自密实预应力混凝土梁的疲劳性能试验研究

Experimental study on fatigue properties of self-compacting prestreesed concrete beams

本文通过5根自密实和3根振捣密实混凝土模型梁的疲劳试验对比,研究了自密实部分预应力混凝土梁的疲劳性能,试验表明自密实与振捣密实混凝土梁的疲劳性能没有明显的差异,自密实混凝土梁的疲劳性能略优于振捣密实混凝土梁,但自密实混凝土结构仍可采用振捣密实混凝土结构疲劳理论和计算方法来进行分析。部分预应力混凝土梁的疲劳破坏一般是混凝土疲劳开裂,受拉非预应力钢筋疲劳断裂,一般不会出现预应力钢筋疲劳断裂和受压混凝土疲劳压碎;考虑混凝土的非线性性能计算受拉钢筋的疲劳应力幅值比按初始弹性状态计算受拉钢筋的疲劳应力幅值估计梁的疲劳寿命与试验结果具有更好的吻合性,更适用于自密实或振捣密实混凝土结构的疲劳寿命估计。

A total of 8 concrete model beams, which are made of concrete with different molding forms, either self compacting or vibro compacting, have been tested. The results indicate that the fatigue properties of two series of concrete beams are almost the same and the fatigue properties of the self compacting concrete beams are only a little bit better than those of the vibro compacting concrete beams, so that they can be analyzed in the same way.The fatigue life of a partially prestessed concrete beam should be decided by non prestressed longitudinal reinforcement rather than by the prestressing steel and concrete according to the results of the experiment and analysis, and the fatigue life of a beam can be predicted more accurately when the stress amplitude of tensile reinforcement under cyclic action is based on non linear analysis than based on the status of elasticity at early stage. And the calculated values agree well with the test ones.