长期以来,对于钢筋混凝土受弯和轴心受拉构件,为满足破坏时的极限强度和使用时的裂缝宽度要求,各国采用的设计方法大都以极限强度为基础,然后根据需要复核使用状态。这种设计方法,对在使用上要求严格限制裂缝宽度的构件,当由强度确定的配筋,经核算不满足裂缝宽度要求时,通常凭经验增加配筋再行复核,很难一次算好,往往要经多次试算才能获得满意的结果。上述 For a long time, for the flexural and axial tension members of reinforced concrete, in order to meet the ultimate strength at breakage and the crack width requirements during use, the design methods used in various countries are mostly based on the ultimate strength, and then review the use status as needed. This kind of design method, for components that require strict restrictions on the width of cracks in use, when the reinforcement determined by the strength does not meet the requirements of the crack width, it is usually based on experience to add reinforcement and then review, it is difficult to calculate it once. It often takes many trials to get satisfactory results. Above