无粘结部分预应力混凝土梁的受力性能分析

建立了基于增量变形的既适用于有粘结部分预应力混凝土梁亦适用于无粘结部分预应力混凝土梁受力全过程数值分析方法。该方法能够模拟构件达到其峰值承载能力后下降段的性能,并可考虑非预应力钢筋及混凝土由于结构进入承载能力下降段引起的卸载而导致的材料应力应变关系的变化情况。在此基础上,研究了不同加载方式、跨高比、综合配筋指标、部分预应力比率、混凝土抗压强度等对无粘结部分预应力混凝土梁延性性能的影响。研究表明,无粘结部分预应力混凝土梁的曲率延性系数随综合配筋指标的增加而减小。利用本文方法可以对无粘结预应力筋的应力变化、有粘结或无粘结部分预应力混凝土梁的抗弯强度等进行较合理而精确地评估。

Analysis on Mechanical Character of Unbonded Partial Prestressed Concrete Beams

An incremental deformation method for the whole process analysis of bonded and/or unbonded prestressed concrete beams was described.The presented method can simulate the post-peak behaviour of the flexural members and can take into account the strain reversal in non-pretressed steel tendons and the behaviour of concrete at the descending branches of the stress-strain curves.Parametric studies were carried out to evaluate the influence of loading type,span-depth ratio,reinforcement index,partial prestressing ratio,and concrete compressive strength,etc.on the ductility behaviour of unbonded partially prestressed concrete beams.The results indicate that the curvature ductility factor of unbonded prestressed concrete flexural members decreases with the increase of reinforcement index.By using the presented method,the stress change in unbonded tendons,the ultimate flexural strength of the bonded and/or unbonded partially prestressed concrete beams can be reasonably assessed under external loading.