【摘要】 为了提高混凝土Lattice模型的计算精度,研究了模型参数修正方法.首先,对比分析了根据Lattice模型与实体模型计算得到的位移与应力,发现单一材料模型中位移比和应力比关联参数均与微单元特征长度成线性关系.其次,提出了一种递进式参数修正方法,即对微杆单元横截面面积和弹性模量依次进行修正.然后,采用多参数同步修正的方法,进一步修正了三相混凝土Lattice模型,修正后模型的位移和应力计算误差均不超过5%.基于该修正模型,模拟分析了钢筋混凝土结构的锈胀破坏过程.结果表明,角筋锈胀会引起竖向和水平向裂纹的共同发展,直至贯穿保护层.锈蚀钢筋间净距显著影响裂纹扩展模式;当净距与保护层厚度相当时,易形成钢筋间水平方向上的主裂纹,且主裂纹对其余方向的裂纹具有一定的抑制作用.更多还原

【Abstract】 A parameter updating method is studied to improve the computational accuracy of the Lattice model of concrete. First,the displacement and the stress computed by using the Lattice model are compared with those by using the general finite element model. The parameters associated to the displacement ratio and the stress ratio are linear with respect to the characteristic length of the rod element in the Lattice model with a single material type. Secondly,a progressive parameter updating method is developed. The section area of the rod element and the elastic modulus are modified successively.Then,by the method of simultaneous correction for multiple parameters,the Lattice model of concrete containing three phases is modified and the computational errors of the displacement and the stress are less than 5%. Finally,the corrosion damage process of reinforced concrete structure is simulated based on the modified model. The results showthat rusting expansion of corner reinforcement drives simultaneously horizontal and vertical cracks in concrete propagating throughout the full depth of cover. The net distance between the rusting rods influences significantly on the cracking pattern. When the net distance is about the same as the depth of the cover,the main crack in the horizontal direction between the rusting rods is likely to form,which may inhibit the cracks along other directions.更多还原