Research On "Strong Column Weak Beam" Yield Mechanism In Reinforced Concrete Frame By Earthquakes

Deformation capacity of the frame are closely related the failure mechanism. Experimental studies have shown that the beam yield first, the whole frame have a larger redistribution of internal force and energy consumption capacity, ultimate story drift increases, have a better seismic performance. In the Wenchuan earthquake, earthquake damage about houses typically expressed as a number of reinforced concrete frame structures were damaged seriously with plastic hinges occurred at column ends rather than beam ends, which is significantly different to the failure mode expected in the seismic design of "strong column weak beam". To achieve "strong column and weak beam" principle become very difficult because many complex factors. Among them, the floor slab strengthen the beams made a large number of plastic hinges appear to column end, and the capacity greatly reduced, along with a large displacement between layers makes the whole structure form institutions, especially when the plastic hinges occurred at column ends in the same layer at the same time, that has a serious threat to the structure safety or result in structural collapse. Therefore, the implementation of "strong column weak beam" is an urgent problem need to study.Based on the facts above, the main works finished preliminarily in this thesis are as follows:1,A RC frame structures are designed strictly according to Chinese code, Established two three-dimensional frame model by ANSYS software, they are frame model without floor slab and frame model with floor slab, and elastic and plastic time history analysis were made on the two models, the performance of the slab on frame structures under earthquake actions have been studid.2,Maintain beam end moment constantly in the frame model with floor slab,the moment amplification factor of column was increased in turn, the column reinforcement in the model was also increased, when plastic hinges appear in the beam end, "strong column weak beam" was achieved.3,Considered the bars in effective range of slab width which contribute the beam bending capacity, reduced Bar area in model with floor slab, elastic and plastic time history analysis was made,and the results by derived to capacity formulas was verified.Through these studies, the main conclusion is as follows:1,Analysis showed that when the moment amplification factor of column is 1.7 can effective achieve "strong column weak beam", and the result is under the premise that the real Bar area of the beam is not more than 10% calculated, when the real Bar area of the beam is more than 10% calculated,propose check with the real Bar area.2,The possible adverse effects of consider the moment amplification factor of column, can be considered the bending capacity of bars within the effective width parallel with beams in slab,to reducing the more bars in beams, to reducing the moment amplification factor of column. For this model, consider these bars,using the existing standard of 1.2 times of the moment amplification factor of column can achieve "strong column weak beam."...