Experimental and numerical assessment of thermal regime of the Self-Compacting Mass Concrete

نوع: Type: thesis

مقطع: Segment: PHD

عنوان: Title: Experimental and numerical assessment of thermal regime of the Self-Compacting Mass Concrete

ارائه دهنده: Provider: Amir Hossein Ghorbankhani

اساتید راهنما: Supervisors: Dr Mahmoud Nili

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr rahmat madandoust - dr mohammad ranjbar - Dr mohammad shooshtari

زمان و تاریخ ارائه: Time and date of presentation: 2022.2.14

مکان ارائه: Place of presentation: Class #02 of eng department of BASU thesis rooms

چکیده: Abstract: The use of concrete in special structures usually faces challenges in implementation. In massive members of reinforced concrete with high conjested rebars, the use of self-compacting concrete will facilitate implementation. On the other hand, by increasing the amount of cement to increase the strength, thermal gradient between the surface and the core of members will increase the thermal stress and therefore it is necessary to know the thermal behavior of this concrete and evaluate thermal cracking. In the present thesis, experimental study of thermal and mechanical properties of self-compacting mass concrete and thermal stress analysis have been done. Fourteen concrete mix designs with three water to cement ratios of 0.44, 0.37 and 0.3 with two amounts of cement 418 and 518 kg per cubic meter of concrete were considered. Mechanical properties tests including strengths and modulus of elasticity, thermal characteristics includes strain and thermal regime done and detailed analysis of thermal stress were assessed. The component separation approach has been evaluated to measure the effect of each affecting factor. Sensitivity analysis is also done by specialized software related to the intended purpose with 4C-Pakage, Neuro Solutions and Expert Choice softwares. The results show that in the conditions of same water to cement ratio and the same cement content, the tensile and compressive strengths of self-compacting concrete increased by sixty and one hundred percent in the optimal design compared to conventional concrete respectively. The corresponding increase of the modulus of elasticity of self-compacting concrete was up to eighty percent. In addition to the lower strain, due to the pleasure difference in the nature of the thermal regime of this concrete, a lower temperature increase was occurred at a same time and the increase in stress conversion occurrence time leads to a decrease in thermal stress. The risk of cracking decreased up to thirty-six percent as a result of differences in thermal behavior. From an executive point of view, it is recommended to remove the molds two days after casting the concrete and consider the geometry of the section in a circular shape. The results of sensitivity analysis indicate the greater impact of concrete type than the slag addition and parameters of concrete mix design. Artificial neural network makes it possible to predict the thermal behavior of mass concrete well and with an error of less than fifteen percent compared to experimental results. Finally, by use of self-compacting concrete in high-strength massive elements, this concrete has a different and more suitable heat regime in comparison with conventional concrete, in addition to more favorable mechanical characteristics at the surface and center of mass concrete

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