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混凝土材料的弹塑性本构模型通常采用剪切型屈服面,剪切型屈服面包括两种硬化方式,即黏聚力(c)硬化和摩擦角(?)硬化.目前大多数本构模型都采用c硬化模式,无法反映应力诱导各向异性.本文的屈服函数是由混凝土材料非线性统一强度准则发展而来,采用φ硬化模式.基于Sargin提出的单轴压缩应力应变关系,提出一个统一硬化/软化参数,即硬化和软化参数具有相同的表达式.将提出的硬化/软化参数与屈服函数相结合,发展了混凝土材料三维统一硬化/软化弹塑性本构模型.该模型能够统一地描述混凝土的硬化/软化,避免了循环加载中再加载过程中硬化或软化参数的判断,从而增加了计算效率.模型有效地确定了塑性势参数,使得建立的本构模型能够合理地控制混凝土的剪胀.建立了峰值应力对应的等效塑性剪应变与围压的关系,使得建立的模型能够描述混凝土材料的应变软化随围压的变化规律.通过与普通强度和高强混凝土的双轴和真三轴试验结果比较表明,建立的模型能够适用于不同类型的混凝土材料,并且能够合理地描述混凝土材料的变形和强度特性.
Elasto-plastic constitutive models of concrete materials usually adopt shear-type yield surfaces, and shear-type yield surfaces include two kinds of hardening methods, namely cohesion (c) hardening and friction angle (?) hardening. Most of the constitutive models are The stress hardening-induced anisotropy cannot be reflected in the c-hardening mode. The yield function in this paper is derived from the nonlinear unified strength criterion of concrete materials. The φ hardening model is adopted. Based on the uniaxial compressive stress-strain relationship proposed by Sargin, a unified hardening is proposed. The softening parameters, ie the hardening and softening parameters, have the same expression. Combining the proposed hardening/softening parameters with the yield function, a three-dimensional unified hardening/softening elastoplastic constitutive model of the concrete material is developed. This model can uniformly describe the concrete. The hardening/softening avoids the judgement of hardening or softening parameters during reloading during cyclic loading, thereby increasing the computational efficiency. The model effectively determines the plasticity potential parameters, so that the established constitutive model can reasonably control the dilatancy of the concrete. The relationship between the equivalent plastic shear strain corresponding to the peak stress and the confining pressure has been established so that the established model can describe the application of concrete materials. The changing law of softening with confining pressure is compared with the results of biaxial and true triaxial tests with ordinary strength and high-strength concrete. The results show that the model can be applied to different types of concrete materials, and can reasonably describe deformation and deformation of concrete materials. Strength characteristics.