How are stresses for the shell elements calculated? Can I compare the calculated stresses directly to the allowable stress of shell material?
Yes, the shell stresses obtained from SAP2000 can be directly compared to the allowable stress of the material. You can display the shell stresses by right-button click on the shell elements when the stresses are displayed or by reviewing the stresses in a tabular format via “Display > Show Tables > ANALYSIS RESULTS > Element Output > Area Output > Table: Element Stresses – Area Shells”. The stresses are calculated as a product of stress-strain constitutive matrix and strain vector which is obtained from joint displacements. The procedure is not based on a simple formula, but rather on several techniques described in the following references cited in the [CSI Analysis Reference Manual]: • A. Ibrahimbegovic and E. L. Wilson: “A Unified Formulation for Triangular and Quadrilateral Flat Shell Finite Elements with Six Nodal Degrees of Freedom,” Communications in Applied Numerical Methods, Vol. 7, pp. 1–9, 1991 • R. L. Taylor and J. C. Simo: “Bending and Membrane Elements for Analysis of T
