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EN
It is a well-identified fact that more elaborate laboratory studies should be carried out for evaluation of dynamic properties of different types of soils. Regardless of the mechanisms affecting the mechanical behaviour of the soils, past studies reveal that existence of fiber positively affects the strength of either cohesive or non-cohesive soils. A short literature survey provides numerous studies on the stress-strain behaviour of fine/coarse soils, reinforced by polypropylene fiber. On the other hand, studies concerning fiber reinforced soils subjected to dynamic loading are relatively rare. Therefore, in this research it was intended to investigate the effects of polypropylene fiber inclusion on the dynamic behavior of a clayey sand soil, within an experimental framework. In this scope, a number of cyclic triaxial compression tests were conducted to assess the effect of fiber presence. The effects of fiber length and content were experimentally evaluated. Hence, the variation of shear modulus ratio and damping ratio values by shear deformation was plotted to observe the effects of fiber length and inclusion level as well. The results are presented along with detailed evaluations.
EN
Automobile wheel rims are critical elements that work under fatigue loading. For this reason, it is very important to determine fatigue damage of the wheel rims. Today, finite element analysis is used to make accurate predictions. In this study, it is aimed to determine Chaboche damage model parameters for an aluminium alloy wheel rim. Msc Marc software is used for finite element analysis. First, Chaboche damage model parameters are obtained using simple Holloman equation for finite element analysis. Model parameters are validated by single element tests. Then, fatigue behaviour of an automobile wheel rim is analysed with verified Chaboche parameters. At last, critical areas under fatigue loading are identified on the wheel rim.
EN
This study presents an investigation of the prediction of impact resistance of steel-fiber-reinforced concrete and ordinary concrete specimens. In the experimental part of this study, parameters identifying impact resistance of various concrete mixtures were determined using an impact test machine, in accordance with ACI Committee 544. For this aim, concrete specimens containing three different aggregates (basalt, limestone and natural aggregate) were cured in water at 20°C for 28 days. After curing impact resistance tests were performed on specimens having compressive strength values between 20 and 50 MPa, to determine the blows to initial crack and failure. The specimens were also subjected to splitting tensile strength and ultrasonic pulse velocity tests. Initially, using blows to initial crack and failure, many attempts were made to classify the impact resistance of different types of concrete in terms of the origin of used aggregate, strength properties or ultrasonic pulse velocity, however, this made no sense. The specimens could only be classified in terms of steel fiber presence. Therefore, radial basis function network, which belongs to another kind of unsupervised classifier network, was used to estimate the two above-mentioned impact resistance parameters. In this scope, independent from aggregate origin used in preparation of specimens, compressive strength, splitting tensile strength and ultrasonic pulse velocity of the specimens were used to predict the impact resistance parameters of the concrete specimens. The results revealed that three listed parameters can be used for estimation of blows to formation of initial crack and failure. Scatter plots, root mean square error and absolute value of average residual parameters were used to verify the errors in predictions, which were very low, compared with the uncertainty in test and ambiguity of data in hand.
EN
This paper reports an experimental study on the design of self-compacting lightweight concrete using acidic pumice with different powder materials. For this aim, nine self-compacting lightweight concretes were designed with inclusion of two different fine aggregates and different powder materials. This way, two groups of concrete were designed. First group was composed of single type of aggregate which is acidic pumice from Bitlis Region with barite powder, fly ash powder and pumice powder inclusion, while the second group was generated with river sand as a fine aggregate and acidic pumice from Bitlis Region, as a coarse aggregate with the same powder addition. In the design process, slump-flow, V-funnel and L-box tests were applied to determine the fresh properties of self-compacting lightweight concrete. After the design, test of compressive strength, which is one of the most important parameters of concrete, was applied to all self-compacting lightweight concretes in early age. Moreover, ultrasound pulse velocity test was also performed on all concrete series at the same ages.
EN
Chopped E-glass fiber-reinforced epoxy composites (10%, 30% and 50%) were fabricated and their mechanical and tribological behaviour was investigated. Three-point bending tests were performed according to the ASTMD790 and tensile tests were performed according to the ASTMD638 standards. Impact tests and hardness measurements of the composites were also carried out. Wear behaviour of composites was studied using pin on disc wear testing device. The design of experiments approach, using Taguchi method, was employed to analyze the results. Signal-to-noise ratio and analysis of variance were used to determine the influence of parameters on the wear rate and coefficient of friction.
EN
This paper reports results of an experimental study of the strength properties of fibre reinforced self-compacting concrete (FRSCC). For this aim, a control self-compacting concrete and 24 FRSCCs were designed, applying fresh self-compacting concrete criteria tests. In the design of FRSCC, four steel and two polypropylene synthetic fibres of different lengths and aspect ratios were used. These fibres were used alone and in combinations with two and four of these fibres. In this way, not only the effect of single fibre and the synergy effect of hybrid fibres, but also the size and concentration effect of fibres, which had different ratios in total fibre volume, were investigated. In the design process, Portland cement and fly ash were used as the binder and the powder material. The compressive and flexural-tensile strength tests were employed at the age of 3, 7, 28, 56 and 90 curing days, to determine the strength properties of FRSCCs. Moreover, ultrasound pulse velocity test was also performed on all concrete series at the same ages.
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