Experimental study on effective preloading performance of concrete with different initial preloading stress levels at given water content under ultralow temperature
To evaluate the design and safety performance of prestressed concrete structures as cryogenic storage tanks,the changing regularity of effective preloading performance was systemati-cally discussed for concrete with various initial preloading stress levels(0.2,0.3,0.4,0.5,0.6 and 0.7)under-160 ℃,and correspondingly the difference of the influence of higher and normal water content on their effective preloading performances was also compared.The results show that with the increase in the initial preloading stress level,the effective preloading stress loss rate of concrete decreases at the cooling target point and the temperature uniformity target point,but its changing rate of effective preloading stress at the cooling stage and the constant temperature stage is complex.After reaching the cooling target point,the effective preloading stress loss of concrete will be recovered during the constant temperature stage,and its recovery degree is more obvious with the increase in the initial preloading stress level.The water content has no effect on the de-veloping trends of effective preloading stress loss rate at the cooling target point and the tempera-ture uniformity target point for the concrete with different initial preloading stress levels,but their changing degrees have obvious difference.
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