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在现行的弯矩-曲率滞回曲线的计算中,有两个关于混凝土的基本假定: (1)混凝土开裂截面再加载时,像未开裂过的截面一样工作。(2)对混凝土受压区采用轴向重复加载的应力-应变关系而不是反复加载的。根据上述假定,在大开裂变形下,计算的弯矩-曲率曲线要出现一个拐点,而它在试验曲线中是没有的。我们发现在再加载时如果考虑了开裂面的局部接触效应,则上述拐点就不再存在。为此,本文提出一个考虑裂面效应的等效应力-应变关系,以代替过去国内外通用的重复加载应力-应变关系,从而使理论与试验结果较好地符合。
In the calculation of the current moment-curvature hysteresis curve, there are two basic assumptions about concrete: (1) When the concrete cracking section is reloaded, it works like an uncracked section. (2) The stress-strain relationship of axially repeated loading is applied to the compression zone of the concrete instead of repeated loading. Based on the above assumptions, under the large crack deformation, an inflection point appears in the calculated moment-curvature curve, which is not found in the test curve. We have found that if the local contact effect of the cracking surface is taken into account during reloading, the above inflection point no longer exists. For this reason, this paper proposes an equivalent stress-strain relationship considering the splitting effect to replace the stress-strain relationship that is commonly used at home and abroad in the past, so that the theoretical and experimental results are in good agreement.