Structural analysis of a braced dome and a torus grid by means of non-coplanar trihedral

For analysis of space grids composed of straight bars and frictionless spherical joints, several methods have been developed. In our method presented here, bars of a space grid are grouped in a way that 3 non-coplanar bars are associated to each node. The configuration determined by these 3 bars is called a trihedron. Trihedra are selected to form a statically determinate structure associated to the original statically indeterminate one. Remaining bars not incorporated in the system of trihedra are redundant bars. The advantage of the triherdon composition is present at tracing the change of state of the structure subjected to increasing load. If bars in trihedra buckle, they get out the trihedron system, and they should be replaced by redundant bars. This operation modifies the basic statically determinate structure, and the inverse of its equilibrium matrix can be obtained by simple modification of the previous one, that speeds up the process. This technique has been used for space grids above a rectangular base. In this paper we will extend it to braced domes and torus grids.

• INTRODUCTION

• AUTOMATIC GENERATION OF TRIHEDRA

• INVESTIGATION OF EQUILIBRIUM

• CHANGE OF STATE

• CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES