Novel Joint for Assembly of All-Composite Space Truss Structures: Conceptual Design and Preliminary Study

Abstract

A space truss is formed of interconnected structural components that transfer loads axially. Pultruded glass-fiber reinforced polymer (GFRP) composites exhibit their best material strength in the axial (pultrusion) direction, and their inherent lack of material stiffness can be compensated by the structural stiffness achieved by space configuration. A novel connector made of pultruded GFRP profiles is proposed in this paper to join diagonal and chord members and to form all-composite free-form space trusses. The proposed truss unit was assembled and tested statically, and the load-displacement responses were recorded. The final collapse of the structural unit evidenced a pull-out shear failure mode in the bolt connections, and the ultimate load can therefore be well predicted by this mechanism. A detailed finite element (FE) analysis considering the interaction between the bolts and FRP profiles was conducted for the structural unit to investigate the effects of pretension force of bolted connections and the stress concentration at the joint region. A simplified FE approach was used to demonstrate one- and two-dimensional space trusses with satisfactory structural stiffnesses.