Push-out Experimental Study On Bond-slip Behaviours Of Checkered Steel Reinforced Concrete Composite Structure

In this paper,checkered steel reinforced concrete composite structure has been proposed based on previous research of bond-slip performance of normal steel reinforced concrete structure.Checkered steel plate was used to form the internal profile steel in this innovative composite structure,thus improving the bonding effect between steel and concrete and their cooperative performance by the checkered pattern.13 push-out specimens were fabricated with the emphasis on the influence of the height of checkered pattern,the position of pattern and transverse stirrup ratio on the bond-slip performance.Load-slip curves at the loading end and strain distribution curves along longitudinal length at different load levels of each specimen were obtained by push-out test.The experimental phenomena during the test were recorded and compared and the gained curves were analyzed.The test results showed that there were something in common of each specimen in the loading process,and the whole process can be divided into several stages,meanwhile the characteristic bond strength was defined and the distribution regularities of strain were summarized.Compared with the bond mechanism between the steel bar and the concrete in the reinforced concrete structure,the bond mechanism between checkered steel and concrete was analyzed.The influence of the above experimental factors on the characteristic bond strength was analyzed,and the calculation formulas of bond strength were obtained by statistical regression method.Piecewise curves were adopted to fit the average bond strength-slip curve((?)-Sl)at the loading end,and the fitting effect is good.According to the experimental data of load and slip at the loading end and the strain distribution along longitudinal length,the accurate slip and stress at different positions can be calculated,and the local bond-slip distribution curves(?-S)of each specimen can be plotted.The average bond strength-slip curve at the loading end can be served as reference curve,and by using the similarity and the introduced position function F(x)and G(x),the constitutive model of bond-slip which takes the position change into consideration can be obtained.