Research On Slab's Influence To "Strong Column Weak Beam" Yield Mechanism Of Framework

"Strong column weak beam" form of frame structure damage is widely considered to be a reasonable framework structure yield mechanism. The current structure design field is mostly on the basis of the expected failure modes for structural seismic design. However, a large number of structural failure tests and earthquake analysis results showed that most of the RC frame structures which designed according to the current code were destroyed with an unexpected mechanism when suffered from complex seismic force,the "Strong column weak beam" yield mechanism did not happen. One of the main reasons is that structural engineers in the aseismic design,generally ignored the bearing capacity contribution of frame beams comes from the slab. In the process of construction, we usually cast the slab with frame beams and columns together, while improving the integrity of the structure, but the complexity of the interaction between them is easy to be ignored; Because of the complexity of frame-slab interaction,The slab is the rigid component,engineers simply use magnification factor to consider the contribution of slab stiffness, while ignoring the core of the problem.This simplified approach is impractical, and leads the major failure mode of the frame structures to plastic hinge mode in column. Which also bring a huge personal security and economic property loss. Therefore,the principle of how the slab make a difference to "Strong column weak beam" yield mechanism has yet to be further research and analysis. This paper analyzes the influence of the destruction of slab form frame structure throughly,Mainly includes the following parts:Collecting the slab test and theoretical analysis papers which considering the effects of slab,in order to find out the core contribution of slab in the process of change frame structure yield mechanism preliminary.Firstly establishes the pure frame, the frame with slab two kind of structural models,calculate the structural inter forces and reinforcement aby to the current codes,and then according to the calculated results , using SAP2000 establish accurate finite element models,doing Push - over analysis respectively for two structure models for the static pushover analysis, to explore the destruction form of difference between two models.Next,change the loading pattern and working condition analysis, further study how slab affect the yield mechanism of frame structure.The Pushover analysis is carried out on the basis of building the modes with different effective flange width to identify the effect of slab on the yielding mechanism of the flame structures, and get the reasonable value of the effective flange width.On the basis of the theoretical derivation and finite element simulation analysis,we could come to a conclusion that when to design a frame structure, many kinds of influence factors such as the plate steel must be taken into account to participate in frame beams flexural bearing capacity , adopting reasonable accurate formula of the effective flange width values, to achieve the requirements of seismic code design "strong column weak beam", also provide a basis for improving the existing structural aseismic calculation method.