Analysis and modelling of the seismic behaviour of high ... - Ingegneria

5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES
wall stiffness modifies the re-distribution of the internal member actions going from
the top storey to the ground level.
(a) (b)
Figure 5.6. Building structures modelled by the SAP2000 program: a) structure with the
masonry infill present in each floor; b) Pilotis Case - structure without the masonry infill
at the first floor
For the assumed load combination, Static, Seismic A and Seismic B, all comes
down to the design of one column (taken with rectangular geometry) which
complies with the worst case of forces among those acting on the considered
elements (n° 260, n° 302 and n° 309) for the load combination under exam.
Nonetheless, as the heaviest forces to be withdrawn arise from the seismic
combination A (Low ductility and behaviour factor q = 1,5), the column width and
depth were fixed in this case varying only the number and distribution of the
reinforcing bars in the others.
In order to have an approximate idea of the re-distribution of internal forces on the
structural members once loaded, some diagrams obtained from SAP2000 and
representing respectively the deformed shape, axial force and bending moment are
shown below.
Moreover, on the basis of the results obtained by applying the forces defined
according to the load combinations A and B to the structure and considering the
seismic wave load acting alternatively in the two directions of the 3D frame, it was
possible to verify the values of the inter-storey drift coefficients. The value of the
inter-storey drift is dr = q ⋅ de
where de is the displacement of the considered point
in the structural system as determined by a linear analysis based on the design
response spectrum. The value of the inter-storey drift sensitivity coefficient is equal
to:
185