预加力对预应力混凝土梁抗弯刚度影响试验

Experiment on Effect of Pre-tension on Flexural Stiffness of Prestressed Concrete Beam

为了解预加力对预应力混凝土桥梁抗弯刚度的影响程度,针对预应力混凝土结构开裂前后受拉区纤维抗拉能力有显著差异的特点,同时考虑到无黏结预应力混凝土梁的可重复张拉和试验数据的可比性,设计制作了2片无黏结预应力混凝土试验梁,详细测试在钢绞线位置、面积不变,不同预加力对无黏结预应力混凝土构件开裂前后控制截面应力和位移变化的影响。试验结果表明:对于未损伤的无黏结预应力混凝土结构,预加力的变化对结构抗弯刚度影响不显著,但对于已经开裂的无黏结预应力混凝土,预加力的变化对结构抗弯刚度有非常显著的影响;研究成果可为今后旧桥安全评估和加固设计、有关规范的完善,以及预应力混凝土干接梁推广实施提供参考。

To comprehend the effect extent of pre-tension on flexural stiffness of prestressed concrete beam,according to the characteristic of the significant difference of fiber tensile strength in tensile region before and after prestressed concrete structure cracking,considering the tension repeatability of unbounded prestressed concrete beam and test data comparability,2unbounded test beams were designed and made.Under the condition of constant strand location and area,the effects of different pre-tensions on the changes of control section stress and displacement before and after the cracking of unbounded prestressed concrete component were tested detailedly.The results show that the change of pre-tension has insignificant effect on flexural stiffness of the structure which is not damaged,but it has significant impact on flexural stiffness of the structure with cracks.These results provide a reference for safety assessment and reinforcement design of old bridges,improvement of relevant specification,as well as the promotion and implementation of the prestressed concrete dry-joint segmental beam in the future.