在计算预应力混凝土管的钢筋有效预应力时,应用如下公式: σ_(y-1)=σ_k-σ_s=nσ_h(σ_s=σ_(s1)+σ_(s2)) σ_(y-3)=σ_k-σ_s (σ_s=σ_(s1)+σ_(s2)+σ_(s3) (1) 式中σ_(y-1)——一阶段管钢筋有效预应力(公斤力/厘米~2); σ_(y-3)——三阶段管钢筋有效预应力(公斤力/厘米~2); σ_k——钢筋控制应力(公斤力/厘米~2), σ_k=KR~b_y (K为控制应力系数, R~b_y为钢丝的标准强度); n=Eg/E_h,(Eg、Eh分别为钢筋、混凝土的弹性模量); σ_h——混凝土预压应力(公斤力/厘米~2) When calculating the effective prestress of steel bars of prestressed concrete pipes, the following formula is used: σ_(y-1)=σ_k-σ_s=nσ_h(σ_s=σ_(s1)+σ_(s2)) σ_(y-3)=σ_k -σ_s (σ_s=σ_(s1)+σ_(s2)+σ_(s3) (1) where σ_(y-1)—the effective prestress of one-stage pipe reinforcement (kg force/cm~2); σ_( Y-3)—Three-stage pipe reinforcement effective prestress (kgf/cm~2); σ_k—reinforced control stress (kgf/cm~2), σ_k=KR~b_y (K is the control stress factor, R ~b_y is the standard strength of the wire); n=Eg/E_h, (Eg, Eh are the elastic moduli of steel bars and concrete, respectively); σ_h is the pre-compressive stress of concrete (kg force/cm~2)