• Structural Engineering and Mechanics
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• 제91권4호
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• pp.369-382
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• 2024

The earthquake loss assessment framework of ductile reinforced concrete (or RC) frame using component-performance -based methodology was studied in this paper. The elasto-plastic rotation angle was used as the damage indicator of structural component, and the damage-to-loss model was proposed on the basis of the deformation indicator of structural component. Dynamic instability during incremental dynamic analysis was taken as collapse criterion, and column failure was taken as criterion that structure has to be demolished. Expected earthquake losses of low-rise, mid-rise and high-rise RC frames were discussed. The expected earthquake loss encompassed collapse loss, demolition loss and repair loss. Furthermore, component groups of RC frame were divided into structural components, nonstructural components and rugged components. The results indicate that ductile RC frame is more likely to be demolished than collapse, especially in low-rise and mid-rise RC frames. Furthermore, the less collapse margin ratio the structure has, the more demolition probability the structure will suffer under rare earthquake. The demolition share of total earthquake loss might be more prominent than repair share and collapse share in ductile RC frame.

• Geomechanics and Engineering
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• 제38권6호
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• pp.571-581
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• 2024

Concrete linings in tunnels constructed by drilling and blasting such as NATM serve as a secondary support structure. However, these linings can face unexpected earth pressures if the primary support deteriorates or if ground conditions become unfavorable. It is crucial to determine the loosening earth pressure that allows the lining to maintain its structural integrity and prevent damage caused by this pressure. This study proposes a numerical model for simulating the trapdoor test and developing a method for calculating the loosening earth pressure. The discrete element method (DEM) was employed to describe the soil characteristics around the tunnel. Using this numerical model, a sequence of experimental trapdoor steps was simulated, and the loosening earth pressure was analyzed. Contact parameters were calibrated based on an analysis of a triaxial compression test. The reliability of the developed model was confirmed through a comparison between simulation results and laboratory test findings. The model was used to calculate the contact force applied to the trapdoor plate and to assess the settlement of soil particles. Furthermore, the model accounted for the soil-arching effect, which effectively redistributes the load to the surrounding areas. The proposed model can be applied to analyze the tunnel's cross-sectional dimensions and design stability under various ground conditions.

• Geomechanics and Engineering
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• 제38권4호
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• pp.397-408
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• 2024

Buried box culverts are crucial elements of transportation infrastructure. However, their behavior under foundation loads is not well understood, indicating a significant gap in existing research. This study aims to bridge this gap by conducting a detailed numerical analysis using the Finite Element Method and Abaqus software. The research evaluates the behavior of buried box culverts by examining their interaction with surrounding soil and the pressures from surface foundation loads. Key variables such as embedment depth, culvert wall thickness, concrete material properties, foundation pressure, foundation width, soil elastic modulus, and friction angle are altered to understand their combined effects on structural response. The methodology employs a validated 2D numerical model under plane strain conditions. Parametric studies highlight the critical role of culvert depth (H) in influencing earth pressure and bending moments. Foundation pressure and width demonstrate complex interdependencies affecting culvert behavior. Variations in culvert materials' elastic modulus show minimal impact. It was found that the lower wall of the buried culvert experiences higher average pressure compared to the other two walls, due to the combined effects of the culvert's weight and down drag forces on the side walls. Furthermore, while the pressure distribution on the top and bottom walls is parabolic, the pressure on the side walls follows a different pattern, differing from that of the other two walls.

• Advances in concrete construction
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• 제17권3호
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• pp.159-165
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• 2024

The interaction of short range zigzag single walled carbon nanotubes CNTs based on modified elasticity model is studied in this paper. The numerical accurate results are presented. Through this model the vibrational frequency of zigzag (5, 0), (12, 0) single-walled CNTs with certain end conditions are estimated. The natural frequencies of single walled carbon nanotubes are obtained by elasticity model. It is considered for various estimation of height-to-diameter ratio of zigzag tube. This simulation is performed to quantify small scale effects. Moreover, the natural frequencies increase by increasing the height-to-diameter ratio. These frequencies are very sensitive with low height-to-diameter ratio. The feasibility and effective use of present model is explained by comparison of outputs of earlier investigations.

• Advances in concrete construction
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• 제17권3호
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• pp.167-177
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• 2024

Disposal of waste glass derived from bottle or packaging glass, flat glass, domestic glass is one of the major environmental defies. Moreover, the remnants of bricks resulting from the remnants of buildings are also considered an important factor in polluting the environment due to the difficulty of filling or getting rid it. The aim of this study is to valorize these wastes through chemical activation to be an environmentally friendly material. The Microstructure, compressive strength, setting time, drying shrinkage, water absorption of different pastes produced by clear glass (CG), green glass (GG) and brick waste (BP) activated were tested and recorded after curing for 3, 7, 28 and 365 days. Five samples of pastes were mixed in proportions represented by: 100% GP (GP), 100% GGP (GGP), 100% BP (BP), 90% GP + 10% BP (GPB) and 90% GGP + 10% BP (GGPB). Various parameters considered in this study include sodium hydroxide concentrations (10 mol/l); 0.4 as alkaline liquid to binder ratio; 2.5 as sodium silicate to sodium hydroxide ratio and cured at 60℃ for 24 hours. Experimental results revealed that the addition of 10% of BP resulted in an increased strength performance of geopolymer paste especially with GGPB compared to GGP in 365 days. In addition, the 10% amount of BP increases the absorption and shrinkage rate of geopolymer pastes (GPB and GGPB) by reducing the setting time. SEM results revealed that the addition of BP and GP resulted in a dense structure.

• Advances in concrete construction
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• 제17권2호
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• pp.67-73
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• 2024

This paper examines the wave velocity of protein microtubules using a elasticity model that incorporates body forces, based on the structure of these hollow cylinder-like structures., the governing equations are analytically solved to determine how the body forces effect the wave velocity. To analyze the microtubule waves velocity, use microtubules with simply supported ends. The electric field of a dipole vibrating at the same frequency as microtubule vibrations approximates the electric field generated by the rhythmic motion of every charge. The numerical findings for the three modes of frequencies in the longitudinal, radial, and torsional directions for the current conditions are compared with the results of previous calculations.

• Computers and Concrete
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• 제34권3호
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• pp.297-305
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• 2024

This study investigates the buckling behavior of CNTRC beams on a Winkler-Pasternak elastic foundation, considering their stiffness. To achieve the highest accuracy, the shear stiffness is taken into account based on the Higher-order Shear Deformation Theory (HSDT). A novel exponential power-law distribution of the CNT volume fraction across the beam thickness is employed to model CNTRC beams. Various reinforcement patterns are incorporated into the polymer matrix, featuring single-walled carbon nanotubes (SWCNT) that are both aligned and distributed. The effective mechanical properties of the CNTRC beam are predicted using the rule of mixtures. Hamilton's principle is applied to derive the differential equations of motion. This theoretical framework enables the validation of the approach by comparing numerical simulation results with previous studies. The impact of the exponent order (n), CNT volume fraction, geometrical ratio, and Winkler-Pasternak parameters on buckling analysis is thoroughly presented and discussed. The results indicate that, among the different types of analyzed CNTRC beams, the X-Beam pattern demonstrates the highest buckling load capacity.

• Advances in concrete construction
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• 제17권2호
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• pp.53-66
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• 2024

Domain Name Systems (DNS) provide critical performance in directing Internet traffic. It is a significant duty of DNS service providers to protect DNS servers from bandwidth attacks. Data mining techniques may identify different trends in detecting anomalies, but these approaches are insufficient to provide adequate methods for querying traffic data in significant network environments. The patterns can enable the providers of DNS services to find anomalies. Accordingly, this research has used a new approach to find the anomalies using the Neural Network (NN) because intrusion detection techniques or conventional rule-based anomaly are insufficient to detect general DNS anomalies using multi-enterprise network traffic data obtained from network traffic data (from different organizations). NN was developed, and its results were measured to determine the best performance in anomaly detection using DNS query data. Going through the R² results, it was found that NN could satisfactorily perform the DNS anomaly detection process. Based on the results, the security weaknesses and problems related to unpredictable matters could be practically distinguished, and many could be avoided in advance. Based on the R² results, the NN could perform remarkably well in general DNS anomaly detection processing in this study.

• Computers and Concrete
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• 제34권3호
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• pp.355-365
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• 2024

TECSolverApp is an application that calculates the total equivalent seismic load (base shear) and shows the design spectra in accordance with the Turkish Earthquake Code (TEC). TECSolverApp software can present the spectral acceleration-period graph and the base shear (in terms of unit building weight) in MATLAB and .NET Core frameworks according to TEC 2007 and TEC 2018. In the software, three different building period evaluation options were provided, as entering the period directly, empirical calculation, and using the period calculation formula. In different period calculation scenarios, particular design input parameters such as site-specific spectral acceleration coefficients, local soil class, building importance coefficient, and structural system behavior coefficient are expected. TECSolverApp was produced in two different programming languages and published in MATLAB App Designer and ASP.NET Core MVC environments. To be shared in MATLAB App Designer, it was aimed at availability through the program and distributability as a desktop application. By deploying in ASP.NET Core MVC, open-source cross-platform coding and web-based accessibility were targeted. One of the strongest aspects of TECSolverApp is its developability thanks to software architecture. In this respect, it can be foreseen that other international seismic codes can be added to the calculations in the future.

• Advances in materials Research
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• 제13권5호
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• pp.375-389
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• 2024

Installing wiring or plumbing fixtures necessitates creating chases within masonry walls, which, while serving practical purposes, raises a crucial concern regarding the potential compromise of the masonry's structural integrity. Given these concerns, it becomes essential to thoroughly understand the impact of incorporating chases on masonry strength. In this study, 37 AAC masonry prisms (200×330×100 mm³) were cast and tested for compression. The prisms were equipped with chases of various depths -10 mm, 20 mm and 30 mm; and orientations (horizontal, inclined, and vertical), which were then filled with mortar using 1:2, 1:4, and 1:6 cement-to-sand ratios. The primary objectives were to assess the strength decrease in the prisms with different chase characteristics compared to a control specimen and to determine the percentage strength increase due to filling materials compared to unfilled chases. Key findings indicate that as chase depth increases, there is a substantial reduction in prism strength. However, the orientation of the chase does not significantly affect strength reduction. Importantly, filling the chases with mortar leads to a significant increase in prism strength. This study not only unveils the complex impact of chase characteristics on masonry strength but also emphasizes the crucial role of filling materials in strengthening these prisms.