无粘结预应力混凝土受弯构件开裂截面受压区高度的计算

Calculation of Compressive Zone Depth of Cracked Section under Service Load for Unbonded Prestressed Concrete Beams

有粘结预应力混凝土梁开裂截面的受压区高度可由一个三次方程确定,但由于平截面假定不能用来确定无粘结预应力钢筋的应变,这个三次方程不适用于无粘结预应力混凝土梁。本文根据等效变形的原理,通过补充变形条件,推导出了计算无粘结预应力梁开裂截面受压区高度的三次方程,使无粘结预应力受弯构件在使用极限状态下开裂截面的应力计算得以顺利进行。

The compressive zone depth of cracked section of bonded prestressed concrete beams can be calculated by a cubic equation, but the equation can not be used to calculate that of unbonded prestressed concrete beams, because the assumption that plane sections remain plane under loading is not correct in determining the strain of unbonded prestressed tendons at the cracked section.In this paper, according to the principle of equivalent deformation, the cubic equation for calculating the compressive zone depth of cracked section of unbonded prestressed concrete beams is proposed with a new deformation condition to unbonded tendons added.