the design-points) is presented through than the published outcomes in the literature. The outcomes of accuracy section of the current research show that the DNN-based model in analysis of the sandwich structure has less error than other models. The results show that the current momentum-based optimizer can be good tool for future researches about stability analysis of the various structure due to its good accuracy.