Contrast Experiment And Analysis Of Three Types Of Prestressed Concrete Frames

These years, internal and foreign specialists in the prestressed concrete field dedicate themselves into the study on statically indeterminate structures of prestressed concrete and get some research findings which are very useful for research and design. Most of the research on moment redistribution is based on continuous beam structures, a little on prestressed concrete frames. Because of the effect of frame columns, load moment distribution, second moment and moment modulation of prestressed frame is different from continuous beam structure. The position of plastic hinge will effect the direction and ability of moment redistribution.Based on contrast experiment and analysis of three types of prestressed concrete frames, including"plastic hinge is made to appear only in beam","plastic hinge is made also to appear in column", and"plastic hinge appear at column top and beam end at the same time in theory", the main conclusions of this paper are below:(1) Moment modulation design of frame is based on elastic load moment, and the final steel decide the position and the appearance subsequence of plastic hinge, so the three type frame all can be found in project and reasonable in structure theory.(2) Elastic moment can be redistributed from support to mid-span, also can be redistributed from mid-span to support in the course of moment redistribution of frame, and both of them can be done.(3) Borrow ideas from moment modulation stipulation and suggestion of prestressed concrete beam, in the sided span column of single frame or the top of frame, when cross section relative compressive region height of column topξ≤0.3 and amount of moment modulation is no more than 30%, the plastic rotation ability of column hinge generally assure the expected moment modulation.(4) Second moment will bring influence to moment modulation of prestressed concrete frame. Take safety factor into consideration, when equivalent load second moment is advantageous to moment modulation and axial force second moment is disadvantageous, total amount of moment modulation should be controlled between 15~20%; when equivalent load second moment is disadvantageous, or both are disadvantageous, total amount of moment modulation should be controlled between 10~15%.