Erectable building structure junction element

Claim 1

A junction element for interconnecting a plurality of expandable trusses forming a portion of an erectable framework for a building structure, each expandable truss comprised of a scissor-type mechanical strut having at least one pair of linkages pivotally connected at a point between their ends, said junction element comprising: a plurality of substantially axially aligned hubs positioned along a rod, the number of said hubs grouped into sets of three; a plurality of lugs fastened around the periphery of each hub; means for pivotally fastening the pivot point of the paired scissors-type linkage at the end of one expandable strut to one lug of the central hub of a group of hubs; a first and second arm pivotally fastened respectively at one end to a lug of the first and third hub of the group, the other ends of the arms being each pivotally fastened to one linkage of the scissor-type mechanical truss at a position between the pivot point of the linkage and the pivot connection to the next linkage; the relative position of the first and third hubs to the central hub of one junction element determining the distance between the common ends of the linkages of the scissors-type struts and thus determining the length of said expandable trusses, said central hub of each group being fastened to said rod while the first and third hubs are slidably fastened thereto.