Yazar "Erdem H." seçeneğine göre listele

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    Bending capacity of T-shaped reinforced concrete beams subjected to high temperatures [Yüksek sicakliga maruz t-kesitli betonarme kirişlerin egilme taşima gücü]
    (2010) Erdem H.
    Fires, which cause life and material loss, result in a decrease both in strength of concrete and steel and moment capacity of reinforced concrete (RC) members. Reinforced concrete (RC) beams are also affected by heat and a decrease in the moment capacity occurs. To investigate hazardous effects of high temperature, temperature distribution, and internal forces in the investigated cross-sections are required. In the present study, the temperature acting on section surfaces is calculated by the equation given in ISO834. The temperature distribution within the section is defined using Laplace temperature transmission equation and losses in the strengths of materials are determined using the given formulation in Eurocode2. The heat conduction equation is solved by finite difference method, and the temperature distribution in small pieces inside the cross-section is obtained. The tensile and compressive forces are calculated using the decreased strengths of materials in small pieces inside the cross-section. Later, the moment capacity is calculated using equilibrium equations. Additionally, a practical method is suggested to determine temperaturedistribution in RC beams with T-section. Efficiency of the suggested practical method and negative effects of high temperature on moment capacity of beams are investigated. According to the obtained results, it is observed that the suggested practical method is quite effective to determine temperature-distribution in T-sections, and bending capacity of the cross-section decreases significantly with increasing fire exposure time.
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    Effect of presence of corpus luteum at the beginning of Ovsynch protocol on pregnancy rates in lactating dairy cows [Laktasyondaki süt i·neklerinde ovsynch protokolüne başlarken korpus luteum varli{dotless}gi{dotless}ni{dotless}n gebelik oranlari{dotless} üzerine etkisi]
    (2012) Çinar M.; Güzeloglu A.; Erdem H.
    The aim of the study was to investigate the effect of presence of CL at the beginning of Ovsynch protocol on pregnancy rates in lactating dairy cows. A total of 218 lactating Holstein cows that were at least 45 days postpartum with no reproductive disorders were used in the present study. Cows were divided into two experimental groups according to the presence and absence of corpus luteum (CL) on the first day of transrectal ultrasonography (day 0). Cows having CL (CL (+)) were randomly allocated to two subgroups as CL (+)/A and CL (+)/B. Cows in CL (+)/A group (n = 74) were treated with Ovsynch protocol, while cows in CL (+)/B group (n = 78) were treated with PGF 2? on the first day of examination and seven days later Ovsynch protocol was started. Cows having no CL (CL (-)) (n = 66) were left untreated on the first day of examination and Ovsynch protocol was started seven days later. Pregnancy rates were found 23%, 25.6% and 40.9% in CL (+)/A, CL (+)/B and CL (-) groups, respectively. The pregnancy rate in CL (-) group was significantly higher than those of CL (+)/A, and CL (+)/B groups (P<0.05). It is suggested that the success of Ovsynch synchronization protocol may be related to starting time of the protocol and to ovarian physiology in cyclic dairy cows.
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    Predicting the moment capacity of RC slabs with insulation materials exposed to fire by ANN
    (Techno Press, 2017) Erdem H.
    Slabs prevent harmful effects of fire that may occur in any floor. However, it is necessary to protect the slabs from fire. Insulation materials may be appropriate to protect reinforced concrete (RC) slab from elevated temperature. In the present study, a model has been developed in artificial neural network (ANN) to predict the moment capacity (M r ) of RC slabs exposed to fire with insulation material. 672 data were obtained for ANN model through author's prepared program. Input layer in model consisted of seven input parameters; such as effective depth (d), ratio of d’/d, thermal conductivity coefficient (k insulation ), insulation materials thickness (L insulation ), reinforcement area (A st ), fire exposure time (t exp ), and concrete compressive strength (f c ). The predicted M r by ANN was consistent with the obtained M r by author. It is proposed to ease computational complexity in determining M r using ANN. The effects of using insulation material on the moment capacity in RC slabs were also investigated. Insulating material with low thermal conductivity has been found to be more effective for durability to high temperature. Copyright © 2017 Techno-Press, Ltd.