| Since1965, when American engineers Fazlur Khan’s first design ofreinforced concrete frame tube structures-Chicago Dewitt-since thecompletion of Chestnut apartment building, tube structure because of its largelateral stiffness, dimensional whole effect is strong, can give full play to theadvantages of material properties and has been widely applied in the practicalengineering.However, an important force characteristics of cylinder structurestill exists obvious shear lag effect, which leads to the axial force value of Angleincreases, and between each column is only small axial force value of axial forcedistribution is very uneven, classic bending stress theory in material mechanics(y) no longer applies to composed of "dense column deep beam tubestructure.Shear lag effect in different degrees weakened the integrity of thestructure and material properties play a "discount", reduces the accuracy of thestructure design.Therefore, to strengthen the research of cylinder structure of theshear lag effect is fully understand the working performance of tubularconstruction, optimizing the structure design of the inevitable requirement, hasvery important engineering significance. Only is to improve the shear lag effect in order to assure efficient spaceoverall reliable stress and stiffness of structure scheme does not mean that theoverall seismic performance of the "security pass," a good structure schemeshould be at the same time satisfy the bearing capacity, stiffness, stability,ductility, and economic aspects of requirements.And the index of seismicperformance of structure schemes can be evaluated at least should comply withthe "small earthquakes not bad, is not repairable, strong earthquakes in the"three seismic fortification level requirements.In recent decades, computer technology and finite element technology alsoget great development.Based on the above background, on the basis of existing achievements, thispaper mainly completed the following work:1.using finite element software Midas/Gen, with a reinforced concrete tubein tube structure as the research object, analyses the outer frame tube of variouscommon flange and the shear lag effect of the web framework.Therefore, set upmany contrast model, explored the outer frame tube development regularity ofshear lag effect and shear lag effect of the causes, the introduction of thequantitative index of the severity of shear lag, the value of shear lag,individually analyzed the window dress beam section height (cross ratio),window dress beam section width, Angle section area, middle the columnsection area, plane shape frame drum, floor plane (outside) stiffness, ratio ofhigh to width box tube may influence factors on the shear lag effect, andsummarizes the corresponding development change rule.2.using the finite element software ABAQUS, a reinforced concrete core tube is analyzed emphatically the shear lag effect, mainly explores the core tubeof the influence factors of shear lag effect.For this, using ABAQUS softwaremodeling, discussed the material selection of constitutive model, the contactrelationship between processing, parameter setting, the choice of units, thedivision of grid, load and boundary conditions of the model, and verified thecore tube is at the bottom of the shear lag effect of the facts, to extract thecontrast model under the compression flange is the strain distribution of theshear wall cross section, summarizes the beam rigidity, axial compression ratio,horizontal force on the core tube the influence law of shear lag effect.3. using finite element software Midas/Gen, with a reinforced concretetube in tube structure as the research object, evaluation around "structureseismic performance".Level of the tube in tube structure under the earthquake ofstatic elastoplastic analysis (a PUSH-OVER), focus on analysis of the structureunder earthquake three level vertex lateral, interlayer displacement Angle andthe development of plastic hinge, to assess whether the model solution have towithstand level aseismic performance required. |
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