Over 200 instrumented buildings in the Los Angeles area were shook by the Whittier 1987 (Magnitude 6.1) earthquake. The data recorded in these buildings contains a wealth of information and many valuable lessons for design engineers and code writers. Six steel frame buildings from five to twenty stories in height will be investigated under this project. Using very detailed analytical models and systems identification techniques the effects of the nonstructural elements and cladding on the response of those buildings will be ascertained. The nonlinear behavior, effective periods, effective damping, torsion and the effectiveness of current modeling practices are among those items that will be considered. This study would provide a careful evaluation of the current ability to model the response of steel buildings including the effects of real and accidental torsion and irregularities.