軸圧をうける H 形鋼柱の弾塑性曲げ変形性状に関する研究 : II : 交番繰返し曲げ : 曲げモーメント-曲率関係

Abstract

In the foregoing paper the authors discussed on the relationships between bendingmoment and curvature or bendingmoment and deflection of wide flange steel columns subjected to constant axial load in elasto-plastic range. There were proposed models for analysis to simplify the treatment and shown their accuracy by the comparison with test results. The analytical studies are extended here in this paper to the elasto-plastic behaviours of wide flange steel columns subjected to alternately repeated loading with constant curvature amplitude. The influences of axial compression radio n=N/N_y or of curvature amplitude upon the bendingmoment-curvature relation-ships are shown in Figs. 14, 15 and 16. Following the increase of number of cycles, the width of hysterisis loop becomes narrower, the resisting moment becomes higher and then the hysterisis loop approaches gradually its final stabil state (in certain cases it becomes straight line……extended elastic state). Such a process and limiting conditions become clear. Following the increase of number of repetition of alternate loading there occures the accumulation of axial strains and these processes are shown in Figs. 17, 18 and 19. There exists a certain limit of accumulation, which are mainly determined by axial compression ratio, the higher the axial compression the higher becomes the limit of accumulation.