非预应力筋对无粘结预应力混凝土梁性能影响分析

ANALYZING INFLUENCE OF NONPRESTRESSED REINFORCEMENT ON THE BEHAVIOR OF UNBONDED PRESTRESSED CONCRETE BEAMS

为跟踪无粘结预应力混凝土梁的全过程响应,建立了一种基于法平面弧长算法的有限元模型。该算法能较好地处理梁加载过程的响应变化,可穿越梁破坏前可能出现的极值点问题。设计了7根含有不同非预应力筋配筋率的无粘结预应力混凝土梁,利用提出的数值模型对这些梁进行非线性全过程分析。分析结果表明,没有配置受拉区非预应力筋的无粘结预应力混凝土梁的弯曲性能非常不理想,在梁内配置少量的受拉区非预应力筋,能极大改善梁的性能;随着非预应力筋配筋率的提高,无粘结部分预应力混凝土梁的开裂刚度和极限承载能力有显著提高,而后弹性挠度以及无粘结预应力筋极限应力则明显降低。

To trace the entire response ofunbonded prestressed concrete beams, a finite element model based on the normal plane arc-length algorithm, which can properly deal with the changes of response during loading and is capable of passing the possible limit points prior to the failure of the beams, was developed. Seven unbonded prestressed concrete beams with different amounts of nonprestressed reinforcement were designed, and then analyzed by the proposed numerical model. The analytical results show that the flexural behavior of unbonded prestressed concrete beam without any tensile nonprestressed reinforcement is poor. With a little amount of tensile nonprestressed reinforcement provided, the behavior of the beam can be greatly improved. With the increase of the nonprestressed reinforcement ratio, the cracked stiffness and ultimate load-carrying capacity of unbonded partially prestressed concrete beam increases remarkably, whereas the post-elastic deflection and ultimate stress in tendons decrease notably.