【摘要】 为获得体外预应力混凝土梁的正截面抗弯强度、必须首先确定体外预应力筋的极限应力。该文建立了分别以FRP和钢材为体外预应力时,构件的等效塑性区长度与破坏截面中性轴比值的转换关系式。并根据相关的试验研究数据,分析了以FRP为体外筋和以钢材为体外筋的情况下,等效塑性区长度与破坏截面中性轴比值的差异及变化。结果表明,对FRP体外预应力混凝土梁,这一比值比较稳定,并可取为常数。但该常数与以钢材为体外预应力筋的有所不同,需用该文建立的转换关系式进行转换。在此基础上,建议了既适用于简支梁,亦适用于连续梁;既适用于常规的体外预应力钢筋,亦适用于非常规的体外预应力FRP筋的体外预应力筋极限应力计算方法。更多还原

【Abstract】 To calculate the flexural strength of externally prestressed concrete beams, the ultimate stress in external tendons must be known firstly. The relationship between the ratios of the equivalent plastic hinge length to the neutral axis depth is established for prestressed concrete beams with external FRP tendons and steel tendons. Based on different investigators’ test data, the ratio of the equivalent plastic hinge length to the neutral axis depth is analyzed for prestressed concrete beams with external FRP tendons. It is found the ratio for prestressed concrete beams with external FRP tendons is stable and can still be treated as a constant,but this constant is not the same as that previously found for prestressed concrete beams with external steel tendons, and it can be transformed by the suggested relationship equation. Finally, a method is proposed for the determination of ultimate stress in external tendons. It is applicable to simply supported beams as well as continuous beams. It is applicable not only to externally prestressed concrete beams with conventional steel tendons, but also to those with non-conventional FRP tendons.更多还原