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.