Abstract
Flange local buckling is one of the important factor to decide the critical strength and deformation capacity of H-shape beams. So the b/t ratios of flanges are proposed with regard to the plastic design methods. But they are generally proposed as the results of monotony loading tests. Accordingly, the investigation under cyclic loading is required. This report is the experimental investigation to know how to influence the strength and the deformation capacity of the H-hape beams under cyclic loads for flange local bucklings. Specimens are the H-shape beams in fig. 1. Their sizes and sections are listed in table 1. The kinds of b/t ratio are four, that is, b/t=15, 12, 10 and 8. In the ratio of cyclic loads, the kinds are five, that is, monotony loading, 1 : 0.6 cyclic loading, 1 : 0 cyclic loading, 1 : 1 cyclic loading (Load Control) and 1 : 1 cyclic loading (Deflection Controll). Test results are shown in table 3 and table 4. The relationships between load and deflection are shown in fig.6 to fig.23. Fig.24 shows (1/2) θ_M/θ_P-b/t relationships. θ_M/θ_P is the value in the table 4. From the experimental investigation in this report, next terms are concluded. 1. About AA-series (b/t=15), the deformation capacity in the plastic region is little or no. 2. About A, B and C series (b/t=12, 10 and 8, respectively), the smallar b/t is, the larger the difference of rotation capacity by the kind of cyclic loading is. 3. The variation of rotation capacity is expressed in equation (1) and (2).
