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针对预应力混凝土梁动力特性退化的问题,选取预应力混凝土简支梁,通过模型进行了单调加载和重复超载作用下梁的加载试验,并测试构件竖向、横向及纵向3个方向的振动参数,从而得到各种荷载状态下构件的动力参数、自振频率和振型;研究分析了预应力混凝土简支梁频率的变化及动刚度随荷载增加而退化的规律。结果表明:梁在荷载损伤之后,其各阶频率随着荷载等级的提高而降低,梁达到屈服荷载,频率下降较为明显;重复超载次数对部分预应力混凝土梁频率退化的影响并不明显,动刚度随着荷载的增加降低也不明显;不同配箍率对纵向和横向基频没有明显影响。
Aiming at the problem of the degradation of the dynamic characteristics of prestressed concrete beams, the prestressed concrete simply supported beams are selected. The loading tests of the beams under monotonic loading and repeated loading are carried out by the model. The vibration parameters of the members in three directions of vertical, horizontal and vertical The dynamic parameters, natural frequency and mode shapes of the members under various load conditions were obtained. The changes of the frequency of prestressed concrete beams and the degradation of dynamic stiffness with load were analyzed. The results show that after the beam is damaged, the frequency of each beam decreases with the increase of the load level. The beam reaches the yield load and the frequency decreases obviously. The influence of repeated overload times on the frequency degradation of some prestressed concrete beams is not obvious. Stiffness decreases with increasing load is not obvious; different stirrup rate has no significant effect on longitudinal and transverse fundamental frequency.