Experimental Investigation On Reinforced Concrete Frames Of "Stronger Beam With Weaker Column" And "Strong Column With Equally Strong Beam"

On the basis of experiment and analysis about two "one story and one bay"reinforced concrete frames, namely "stronger beam with weaker column"and "strong column with equally strong beam", the characteristic of internal force redistribution is investigated, and the relative features of the three kinds of frames including "stronger column with weaker beam", "stronger beam with weaker column"and "strong column with equally strong beam"are compared primarily. So some conceptual cognition and conclusion are got, such as: 1) To "stronger beam with weaker column"frame, the plastic hinge in the top of column comes into being firstly, and then positive moment modulation from the top of column to the middle of beam has happened in the process of loading. 　2) The most important characteristic about internal force redistribution of the "stronger beam with weaker column"frame is the crack development at the end of beam, in other words, the crack has been developed at all times till the frame is destroyed at end. 3) To the "stronger beam with weaker column"frame, the final destruct form of frame may be the "one hinge", the "two hinges"or "three hinges"destruction. However, the experiment turns out to be the "three hinges"destruct machine in the top of both two columns and in the middle of beam. 4) To the "strong column with equally strong beam"frame, the actual frame can not be accordance with the theoretic frame for some seasons. So the actual behavior may be the "stronger column with weaker beam"frame, or the "stronger beam with weaker column", and then the destruct form is different correspondingly. But no matter what behavior has been formed, the positive moment modulation is weak. 5) To this experiment, the crack width is the primary factor which controls the internal force modulation extent. However, the relative compressive height of concrete and the ratio of axial pressure to section are far from the limited value prescribed by the building code, so the two factors have caused little effects to the experience. 6) Through the comparison of the following four aspects, namely, the crack development, the destructive form, the calculating method and the moment modulation ability, the objectivity of "Three kinds of frame"is believed to exist, and the characteristic of internal force redistribution is disparate, so different methods of modulation design should be taken into account to different kind of frame. 7) A simple method, namely sectioned dropping rigidity method, which can work out the ultimate load and the ultimate moment before experiment, has been sought for. By the analysis of the two experimental frames with both two methods, that is, "sectioned dropping rigidity method"and "ideal elastic and plastic method", and by the comparison between the calculating result with foregoing two method and the experimental result, it is proved that the "sectioned dropping rigidity method", which can work out the ultimate load and the ultimate moment, is available and quite exact.