Una struttura intelaiata a due piani a campata singola è soggetta a carichi sismici. The modulus of elasticity and cross‑section of the frame beams are much larger than those of the columns, so the beams can be considered rigid. The elastic response spectrum is given by the standard SIA 261/1:2003. Neglecting self-weight and assuming the lumped masses are at the floor levels, determine the natural frequencies of the structure. For each frequency obtained, specify the standardized displacements of the floors as well as equivalent forces generated using the elastic response spectrum according to the standard SIA 261/1.2003.
Quattro colonne sono fissate nella parte inferiore e collegate da un blocco rigido nella parte superiore. The block is loaded by pressure and modeled by an elastic material with a high modulus of elasticity. The outer columns are modeled by linear elastic material and the inner columns by a stress-strain diagram with decaying dependence. Assuming only the small deformation theory and neglecting the structure's self-weight, determine its maximum deflection.
Determina l'inflessione massima di quattro colonne fissate nella parte inferiore e collegate da un blocco rigido nella parte superiore. The block is loaded by pressure and modeled by an elastic material with a high modulus of elasticity. The outer columns are modeled as orthotropic elastic material, and the inner columns as orthotropic elastic-plastic material with the same elastic parameters as the outer columns and plasticity properties defined according to the Tsai-Wu plasticity theory.