| Grids, a lattice of inter-connected beams, are a common structural design. They are classified according to the number of beam orientations: bi-grids, tri-grids, quadri-grids, etcetera. The most common are orthogrids (0{dollar}spcirc{dollar}/90{dollar}spcirc{dollar}) and isogrids (0{dollar}spcirc{dollar}/{dollar}pm{dollar}60{dollar}spcirc{dollar}). They are found in many applications; including aircraft, aircraft engines, and satellites.; Grids are generally manufactured from isotropic materials, which wastes their three-dimensional strength and stiffness in this one-dimensional application of axially loaded beams. Unidirectional composites materials have one major strength and stiffness direction, ideal for application to grids which use multidirectional beam placement to enhance the unidirectional beam behavior. Unfortunately, all known grid manufacturing methods produce poor quality grids with root problems of: poor interlacing, no fiber tension, and no nodal fiber spread. New tooling is presented which resolves these problems through use of nodal guide pins. A second process is also described which uses disposable composites tooling which remains in the grid as reinforcement.; The second part of this dissertation applies the orthogrids as concrete reinforcement. An overview is given of the grid reinforced concrete concept. A numerical model is presented to describe grid reinforced concrete beams using lamination theory. Various representative laminate materials are positioned and interchanged to produce a smooth bending stress profile through-thickness. This refined model gives accurate load/deflection and load/strain information. Finally, general grid reinforced concrete structural behavior is demonstrated. Of interest is slab behavior in the yield and failure regions, particularly failure toughness and concrete containment capabilities. |
