预应力钢筋理论伸长值计算 计算钢束编号：预应力钢束采用一束预应力筋张拉控制应力预应力筋截面面积超张拉系数预应力筋弹性模量预应力筋的锚下张拉力：Ncon=σcon×Ap×b/1000=损失后的张拉力N=Ncon[1-e-（μθ+kx）]预应力筋理论伸长值p×l/（Ap×Ep）Δl=预应力筋平均张拉力Pp=Pp×[1-e-（μθ+kx）]/（μθ+kx）根据以上公式分段计算，结果如下表：781.2kN预应力筋伸长量分段计算，考虑预应力钢筋与管道壁间摩擦引起的预应力Ap=b=14σcon=13955601Mpaφ15.20 钢铰线；Mpamm2Ep=2E+05线段ABBCCDDE张拉控制力（kN）781.2779.411768.071765.506Ap(mm2)Ep(Mpa)l(m)θ(rad)5605605605601950001.52460μ0.25kμθ+kxe-（μθ+kx）终点力（kN）779.411768.071765.506716.973Δl(mm)10.97.415.600.00150.002290.997710.00150.014660.9850.00150.003350.996660.00150.06550.93661950001.04510.052360.251950001950002.23000.2620.250.25由表中数据分段求得Δl=33.9mm
