Primjena metode konačnih elemenata za modeliranje drvno-plastičnih kompozita ojačanih vlaknima za uporabu u konstrukciji namještaja s polukrutim vezovi

In this study, control samples of pine (Pinus slyvestris L.), beech (Fagus orientalis L.) and oak (Quercus petreae L.) species were obtained by using fi ber reinforced finger corner joints. Teknobont 200 epoxy and polyvinyl (PVAc) adhesives were used as glue. Bearing in mind the critical loads that may affect their use, experimental samples were tested under diagonal loads. Experimental samples were also analyzed by a computer program using the finite element method (FEM). Finally, experimental data were compared with the results of FEM. The comparisons clearly showed that experimental results and finite element solutions (SAP2000 V17) including semi-rigid connections are in good agreement. As a structural analysis program in furniture engineering designs, FEM can be preferred in terms of reliability and cost.U radu se prikazuju rezultati istraživanja uzoraka borovine (Pinus slyvestris L.), bukovine (Fagus orientalis L.) i hrastovine (Quercus petreae L.) spojenih kutnim zupčastim spojevima i ojačanih vlaknima. Kao ljepilo upotrijebljeno je epoksidno ljepilo Teknobont 200 i polivinilacetatno ljepilo (PVAc). Imajući na umu opterećenja koja se pojavljuju tijekom uporabe, eksperimentalni su uzorci ispitivani pri dijagonalnim opterećenjima. Uzorci su također analizirani računalnim programom primjenom metode konačnih elemenata (FEM). Eksperimentalni podatci i podatci dobiveni FEM analizom uspoređeni su te se jasno može vidjeti da se ti podatci za polukrute vezove podudaraju. Glede pouzdanosti i troškova, kao strukturnom programu analize u dizajniranju namještaja prednost se može dati FEM analizi

Elastic foundation effects on arch dams

Earthquake response of an arch dam should be calculated under ground motion effects. This study presents three-dimensional linear earthquake response of an arch dam. Thereby, we considered different ground motion effects and also foundation conditions in the finite element analyses. For this purpose, the Type 3 double curvature arch dam was selected for application. All numerical analyses are carried out by SAP2000 program for empty reservoir cases. In the scope of this study, linear modal time-history analyses are performed using three dimensional finite element model of the arch dam and arch dam-foundation interaction systems. According to numerical analyses, maximum horizontal displacements and maximum normal stresses are presented by dam height in the largest section. These results are evaluated for rigid and various elastic foundation conditions. Furthermore, near-fault and far-field ground motion effects on the selected arch dam are taken into account by different accelerograms obtained from the Loma Prieta earthquake at various distances

Automatsko otkrivanje oštećenja na tradicionalnim drvenim konstrukcijama metodom klasifikacije slika utemeljenom na dubokom učenju

Wood has a long history of being used as a valuable resource when it comes to building materials. Due to various external factors, in particular the weather, wood is liable to progressive damage over time, which negatively impacts the endurance of wooden structures. Damage assessment is key in understanding, as well as in effectively mitigating, problems that wooden structures are likely to face. The use of a classification system, via deep learning, can potentially reduce the probability of damage in engineering projects reliant on wood. The present study employed a transfer learning technique, to achieve greater accuracy, and instead of training a model from scratch, to determine the likelihood of risks to wooden structures prior to project commencement. Pretrained MobileNet_V2, Inception_V3, and ResNet_V2_50 models were used to customize and initialize weights. A separate set of images, not shown to the trained model, was used to examine the robustness of the models. The three models were compared in their abilities to assess the possibilities and types of damage. Results revealed that all three models achieve performance rates of similar reliability. However, when considering the loss ratios in regard to efficiency, it became apparent that the multi-layered MobileNet_V2 classifier stood out as the most effective of the pre-trained deep convolutional neural network (CNN) models.Drvo kao vrijedan građevni materijal ima dugu povijest uporabe u graditeljstvu. No zbog brojnih vanjskih čimbenika, posebice vremenskih utjecaja, drvo tijekom vremena postaje podložno progresivnom propadanju, što negativno utječe na izdržljivost drvenih konstrukcija. Procjena šteta na drvu ključna je za razumijevanje problema koji će vjerojatno nastati na drvenim konstrukcijama, kao i za njihovo učinkovito ublažavanje. Primjena sustava klasifikacije uz pomoć dubokog učenja može potencijalno smanjiti vjerojatnost oštećenja u inženjerskim projektima koji se oslanjaju na drvo. U ovom je istraživanju primijenjena tehnika transfernog učenja kako bi se postigla veća točnost modela umjesto da se model za utvrđivanje vjerojatnosti rizika za drvene konstrukcije radi prije početka projekta. Za prilagodbu i inicijalizaciju težina primijenjeni su unaprijed osposobljeni modeli MobileNet_V2, Inception_V3 i ResNet_V2_50. Za ispitivanje robusnosti modela upotrijebljen je zaseban skup slika koji nije prikazan u osposobljenome modelu. Spomenuta tri modela uspoređena su s obzirom na njihove mogućnosti procjene vjerojatnosti i vrste oštećenja drvenih konstrukcija. Rezultati su otkrili da sva tri modela imaju sličnu pouzdanost. Međutim, kada se uzmu u obzir omjeri gubitaka u odnosu prema učinkovitosti, postalo je očito da se višeslojni MobileNet_V2 klasifikator istaknuo kao najučinkovitiji od unaprijed pripremljenih modela dubokih konvolucijskih neuronskih mreža (CNN)

Real-world efficacy and safety of Ledipasvir plus Sofosbuvir and Ombitasvir/Paritaprevir/Ritonavir +/- Dasabuvir combination therapies for chronic hepatitis C: A Turkish experience

Background/Aims: This study aimed to evaluate the real-life efficacy and tolerability of direct-acting antiviral treatments for patients with chronic hepatitis C (CHC) with/without cirrhosis in the Turkish population.Material and Methods: A total of 4,352 patients with CHC from 36 different institutions in Turkey were enrolled. They received ledipasvir (LDV) and sofosbuvir (SOF)+/- ribavirin (RBV) ombitasvir/paritaprevir/ritonavir +/- dasabuvir (PrOD)+/- RBV for 12 or 24 weeks. Sustained virologic response (SVR) rates, factors affecting SVR, safety profile, and hepatocellular cancer (HCC) occurrence were analyzed.Results: SVR12 was achieved in 92.8% of the patients (4,040/4,352) according to intention-to-treat and in 98.3% of the patients (4,040/4,108) according to per-protocol analysis. The SVR12 rates were similar between the treatment regimens (97.2%-100%) and genotypes (95.6%-100%). Patients achieving SVR showed a significant decrease in the mean serum alanine transaminase (ALT) levels (50.90 +/- 54.60 U/L to 17.00 +/- 14.50 U/L) and model for end-stage liver disease (MELD) scores (7.51 +/- 4.54 to 7.32 +/- 3.40) (p<0.05). Of the patients, 2 were diagnosed with HCC during the treatment and 14 were diagnosed with HCC 37.0 +/- 16.0 weeks post-treatment. Higher initial MELD score (odds ratio [OR]: 1.92, 95% confidence interval [CI]: 1.22-2.38; p=0.023]), higher hepatitis C virus (HCV) RNA levels (OR: 1.44, 95% CI: 1.31-2.28; p=0.038), and higher serum ALT levels (OR: 1.38, 95% CI: 1.21-1.83; p=0.042) were associated with poor SVR12. The most common adverse events were fatigue (12.6%), pruritis (7.3%), increased serum ALT (4.7%) and bilirubin (3.8%) levels, and anemia (3.1%).Conclusion: LDV/SOF or PrOD +/- RBV were effective and tolerable treatments for patients with CHC and with or without advanced liver disease before and after liver transplantation. Although HCV eradication improves the liver function, there is a risk of developing HCC.Turkish Association for the Study of The Liver (TASL

3D Nonlinear Analysis of Ataturk Clay Core Rockfill Dam Considering Settlement Monitoring

WOS: 000462449600019One of the most important causes of damages in clay core rockfill (CCR) dams is the deterioration of the rockfill material over time and big settlements in the dam body. Therefore, the forecast of the settlements and principal stresses in a CCR dam is extremely important for the safety and future of these important water structures. In this study, changes in the nonlinear behavior of a CCR dam were examined by effects of the various reservoir water heights. Moreover, the geodetic measurements were confirmed with the nonlinear analysis results. Ataturk Dam, which is the largest CCR dam in Turkey, was selected for three-dimensional (3D) nonlinear analyses. First, a 3D finitedifference model of Ataturk Dam was created using the FLAC3D software, which is based on the finite-difference method. A Mohr-Coulomb material model was used for the dam body materials (e.g., clay core, filters, alluvium, rockfill) and foundation for the 3D numerical analyses. Numerical analyses were carried out for five various reservoir water heights: empty reservoir, 50, 100, 153, and 170 m (full reservoir). According to the finite-difference analyses, the effect of various reservoir water heights on the nonlinear behavior of the Ataturk dam was assessed in detail, and how much maximum vertical settlement will occur in the Ataturk Dam body in the future was determined. In addition, principal stresses and horizontal displacements were evaluated for each reservoir condition, and these results were compared with each other. This study demonstrated that as the reservoir water height increased at the upstream side of the dam, the principal stresses and verticalhorizontal deformations occurring in the dam body obviously changed and increased. In the second part of this study, the geodetic vertical settlement results observed by the General Directorate of State Hydraulic Works (DSI) between 1992 and 2013 were presented graphically. These geodetic observation results and numerical analyses were compared in detail, and the geodetic measurement results were confirmed by numerical analysis results. (c) 2019 American Society of Civil Engineers

The Effect of Concrete Strengths Obtained from 2011 Van Earthquake on the Structural Performance of RC Buildings

Earthquakes cause a high risk in reinforced concrete (RC) structures with respect to life and property loss. As a result of the earthquake occurred on October 23, 2011, and November 9, 2011, in Van, a large-scale loss of life and property has been observed. A lot of constructive problems were determined after the examinations of demolished or damaged buildings. One of the most important reasons of damage is that concrete strength is much lower than the expected one. The main purpose of this study is to examine the effect of the concrete strength of the demolished or damaged RC buildings on the performance of buildings. For this purpose, various concrete strengths have been selected among the reports which were prepared after the earthquake. In this manner, structural performances of three story buildings with three bays which have various concrete strengths are compared. The damage-limitation limit states are recalculated with cross-sectional analysis program. Then, static pushover analysis is performed and thereby modal capacity curve is obtained and the target displacement is calculated. In addition to this, damages occurred in the cross sections are examined. National and international specifications such as ATC 40 and TEC-2007 are used in the numerical analyzes and evaluations. According to the obtained numerical results, the concrete strength has significant effects on the behavior of the RC load-bearing system

The effect of concrete slab-rockfill interface behavior on the earthquake performance of a CFR dam

WOS: 000285901900005Earthquake response of the concrete slab is mostly depended upon its conjunction with rockfill This study aims to reveal the effect of concrete slab-rockfill interface behavior on the earthquake performance of a concrete-faced rockfill dam considering friction contact and welded contact Friction contact is provided by using interface elements with flue numbers of shear stiffness values 2D finite element model of Torul concrete-faced rockfill dam is used for this purpose Linear and materially non-linear time-history analyses considering dam-reservoir interaction are performed using ANSYS Reservoir water is modeled using fluid finite elements by the Lagrangian approach The Drucker-Prager model is preferred for concrete slab and rockfill in non-linear analyses Horizontal component of 1992 Erzincan earthquake with peak ground acceleration of 0 515g is used in analyses The maximum and minimum displacements and principal stresses are shown by the height of the concrete slab and earthquake performance of the dam is investigated considering different joint conditions for empty and full reservoir cases In addition potential damage situations of concrete slab are evaluated (C) 2010 Elsevier Ltd All rights reserve

OPTIMIZATION OF HEAT EXCHANGER SYSTEMS USING A FUZZY REINFORCED SWARM INTELLIGENCE

The significance and popularity of heat exchangers in industrial applications cause their cost-efficient design to become an important issue. This aim can be accomplished by optimizing the features of these systems in order to reduce their total cost. In this respect, the current study deals with employing a nongradient-based swarm intelligence the so-called interactive fuzzy search algorithm (IFSA) for the optimal designing of heat exchangers. The IFSA is a parameter-free and self-adaptive method applying a fuzzy decision-making mechanism that utilizes two nine-rule fuzzy mapping mechanisms to regulate the exploitation and exploration search behaviors of the optimization algorithm. In line with the subject of the current study, double-pipe and shell-and-tube heat exchangers cost optimization models and a suite of benchmark mathematical functions are considered as constrained and unconstrained optimization problems. The achieved outcomes are compared with the results obtained using five other well-known metaheuristic optimization methods. The attained results indicate that thanks to its fuzzy module the proposed approach can adapt itself to governing conditions of the problems and provides promising results in solving the thermo-economic model of heat exchanger systems

Investigating buckling load of orthotropic plates with a circular cut-out

Bu çalışmada, bir doğrultulu statik düzlemsel yükler etkisindeki, basit mesnetli, tabakalı, dairesel delikli, ortotropik dikdörtgen plakların burkulma analizi sonlu elemanlar yöntemi kullanılarak yapılmıştır. Ortotropik plaklarda çeşitli geometrik deliklerin bulunması halinde elemanın taşıyabileceği burkulma yükünün incelenmesi oldukça önemlidir. Bu nedenle, bu çalışmada altı tabakalı, merkezi dairesel delikli ve tabakaları uygulanan yüke 0° ve 90°’lik açılarla yerleştirilmiş plaklar dikkate alınmıştır. Plak merkezine yerleştirilmiş daire şeklindeki deliğin yarıçapının değişmesi durumunda kritik burkulma yüklerinin değişimi araştırılmıştır. Ayrıca kritik burkulma yükü değişimleri için regresyon analizi yapılmıştır.In this study, buckling analysis of simply supported, laminated and orthotropic rectangular plates with circular cut-out subjected to uniaxial static in-plane loads are performed by using finite element method. It is important to investigate buckling load, which plate will bear, on orthotropic plates while those have various geometrically cut-outs. So, six laminates, central circular cut-out and cross-ply plates are taken into consideration. It is studied that when radius of central circular cut-out of plate increases, how the critical buckling load changes. Besides, a regression analysis is performed for the buckling loads

Reservoir water effects on earthquake performance evaluation of Torul Concrete-Faced Rockfill Dam

This study presents earthquake performance analysis of the Torul Concrete-Faced Rockfill (CFR) Dam with two-dimensional dam-soil and dam-soil-reservoir finite element models. The Lagrangian approach was used with fluid elements to model impounded water. The interface elements were used to simulate the slippage between the concrete face slab and the rockfill. The horizontal component of the 1992 Erzincan earthquake, with a peak ground acceleration of 0.515g, was considered in time-history analysis. The Drucker-Prager model was preferred in nonlinear analysis of the concrete slab, rockfill and foundation soil. The maximum principal stresses and the maximum displacements in two opposite directions were compared by the height of the concrete slab according to linear time-history analysis to reveal the effect of reservoir water. The changes of critical displacements and principal stresses with time are also shown in this paper. According to linear and nonlinear time-history analysis, the effect of the reservoir water on the earthquake performance of the Torul CFR Dam was investigated and the possible damage situation was examined. The results show that the hydrodynamic pressure of reservoir water leads to an increase in the maximum displacements and principal stresses of the dam and reduces the earthquake performance of the dam. Although the linear time-history analysis demonstrates that the earthquake causes a momentous damage to the concrete slab of the Torul CFR Dam, the nonlinear time-history analysis shows that no evident damage occurs in either reservoir case