Study On Difference Of Internal Force Of Coupling Beam Under Different Calculation Models

Coupling beam for the seismic design of shear wall structure is not to be underestimated.Its existence is closely related to the energy dissipation and ductility of shear wall structures.So,the coupling beam is as a very important component of shear wall structure,which should be worth paying attention to research.In the analysis and design of the coupling beam,structure calculation model selection is the key,which determines the software calculation results of accuracy and reliability.Different calculation model for the same structure,the coupling beam internal force calculation results will be a big difference.In view of this situation,in this paper,through the difference of internal force of coupling beam comparison under different model,and analyzes the influence of different calculation models and selecting problem.Specific research contents are as follows:(1)Structure design software of coupling beam mainly adopt two kinds of model: shell element and bar element,the design industry in general practice is will span depth ratio less than 2.5 beams simulate according to the shell element;the span depth ratio greater than 5 beams to simulate according to the bar element;and the span depth ratio of coupling beam between them,using what kind of calculation model is no clear rules.So the PKPM software to two elements in the span to depth ratio in the range of 3 to 5 of coupling beams is studied,detailed analysis of two calculation model results differences,and referring to the results of MIDAS/Gen software.It can be concluded that the basic cycle of shell element model is smaller than that of the bar element model,and the two models are gradually increasing with the increase of the span ratio.The span depth ratio is equal to 5,the deviation of the two models is above 10%.The structural stiffness of the shell element model is larger than that of the rod element,and the change law of the stiffness is the same as that of the periodic variation.From the perspective of internal force,under the action of dead load,the shear force of the beam end,the midspan moment of the coupling beam and moment at beam end of the coupling beam,are smaller than those of the bar element model.Under the earthquake load and wind load,when the span depth ratio is less than 4,the internal force of coupling beam shell element model is smaller than bar element model;and when the span depth ratio greater than 4,the internal force of coupling beam shell element model is larger than bar element model.Through the calculation results with the MIDAS / Gen that,when the span depth ratio is less than 4,the shell element model to simulate coupling beams is more accurate;when the span depth ratio greater than 4 by bar element model to simulate coupling beams is more accurate.(2)The effects of the floorslab on the internal force of coupling beam of frame shear wall structure were analyzed,the finite element analysis by MIDAS/Gen software using,and the results were compared with PKPM software calculation.On the one hand is the impact on the internal force of beams with changes of slab thickness;on the other hand is the beam section height variation,floor on the influence degree of change.The results show that both ends of the beams are shear wall,floor has a great influence on the internal force of the beams,can not ignore the influence of floor,and with the increase of thickness,the influence degree is increased;and one end of the beam to column,one end is shear wall,effect of floorslab on the beam internal force is very small,can ignore the influence of floor.Influence degrees on the internal force of coupling beam for floorslab deepen with the decrease of the height of the beam section.Other conditions in the same situation,the higher the coupling beam,the smaller the floor impact.