一、前言当前国内对部分预应力混凝土构件所采用的设计计算方法较多。在桥梁方面我国土木工程学会部分预应力混凝土委员会推荐采用“名义拉应力法”进行构件截面的设计。所谓“名义拉应力”是当构件混凝土受到荷截作用已开裂时,仍假定混凝土未开裂而以均质截面计算 I. Preface At present, there are many design and calculation methods used in some prestressed concrete members in China. In the aspect of bridge, some prestressed concrete committees of China Civil Engineering Society recommend the “nominal tensile stress method” to design the cross-section of components. The so-called “nominal tensile stress” is when the load-bearing concrete member has been cracked, it is still assumed that the concrete is not cracked and calculated in homogeneous cross-section