Performance Of Reinforced Concrete Columns Considered Axial-shear-flexure-interaction Approach

Columns are key components in reinforced concrete (RC) structures resistingvertical and lateral loads. They are usually subjected to the combined loads of axial,shear and flexure. In the current structural design methodology, only the bearingcapacity should be satisfied, however, in performance-based design methodology,displacement-based concept should also be taken into consideration. Therefore, it isimperative to choose an appropriate method to assess the load-displacementperformance of the structure. This thesis improves the axial-shear-flexure interaction(ASFI) approach, uses the modified method with OpenSees, and finally, makes aexploration of this evaluation method.Calculation principles of the fiber model, modified compression field theory(MCFT) and ASFI are compared. Results show that ASFI can make a reasonableassessment for both flexure behavior and shear behavior, but its existed procedure isunstable and it is difficult to converge. Therefore, the calculation procedure ismodified by reducing the loop variables, unifying parameters, reselecting theconstitutive relations of concrete and steel bars. Using this new procedure, an existingexample is recalculated and five reinforced concrete columns are analyzed. Resultsshow that the modified procedure is reasonable. The calculated load-displacementcurves of five columns agree with the experimental curves very well.RC columns are calculated using OpenSees and its results are compared with testdata. Results show that for a flexure failure column, OpenSees simulate theload-displacement curves well, but for a shear failure one, it cannot agree with testresult of capacity, deformation, ductility, and etc, because of its lacking considerationof the impact of shear behavior. This thesis adds a trilinear model, which is aequivalent of shear–shear deformation curve calculated by ASFI, into OpenSeesprocedure. Results show that OpenSees with this model can simulate theload-displacement curves of columns occuring shear failure. By defining thereloading and unloading parameters of the hysteretic material, the trend of thecalculated hysteretic curves is consistent with test curves.