Laboratory large-scale pullout investigation of the twisted steel strip reinforcement system

Conducting pullout tests has been considered a common approach to assessing the interfacial behaviour between inextensible reinforcement systems and soils. This study evaluated the pullout mechanism of an inextensible reinforcement system called a twisted steel strip by way of large-scale pullout tests. Adding multiple twisted bearing members in the anchorage zone to a conventional steel strip can create this cost-effective reinforcement without requiring any particular skill. The twisted steel strip was made with different bearing areas. According to the pullout tests conducted, the failure displacement of the twisted steel strip systems was about four times higher than the pertinent displacement of the conventional steel strip systems. Compared with the conventional steel strip system, pullout resistance factors were significantly enhanced in the twisted steel strips (i.e. improving soil reinforcement interaction between 3·3 and 4·8 (over the range investigated)). Notably, the weight of some twisted steel strips was significantly reduced compared with the conventional reinforcement system, although their pullout resistance factors significantly increased. Last but not least, the interference among the bearing twisted elements could affect the developed pullout resistance factor.