从结构工程的角度看混凝土在冻融循环下的破坏标准

Concrete failure criterion under freeze-thaw condition in structural engineering

混凝土冻融破坏的标准通常应用材料学的观点,认为动弹模损失达到一定程度即为破坏,但材料学的冻融破坏观点在工程结构中并不实用。工程结构的破坏传统上是以混凝土强度理论为基础、以构件的极限承载力为标准来判断的。为比较二者的差异,本文将考虑冻融循环影响的混凝土在主应力空间的破坏面模型嵌入通用有限元程序MSC.Marc中,利用已有的试验数据验证这种二次开发的有效性,然后通过一系列有限元计算模拟不同冻融条件下混凝土试件破坏的极限承载力,从而将材料学角度的混凝土冻融破坏标准和结构工程角度的混凝土冻融破坏标准联系起来。基于现有的试验数据对比表明,目前从材料学角度采用的冻融破坏标准相对在结构工程领域而言偏松。

Concrete failure criterion under freeze-thaw condition is often studied from engineering material field. It is considered that concrete is damaged when the loss of dynamic modulus is to be some degree. This viewpoint is not unified with that in structural engineering. In the field of structural engineering, concrete strength is the first, ultimate bearing capacity should be used for estimation. To compare the difference in two fields, a concrete failure surface model in principle stress space, considering the damage under freeze-thaw condition, is set into general finite element program, MSC. Marc. The validity of secondary development in the present software is verified by existing test data. Based on a number of calculations considering different environment conditions, two kinds of concrete failure criterions under freeze-thaw condition, from the point of engineering material and the point of structural engineering, are compared. A conclusion is educed that concrete failure criterion in the field of engineering material is too tolerant to be used in structural engineering.