中文摘要：

利用新设计的一套试验装置，对钢筋混凝土梁进行在钢筋加速锈蚀条件下的准长期静力荷载试验。通过对纵向受力钢筋通稳压直流电，采用氯化钠溶液作为电解液等实验方法，实现了被混凝土所包裹的主筋的快速均匀锈蚀。在长期恒定荷载条件下，观测了试验梁的固有频率、挠度、混凝土应变随时间的变化。通过对比，建立了恒载作用下，钢筋锈蚀量与试验梁固有频率、挠度、混凝土受压区应变变化的对应关系。并利用根据纵向裂缝宽度分布修正之后的截面抗弯刚度，采用差分法计算钢筋锈蚀后梁的挠度，试验值与实测值吻合良好。分析结果表明，梁的固有频率对锈蚀的发展敏感，在实际工程中可以通过动测方法诊断钢筋锈蚀导致的结构损伤。

英文摘要：

A series of special apparatus was designed for accelerating the corrosion of steel bars in a reinforced concrete beam under long-term quasi-static loading. The corrosion of longitudinal main-bar in the concrete was accelerated by an electrochemical cell in which the steel bar serves as an electrode, and the test beam was submerged in saltwater （3% NaCl, electrolyte）. The changes in natural frequency, deflection, concrete strain of the beams subjected to long-term loads were measured. A number of different beams were tested to find the relationships among these three factors. After analyzing the change in natural frequency of the beam and mass loss of steel bars, one may be able to assess the corrosion level of the beam. From the distribution pattern of the longitudinal corrosion cracks, the bending stiffness of the beam has to be reduced, subsequently the deflections of the beam were calculated from the finite difference equations. The analytical prediction correlates quite well with the test results. Based on the analysis, it was found that the fundamental frequency of the concrete beam is sensitive to the corrosion of the steel bars. In practice, one may employ the vibration test to evaluate the extent of corrosion damage of the steel bars in concrete beams.