Member capacity of columns with semi-rigid end conditions in Oktalok spaceframes

The Oktalok nodal connection system is an aesthetic and efficient system. I t has been widely used throughout Australia. The paper will briefly introdu ce the concept and application of the Oktalok nodal system. The existing de sign method is based on the assumption that the joints are pin-ended, i.e., the rotational stiffness of the joints is zero. However the ultimate capac ity of the frame may increase significantly depending on the rotational sti ffness of the joints. Stiffness tests and finite element simulations were c arried out to determine the rotational stiffness of the Oktalok joints. Col umn buckling tests and nonlinear finite element analyses were performed to determine the member capacity of columns with semirigid end conditions. A s imple formulae for the effective length factor of column buckling is derive d based on the above experimental and theoretical investigations.