An investigation of the effects of socket joint flexibility in space structures

• Study of effects of socket joint deformability on the behavior of space structures
• Considering joint flexibility using joint biaxial test data in nonlinear analyses
• Significant redistribution of member axial forces was observed.
• Node deformability may alter the limit load behavior of space structures.

Connection of truss elements using socket joints is one of the more common practices in the construction of space structures. Although these hollow spherical joints may deform due to the applied loads, these deformations and the resulting effects on the member axial forces are usually ignored in the analysis and design. This work is an investigation of the effects of socket joint deformability on the behavior of space grid structures. Here, the load–deformation relationships obtained from a series of biaxial loading tests on actual socket joints have been used to represent their behavior in several finite-element analysis models. These models have been analyzed using a special-purpose substructure finite element analysis program developed to account for full geometric and material nonlinear behavior. It has been demonstrated that in many occasions, node deformability results in significant changes in internal member forces, overall structural stiffness, and the limit load behavior of the structure.