反复荷载作用下的混凝土损伤本构模型

混凝土损伤模型的研究,实际上是研究混凝土材料的本构行为。在外界因素作用下,材料的累积变形引起结构内部损伤发展,最终的损伤将产生宏观裂缝直至整个结构破坏。根据Najar损伤理论,提出了新的分段曲线混凝土受压损伤变量模型和混凝土受拉软化段损伤变量模型,给出了不同强度混凝土损伤变量方程和损伤演化方程。通过计算对比分析认为,建议的损伤模型与已有的混凝土本构模型较吻合。该方法的优点是参数少,不同的混凝土强度有确定的损伤演变方程,可以动态分析混凝土的累积损伤程度。在此基础上,根据已有混凝土反复荷载作用下的滞回规则,建立了在某一循环荷载下的加载、再加载、卸载路径下的损伤本构模型,该模型考虑了混凝土在反复荷载作用下的应力跌落、裂面效应、强度下降、刚度退化等力学性能。应用本文建议的模型进行反复荷载下的截面损伤计算,试验结果与文献计算结果较吻合。

Damage constitutive model of concrete under cyclic loading

Research of concrete constitutive model is actually to study constitutive behavior concrete.Cumulate deformation of material will cause interior damage of structure under exterior load and the entire structure will collapse due to damage of concrete.Due to damage theory by Najar given,a new segments curves damage variable model of concrete compression and damage model of concrete tension with soft curve segment is investigated and equations is put forward to about damage variable and evolvement with variety degrees of concrete.In order to testify the validity of the model,the calculated result are compared with the existing constitutive model and resulting shows that the proposed model is agreed with the existing model.Advanced of this new method is there are different damage equations due to concrete degrees and can dynamically analysis concrete damage.Based on hysteresis rules of exist concrete under cyclic loading,damage constitutive model is suggested under one cyclic,stress deterioration,crack effect,carrying capacity decline and stiffness degenerate of concrete under cyclic loading are considered in this model.