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预应力钢筋混凝土结构的耐久性,尤其是使用高强度钢丝时,极大程度上决定于这样的因素,即整个的使用期间能保持其抗裂性的程度大小,而这使用期间一般是很长的,至少在50年以上,某些工程中甚至超过100年。因此,必须首先需要钢筋预应力的大小在预定的期限内不致降低。计算所得的预应力损失的总值中,钢筋应力的松弛占较大部分。这种损失随着初应力的增大的趋势,承受着高温的预应力钢筋混凝土结构中应用的趋势而增大。
The durability of prestressed reinforced concrete structures, especially when using high-strength steel wires, depends to a large extent on the extent to which the crack resistance is maintained throughout the life of the use, At least 50 years or more and in some projects even more than 100 years. Therefore, it must first require that the magnitude of the prestress of the rebar be not reduced within a predetermined period of time. In the total value of the calculated prestress loss, the relaxation of the steel bar stresses accounts for the most part. This loss increases with the increasing of initial stress, and is under the trend of application in prestressed reinforced concrete structures with high temperature.