缓粘结预应力混凝土结构张拉摩阻试验研究

Experimental study of stretching friction in a bond-retarded prestressed concrete structure

本文对用光圆钢筋和螺纹钢筋制作成的缓粘结预应力筋进行了不同龄期下的拉拔试验。对于光圆钢筋，30d前拉拔摩阻力基本保持稳定，单位静摩阻力为3．0—4．5N／cm^2，单位滑动摩阻力为1．77—3．5N／cm^2，龄期大于30d后，拉拔摩阻力急剧增大，龄期大于60d后，单位摩阻力达到145N／cm^2；对于螺纹钢筋，30d前拉拔单位静摩阻力在2．47—4．5N／cm^2之间，龄期大于30d后，拉拔摩阻力急剧增大。通过两种缓粘结预应力筋拉拔单位摩阻力的结果对比，得出了光圆钢筋单位面积的拉拔摩阻力与螺纹钢筋的单位面积的拉拔摩阻力基本相等、拉拔摩阻力与钢筋表面形状关系不大的结论，为缓粘结预应力混凝土这一新型的预应力体系在设计中张拉摩阻力计算提供了依据。

The bond-retarded tendons made of plain round bars and indented steel bars are respectively stretched at different age. For the tendons made of plain round bars the stretching friction keeps comparatively steady with the unit static friciton of 3.0 -4.5N/cm^2 and the unit slipping friction of 1.77 - 3.5N/cm^2 before the age of 30d; after that, the stretching friction increases dramatically; and the unit friction can reach 145N/cm^2 when the age is over 60d. Similarly, for the tendons made of indented steel bars, the stretchning friction is 2.47 -4.5N/cm^2 before the age of 30d. While after that, it also increases sharply. Through comparing the stretching frictions of the two types of tendons, it is concluded that the unit stretching friction of plain round bar is nearly equal to that of indented steel bar and the stretching friction is not much correlative with the bar surface shape, which provides the basis for the calculation of stretchning friction of the new bond-retarded prestressed concrete systems.