Study on Quantitative Evaluation Method for Local Buckling of Flange of H-Section Steel Beam by Micro Strain Amplitude Measurement

The final purpose of this research is to establish a method for evaluating damage and residual performance of steel structural member after local buckling occurred. This paper quantitatively clarifies the change of strain amplitude caused by local buckling through analysis and discusses the possibility of its application in local buckling damage assessment. When a small shape change occurs in the steel frame member due to local buckling, the distribution of strain amplitude caused by microtremor or small earthquake would change, and it is expected that damage assessment can be made by capturing this change. When a static cyclic loading analysis using a finite element model was performed to simulate the local buckling of the H-shaped steel beam, and at the step where the load returned to zero for each loading cycle, the ratio between the strain and displacement, which we call “local stiffness,” is calculated and it was used to discuss the damage. As a result of the analysis, it was shown that the local stiffness changes as the local buckling progresses. If such changes in local stiffness can be captured by actual measurement, it is expected to lead to the establishment of damage evaluation technology.