两跨预应力混凝土框架内力重分布试验研究及分析

基于两榀接近足尺的后张有粘结预应力混凝土框架的试验,对多跨预应力框架的内力重分布进行了研究,重点考虑了框架的连续性和轴压比的影响。研究结果表明,我国现行规范基本能满足预应力框架弯矩调幅的设计需要,但当控制截面相对受压区高度较大时,框架连续性对弯矩调幅影响较大。第一塑性铰的转动能力对结构弯矩调幅起主要作用,次弯矩越大,该截面总弯矩调幅越大。其他塑性铰截面以次弯矩调幅为主,结构往往不能实现完全内力重分布。另一方面,随轴压比增大,梁柱上弯矩分配虽略有变化,但对整榀框架的极限承载能力和总的弯矩调幅能力影响不大。

Experimental study on internal force redistribution of two-span prestressed concrete frame

Based on tests of two full-scale double-span prestressed frames,internal force redistribution of frame was studied and continuity of structures and axial compression ratio of column were analyzed.It is confirmed that for most cases,the Chinese code can be used well in design of moment modulation of prestressed frames,but when relative height of compression zone is large,continuity of structures affects the modulation sufficiently.The rotational capacity of the first plastic hinge always controls the modulation and the larger the secondary moment results in larger modulation.The secondary moment modulation also dominates the modulation of other plastic hinges and a full redistribution cannot be realized.On the other hand,though increasing axial compression ratio of column changes the moment redistribution in frame,the effect on ultimate loads and total modulations is insignificant.