Nonlinear finite element buckling analysis of rectangular reinforced concrete long columns confined with carbon fiber reinforced plastic sheets under small eccentric compression

Owing to some problems in their stability of existent building structures, the general software ANSYS is adopted to establish the finite element solid models of rectangular reinforced concrete long columns confined with CFRP sheets under eccentric compression and used to analyze the influence of CFRP sheets to these structural buckling loads. Height of columns, layers of CFRP sheets, concrete grade, longitudinal rebar diameter, stirrup diameter, stirrup spacing and eccentric distance are some factors considered. Based on the nonlinear finite element buckling analysis of these columns, some major conclusions are summarized as follows: (1) The enhanced level of buckling load is descending with the increasing columns' height and increasing with the increasing layers and eccentric distance; (2) The buckling load increment is independent of concrete grade, longitudinal rebar diameter, stirrup diameter and stirrup spacing; (3) The improvement is comparatively obvious to use CFRP sheets to strengthen the structure when its stability is poor. Influences of CFRP sheets to rectangular reinforced concrete long columns can be found by analyzing the stability of these columns, and the analysis results are available for the strengthening of some concrete structures in practice