Experimental Research on Precompression Deformation Performance of Prestressed Concrete with Different Strength Grades Experiencing Given Ultralow Temperatures

Through experiments of the prestressed concrete with strength grades of C40, C50, C60 and C70 experiencing given ultralow temperatures, the changing regularities of precompression deformation performances of the prestressed concrete were investigated and the corresponding influence difference of two typical low temperature environments with –80 and ℃ –160 on them ℃ was examined. The results showed that the precompression strain differential rates at the cooling target points and the temperature uniformity target points increased evenly with the increase in the concrete strength grade under low temperature condition, but there were apparent differences for the influence of different low temperatures on them; for different low temperature conditions, the transient precompression strain changing rates and the precompression strain relative changing rates of prestressed concrete at the cooling stages generally increased with the increase in the concrete strength grades except for the strength grade of C40, but varied complexly at the constant temperature stages; while the precompression strains of the prestressed concrete with different strength grades still increased at the constant temperature stages under low temperatures, but likewise there were apparent differences for the influence of different low temperatures on them. The experimental results and corresponding fitting formulas can provide valuable references for the design and safety assessment of prestressed concrete structures as LNG storage tanks.