Abstract: The tests have shown that flexuval fatigue failure in partially prestressed concrete beams often results from the fracture of non-prestressed steel. A good knowledge of the stress state of non-prestressed steel in the beams is essential. based on the measured results of the load-induced strain and the residual strain in non-prestressed steel in seventeen beams, a high compression stress state due to shrinkage and creep prior to the test was verified, and the empirical formulae for predicting the residual strains in non-prestressed steel under static and repeated loadings were presented. Moreover, the effects of repeated loading on the stress state and fatigue strength of non-prestressed steel are also analyzed and discussed.

Key words: partially prestressed concrete, mixed steen, stress state of non-prestressed steel, residual stress, fatigue strength

摘要： 试验表明,部分预应力混凝土梁的弯曲疲劳破坏通常由非预应力钢筋疲劳断裂所致。因此,清楚地认识梁中非预应力钢筋应力状态及其变化十分必要。本文基于17片梁非预应力钢筋荷载应变及卸载后残余应变的量测结果,直接证实了试验加载前由于混凝土收缩、徐变,在非预应力钢筋中所引起的一个较大的压应力状态,初步建立了预测静力循环加载及高周重复加载下非预应力钢筋残余应变的经验公式,并分析和讨论了重复加载对非预应力钢筋应力状态及疲劳强度的影响。

关键词: 部分预应力砼, 混合配筋, 非预应力钢筋应力状态, 残余应力, 疲劳强度