预应力混凝土内部锚固区拉压杆模型的修正

MODIFICATION OF FIP STRUT-AND-TIE MODEL FOR DESIGN OF INTERIOR ANCHORAGE ZONES OF POST-TENSIONED CONCRETE STRUCTURES

针对国际预应力协会(FIP)给出的预应力混凝土内部锚固区拉压杆模型的缺陷和不足,基于有限元分析和拉压杆模型基本理论,提出一种修正FIP模型的方法,适用于各种构件尺寸比(b/h)的情况。通过有限元分析,得出构件的内力比F/P与尺寸比b/h曲线。并对FIP模型的应用局限性和模型修正的方法进行讨论。与FIP模型相比,修正后模型中拉杆的内力大小和相对锚具的位置均做出调整,并且按修正后的模型设计配筋,可节约近30%的内部锚固区普通钢筋用量。

A stress analysis of the interior anchorage zones of post-tensioned concrete structures （IAZPTCS） is conducted using FEM. According to the analytical results, it is found that there are some limitations of the present design method （strnt-and-tie model, STM） for IAZPTCS as recommended by International Federation for Prestressing （FIP） in 1996. A modified approach of STM is proposed. Comparing with the original FIP model, in the proposed approach, the locations and the internal forces of the ties and struts are adjusted, and the dimensional ratio of the width of the anchorage over the width of the member （b/h） can be varied in a wide range. By using the proposed model, the amount of reinforcement can be decreased by about 30% in the interior anchorage zones.