基于非线性振动特性的预应力混凝土梁损伤识别

DAMAGE DETECTION OF PRESTRESSED CONCRETE BEAMS BASED ON NONLINEAR DYNAMIC CHARACTERISTICS

对2根后张有粘结预应力混凝土简支梁分别进行单调加载和二级等幅值疲劳加载试验,在各级加载后对试验梁进行动测得到自由振动加速度信号,对加速度信号进行盲源分离并进行Hilbert变换,得到各损伤状态下梁的频率-振幅曲线簇,分析其非线性振动特性随损伤状态的变化规律。结合裂缝开展情况和钢绞线的应力变化,探讨梁的非线性振动特性的变化与其损伤之间的关系。结果表明非线性振动特性适合于预应力混凝土梁的损伤检测。

Two post-tensioning tests for bond prestressed concrete beams were used to carry out a static test and a two-stage fatigue test respectively. Under each damage level, the beams were excited by a hammer and their acceleration signals of free vibration were recorded. Then the signals were processed by the blind source separation algorithm and Hilbert transform to obtain frequency-amplitude curves, from which the change of nonlinear dynamic characteristics of the beams with the damage level was analyzed. The strain of the prestressing strand and cracking of the beams under each damage level were utilized to investigate the relation between the change of the nonlinear dynamic characteristics and the damage of the beams. The results prove that the nonlinear dynamic characteristics can be used to detect the damage of prestressed concrete beams.