混凝土开裂对地基板弯矩的影响

Influence of concrete cracking on bending moment of plate on foundation

当前地基板的配筋设计均按弹性体计算得到的弯矩进行,这在理论上是不合理的,因为地基板是高次超静定问题,地基板开裂后其弯矩会有较大的改变。笔者通过合理模拟地基板裂缝开展过程及土-结构的相互作用,采用非线性有限单元法对地基板进行了分析,着重讨论了不同计算方法及裂缝对地基板弯矩的影响。计算结果表明,按平面问题计算得到的弯矩比按空间问题大 40 %左右,地基板开裂后弯矩减小,且裂缝越多,弯矩减小越多。

It is obvious there are shortcomings in the present design of the plate on foundation, in which the amount of steel is based on the bending moment obtained by elastic theory, because the plate on foundation is high-order statically indeterminate problem, and the bending moment will change considerably after the plate on foundation cracks. This paper is based on rational simulation of the progress of the cracking of the plate on foundation and the interaction of soil and structure by means of the nonlinear finite element method. Emphasis is put on the discussion of the influence of concrete cracking on the bending moment of the plate on foundation by different computational methods. The result shows that the bending moment computed as plane problem is 40% larger than that computed as space problem. The bending moment decreases after the plate on foundation cracks, and the more the cracks, the smaller the bending moment.