Experimental study on bond-slip constitutive relationship between checkered c-shaped encased steel plate and concrete

In order to investigate the bond slip behavior of checkered c-shaped steel encased concrete composite beams with braces under load, a total of 12 checkered c-shaped steel encased concrete push-out specimens were tested based on the orthogonal design method, with the consideration of the bonding performance of steel and concrete affected by the height of the patterned steel plates, the concrete strength grade, the spacing of the brace, the width of the cross-section, and the flange form. Each specimen's relevant data, including the load-slip curves of the steel plate, the strain of the steel plate distributed along the longitudinal direction, and the characteristic bond strengths were all analyzed during the test. The experimental results show that the effect of increasing the pattern height is the most beneficial way to improve bond performance; the characteristic bond strength increases with the increase of the concrete strength and decreases with the increase of the sectional width-height ratio and brace spacing. Under the same conditions, the bonding of the specimens with the inward-bent flange outperforms that of the specimens with the outward-bent flange. With different effects being considered, the formula of characteristic bond strength is calculated by statistical regression and the average bond strength-loaded end-slip constitutive model is presented. Based on two introduced position functions, the local bond strength-relative slip constitutive model (τ-S) of different longitudinal positions are established. In general, the calculation results of the statistical regression formula are in good agreement with the experimental result, the average bond strength-loaded end-slip constitutive model fits in well with the test curves, and the τ-S model of different embedded positions satisfies the accuracy of the finite element analysis. © 2021