Seismic behavior of passively controlled frames under structural uncertainties

This paper examines the sensitivity of optimal designs of seismic retrofitting by means viscous dampers attained using the nominal properties of the structure to uncertainty in structural properties. Viscous dampers are first optimally designed for the nominal properties of the retrofitted structures and given ensembles of records. The behavior of the retrofitted structures considering uncertainty in their properties is then tested using monte-carlo simulation. It is shown that the uncertainty leads to larger mean drifts then expected and that some designs are more sensitive than others. The physical reason for that is discussed and some rules as to what designs are expected to be more sensitive are given.