Research On Deformation Limits Of RC Beams, Columns And Shear Walls Based On Material Strain

The concept of performance-based design is to provide the owners and engineers theability to select a desired level of structural performance for several different levels of groundmotion. The most important things for the estimation of the structural performance level arethe structural analysis technique and adequate selection of damage parameters. An importantstep towards reaching these goals is to define an adequate measure of building performancewith global and local response parameters. In the performance-based design, overall buildingperformance during an earthquake is measured by the inter-story drift. For example, on thebasis of "three seismic fortification levels and two-stage design methods" proposed in oldCodes, the performance-based seismic design idea was preliminarily introduced in the currentSeismic Design Code"(GB50011-2010).4performance objectives,3seismic levels,7performance levels were carried out, including a detailed definition of macroscopic damagedegree, combination of internal forces, the strength value of the material, and inter-story driftcorresponding to each performance level. But the local components deformation parameterswere not mentioned. The ductile demands of components are ensured by correspondingstructural measures. The quantitative criteria of the deformation properties for structuralcomponents are not given in current Chinese codes. Therefore, the performance states ofstructural components under earthquake cannot be evaluated properly. This paper mainlystudies the seismic performance and the deformation performance index limits of5limitstates. The main contents include following aspects:(1) Gather a patch of experimental data of RC beams, columns and shear walls. Thenusing ABAQUS to simulate the specimens. The damage-plasticity model of concrete and theideal elastoplastic model of reinforcement are adopted. The simulated load-displacementcurve and the failure modes are in good agreement with the experimental results, whichindicates that in conditions of reasonable material constitution and FEA parameters,simulation of the stress state and failure mode of RC components is feasible.(2) With reference to the latest research at home and abroad, this paper considers the seismic performance of structural components, crack width, material strain and repairmethods to classify the performance state of RC components into5performance states: intact,slightly broken, light medium broken, medium broken, severe broken. Thus a new type ofcomponent performance index based on material strain is carried out, which quantifies thedeformation ability of components under certain structural conditions.(3) Discuss the classification of the failure modes of RC components. Collecting andanalyze the experimental data of50beams, bring up to use shear-span ratio, flexural shearratio, nominal shear stress as parameters to classify the failure modes of RC beams; collectthe experimental data of111columns from references, analyze the relationship betweenfactors as flexural shear ratio, shear span ratio, stirrup spacing and the failure modes of RCcolumns, using Fisher’s and Bayesian discriminants, bring up to use shear-span ratio andflexural shear ratio as parameters to classify the failure modes of RC columns, and providedetailed classification.(4) On the basis of verification of the rationality and reliability of FEA method, bychanging parameters as shear span ratio, stirrup ratio, reinforcement ratio, K value, relativeheight of compression zone and nominal shear stress etc,468RC beam specimens aredesigned, which had been numerically simulated by ABAQUS to analyze the influence of theabove parameters on the elastoplastic deformation ability of RC beams. Then deformationlimit values of RC beams in different failure state are given.(5) By changing shear span ratio, stirrup ratio, reinforcement ratio, flexural shear ratioand design value of axial compression etc,380RC column specimens are designed andnumerically simulated by ABAQUS. By the correlation analysis of Spearman, therelationships of the above parameters and the5performance states mentioned above arecarried out. Then deformation limit values of RC column in different failure state are given.And the corresponding calculation equations have been given by stepwise regression analysis,which have been examined to possess high reliability according to the correlation coefficient.(6) By changing aspect ratio, design value of reinforcement ratio, actual reinforcementflexural shear ratio, the stirrup characteristic value of concealed columns,524RC shear wall specimens are designed and numerically simulated by ABAQUS. By the correlation analysisof Spearman, the relationships of the above parameters and the5performance statesmentioned above are carried out. And the corresponding calculation equations have beengiven by stepwise regression analysis, which have been examined to possess high reliabilityaccording to the correlation coefficient.This paper carries out the deformation performance index limits of beams, columns andshear walls on component level. Compensate for the inadequacy of the insufficientquantitative description of bearing capacity and deformation state of components in theexisting Seismic Design Code"(GB50011-2010). Achieve the transfer from ensuring thedeformation demands mainly by relative structural conditions to the quantitative measurementof the deformation demands. This provide a theoretical basis of performance-based seismicdesign and evaluation on component level.