From construct to type - the transformation of constituents in the development of trusses

When large span structures have been composed of single elements the incorporated structural mem- bers were direct responses to certain structural needs. Basing on the antique girder principle load bearing units have been developed consisting of struts and hanging columns. These units, relying on the early antique model, represent- ed the constituent parts of the overall structural entity and were arranged and adapted in respect to boundary condi- tions and formal requirements. The establishment of theory-based simplified truss types in form of overall models and a formal structural classification system saw the framework members step back behind the overall truss layout. Their role and function was then suppressed by the regime of the truss type not admitting any formal variation in or- der to satisfy the explicit postulation of a regular triangulated pattern. Apart from the deficiency of specific articula- tion the narrow understanding of trusses also limits the understanding and judgement of such structures.