In tall and very tall reinforced concrete buildings, long term column shortening
due to creep and shrinkage affects the service life behavior of structural elements.
Creep-induced column shortening depends on the axial stress level in the column
cross sections and on its evolution in time. For this reason, the construction method
and phases must be taken into account as a key factor in defining the evolution of
the stresses. If approached in its comprehensive theoretical formulation, the
problem of column shortening in tall buildings exhibits high computational and
analytical complexity, because the different construction phases must be taken into
account, together with the loading history and the rheological non-homogeneity of
the different concrete elements at the times when loading is applied. Anyway, to
approach the general problem more easily, a few assumptions can be made allowing
to derive, by means of simplified calculations, the upper and lower boundaries of the
exact general analytical solution. In the present paper, at first, the problem of long
time column shortening will be discussed, then approximate solutions will be derived
and applied with reference to the case study of Palazzo Lombardia, at present the
tallest building in Italy.