I tried to model a bridge pier with shell elements but the results I obtained with SAP2000 from a "QUAKE" load (UBC94) are different from the results obtained from the frame model;
i have to model a circulare shell with a hole inside ; the load is radial (compression) applied to the external circumference of the shell; if the load is 1t/sm the results which SAP calculates are different from the results calculated with formulas from elasticity theory.