Experimental Research On Long RC Columns Strengthened With The Combination Of CFRP And Angle Steel

Retrofitting and strengthenin of RC structures by fiber-wrapping and steel-bonding have become very popular. A satisfactory conclusion of the short columns strengthened with a combination of the two materials is acquired for the merits of Carbon Fiber reinforced plastic (CFRP) include anti-corrosion, lightweight and low manpower for application, as well as high strength and high elastic modulus, and angle steel resisting compression direct and good ductility, but it not be seen in foreign and native literature that the long concrete columns are strengthened with the combination of the two materials.Basis on the analysis above, 12 columns are studied in the experiment whose slenderness ratio were 8,10,12,15. Columns slenderness ratio of 8 are under different strengthening conditions of unstrengthen, fiber-wrapping, steel-wrapping and wrapping with a combination of the two materials. Other columns strengthened with a combination of the two materials by changing the parameter of CFRP, angle steel and "stirrup" plate. Ultimate load and failure mode were measured and observed. This paper mainly study the effect of changing the parameter of CFRP, angle steel and "stirrup" plate on the ultimate load and other behavior of the columns strengthened with the combination of the two materials.The result of experiment shows that wrapping CFRP and angle steel can significantly improve the resisting load-compression capacity and ductility of member. It also indicate that the more angle steel wrapping the fuller the strengthen of CFRP has been used, and the effect of strengthening greatly depend on the slenderness ratio, the load drop greater than that of contrast if the slenderness ration is larger than a certain one. Compared to short columns strengthened with the combination of CFRP and angle steel ,the factor of stirrup spacing affects the load of long columns greater.Based on the theoretical analysis, an available analytical proceduce is presented . The load梔isplacement curves that calculated from the full-course analysis program are in accordance with the results of experimental.In the terms of the Reduced Modulus Theory, formulation of calculation is established. Based the analysis of formulation of calculating short RC columns strengthened with the combination of CFRP and angle steel, a method of analyses of stability of bearing capacity of long RC columns strengthened with the combination of CFRP and angle steel is presented, in which various parameters, such as slenderness ration, quantity of CFRP and angle steel, space of "stirrup"plate, have been considered, the calculating results of both methods cohere to the experimental results well.