The SEO space grid constructional system is based on bars and joints that are united together by means of cones and bolts.
The joint consists of a one-piece forged node having a given number of threaded holes according to geometry and to the node position in space, the number of holes being restricted only by the minimum angle determined by adjacent bars interference.
The bars are made of structural steel (whose technical data are indicated hereafter). Two trunco-conical elements (cones) specially designed to place bolts are welded at both ends of each bar.
These bolts are two-start type: one of them is hexagonal and the other circular screwed. Over the hexagonal part a separative cap is placed to fix the distance between nodes and bars. The screwed part is inserted into the node.
The node-bar union is achieved actuating with a spanner on the caps.
Thanks to this method, the torques required are achieved and it can be assured that there has been no slackening at the opposite end of the bar.
The union system makes it possible to change any bar of the frame, even in its final position, by unscrewing the caps. This causes the bolt to retract inside the bar far enough to permit the removal of the bar and its replacement if necessary.
Owing to this design, a system of great axial stiffness is achieved, that minimizes the performance discontinuity produced in bolted unions, thanks to the bolt and node dimensioning which ensures a similar pull and compression behaviour. As a result, structure design can be realized within the linear elastic field within a highly reliable pattern.