江浙等省的社队企业一般都能生产预应力钢筋混凝土多孔板、挂瓦板、薄板等预制构件(预应力钢筋一般都采用低碳冷拔钢丝),但对其张拉应力σ_l,却往往认为其值取得越高,构件质量就越好。其实并不如此,当σ_k值取得过高,反而会引起沿预应力筋方向出现不可恢复的纵向水平裂缝,并且使构件本身的塑性减少,容易发生脆断。在冬季, Corporations in Jiangsu and Zhejiang provinces and other provinces can generally produce prefabricated reinforced concrete perforated plates, hanging tiles, thin plates and other prefabricated components (prestressed steel generally use low-carbon cold drawn steel wire), but their tensile stress σ_l, but often The higher the value, the better the quality of the components. In fact, this is not the case. When the σ_k value is too high, it will cause irreversible longitudinal horizontal cracks along the direction of the prestressed tendons, and the plasticity of the components themselves will decrease, and brittle fracture will easily occur. in the winter,