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引言关于混凝土徐变及收縮变形对鋼筋混凝土結构的影响,近来已引起人們的注意。它的影响在普通鋼筋混凝土结构中,有时将使鋼筋的应力增大1～1.5倍,杆件的挠度增大3～4倍,对于超静定結构,甚至可改变内力的符号。如果在超静定結构中施行人工调整内力,由于混凝土徐变的結果,可使人工调整内力失去絕大部分效用。在预应力鋼筋混凝土結构中,将使鋼筋的预应力值减少1000kg/cm~2以上。由此可見,正确地了解混凝土徐变及收縮变形的性质和在設計中适当地考虑其影响,是十分必要的。
Introduction The impact of concrete creep and shrinkage on the structure of reinforced concrete has drawn the attention recently. Its effect in ordinary reinforced concrete structures sometimes increases the stress on the bars by 1 to 1.5 times and the deflection on the bars by 3 to 4 times. For statically indeterminate structures, it even changes the sign of internal forces. If artificial adjustment of internal force in the statically indeterminate structure, as a result of concrete creep, can make the manual adjustment of internal forces lose most of the utility. In prestressed reinforced concrete structures, the prestressing value of steel bars will be reduced by more than 1000kg / cm ~ 2. Thus, it is necessary to correctly understand the nature of concrete creep and shrinkage deformation and to properly consider its impact in the design.