Stressed Skin Design Versus Braced Frame Design Through Efficient Numerical Modelling

Steel frame structures are traditionally designed with bracings that stabilize the main bearing structure.Another approach is to apply the “stressed skin design” where the cladding structure takes the role of the bracings. In this research, the two approaches were analysed and compared in order to find advantages of any. A typical steel frame structure was chosen, and for the cladding, trapezoidal sheet metal was selected. Optional bracings were also considered. All static analyses were done using the finite element method (FEM) and ANSYS Workbench software, including geometric and material nonlinearity. The structure was loaded perpendicularly to its gable, thus simulating typical wind action. Number of fasteners connecting the cladding and the frame is crucial for the “stressed skin design” concept, so this parameter was varied through the analysis. The stiffness of the fastener devices was simulated in two ways: (1) simplified, by merging of the adjacent nodes of the cladding and the frame, and (2) more accurately, using special joint elements with prescribed stiffness. Obtained stresses and deformations were compared, and they showed obvious advantages of the “stressed skin design” over braced frame design, both in structural, and in economical aspect. In addition, important practical guidelines for the “stressed skin design” using FEM were proposed.