无粘结预应力技术在大直径圆柱壳中的应用和问题探讨

Application and Investigation of Unbonded Prestressed Technique on the Cylindrical Shell with Large Diameter

利用轴对称圆柱壳有矩理论进行水池设计,并进行了现场测试。设计中预应力钢筋的摩擦损失取自现场试验数据,为张拉控制应力的1 9%。工程实例表明,无粘结预应力混凝土技术应用于大直径圆柱壳可有效地控制裂缝产生,获得可观的经济和社会效益。在使用阶段,建议对0 4倍池壁高度以下截面应按偏心受拉构件计算,以上截面仍按轴心受拉构件计算。底板下的锚桩除了有效抗浮之外,还能大大降低底板的厚度。施工时应保证钢绞线与锚固壁柱上的锚垫板垂直,并选用适当的夹片式锚具,使其表面硬度与钢绞线的表面硬度差≥HRc1 0 (HRc为洛氏硬度)。

The design of water tank using the axisymmetrical cylindrical shell theory with moment and in situ tests are presented. The friction loss of the prestressing tendon in tests equals to 19 percent of the controlling axial tension stress. The application and test show that unbonded prestressed concrete technique used in cylindrical shell with large diameter can restrain the development of crack effectively, and its economic and social benefits are significant. The tank wall panels whose height from the top is greater than 40 percent of total height, are subjected to both flexure and axial tension, otherwise are subjected to pure tension. The anchor piles can prevent floatage of the tank, as well as decrease the thickness of the floor slab. In construction, the steel strand should be perpendicular to the plate embedded in the buttress panel. The differences of the surface hardness between the jaw vice anchorages selected suitably and the steel strand should not be less than HRc10(HRc means Rockwell hardness).