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Bu çalışmada yangın sonrası farklı soğutma modellerinin etkisi incelenmiştir. Isıtılan kayaçlar; (1) doğal çevre koşullarını temsil etmek için oda sıcaklığında, (2) soğuk mevsimleri temsil etmek için sıfırın altında ve (3) yangına müdahale senaryosu göz önüne alınarak suda soğumaya maruz bırakılmıştır. Çalışmada yapı taşı olarak sıklıkla kullanılan 3 farklı karbonat kayaç, traverten, mermer ve kireçtaşı kullanılmıştır. Kayaçların mineralojik bileşimlerini ve ısıtma-soğutma işlemlerinden sonra mineralojik değişimleri belirlemek için ince kesit incelemeleri ve XRD analizleri yapılmış, mikro-kırık gelişimini ortaya çıkarmak amacıyla SEM görüntüleri kullanılmış, fiziksel ve dayanım özelliklerindeki değişimleri belirlemek için jeomekanik deneyler uygulanmıştır. Soğuma sonrasında, yeni mikro-çatlakların oluşumundan ziyade, mevcut mikro-çatlakların büyüdüğünü görülmüştür. Kayaçların dayanım özellikleri, soğuma süreçlerinden fiziksel özelliklere göre daha fazla etkilenmiş ve en düşük dayanım değerleri suda soğuma sonrası gözlenmiştir. Ani soğuma sonrası traverten ve mermerlerin çekme dayanımı %70-80 arasında azalırken, kil içeren kireçtaşlarında bu değer %30'u geçmemiştir. Sonuçlar, mevcut mikro-çatlakların büyümesi nedeniyle ani soğumanın genellikle yavaş soğumaya göre daha fazla termal hasara neden olduğunu, soğumanın kayaçların termal bozunması üzerinde ısıtmadan daha etkili olduğunu ve kil içeriğine bağlı olarak bu etkinin arttığını göstermektedir.

This study describes a strength-based design analysis protocol by means of finite element analysis (FEA) for a damaged engine mounting bracket in a converted electric vehicle. The mounting bracket considered in the study is a product specifically designed and manufactured for a converted electric vehicle and failed during conventional operation of the vehicle. Thus, design improvement/revision (redesign) on the bracket geometry was investigated. In this context, to prevent such undesired failures, strength-based design features such as deformation behaviour and stress distribution under projected loads on the bracket should be properly described; however, an accurate description of these features of the bracket may become a complex experimental problem to be solved by designers. This study described redesign of the strength-based design features of the engine mounting bracket through finite element analysis under torsional loading generated by the electric engine that was determined to be the reason for the failure and thus the motivation to realise a safer design. Visual and numerical results obtained from the simulation revealed a clear understanding of the failure behaviour of the bracket and therefore enabled an informed approach to the redesign stage. The initial FEA of the part design mapped the damage regions on the part geometry and indicated the stress magnitudes that were more than the material’s stress limits. The comparison of the failure plots and numerical data obtained from this initial FEA and physically damaged part was consistent. This concluded that the FEA satisfactorily exhibited the deformation behaviour and the main reason for the failure was insufficient geometry thickness and notch effect against pre-defined loading conditions. Therefore, the main design improvement was realised on these geometric features. Subsequently, the final FEA highlighted that the redesign would enable safe operation. This work contributes to further research into usage of numerical method-based deformation simulation studies for the mounting elements used in customised electric vehicles.

In this study, geophysical and geotechnical studies were carried out in NE Turkey to evaluate the stability and support design of cut slopes that will be excavated during the construction of a new border control complex. 13 vertical and 3 inclined boreholes were drilled, and 2D electrical resistivity tomography surveys were conducted along 8 profiles to investigate the horizontal and vertical continuity of the geological units. Strength characteristics of all units were determined by laboratory tests. Limit equilibrium (LE) slope stability analyses were conducted on the geological model for static and pseudo-static conditions and factor of safety values as low as 0.227 were determined for post-excavation. Back analysis was conducted for the determination of required support forces on the slopes to achieve a factor of safety of 1.3. A feasible support system consisting of bored piles and rock anchors was designed based on back analysis results for each cut slope. LE analyses were repeated after the implementation of the designed support systems and the lowest factor of safety value increased to 1.35. The utility and safety of the designed support systems were investigated using finite element slope stability analyses and strength reduction factor values higher than 1.3 were determined which means support systems will function as intended and no support failure will occur. Lastly, quick reference charts were created for alluvium and residual soil materials to easily determine the safe slope angle in the future in case no support measures will be applied.

Almost all systems generate acoustic signals when operating or when a process is being performed. These signals contain certain data related to the operating performance of systems. In this study, acoustic data were used to study the performance and to identify the optimum operating points of natural gas burners that are used in steam boilers. The sound recordings of burners obtained under different operating conditions were examined with acoustic analysis methods. The impact of various operating parameters on acoustic values was determined using time series analysis, frequency spectrum data and then power spectral density values. When the excess air coefficient and emission and efficiency values of boilers were compared with the acoustic data, it was determined that the Yule–Walker algorithm contained distinct and explanatory values. The steam boiler and the natural gas burner within were considered a system for the analysis. Measurement results showed that operating parameters and acoustic analysis results were correlated. Moreover, the results were confirmed with the emission measurement results. Finally, it was deduced that the acoustic values can be used for obtaining the optimum operating points in similar systems where inlet and outlet parameters cannot be measured, and the related principles were revealed.

This study investigates the effects of thermal treatment and exposure time on the physico-mechanical properties related to the mineralogical and structural changes of clayey rocks at temperatures of up to 1000 °C. Vitric-crystal tuffs were studied because they show different engineering behavior than most rocks at high temperatures. The samples were heated at the rate of 10 °C/min, exposed to the desired temperatures for 2 h, and cooled at room temperature. Then a series of geo-mechanical tests was performed, thin sections and SEM images were prepared, and XRD and DTA analyses were carried out. Depending on the increase in the high temperature, the strength increased by 50% in the samples exposed to 400 °C, and a higher strength value was recorded than the initial strength even at 600 °C. Thin sections and SEM images showed that while the primary void ratio decreased until 400 °C because of the melting and expansion of clay-sized particles, new micro-cracks formed at the boundaries of quartz and plagioclase. Although the secondary micro-crack ratio increased, the sintering, cementation, and fusing between clay minerals were the main reasons for the increase in strength until 600 °C. After this temperature, the strength suddenly decreased due to the transformation of minerals, especially the formation of muscovite, and the development of secondary glasses. These changes were observed in DTA peaks and XRD analysis results. The unit weight decreased until 600 °C due to dehydration of absorbed water and hydroxylation reactions of the clay minerals and then remained constant. Despite the decrease in strength, the filling of primary voids by molten clay minerals and the formation of high-density minerals like clinoptilolite and muscovite prevented decreases in unit weight after 600 °C. In addition, the investigation of the exposure time showed that 90% of the strength loss occurs within the first 20 min at the threshold temperature, after which time does not affect the change in strength.

While chemical weathering is the most significant geochemical process that affects the engineering behavior of rocks, the fact that authigenic soils present different values of their physical and mechanical properties depending on the depth is also directly related to weathering. Although it is known that such variation is applicable for regolith soils with thickness reaching tens of meters, significant differences can be observed through the depth of residual soils with the thickness of only a few meters. Ignoring such aspects especially in sites with a high risk of landslide leads to many engineering problems. Therefore, Trabzon Province, which has the highest potential of landslide in Turkey, has been selected as the pilot area within the scope of this study. The variations in engineering properties of regolith soils, which have a depth of up to 15 m and are weathered products of volcanic rocks, have been researched as a function of geochemical properties. For this purpose, the data collected from borehole applications, geophysical surveys, in situ cone penetration tests (CPT), and standard penetration test (SPT) as well as laboratory experiments have been evaluated; and it is observed that physico-mechanical properties are directly based on geochemical variations. While the zones with low SiO2 and high Al2O3 and Fe2O3 values are characterized with high content of clay and cohesion, depths with low S wave velocity correspond to areas with the highest chemical alteration index values and the highest degree of weathering. And high liquid limit (LL) values correspond to areas with high illite content as well as high Al2O3 and Fe2O3 values. At these depths, high friction ratio values are observed in CPT results. Obtained data indicate that physico-mechanical properties vary as a function of the depth based on geochemical properties, and this suggests that the soil in projects with regolith soils needs to be separated into different layers and analyzed.

This paper focuses on the evaluation of temporal and spatial propagations of impulse waves using 3D numerical simulation-based models for a potential landslide area in the Tersun Dam reservoir, Northeast Turkey. The topographical model was created using Stereo Lithography files, and a drift-flux model was used to simulate the landslides. The wave generation was simulated using the Reynolds-averaged Navier–Stokes equations. The Drift-Flux approach was selected, and a renormalization group-based k-e turbulence model was used to create a fluid–solid coupled model. The results show that a 16.5-m impulse wave is created as a result of sliding material hitting the water at a velocity of 16.4 m/s. The wave will reach the opposite shore in 27.4 s, and the run-up height will reach up to 48.8 m. As the wave, with an average velocity of 11.6 m/s in the reservoir, propagates toward the dam body, its height will decrease, and a 3.7-m-high wave will hit the dam in 155 s. A validation analysis performed using empirical equations and laboratory model tests indicates small differences in the results. The main reason for these differences is that the evaluation of wave properties is independent of the type of mass movement in empirical methods. A proper stability analysis is required to have a better estimation of the volume and the velocity of the sliding mass.

In the present work, natural radionuclide levels and mass attenuation coefficient of obsidian samples taken from Rize İkizdere region were investigated. The mass attenuation coefficient (μ ρ-1) is investigated experimentally and theoretically for 14 İkizdere obsidian rocks. The mass attenuation coefficients of the samples were measured experimentally at photon energies of radioisotopes 133Ba (81 keV, 302 keV, 356 keV), 137Cs (662 keV), Theoretically, the simulation results of μ ρ-1 using XCOM code was compared with experimental results. In addition, elemental analyzes of obsidian samples were made. Average 238U, 232Th and 40K activities were determined as 93±9, 67±7, 1027±19 Bq m-3, respectively. The absorption coefficient of obsidian at 356 and 662 keV energies is not much different from other rocks.

In the present study, the radioactivity levels of water samples collected from the main water supply network in Trabzon province and districts and soil samples taken from the vicinity of the water network were measured. An Alphaguard-PQ2000 radon gas detector was used to determine the seasonal radon gas level in the water samples. An HPGe detector was used to determine the level of radioactivity in soil and water samples. The average concentration of 222Rn in drinking water ranges from 0.56 ± 0.51 to 13.3 ± 5 Bq L-1. In water samples, average gross alpha and gross beta values were measured as 8 ± 1 and 43 ± 1 mBq L-1, respectively. The average concentrations of 238U, 232Th, 137Cs, 40K radionuclides in soil were measured as 51 ± 2, 21 ± 2, 16 ± 1, 28 ± 7 Bq m-3, respectively. The average concentrations of 238U, 232Th, 137Cs, 40K radionuclides in drinking water were measured as 147 ± 5, 25 ± 2, 77 ± 2, 12 ± 2 mBq L-1, respectively. When the radon concentrations for drinking water were examined, it was found that the radon concentration of the three samples was above the limit value (11 Bq L-1) allowed by the US-EPA for drinking water. All other results are below the limit values.

Though the velocity of ultrasonic waves passing through materials is a highly preferred parameter to indirectly and non-destructively determine the strength properties of rock and concrete, many studies have emphasized that such waves are influenced by many factors, such as sample diameter, length, and measurement techniques (semi-direct or indirect). Direct techniques use opposite sides of the materials, semidirect techniques use adjacent faces, and indirect techniques use the same face. In contrast to the results given in many studies so far, the results from this study indicate that the ultrasonic wave velocity is not dependent on the sample geometry and measurement techniques. The tests conducted on the materials of three different lengths showed that ultrasonic wave velocity was not affected by sample length because the differences in values obtained from different lengths were 20 cm. The results clearly indicated that the ultrasonic velocity value of the materials is related to the material homogeneity rather than the sample diameter, length, and different measurement techniques.

Due to the burgeoning energy demand in Turkey, there has been a significant increase in the number of dams and hydroelectric power plants constructed; >250 dams have been built in the past 10 years. Consequently, various engineering problems were encountered due to landslides near reservoirs, both during and after the construction. Generally, two-dimensional (2D) and three-dimensional (3D) empirical equations have been used to calculate the physical properties and propagation of the landslide-induced impulse waves; however, 3D numerical simulation-based methodologies are rarely used, although they can model the complex geometry of dam reservoirs better, using detailed topographic data. In this study, therefore, 3D numerical analysis is carried out for a potential generation of impulse waves, using the data of paleo-landslide at the Artvin Dam reservoir (NE Turkey), and the results are compared with the calculated results by empirical equations. A finite element method-based shear strength reduction analysis (FEM-SSR) was performed to analyse the slope stability. After the establishment of the correct propagation model, the equations were utilised with different input parameters and 3D numerical analysis-based simulations to evaluate the characteristics of the impulse waves. In the numerical model created using the FLOW-3D software, the ‘drift-flux model’ was used to simulate the probable landslides. The Reynolds-averaged Navier–Stokes equations were used in a free-surface modelling technique together with the volume of fluid (VOF) model for simulating the wave generation. The renormalised group model (RNG) for viscous flow and k-e turbulence model for fluid–fluid coupled condition, were used as the boundary conditions. The results indicated that the values obtained from the proposed empirical equations and 3D numerical analysis were not similar. Thus, if the reservoir geometry is very complex and the wave propagation distance is more than a few kilometers (as in this study), highly detailed engineering geological studies should be performed to accurately define the boundary conditions, and three-dimensional numerical analyses should be performed to construct the impulse wave model.

In the current article, in the presence of thermal and diffusion processes, the equations governing elastic materials through thermodiffusion are obtained. The Moore–Gibson–Thompson (MGT) equation modifies and defines the equations for thermal conduction and mass diffusion that occur in solids. This modification is based on adding heat and diffusion relaxation times in the Green–Naghdi Type III (GN-III) models. In an unbounded medium with a cylindrical hole, the built model has been applied to examine the influence of the coupling between temperature and mass diffusion and responses. At constant concentration as well as intermittent and decaying varying heat, the surrounding cavity surface is traction-free and is filled slowly. Laplace transform and Laplace inversion techniques are applied to obtain the solutions of the studied field variables. In order to explore thermal diffusion analysis and find closed solutions, a suitable numerical approximation technique has been used. Comparisons are made between the results obtained with the results of the corresponding previous models. Additionally, to explain and realize the presented model, tables and figures for various physical fields are presented.

This paper presents the dynamic responses of a fiber-reinforced composite beam under a moving load. The Timoshenko beam theory was employed to analyze the kinematics of the composite beam. The constitutive equations for motion were obtained by utilizing the Lagrange procedure. The Ritz method with polynomial functions was employed to solve the resulting equations in conjunction with the Newmark average acceleration method (NAAM). The influence of fiber orientation angle, volume fraction, and velocity of the moving load on the dynamic responses of the fiber-reinforced nonhomogeneous beam is presented and discussed.

İtki dalgaları, baraj veya göl alanlarında heyelan,kaya düşmesi, çığ, moloz ve çamur akması gibi doğal jeolojik olaylarıntetiklemesi sonucu meydana gelmektedir. Oluşan dalganın hızı ve yüksekliğiyamaç boyunca eğim aşağı hareket eden kütlenin suya çarpma hızına bağlıdır.Çarpma hızı ise yamaç eğimine, hareket eden kütlenin konumuna, fiziksel vemekanik özelliklerine bağlıdır. İtki dalgalarının özellikleri, sayısal veampirik yaklaşımlarla belirleneceği gibi hidrolik modellerle debelirlenebilmektedir. Bu çalışmada ise ölçek etkisi ve hareket eden kütleninsuya çarpma hızları farklı yöntemler kullanılarak modellenmiş ve elde edilensonuçlar karşılaştırılmıştır. Çalışma kapsamında tasarlanan bir hidrolik modelüzerinde fiziksel deneyler yapılmış, 0.4 m3 hacimli bir havuz, yüklemerampası, yüksek hızlı kamera ve akışkan olarak su kullanılmıştır. Farklı rampaaçılarında hareket eden suyun havuz tabanına ulaşma süresi, çarpma hızı vehavuzda oluşan dalga yüksekliği değerleri hesaplanmıştır. Aynı model, 3 boyutlunümerik çözümleme yapan FLOW-3D programı kullanılarak farklı ölçeklerdetanımlanmış (0.1x, 1x, 10x, 100x, 1000x), farklı yoğunlukta akışkanlar(800-2000 kg/m3) kullanılarak çözümleme yapılmış ve serbest suseviyesi yükseklikleri tespit edilmiştir. Nümerik ve hidrolik modelkullanılarak tanımlanan parametreler ampirik ilişkiler kullanılarak dabelirlenmiştir. Yapılan nümerik çalışmalardan elde edilen sonuçlara görehidrolik model hangi ölçekte olursa olsun elde edilen sonuçların ölçektenetkilenmediği tespit edilmiştir. Her 3 yöntem kullanılarak belirlenen, suhareket hızı, çarpma hızı ve maksimum dalga yüksekliği değerleri arasındakifarkın %2-3 arasında değiştiği tespit edilmiştir. Elde edilen sonuçlar basitrezervuarlar için ve kısa mesafeler için ölçek etkisinin önemsiz olduğunu vehesaplamalarda ampirik ilişkilerin yeterli olabileceğini göstermiştir., Impulse waves occur as a result of natural geological events such aslandslides, rock falls, avalanches, rubble and mudflows in dam or lake areas.The celerity and height of the formed wave depends on the impact velocity ofthe mass moving into the water. The impact velocity depends on the slope, thelocation of the sliding materials, and their physical and mechanicalproperties. The characteristics of the impulse waves can be determined bynumerical and empirical approaches as well as by hydraulic models. In thisstudy, the scale effect and the slide impact velocity were modeled usingdifferent methods and the results obtained were compared. A hydraulic model,which was made of a pool of 0.4 m3 volume, loading ramp, high speed camera, andwater as fluid, was designed to carry out the physical experiments within thescope of the study. The time it takes for the fluid to reach the bottom of thepool, the impact velocity of the fluid and the wave height were calculated forvarious ramp angles. Thesame model has been defined in different scales (0.1x, 1x, 10x, 100x, 1000x)using FLOW-3D program that performs 3-dimensional numerical analysis. Analysiswere carried out using different density fluids (800-2000 kg/m3),and values of free surface elevation were determined. The parameters definedusing the numerical and hydraulic model were also determined using empiricalrelationships. According to the results obtained from thenumerical studies, it has been determined that the results obtained are not affected by the scale regardless of the scaleof the hydraulic model. It has been determined that the difference betweenwater celerity, impact velocity and maximum wave height values determinedbetween all 3 methods varies between 2-3%. The results showed that the scaleeffect is insignificant for simple reservoirs and for short distances andempirical relationships may be sufficient for the calculations.

Bu çalışmada Kuzey Kıbrıs Türk Cumhuriyeti’nde yapı taşı olarak yaygın şekilde kullanılan kalkarenitlerin 200-1000o C arasındaki yüksek sıcaklıklara tabi tutulduktan sonraki indeks ve dayanım özelliklerindeki değişimler incelenmiş, elektron mikroskop görüntülerinden yararlanarak yüksek sıcaklıkların mikro yapı üzerindeki etkisi araştırılmıştır. Gerçek bir yangının temsil edilmesi amacıyla örnekler Eurocode tarafından önerilen sıcaklık-zaman eğrilerine ait değerler kullanılarak ısıtılmış, hedeflenen sıcaklıkta 2 saat bekletildikten sonra oda sıcaklığında soğumaya bırakılmıştır. Yapılan deneysel çalışmalar sonrasında ilk 600o C’ye kadar yoğunluk ve ağırlık kaybı değerlerinde belirgin bir değişim olmadığı görülmüştür. 600o C’den sonra yoğunlukta ani bir azalma kaydedilmiş, 1000o C sıcaklıklarda mikro-kırıklara bağlı olarak yoğunluk 1’in altına düşmüştür. Aynı şekilde ağırlık kaybı değeri kalsitlerde görülen kalsinasyon sürecine bağlı olarak %41’e ulaşmıştır. P-dalga hızı ve çekme dayanımı değerleri sıcaklığa bağlı olarak sürekli azalmıştır. Ancak bu azalma 600o C’den sonra daha belirgin olurken 800o C’den sonra en belirgin düzeye ulaşmıştır. SEM görüntülerinde yapılan incelemelerde de özellikle 600o C’den sonra gelişen topaklaşmaya bağlı olarak süreksizlik oluşumu gözlenmiştir. Bu durum dayanımdaki azalmanın asıl nedeni olarak görülmektedir. Eurocode tarafından uygulanan deneysel çalışmalarda bina dışında meydana gelecek bir yangının sıcaklığının 680o C’yi geçmeyeceği, iç mekânda meydana gelecek bir yangında ise sıcaklığın 1000o C’yi aşabileceği belirtilmektedir. Bu nedenle çalışma konusu kalkarenitlerin yapılarda sadece dış kaplama olarak kullanılması önerilmektedir.

The purpose of this study is to investigate the slope stability problem that occurred in the Ulubey (NE Turkey) during the construction of a hospital building and to propose a reliable support design. The borehole applications, geophysical surveys, groundwater measurements, soil sampling and SPT were performed to establish the geotechnical model. Based on the site characterization investigations, three units were defined as sliding material, residual regolith and volcanic rocks. Strength parameters of the sliding and residual soil materials were obtained from the back analysis. The long-term performance of the double row-bore piles was proposed as support measures and was controlled using the limit equilibrium (LE) and finite element (FEM) analyses methods under a dynamic condition. The 2D-LE and 2D-FEM analysis results showed that the suggested support design is reliable for long-term stability. The locations of the critical shear surface determined by 2D methods were almost the same as those obtained from 3D-FEM method and the total displacement values obtained from the 3D-FEM model were smaller than those obtained from the 2D-FEM model. These results indicated that 2D and 3D stability analyses were sufficient to evaluate the stability of uncomplex slope geometry when a reliable design with simple solutions was required.

In the present paper, rotary inertia and small size effects on the free vibration response of single-walled carbon nanotubes are examined. The equations in motion and associated boundary conditions are obtained by using Hamilton’s principle on the basis of modified couple stress and Rayleigh beam theories. The size effect is taken into account by modified couple stress theory while the rotary inertia effect is considered by Rayleigh beam theory. The resulting equations are analytically solved by implementing Navier’s solution technique for pinned-pinned carbon nanotubes. Influences of slenderness ratio, length scale parameter and rotary inertia on the natural frequencies of single-walled carbon nanotubes are studied in detail.

The aim of this study was to determine the soil profile of the Yesilyurt Landslide Area (NE Turkey) and to investigate the stability of the landslide area after the excavation planned by back analysis for support design. For these purposes, after the 1/1000 scaled engineering geological map was prepared, seismic refraction, electrical resistivity tomography and ground penetrating radar measurements were performed on different profiles to understand vertical and horizontal homogeneity of the landslide materials and undisturbed/disturbed soil samples were obtained from the test pits to determine the geotechnical properties of the soil. The results of the geophysical measurements showed that the landslide material was composed of two different soil zones. While the maximum thickness of the upper zone is 2.5, the thickness of the lower zone is about 5 m. The depth of dasidic rock mass is about 7 m. Residual cohesions of the soil samples obtained upper and lower zones were determined as 38 kPa and 44 kPa, and their residual friction angles were determined as 18° and 15° respectively. Unit weight values of the soil samples obtained from both zones were 16.9 kN m−3. The data obtained from laboratory tests showed that the landslide material is a uniform lithology. The geophysical measurements indicate that the wave velocity and resistivity values of these profiles differ from each other due to groundwater at a depth of 2.5 m. Limit equilibrium analysis were carried out with Slide v5.0 software using data obtained from the field measurements and laboratory tests to evaluate current and supported cases of the studied area. Because the safety factor of the slope obtained from the LE analyses is 0.99 and the studied soil environment is considered as unstable, the reliable and economical reinforcement was suggested using the retaining wall. The back-analysis method was evaluated to ensure the stability for a 1.5 safety factor and finally the lateral active forces for the retaining wall were calculated in the LE analysis as 718 kN and 1839 kN for without and with seismic load respectively.

Free vibration analysis of curved structural components such as truncated conical shells, circular cylindrical shells and annular plates has been investigated numerically in this paper. The method of discrete singular convolution (DSC) and the method differential quadrature (DQ) are used for numerical simulations, respectively. Related partial differential equations governed the motion of the structures obtained from higher-order shear deformation theory have been solved by using these two methods in the space domain. Different material properties have been considered such as isotropic, laminated and functionally graded material (FGM). Four-parameter power law and simple power law distributions have been used for ceramic volume fraction in FGM cases. The numerical results related to free vibration of conical shells have obtained by the present two techniques compare well with the results available in the literature. Results for circular cylindrical shells and annular plates have also been presented for different geometric and material parameters. The effects of grid number and types of the grid distribution have also been investigated for annular plate and shells.

Free thermal vibration analysis of nanobeams surrounded by an elastic matrix is examined via nonlocal elasticity and Timoshenko beam theories in this article. Elastic matrix is formulated with a two-parameter elastic foundation modelled by combining Winkler and Pasternak assumptions. The equation of motion for free vibration is reached via Hamilton’s principle and solved by analytical method (separation of variable). However, since the separation of variable cannot be applied for boundary conditions other than simply supported nanobeams, a weighted residue-based finite element formulation is developed. Within the scope of numerical results, firstly, it is understood from the comparisons given for nondimensional frequencies that the nonlocal finite element formulation has a high accuracy and then, using this formulation, nondimensional frequencies of nanobeams with different boundary conditions are computed under different parameters. Additionally, the detailed discussions of the numerical results are presented. Finally, by giving some general results, the effect of size dependency and environmental factors on the dynamic behavior of nanobeams is expressed.

In this study, the engineering behaviors of rocks exposed to temperatures ranging from 200 to 1000 °C were investigated and changes in the geomechanical properties, as well as related mineralogical changes, were examined. To reduce the effect of rapid heating and prevent the formation of new thermo-mechanical cracks, a heating rate of 10 °C/min was used. In addition, a heating time of 2 h was applied for each temperature degree to observe the thermal heating effect. After heating, the samples were left to cool to room temperature, both dry or immersed in water. The strength of the samples gradually decreased from 128 to 25 MPa with increasing temperature. The strength value decreases by about 70% for the samples cooled in air and by about 80% when cooled in water. The strength decrease was greater for the water-cooled samples because of new microcracks and glass material formed during sudden cooling. The effect of different temperature degrees on rock samples was evaluated separately and approximately 80% of total strength decrease occurred in the 600–700 °C range. Also, new mineral formation and melting of the existent minerals were not observed, although the structural properties were significantly changed at these temperatures. At 800 °C and above, some secondary minerals (e.g., melilite and augite) were formed. Partial melting was seen at temperatures higher than 1000 °C. In the study, a predictive model as a function of the strength for determination of thermal damage on rocks was also suggested. Some equations characterized by a correlation coefficient of 96% were suggested, based on the curves of thermal damage, to predict the uniaxial compressive strength for the designed temperature.

Bu çalışmada grafentabakaların membran gibi modellenerek serbest titreşim analizleri yapılmıştır.Membranlar eğilmeye ya da burkulmaya karşı rijitliği olmayan ince plaklardır.Yanal güçleri eksenel ve merkezi kesme kuvvetleri ile taşırlar. Böyle yüktaşımaları, aşırı incelikleri ve moment taşıma kapasitelerinin ihmal edilebilirolmasından dolayı gergin kablo ağlarına benzetilebilirler. Grafen tabakalardikdörtgen ve kare geometriye sahip olmak üzere değişik boyutlardamodellenmiştir. Elde edilen denklemin çözümünde hem ayrık tekil konvolüsyonyöntemi ve hem de analitik yöntem kullanılmıştır. Literatürde bulunan plakmodeli ile ilk defa yapılan membran modelinin sonuçları karşılaştırılmıştır. Bulunandeğerler grafik ve tablo halinde sunulmuştur., In this present studyvibration analysis of graphene sheets have been carried out by modeling asmembrane model. Membranes are thin plates without the stiffness against bendingand buckling. They carry lateral forces with axial and central shear forces.This specification, its extreme thinness and negligible moment capacity ofmembranes can be likened to the tense cable network. Graphene sheets aremodeled in square and rectangular geometry. The resulting equation have beensolved both analytically and the method of discrete singular convolution. Thefirstly obtained membrane results have been compared with results obtained byplate models in the literature. Results are given in graphics and tables.

There are good quality natural stones having different color and texture especially in the Turkey located in Alpine–Himalayan Orogenic Belt. However, there are limited natural stone reserves in NE Turkey. Because Kiratli travertine site is the second largest area with a reserve of 250,000 m3 in the region, this travertine site was chosen as a pilot site for this study. Geological, geophysical and geotechnical investigations were carried out in the study and laboratory tests were conducted. The discontinuity properties of travertine mass were investigated using Ground Penetrating Radar (GPR) method to guide for suitable operating techniques in the natural stone quarry. According to the tests results uniaxial compressive strength values are 25 and 51 MPa, indirect tensile strength values are 3.98–9.18 MPa, P-wave velocities for dry condition are 3717 and 4154 m/s, respectively, for parallel and perpendicular core samples to the deposition direction. The uniaxial compressive strength of the samples was also determined after cycling tests such as wetting–drying and freezing–thawing tests. The travertine samples have less than 10% deterioration after these tests. On the investigated area, the GPR data were acquired with 100 MHz antenna using GPR technique being one of geophysical methods on 7 lines parallel each other in the study. The data were processed utilizing with ReflexW software. It was concluded that the reflection boundaries observed on obtained radargrams originated in discontinuities and weathered parts in dominant rock. It has been suggested that productive raw materials could not be got during the extraction of material travertine in the orientation of quarry when it comes to discontinuities and weathered parts in dominant rock. In these parts, quality travertine material can not be obtained.

In this paper, free vibration analysis of annular sector plates has been presented via conical shell equations. By using the first-order shear deformation theory (FSDT) equation of motion of conical shell is obtained. The method of discrete singular convolution (DSC) and method differential quadrature (DQ) are used for solution of the vibration problem of annular plates for some special value of semi-vertex angle via conical shell equation. The obtained numerical results based on the two numerical approaches for annular sector plates compare well with the results available in the literature. The effects of some geometric parameters, grid numbers and types of the grid distribution have been discussed for curved plates.

This paper dealt with the geotechnical characterization of the andesitic rock mass cropped out at the Ayvali Dam Site (NE, Turkey) and aimed to determine how well the obtained results corresponded to the situations that emerged after the dam construction was completed. Scan-line surveys, boreholes, and the related field tests were conducted and the laboratory tests were carried out for determination of index, strength, and deformation characteristics of the rock mass. The excavation class of the rock mass was defined as hard ripping, and according to limit equilibrium (LE) and kinematical analyses, the risk of wedge failure could possibly occur at the rock slopes. Additionally, shear strength reduction (SSR) analysis was carried out using finite element (FE) methods to determine whether a circular failure on the right and left slopes could arise or not, and strength reduction factor (SRF) for the rock slopes were determined as 3.4 and 4.9. The different empirical equations pointed out that the ultimate bearing capacity was in the range of 1.4 to 5.8 MPa. Thus, water absorption tests pointed out that permeability of the rock mass is about 10−6 m/s. Based on the results of the numerical analyses, grout curtain depth was assumed to be maximum 60 m and 40 m at the river bed and the abutments, respectively. The data obtained from the numerical seepage analyses were compared to the conditions showed up after the construction completed, and the applied injection depths showed similarity to those obtained from the numerical analyses.

In most studies focusing on the engineering behaviour of rocks exposed to high temperatures, thermal procedure tends to apply a slow and linear heating rate, and constant exposure time. Also, granite, marble, limestone, and sandstone are generally used because many mineralogical features of these rocks such as texture, mineral size and mineral content can be easily determined under polarized microscope. Contrary of literature, engineering behaviours of the highly porous calcareous rocks (calcarenites and chalk) were evaluated considering logarithmic/exponential heating rates and different exposure times as in a real fire in this study. The porous structure of the carbonate rocks depending on the primary voids was observed in SEM images for initial condition. SEM images of the samples exposed to high temperatures indicated that thermal treatment plays an important role on developing of secondary porosity due to the grain clumping in calcarenites and forming of new micro fissures in chalks. Lumping of minerals observed in calcarenite samples due to increasing temperatures is the main reason for the continuous decrease in strength. Decrease in porosity due to the sintering and fusing between clay minerals up to 600 °C caused the increase in strength of the chalks unlike coarse grained calcarenites. While high temperatures caused strength decrease in coarse crystalline calcarenites by creating thermal stress in the crystal grains due to expansion, on the contrary, fine crystalline chalks were more resilient to this stress because smaller crystals acted as expansion hinges during heating. Also, exposure time was insignificant in fine crystalline rocks, whereas coarse crystalline rocks showed great thermal damage. Depending on the increased temperatures, considering to the strength of some rocks increases while some decreases, a new thermal treatment coefficient graph was suggested to evaluate the rocks with different behaviours together. Because P-wave velocity tends to decrease in almost all rocks whether the strength increases or decreases, it was proposed to use tensile strength as an input parameter in the suggested approach.

Turkey located in the Alpine-Himalayan Mountain Belt has 35% of the natural stone reserves of the world and has good quality marble, limestone, travertine and onyx reserves especially in the western regions of the country. The eastern Black Sea Region with a 1.4 million meters cubes reserve has a little role on the natural stone production in the country. For this reason, this paper deals with investigation on the potential of carbonate stone in the region and determination of the geological and geo-mechanical properties of these rocks in order to provide economic contribution to the national economy. While the study sites are selected among the all carbonate rock sites, the importance as well as the representative of the sites were carefully considered for the region. After representative samples were analyzed for major oxide and trace element compositions to find out petrochemical variations, the experimental program conducted on rock samples for determination of both physical and strength properties of the carbonate rocks. The results of the tests showed that there are significant variations in the geo-mechanical properties of the studied rock groups. The density values vary from 2.48 to 2.70 gr/cm 3 , water absorption by weight values range from 0.07 to 1.15% and the apparent porosity of the carbonate rocks are between 0.19 and 3.29%. However, the values of the UCS shows variation from 36 to 80 MPa. Tensile and bending strength values range from 3.2 to 7.5 MPa and 6.0–9.2 MPa respectively. Although the onyx samples have the lowest values of apparent porosity and water absorption by weight, these samples do not have the highest values of UCS values owing to occurrence of the micro-cracks. The UCS values of the rock samples were also found after cycling tests However, the limestone samples have less than 5% deterioration after freezing-thawing and wetting-drying tests, but travertine and onyx samples have more than 15% deterioration. Exception of the apparent porosity values of travertine samples, all geo-mechanical properties of the studied carbonate rocks were determined in the acceptance values given by Turkish Standards Institute (TSE) for using as a natural dimension stone. After these investigations, it is anticipated that in the near future the number of quarries and factories will increase and more types of natural stones will be discovered in the eastern Black Sea Region and thus this will provide economic contribution to the economy of the country.

Static analyses of laminated conical and cylindrical shell are presented. The governing equation is derived using Love’s first approximation thin shell theory for conical geometry. Then, the method of Discrete Singular Convolution (DSC) is applied to the solution of the resulting governing equation and boundary conditions for bending. Numerical results for stress and deflections of laminated conical and cylindrical shells are presented for different geometric and material parameters. The numerical results show that the present method is quite easy to implement, accurate and efficient for the problems considered.

Economic development, industrialization and dense population in Trabzon City have caused residential construction to increase by 300% in the last decade. The settlement area is mountainous and covered with heavy vegetation. Thus, the steep-sided topography and heavy precipitation means floods and landslides are common and in areas with little flat land. Since the mass movements in some parts of city create an enormous danger for buildings, site selection for residential areas becomes increasingly important. This paper describes geotechnical and seismic properties of Tertiary volcanic rock and establishes the link between these units and construction. In this study, refraction tomography and multichannel analysis surface wave methods were applied in order to seek the best construction site in the residential area. The results of the geophysical study were compared with the borehole applications. A series of geomechnical tests were carried out on the core samples. Following that, statistical correlations were conducted by regression analysis to evaluate relationships between measured parameters. Rock Quality Designation and weathering degree were also determined. The methodology defined in this investigation proves to be an appropriate approach to determine geotechnical properties of the foundation rocks and soils and a proper guide on future geotechnical studies for other cities.

The uniaxial compressive and tensile strength of rocks are crucial parameters in the design stage of geotechnical structures. However, direct determination of these parameters is expensive, troublesome, time consuming, and sometimes requires high-quality core samples for tests. Therefore, this study aimed to determine the applicability of the point load strength index and Schmidt hammer hardness values to estimate the uniaxial compressive strength and tensile strength of rocks based on the regression analyses. Further, multiple regression analysis was used on datasets obtained from tested rocks. For these purposes, representative samples of volcanic, sedimentary, and metamorphic rocks were collected from 37 different points along a tunnel alignment in Northeast Turkey where hundreds of underground projects are being constructed. Results from the regression analyses showed the existence of satisfactory correlations. The results were also compared and discussed with the results obtained by other researchers conducted on different types of rocks.

This study aimed to improve the mechanical productivity of the conventional Savonius rotor by using new type flexible and moving fabric curtains, termed “sails.” To this end, addition moving-type sails were designed to be mounted on a single-stage, four-blade rotor. After the theoretical positive effects of the new design on the mechanical productivity of the rotor were represented mathematically, a prototype of the rotor was built and its practical performance was tested under field conditions. The test results were compared to the performance of the conventional design. The new design was found to outperform the classical design in terms of starting and torque production, particularly at low wind speeds. Thus, the design changes reported in the present study contribute to improving the productivity of the conventional Savonius-type wind rotor, which is known to have a simple and easily implemented design but low mechanical efficiency.

In practice, a structure is subjected to given loads and boundary conditions, and a multitude of stress and strain states may exist in the structure; hence, optimal construction of a laminate in a structure cannot be sought by considering only a limited number of stress resultants in the existence of multiple load cases. Then, another design objective based on optimization of a laminate for the worst possible load case emerges which is formulated as a minimax problem whose solution is shown to be equivalent to singular value minimization problem. As the squares of singular values are the bounds of power, energy and power spectral density ratios between the input and output vectors, shaping the singular values of a composite material is equivalent to shaping the response of the material. As a novel approach, singular values are used for the layout optimization of laminate. In this method, the main idea is minimization of the largest singular value of the transfer function matrix between force/moment resultants and outputs stress/strain. Thus the overall optimization problem is reduced to a simple minimization problem. Numerical examples and finite element simulations are presented for several test problems. In particular, it is shown that the use of singular values and singular vectors is computationally advantageous in case of multiple load case.

The objectives of the study are to improve the standard of waste disposal and to provide guidelines for an environmentally acceptable waste disposal strategy in the biggest city of the eastern Black Sea region (NE Turkey). The requirements for waste disposal by landfill were investigated in three important stages: site selection (SS), engineering geological investigation (EGI) and finally site evaluation (SE). Because one of the serious and increasing potential problems in the growing urban regions is the shortage of land for waste disposal, the candidate sites for an appropriate landfill area in the major city of the region were determined by using the integration of spatial and multi-criteria decision analysis based methodology. Due to the fact that the main issue in this investigation is description of engineering suitability of the rock masses exposed at the proposed landfill site, the rock properties to be required for landfill construction and design were identified as a priority, and finally drainage and filtration materials, leachate collector system, covering and gas venting system were proposed. For these purposes, the borehole applications, in-situ and laboratory tests, scan-line and seismic surveys were conducted to characterize the engineering properties of the rock masses exposed at the proposed landfill site, and the Lugeon tests were applied to determine bedrock permeability. The methodology defined in the study proves to be an appropriate method for site selection, design and construction process in sustainable solid waste management program for other growing urban regions in the country.

In this study, the petrographic characteristics affecting the strength of granitic rocks were investigated and a new mineralogical-based model was suggested for the prediction of uniaxial compressive strength (UCS) in line with the obtained data. Increase in quartz and alkali feldspar contents with decrease in plagioclase content partially increase the strength of granitic rocks. However, the results of modal analyses show that the rate of physically competent minerals do not directly affect strength of the granitic rock because the mineral size has a greater effect on strength than that of mineral type. The higher strength values were determined for the rocks containing monotype mineral in terms of size and quantity. In the scope of the study, significant relationships with a 0.89 correlation coefficient between UCS values and the Quality Index values (QI) were determined using mineral percentages, content and size. Because the modal analysis technique is a time-consuming process, ultrasonic velocity ratio (UVR) was defined in order to evaluate rock strength in the study and significant relationships were found with the correlation coefficient of 0.77 between UVR and QI. To estimate UCS using only ultrasonic wave velocity, it was determined whether there is a statistical relationship between UVR and UCS. The test result shows significant relation was found characterized with correlation coefficient of 0.84 value. UCS values obtained from the proposed equation and experimental studies were compared to test the suggested model; the results of the study showed that UCS values can be predicted without needing modal analysis with the new method proposed.

The aim of the present paper is to investigate effect of thickness on frequency. For this, free vibration analysis of circular shells is made via ANSYS and numerical method. Discrete singular convolution (DSC) and differential quadrature methods have been proposed for numerical solution of vibration problem. The formulations are based on the Love’s first approximation shell. The performance of the present methodology is also discussed.

In 2001, rock falls occurred on the southern slope of the Sumela Monastery, which was built on a cliff in Trabzon, north east Turkey, and is visited by many tourists. Considering the steepness of the slope and difficulty of access, rock classifications were made based on seismic wave velocity, rock mass quality (Q), rock quality designation (RQD) and rock mass rating (RMR). The results indicated extremely poor to very poor rock in the cracked, fractured and weathered parts and poor to fair rock in the intact parts of the monastery slope. As a consequence, rock fall, slide and rolling may occur from time to time. These constitute a hazard to the facilities of the monastery and access paths. It is recommended that cracked areas are strengthened with cement-based materials, that accumulated rocks are removed, and that retaining walls are constructed on solid rock around the unstable rock blocks.

This paper presents the discrete singular convolution (DSC) method for the free vibration analysis of laminated trapezoidal plates. The plate formulation is based on first-order shear deformation theory (FSDT). The straight-sided trapezoidal domain is mapped into a square domain in the computational space using a four-node element by using the geometric transformation. The frequency parameters are obtained for symmetric angle-ply and cross-ply laminated trapezoidal plate. The accuracy of the present method is demonstrated by comparing with numerical and analytical solutions available in the literature.