在多向应力作用下从混凝土的特性看受弯钢筋混凝土梁 变化的一个基本试验

　　A fundamental explanation of the behaviour of
　　reinforced concrete beams in flexure based
　　on the properties of concrete under multiaxial stress
　　M. D. Kotsovos
# a  ?$ b8 B( f　　Department of Civil Engineering, Imperial College of Science and Technology, London (U. K.)
3 P: D+ f, A: h　　The paper questions the validity of the generally accepted view that for a reinforced concretestructure to exhibit "ductile" behaviour under increasing load it is necessary for the stressstrain relationships of concrete to have a gradually descending post-ultimate branch.Experimental data are presented for reinforced concrete beams in bending which indicate the presence of longitudinal compressive strains on the compressive face in excess of 0.0035. It is shown that these strains, which are essential for "ductile" behaviour, are caused by acomplex multiaxial compressive state of stress below ultimate strength rather than postultimate material characteristics. The presence of a complex stress system provides a fundamental explanation for beam behaviour which does not affect existing design procedures.
0 p5 `- `9 p4 E# a1 H　　在多向应力作用下从混凝土的特性看受弯钢筋混凝土梁
　　变化的一个基本试验
　　M. D. Kotsovos  伦敦皇家科学与技术学院土木工程系
2 z' }$ X1 m+ I. l+ j- {# e1 ~2 F( R　　本文所探讨的问题是通常认为在荷载递增下钢筋混凝土结构呈现弹性状态，这必须是因为混凝土的应力-应变关系有一个逐渐递减的临界部分的真实性。试验数据显示受弯钢筋混凝土梁会在受压面的纵向压应变超出0.0035。这表明这些应变是钢筋混凝土结构的本质，它是由于一个比极限强度小的复杂多向的应力状态而不是塑性材料的特性引起的。一个复杂应力系统的存在为梁的状态提供了一个基本试验，而不是想象的一个现有设计过程。

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