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This study presents an experimental evaluation of fiber-reinforced polymer (FRP) strengthening in concrete specimens damaged by exposure to high temperatures. For this purpose, sixty cylindrical concrete specimens were produced. Specimens exposed to temperatures of 200 °C, 400 °C, and 600 °C were strengthened using carbon and glass FRP fabrics in two or three layers. Compression tests were conducted to assess the strength of the specimens. The impact of temperature, fabric type, and the number of fabric layers on the concrete's strength was thoroughly investigated. Digital microscopy was employed to explore the formation of cracks due to temperature changes, followed by Scanning Electron Microscopy (SEM) analyses to examine the microscopic structural changes in the concrete samples. The study highlights the importance of considering changes in both strength and behavior models together when evaluating the strengthening contributions provided by FRP. The results indicate that FRP applications on fire-damaged concrete structures can provide effective strengthening up to 400 °C but may be insufficient at temperatures of 600 °C and above. Although an effective increase in strength was achieved at 600 °C, low levels of ductility were observed, which is undesirable for an engineering structure. Therefore, it has been determined that FRP-strengthening applications may not be effective in reinforced concrete (RC) structural elements exposed to temperatures of 600°C and higher.

The aim of this study is to investigate environmental effects of impulse waves originated from reactivation of a paleo-landslide located 4 km far from the dam body in Borçka Dam reservoir using empirical relations. Considering different values of landslide width and thickness, 3 different scenarios were defined for the slide of landslide material in volumes ranging from 0.5 to 1 million cubic meters. The wave propagation in the reservoir was defined as radially, and properties of landslide generated impulse waves were evaluated using 3D empirical approaches. For different scenarios, it is determined that the wave height values range between 27.1 and 27.7 m/s, the wave height value for opposite shore reaches 23 m and run-up height value is 42.3 m for highest wave celerity value. The values of wave height and run-up height were calculated as 18.5 m and 32.5 m respectively for lowest wave celerity value. Considering the 4-meter freeboard for the dam, it was determined that the wave propagating through the reservoir and reaching the dam body would not create a danger for the body. Empirical equations can be used for the calculation of landslide-induced wave characteristics for simple reservoir geometries and short distances. But 3D numerical models should be preferred for complex reservoir geometries, and the need to use the landslide volume value to be calculated by applying numerical based slope stability analyzes should not be ignored in these models.

This study examines surface roughness measurements via piezo acoustic disks and appropriate signal processing. Surface roughness is one characteristic of surface texture that can have various irregularities inherent to manufacturing methods. The surface roughness parameters and corresponding surface profiles are acquired by a stylus profilometer. Simultaneously, elastic waves propagated along metal surfaces caused by the friction of a diamond tip are obtained in the form of raw sound via piezo acoustic disks. Frequency spectrum analysis showed apparent correlations between the traditionally obtained measurement parameters and the piezo acoustic measurement data. Thus, it is concluded that acoustic friction measurement shows promising results as a novel measurement method for the surface roughness states of certain materials.

Bu çalışmada grafen tabakaların 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 yük taşımaları, aşırı incelikleri ve moment taşıma kapasitelerinin ihmal edilebilir olmasından dolayı gergin kablo ağlarına benzetilebilirler. Grafen tabakalar dikdörtgen ve kare geometriye sahip olmak üzere değişik boyutlarda modellenmiştir. Elde edilen denklemin çözümünde hem ayrık tekil konvolüsyon yöntemi ve hem de analitik yöntem kullanılmıştır. Literatürde bulunan plak modeli ile ilk defa yapılan membran modelinin sonuçları karşılaştırılmıştır. Bulunan değerler grafik ve tablo halinde sunulmuştur.

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.

Plates and shells are significant structural components in many engineering and industrial applications. In this study, the free vibration analysis of annular plates is investigated. To this aim, two different numerical methods including the differential quadrature and the discrete singular convolution methods are performedfor numerical simulations. Moreover, the Frequency values are obtained via these two methods and finally, the performance of these methods is investigated.

Abstract  Each day some 400–450 ton solid waste is dumped on land and in the sea and rivers in the coastal cities of the eastern Black Sea, creating serious environmental problems. The paper reports the engineering geological studies of a proposed landfill site for Trabzon, a major city in the region. Fieldwork included scan-line and seismic surveys as well as boreholes and in-situ testing. Water absorption tests indicated permeabilities in the order of 10−8 m/s. [ABSTRACT FROM AUTHOR]