Study On The Influencing Factors Of Column-end Destruction Of Frame Structures Under Earthquake

During the design of reinforced concrete frame structure,according to strong column and weak beam design concept,at the time of the earthquake,reinforced concrete frame structure,plastic hinge should be appear firstly at beam-end,the plastic hinge at the end of the column should appear lightly after beam or not appear at all,and he plastic hinge should not appear at both ends of one column.However,by reading a large number of earthquake damage analysis of Wenchuan earthquake,I found out that during Wenchuan earthquake,many columns broke at the end of it,while the beams had no damages.In the failure form of the "strong beam weak column" type,plastic hinge at the end of the column absorbed most of the energy,so that the elasto-plastic of structure has been decreased.And much failures of the end of the column cause structural collapse easily.There are many scholars study on the "strong beam weak column" failure type,they put forward some reasons for the destruction of this form,like:cast-in-place concrete floor,filler walls,Limit values of axial compression ratio,the span of a girder and vertical seismic action etc.In this paper,I took the vertical seismic action,the existence of floor and the floor rebar as influencing factors to analysis.The main conclusions are as follows:1.The main factors affecting the form of structural damage is the discreteness of seismic action,the result of the same structure under different seismic action differs considerably,but under the same seismic action,the calculation results of different structures are relatively small.2.Under the same horizontal seismic action,the vertical earthquake action has little effect on the final failure mode of the structure,but under Three Dimensional Earthquakes,the maximum of the displacement-angle between floors is smaller than that under Two-directional Horizontal Earthquake.In general,the Bending bearing capacity ratio of column to beam under Three Dimensional Earthquakes is greater than that under Two-directional Horizontal Earthquake.3.Under the same seismic action,the model without floor is less damaged than that which with it.And no floor model is more likely to be damaged at beam-end.In general,the maximum of the displacement-angle of no floor model is less than the model with floor.The Bending bearing capacity ratio of column to beam of no floor model is less than the model with floor.4.Under the same seismic action,the bearing negative reinforcement of the plate has little effect on the final failure mode of the structure,but influence the Damage degree of model,the maximum of the displacement-angle between floors,and the Bending bearing capacity ratio of column to beam,concrete influence and seismic action.5.Under the same seismic action,the slab bottom reinforcement has little effect on the final failure mode of the structure,but influence the Damage degree of model,the maximum of the displacement-angle between floors,and the Bending bearing capacity ratio of column to beam,concrete influence and seismic action.