预应力混凝土结构中张紧弦式束筋索力静态获取方法与试验研究

Identification on cable tension of prestressed strand by static principle in PC structure and test study

在采用后张法建立预应力体系的预应力混凝土结构中,由于预应力损失各因素的影响,其索力当前值是未知的.为对其实际值进行精确度量,以便把握结构当前预应力储备状况等级,将自主研发的"预应力钢索张力测试仪"应用于大比例模型试验梁试验检测.综合考虑模拟边界修正条件并结合二级差测定法的误差修正技术,建立了基于静力学原理获得束筋索力的静力参数静载检测法.通过试验分析得出:索力测试值与真值的相对误差不超过6%,并且随着张力等级的增大而呈现减小的趋势.因此,该方法精度满足要求并易于工程中推广应用.

Considering the influence of prestress losses on effective cable tension of prestressed strand among post-prestressed structures, the current value is still unknown. For the sake of measuring it exactly to estimate the condition for prestressing reservation, a speeial instrument Stretching Force Tester was invented and applied to measure the effective prestressing force of strand in a large-scale PC beam model. Thus the static parameter loading method was obtained by means of amending analogous boundary condition and minimizing test errors through the tool of double-stage differences. The results showed that the relative error for cable tension force between test value and standard one was less than 6 percent and it decreased with the growth of tensional grades simultaneously. Therefore, the precision of this method meets the project requirements and is easy to apply.