Pull-out behavior of metallic strips with structured surface elements for use in reinforced soil bridge abutments

• The pull-out behavior of conventional smooth and structured rough metallic strips was experimentally evaluated. • Apparatus was developed to investigate the role of surface design of metallic strips in reinforced soil bridge abutments. • Pull-out tests conducted on conventional smooth and three structured rough surfaces in sand specimens. • Metallic strips with structured elements mobilized larger pull-out (shear) resistance against conventional smooth strips. • The Pull-out capacity of metallic strips could be enhanced using structured elements. In this paper, metallic strips with structured surface elements of different shapes were introduced. Experimental tests performed on metallic strips sheared against poorly-graded sand have shown the key role of surface texture on the pullout (shear) resistance at the interface between sand and strip surface. Four metallic strips: strip I – smooth (no elements), strip II – rough (triangle-like elements), strip III – rough (ribbed elements), and strip IV – rough (circle-like elements) were examined in a pullout test apparatus under different levels of confinement stress. The results of the pullout tests indicate that surfaces with structured elements mobilized a significantly high pullout resistance when compared to conventional smooth (untextured) baseline strip. It was observed that pullout resistance increased with confining stress (i.e., confinement level), strip IV mobilized the largest resistance followed by strip II then strip III at the same test conditions. The increase in mobilized resistance is attributed to the development of passive soil wedges at the face of structured elements under confinement, which leads to additional passive resistance. The pullout resistance of strip IV exhibited an increase up to 208 % of the baseline resistance of untextured strip. These findings could be beneficial for enhancing the pullout capacity of metallic strips in reinforced soil bridge abutments.