Abstract: Based on the test results,this paper analyses shear fatique behavior and shear fatique failure char-acteristics of partially pretressed concrete beams and srudies shear fatique strength and calculatingmethed of shear fatique capacity of P.P.C. beams. Test results shown that beams were able to sustainload for over one million cycles following initial stirrup fracture,t is not proper that the fracrure of thefirst stirrup is regarded as failure of beams and further contribution to shear capacity would be consid-ered.

Key words: fatique, shear, prestressing

摘要： 本文根据试验结果，分析了部分预应力梁的剪切疲劳行为和剪切疲劳破坏特征，研究了部分预应力梁的疲劳抗剪强度及疲劳寿命的计算方法。阐述了箍筋应变及预应力度对疲劳寿命的影响；试验表明，预应力度愈高，梁的疲劳寿命愈长，本文分析了这种现象的原因。在试验中我们观察到，在第一根箍筋疲断以后，梁还可以承受数十万次乃至上百万次的循环荷载，有些文章也报道了这一现象，但却仍把第一根箍筋的疲断看作梁的破坏，本文认为：应该考虑在第一根箍筋疲断之后梁对抗剪强度的进一步贡献。因此，本文首次提出了计算这种梁疲劳寿命的概念及公式。

关键词: 疲劳, 抗剪, 预应力