Contrast Analysis And Experimental Study Of Mechanical Behavior Of Confined Concrete

Confined concrete has been studied glorious history. It can effectively raise the bearing capacity and distortion ability of the concrete that restraint materials are used to force the concrete to be in three axial compressing states, which has already been widely approved by the academic circles and engineering circles, and applied to practice a lot. The normal confined concrete forms are the hoop-confined concrete, the FRP-confined concrete and the steel tube concrete. Different confining forms have different effects to the concrete. Therefore, it is of certain significance to carry on comparative analysis of mechanical behavior in different confined states, then seek a more scientific and rational confining plan and the best confining effect.The most common two forms are the hoop-confined concrete and the carbon fiber confined concrete. Taking the circular column and the square column, mechanical behaviors at axial compression between the hoop-confined concrete and the carbon fiber confined concrete are theoretical analyzed and compared, and its confined effect is presented. Firstly, the domestic and foreign typical experimental data of hoop-confined concrete and the carbon fiber confined concrete are collected, the circular column and square column are introduced, and mechanical behaviors and influence factors to confining effect of two confined concretes are summarized. Based on the analysis of a large number of existed testing data, through the regression analysis, the formulae of peak stress, peak strain and ultimate strain of two kind of confined concretes are established, and the contrastive analysis to its confining effect is carried on. The analysis results indicate that in circular column of axial compression confined concrete, the confinement effect changes with lateral confining stress, so the peak stress and the ultimate strain empirical formulas are established which take lateral confining stress as the parameter. The comparison results indicate that the carbon fiber confined concrete intensity is higher than hoop-confined concrete, but its distortion ability is not good as the hoop-confined concrete. In square column of axial compression confined concrete, the confining effect changes with hoop (carbon fiber) characteristic value, so the peak stress and the ultimate strain empirical formulas are established which take hoop (carbon fiber) characteristic value as the parameter. The comparison results show that the intensity and distortion ability of the hoop-confined concrete are better than the carbon fiber confined concrete as a whole.In addition, the influence of eccentricity and the volume ratio of hoop reinforcement and hoop arrangement on the behavior of confined concrete are studied based on the experiments of five compound spiral hoops confined concrete square column, under eccentric compression load. Meanwhile, the compressive ultimate strain and normal section bearing capacity computation of compound spiral hoops confined concrete square column are discussed under eccentric compression load.