Flexural strength of a hybrid member for culverts consisting of mortar-filled steel tubes laterally connected by headed reinforcements

In this study, the temporary structural system for a trenchless method was developed. The developed structural system is a type of hybrid member consisting of mortar-filled steel tubes laterally connected by headed reinforcements. This lateral connection gives this system not only longitudinal but also lateral stiffness. Experimental studies were carried out to evaluate the flexural strength of the developed hybrid structural system. Behaviors of each component of this structural system, such as wing plate, connection plate and headed reinforcement were also studied. Experimental results showed that the developed system had superb flexural strength. The wing plate and connection plate had a positive effect on the flexural strength. Based on the experimental results, a simple design equation to evaluate the flexural strength of the developed structural system was suggested and compared with experimental results.