索塔锚固区环向预应力束伸长值的影响因素和理论计算方法

Influencing Factors on Elongation of Circumferential Prestressing Tendons in Anchorage Zone and Theoretical Calculation Method

针对小半径环向预应力束的伸长值多大于按照相关规范计算所得伸长值这种现象,分析了影响环向预应力束伸长值的各种因素,提出应把影响实际伸长值的因素产生的效应计入理论伸长值的计算方法中。给出了径向荷载效应引起的波纹管变形从而导致预应力束伸长值的计算公式以及由预应力束的挤压效应引起的修正系数,同时提出了由预应力束束效应导致的钢绞线受力不均匀引起的预应力束伸长值的计算方法。最后,给出了计算小半径环向预应力束理论伸长值的计算公式,并利用多个工程数据进行了验证。结果表明:小半径环向预应力束的实际伸长值与按照本文提出的理论计算方法所得的计算值比较,可以满足规范要求的±6%误差范围。

In view of the phenomenon that the elongation of small-radius circumferential prestressing tendon is much longer than the elongation which calculated according to the relevant specifications, we analyzed different influencing factors which affect circumferential prestressing tendons, put forward that the effect of the factors influencing real elongation should be considered in theoretical calculation method. We gave a calculation method of the elongation of prestressing tendon due to deformation of corrugated pipe caused by radial load effect, and modified the friction coefficient caused by the squeeze effect of the prestressing tendon. At the same time, we provided the calculation method of the elongation of prestressing tendon due to non-uniform prestress caused by the strand effect. Finally, we gave a formula which suitable for calculating the elongation of small-radius circumferential prestressing tension, and verified the formula by measured data from several engineering projects. The results show that the elongation deviation between measured value and calculated value of small-radius circumferential prestressing tension can be controlled within ±6% if use the presented formula.