A modified Timoshenko Beam Model for fast estimation of dynamic properties in buildings with vertical irregularity

A new fast track method for determining the dynamic properties of buildings, including mode shapes, modal periods, participation factors, and effective modal masses is introduced in this article. The study is motivated by the need for reliable independent verification of results obtained from finite element analysis of building structures, which are typically conducted using commercial software based on modal superposition principles. The Timoshenko Beam Model is used to bypass memory-intensive finite element modelling while leveraging classical theories to account for wall-frame interactions and coupling of structural walls by crossbeams. An important original contribution of the study is a modification to the Timoshenko Beam Model for accommodating vertical irregular features such as setbacks and podiums. Accuracy of the modelling was validated against experimental measurements taken from a full-scale E-Defense building along with results from numerical simulations of nine finite element models of buildings of different floor plans and heights. The predicted dynamic properties were consistent with full-building analyses in SpaceGass, with deviations within 10%. The fast-track methodology can be used to expedite conceptual design aimed at optimisation, or to predict the potential performance of existing buildings in a projected earthquake scenario without the need to salvage, nor reconstruct, finite element models. • Modified Timoshenko Beam Model for buildings with vertical irregularities • Fast-track method to estimate dynamic properties of buildings • Accurate dynamic properties without detailed finite element modelling • Validated against full-scale E-Defense tests and numerical simulations • Useful for early-stage seismic design and rapid structural assessments