一种受剪细观损伤单元模型及其应用

A Shear Damage Element Model for Concrete and Its Application

基于剪切损伤破坏机制,发展了相应的细观损伤单元模型,它由弹脆性的微弹簧和模拟裂缝滑移的塑性元件组成.混凝土单轴受压时的宏观性能可用受剪细观损伤单元的并联体来解释,由此建立了混凝土单轴受压的损伤本构关系模型,并建议了塑性变形的简化计算方法.通过引入混凝土剪切单元破坏应变分布随机场,推导了应力与损伤的均值、标准差的表达式.根据混凝土单轴受压时的应力—应变全曲线试验结果,结合随机建模原理和优化算法确定随机场参数和材料参数,将分析得出的受压随机应力—应变关系与试验结果进行比较,二者吻合良好.

Based on the features of shear failure of concrete, the shear damage element, which comprises the elastic part and the plastic part, is introduced. Furthermore, a new kind of idealized mesescopic damage model, which the material is represented by a set of the elements of equal stiffness that are joined in parallal, is developed for concrete under monotonic axial compressive loading. The model can well explain the experimentally-observed nonlinearity of stress-strain curve, stiffness degradation and strain softening, etc.. The constitutional law for concrete under axial compression is established. Also, a simple analysis method for plastic strain is put forward. With damage and elasticity modulus as random variables, stochastic equations of damage growth and stressstrain are presented. With the help of stochastic structural modeling and optimization methods, coefficients in the model, for example, the distribution parameter of the random field of failure strain, can be easily determined by the full stress-strain curves of concrete specimens under axial loading. Comparison with the test results shows that the analytical values agree well with the test.