Shaping of Architecturally Exposed Steel Structures

Architecturally Exposed Structural Steel (AESS) is steel that must be designed to be structurally sufficient to support the primary needs of the structure and -at the same time - remains exposed to view, being a significant part of architectural language of the building [4, 6]. The quality requirements of AESS typically exceeds the requirements of Standard Structural Steel (SSS), what increases the time and costs of the design and execution of AESS. Currently used classification of AESS distinguishes 5 categories of execution quality. This categorization has a hierarchical structure, each higher category of structure execution contains all the properties of lower category. The basis of presented classification is the degree of human visual perception of the structure. It is mainly related to the distance of the potential observer from the structure, which allows in varying degrees to see the details of structure execution. Joints and connections are the main means of architectonic expression in architecturally exposed steel structures. The principles of joints and connections shaping in AESS are the same as for SSS but additionally some requirements to the expected aesthetic are formulated. This additional requirements cause that AESS can be significantly (even a few hundred percent) more expensive than SSS with exactly the same functionality and durability. However, PN-EN 1090-2 [7] gives no provisions about AESS executions, which may impede mutual understanding between architect, structural engineer, contractor and investor.