Experiment And Research Of Reinforced Concrete Eccentrically Loaded Column Bonded With CFRP

In recent years, considerable attention has been focused on the use of carbon fiber-reinforced polymer/plastic (CFRP) for structural rehabilitation and strengthening. Because of many advantages such as high-strength and stiffness-weight ratio, a high degree of chemical inertness, widely applied, convenient construction, CFRP has been popular and praised highly. Necessarily, this paper is engaged to research the behavior of reinforced concrete eccentrically loaded column strengthened with CFRP.Based on the tests of 23 RC columns, the strength capacity, stiffness of the columns strengthened with CFRP have been researched; ductility, the distribution of cracks and failure modes of retrofitted columns have been analyzed.This paper investigated the degree of CFRP function on different eccentricities, and discussed the influence to strengthening effect on the basis of different strengthening mode and concrete strength. Experimental results indicate that the strength capacity, stiffness of columns have a certain extent increasing as a result of the action of CFRP, repaired columns' cracks show little and distribute uniformly. The ultimate strength and ductility of column improved due to the transverse strengthening with CFRP and display more distinct benefit when strengthened by the combined action of the longitudinal and the transverse straps of CFRP. In addition, Many parameters including anchorage length of CFRP, thickness of CFRP are considered on the effects of CFRP on strength, and failure modes of columns.Based on plane section assumption, this paper presents the methods of calculating the ultimate strength of the columns strengthened with CFRP, and makes a simplification of the methods. A FORTRAN program on nonlinear method is presented to numerically analyze the characteristics of large eccentrically loaded columns strengthened by longitudinal straps of CFRP, calculating results compare well with experimental data.Influential factors and behavior of concrete prism confined with CFRP have been studied, Based on the effective confined concrete area with CFRP, the peak stress and peak strain of CFRP-confined concrete prism depend on , and calculating equation is put forward. On the basis of the stress-strain relationship of steel stirrup-confinedconcrete, a certain stress-stain relationship model of CFRP-confined concrete prism is presented.Behaviors of reinforced concrete columns confined with CFRP have been researched. Based on the progressed stress-strain relation of CFRP-confined concrete, a calculating moment-curvature relationship program is presented; the moment-curvature relationship of CFRP-confined rectangular RC columns was nonlinearly analyzed. The effect of parameters including axial compression ratio, layers of CFRP on the ultimate strength, curvature ductility is discussed. A load-displacement full-process analyzing program of CFRP-confined RC eccentrically loaded columns is given. The computed results of load-displacement coincide with test results.Neglecting the influence of concrete stress-path, relative program is presented to make full-process analysis on compression-flexure members confined with CFRP in the compression zone, a key research is to analyze the effect of some parameters including axial compression ratio, thickness of CFRP, concrete strength on strength capacity and displacement ductility of reinforced compression-flexure members. The theoretical values well agree with test results.