混凝土弹性-徐变的本构关系

混凝土的变形不仅和加荷后的时间(t-τ)有关,而且和加荷时刻混凝土的龄期有关,应变和应力之间成复杂的积分式关系。由于本构关系的复杂性,对钢筋混凝土或预应力混凝土超静定结构未能圆满求解。在特定情况作者曾给出本构关系的Laplace变换形式并提供求解方法。本文就当前国际上所给出的弹性-徐变的普遍形式给出t→∞时应变、应力之间的代数关系(线性或非线性),以及在周期荷载下,例如长期温度变化,应变、应力的线性关系。为简单计,本文仅考虑一维的应变、应力问题,不难按照文2]推广到三维情况。当本构关系确定后可按文献1]、2]方法求解预应力混凝土的框架和板、壳问题。

ON THE CONSTITUTIVE RELATIONS OF ELASTICITY-CREEPS OF CONCRETE

The deformations of concrete are related to not only the loading time interval (t-τ) but also the age of concrete while loading, the relation between strain and stress takes a complex integral form. Because of the complexity of the constitutive relations, the problem of R.C. or P.C. structures can not be solved satisfactorily in a special case, the author has given the constitutive relation in the form of Laplace transformation, and presented the solving method, respect to the general constitutive relation of elasticity-creeps used in current international literatures, the author gives the algebraic (linear or nonlinear) strain-stress relations while strain and stress tend to constants when t→∞, and the linear relation while strain and stress are periodic functions when t→∞. For simplicity, only one dimensional case is considered, it is easyto extend to the three dimensional case by2]. When the constitutive reintions are given, the structural problems of frames, plates and shells can be calculaed by 1]and2].