对于混凝土的徐变现象,从本世纪初由Woolson等开始研究,到1930年Davis,Glanville等人进行正式研究,这以后有很多有关论文发表,研究成果是很显著的。1935年Hummel推断:徐变的成份中,不仅有残存的变形部分,而且有恢复的变形部分(恢复性徐变部分)。这个推断已经被大家接受。但是对于这个恢复性徐变(以后称之为“徐弹”或滞后弹变)的定义并没有明确建立,直到 From the beginning of this century, Woolson et al. Started to study the concrete creep phenomenon. By 1930, Davis and Glanville et al. Conducted formal studies. Since then, many papers have been published and the research results are very significant. In 1935, Hummel concluded that the creeping elements not only have residual deformations but also restored deformations (recoverable creep). This inference has been accepted by all. However, the definition of this recoverable creep (hereafter called a “slug” or lag) has not been clearly established until