Figure 2.1-3. SPS Frame Girder Generation Sequence A portion of the exposed framework, including tension-element crossbracing is illustrated in Figure 2.1-5. The tribeam girder is used as an SPS longitudinal column, and the basic sheetmetal triangular element is used as column elements and as support elements for the columns. The column and support element material gages are determined by environmental loading or assembly loads, whichever are most critical. Pretensioned cross-bracing by small diameter composite or metallic "wires" stabilizes the square bays formed by the tribeam column element and column support element for a tribeam section. Likewise, the square panels formed by the major column tribeams and the major frame tribeams are cross-braced by pretensioned wires. The amount of pretension in the cross-bracing is such that slack wire brace conditions are avoided. A typical frame station structure for SPS is illustrated in Figure 2.1-6. Typical major intersections of the tribeam structure are shown to indicate the orientation of individual elements. Cross-brace wires are not shown for reasons of clarity. Each type of major structural intersection was thoroughly analyzed for member orientation versus simplicity of fabrication and assembly. The results of the study are shown on Figure 2.1-7. The least complex joint (shown upper left) results when the apex orientation of the sheet metal equilateral triangle is oriented 180° away from the apex of the tribeam truss. A simple bent tube fastened to the sheet metal element as shown permits the ends of a second sheet metal element, equipped with quick-connect fasteners to be located and secured by automatic machine means.
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